JP2011002522A - Optical modulation element and spatial light modulator using the same, display, holography device, hologram-recording device, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical modulation element, with the degree of optical modulation enhanced by a spin injection magnetization reversal element of high definition and high-speed response.SOLUTION: In the optical modulation element 5, the magnetization direction of a magnetization reversal layer 53 is reversed by current from electrodes 2 and 3 connected to upper and lower parts of the optical modulation element 5, respectively and thereby an incident light is emitted so that the direction of the light is changed and the light is rotated. A pinned magnetic layer 51 and the magnetization reversal layer 53 layered on the same via an intermediate layer 52 are formed as Co/Pd multilayer films, formed by alternately layering Pd films and Co films to have intensive perpendicular magnetic anisotropy and the degree of optical modulation is enhanced by polar Kerr effect and by the fact that the magnetization reversal layer 53 is constituted of the Co/Pd multilayer film having a large Kerr rotation angle. In the magnetization reversal layer 53, the film thickness tf of the Co film is made thicker than the film thickness tp of the Co film of the magnetization pinned layer 51 or the film thickness tf of the Pd film is made smaller than the film thickness tp of the Pd film of the pinned magnetic layer 51; and thereby the coercive force Hcf of the magnetization reversal layer is made lower than coercive force Hcp of the magnetization pinned layer 51 and a magnetization reversal current is suppressed.

Description

  The present invention relates to a spatial light modulator that spatially modulates the phase and amplitude of light by magneto-optic effect and emits the incident light, a light modulation element used therefor, and a display device using the spatial light modulator, The present invention relates to a holography device, a hologram recording device, and an imaging device.

  A spatial light modulator uses an optical element (light modulation element) as a pixel and arranges it in a two-dimensional array to spatially modulate the phase and amplitude of light. Widely used in fields such as equipment, display technology, and recording technology. In addition, since optical information can be processed in two dimensions in parallel, its application to optical information processing technology is also being studied. As a spatial light modulator, liquid crystal has been conventionally used and widely used as a display device, but for holography and optical information processing, since response speed and high definition of pixels are insufficient, in recent years, Development of a magneto-optical spatial light modulator using a magneto-optical material that is expected to be capable of high-speed processing and pixel miniaturization (for example, Patent Documents 1 to 3).

  In a magneto-optical spatial light modulator (hereinafter referred to as a spatial light modulator), when light incident on a magneto-optical material, that is, a magnetic material is transmitted or reflected, the direction of polarization is changed (rotation) and emitted. The effect (Kerr effect in the case of reflection) is used. That is, assuming that the magnetization direction of the light modulation element in the selected pixel (selected pixel) is different from the magnetization direction of the light modulation element in the other pixel (non-selected pixel), the light emitted from the selected pixel and the non-selected pixel The emitted light causes a difference in the rotation angle (rotation angle) of the polarized light. As a method of changing the magnetization direction of the light modulation element, in addition to a method of applying a magnetic field to the light modulation element (Patent Documents 1 and 2), there is a method of injecting spin into the light modulation element (Patent Document 3) in recent years. .

  In order to apply a magnetic field to the light modulation element for each pixel, in Patent Documents 1 and 2, current is supplied to the periphery of the light modulation element by extending electrode wiring around the periphery of each pixel. Further, by arranging the wiring between the pixels in this way, incident light and outgoing light to the light modulation element are not blocked by the metal wiring. On the other hand, when spin is injected, a spin injection magnetization reversal element (Non-Patent Document 1) such as a CPP-GMR (Current Perpendicular to the Plane MagnetoResistance) element is used as a light modulation element. A pair of electrodes are connected to the top and bottom of the light modulation element to supply current perpendicular to the film surface. In addition, since such a light modulation element (spin injection magnetization reversal element) is once supplied with a current having a predetermined magnitude and direction, the magnetization direction is maintained until a reverse current is supplied. As in Patent Document 3, by arranging strip-like electrodes vertically and horizontally on the upper side and the lower side, respectively, a current that changes the magnetization direction can be supplied to the light modulation element for each pixel. . Further, in this way, in the magneto-optic spatial light modulator by spin injection, since the electrodes are arranged above and below the light modulation element, a transparent electrode material such as indium zinc oxide (IZO) is used. The light is transmitted through the electrode and is incident on the light modulation element.

  In addition, the imaging device (solid-state imaging device) uses imaging elements as pixels and arranges them in a two-dimensional array like the spatial light modulator. Conventionally, CCD (Charge Coupled Device), CMOS, etc. are used as this image sensor, but in order to obtain a high-definition image, a magneto-optical material is used like a spatial light modulator. The light modulation element that has been used can be applied.

Japanese Patent Laying-Open No. 2005-70101 (Claim 2, FIG. 5) JP 2005-221841 A (Claim 1, FIG. 6) JP 2008-145748 A (Claim 7, FIG. 4)

K. Aoshima et. Al, “Spin transfer switching in current-perpendicular-to-plane spin valve observed by magneto-optical Kerr effect using visible light”, Appl. Phys. Lett. 91, 052507 (2007)

  The spatial light modulators described in Patent Documents 1 and 2 have a structure in which the XY drive lines are arranged along the outer periphery of the pixel, so that it is difficult to form a fine pixel of several μm or less. In addition, if the pixels are further miniaturized in order to use a combined magnetic field by current, there is a problem that crosstalk to adjacent pixels increases.

  On the other hand, since the spatial light modulator described in Patent Document 3 supplies current perpendicularly to the film surface of the light modulation element, it can cope with pixel miniaturization. However, since the layer (magnetization reversal layer) in which the magnetization direction changes in the spin injection magnetization reversal element is generally limited to tens of nanometers or less, if the spin injection magnetization reversal element is a light modulation element, the change in polarization direction Is extremely small (Non-patent Document 1), and there is room for improvement in the extraction efficiency of the polarized light from the selected pixel, that is, the pixel selectivity.

  The present invention was devised in view of the above-mentioned problems, and is a light modulation element with an improved degree of light modulation by a spin-injection magnetization reversal element capable of high-definition and high-speed response, and spatial light with improved pixel selectivity. It is an object of the present invention to provide a modulator, an imaging device, and a display device, a holography device, and a hologram recording device using the spatial light modulator.

  In order to solve the above-mentioned problems, the present inventors have found that the Co / Pd multilayer film has a strong magnetic anisotropy perpendicular to the film surface, and has a large optical rotation angle due to the polar Kerr effect and a small operation variation. This has been applied to a spin-injection magnetization reversal element.

  That is, the light modulation element according to the present invention is formed by laminating a magnetization fixed layer, an intermediate layer, and a magnetization reversal layer having a coercive force smaller than the coercive force of the magnetization fixed layer in this order. Is a light modulation element that changes the magnetization direction of the magnetization switching layer and emits the incident light by changing the polarization direction of the magnetization switching layer, and at least one of the magnetization fixed layer and the magnetization switching layer Is a multilayer film in which Pd films and Co films are alternately stacked.

  With this configuration, the light modulation element has a perpendicular magnetic anisotropy and at least one of the magnetization fixed layer and the magnetization inversion layer has a perpendicular magnetic anisotropy and has a small operation variation. The light can be incident parallel to the magnetization direction, and the polarization direction of the emitted light can be greatly changed. Furthermore, the process resistance is good, and the deterioration of the magnetic characteristics during manufacturing is small. Further, by making the coercive force of the magnetization switching layer smaller than the coercivity of the magnetization fixed layer, the magnetization of the magnetization switching layer can be reversed by supplying current.

  Further, in the light modulation element according to the present invention, it is preferable that both the magnetization fixed layer and the magnetization switching layer are multilayer films in which Pd films and Co films are alternately laminated. At this time, in the magnetization switching layer, the thickness of one layer of the Co film is made thicker than the Co film of the magnetization fixed layer, or the thickness of one layer of the Pd film is made thinner than the Pd film of the magnetization fixed layer.

  With this configuration, since both the magnetization fixed layer and the magnetization reversal layer are multilayer films, the light modulation element has a stronger perpendicular magnetic anisotropy and a small variation in operation, and further has process resistance. It becomes a good light modulation element. By controlling the film thicknesses of the Pd film and the Co film, the coercivity of the magnetization switching layer can be easily made smaller than the coercivity of the magnetization fixed layer. Further, by forming the magnetization switching layer as a multilayer film, the Kerr rotation angle or the Faraday rotation angle can be increased to improve the light modulation degree of the light modulation element.

  In the light modulation element according to the present invention, one of the magnetization fixed layer and the magnetization inversion layer is a multilayer film in which Pd films and Co films are alternately stacked, and the other is a transition metal selected from Fe, Co, and Ni. And a rare earth metal alloy selected from Sm, Eu, Gd, and Tb.

  With this configuration, the light modulation element uses one of the magnetization fixed layer or the magnetization reversal layer as an alloy of a transition metal and a rare earth metal to lower the saturation magnetization, and in the magnetization fixed layer, the magnetization is positive and negative. Stable operation can be obtained by setting the currents to be reversed to substantially the same magnitude, and the magnetization can be reversed at a lower current in the magnetization switching layer.

  Furthermore, in the light modulation element according to the present invention, at least one of the magnetization fixed layer and the magnetization switching layer is a multilayer film in which Pd films and Co films are alternately stacked, and the Co film is stacked at the interface with the intermediate layer. It is preferable. In the light modulation element according to the present invention, at least one of the magnetization fixed layer and the magnetization switching layer includes at least one transition metal selected from Fe, Co, and Ni at the interface with the intermediate layer or the transition metal. It is preferable to further include a metal film made of an alloy.

  With this configuration, the light modulation element increases the spin polarization at the interface between the magnetization fixed layer or the magnetization reversal layer and the intermediate layer, and uses the spin injected from the magnetization fixed layer to the magnetization reversal layer via the intermediate layer. Since the spin torque increases, the magnetization can be reversed at a lower current.

  In addition, by forming a pixel including the light modulation element and an upper electrode and a lower electrode that supply current to the light modulation element, a spatial light modulator having excellent pixel selectivity and less operation variation can be obtained. it can. That is, the spatial light modulator according to the present invention includes a plurality of the two-dimensionally arranged pixels, a pixel selecting unit that selects one or more pixels from the plurality of pixels, and a predetermined pixel for the pixel selected by the pixel selecting unit. Current supply means for supplying the current, and the polarization direction of the light incident on the pixel selected by the pixel selection means is changed in a specific direction and emitted. Further, one of the upper electrode and the lower electrode is provided with a transparent electrode material and transmits light incident on the pixel and light emitted from the light modulation element, and the other is formed of a metal electrode. With this configuration, a reflective spatial light modulator is obtained.

  In the spatial light modulator according to the present invention, the upper electrode and the lower electrode include a transparent electrode material, one of which transmits light incident on the pixel, and the other of which transmits light emitted from the light modulation element. It is good also as a structure which permeate | transmits. With this configuration, a transmissive spatial light modulator is obtained.

  The display device according to the present invention has a configuration in which the spatial light modulator further includes image display means for projecting light emitted from the spatial light modulator. With this configuration, a display device that displays a clearer image with less variation is obtained.

  The holography apparatus according to the present invention further includes an imaging unit that images the interference fringes formed by the object light and the reference light and converts the interference fringes into an image signal, and the spatial light modulator includes: The light output from the image signal is used as a reproduced image. With this configuration, a holographic device that displays a clearer and less uneven stereoscopic image is obtained.

  The hologram recording apparatus according to the present invention records information on a recording medium using signal light and reference light. When the signal light and reference light are further incident on the recording medium. The spatial light modulator is configured to modulate at least one of the signal light and the reference light based on the phase information. With this configuration, a hologram recording apparatus with improved recording multiplicity is obtained.

  The imaging apparatus according to the present invention further includes a polarizer that transmits light emitted from the pixel selected by the pixel selection unit to the spatial light modulator, and a photoelectric that converts light transmitted through the polarizer into an electric charge. The image forming apparatus includes a conversion unit and a charge storage unit that stores the charge, and images subject light incident from the upper electrode side. With such a configuration, an imaging apparatus having excellent pixel selectivity, in which light emitted only from the selected pixel is accurately obtained as a charge, is obtained.

  According to the light modulation element of the present invention, it is possible to simultaneously achieve high definition with a visible light wavelength size (blue: 400 nm) from several μm or less and a high-speed response of about several ps in principle, and further to selectivity. Since the operation variation is excellent and the deterioration at the time of manufacture is small, a spatial light modulator having favorable magnetic characteristics or a pixel of an imaging device can be obtained. According to the spatial light modulator, the display device, the holography device, the hologram recording device, or the imaging device according to the present invention, the high-definition, high-speed response and excellent pixel selectivity can be achieved.

It is sectional drawing which shows typically the structure of the light modulation element which concerns on 1st Embodiment. It is sectional drawing explaining typically operation | movement of the light modulation element which concerns on this invention. It is sectional drawing which shows the structure of a light modulation element typically, (a) is the light modulation element which concerns on 2nd Embodiment, (b) is the light modulation element which concerns on 3rd Embodiment. It is sectional drawing which shows typically the structure of the light modulation element which concerns on 4th Embodiment. 1 is a plan view schematically showing a configuration of a spatial light modulator according to a first embodiment of the present invention. FIG. 6 is a schematic diagram for explaining a configuration of a display device using a spatial light modulator and a pixel selection operation according to the first embodiment of the present invention, and corresponds to a cross-sectional view taken along line AA of FIG. 5. It is a schematic diagram explaining the structure of the display apparatus using the spatial light modulator which concerns on 3rd Embodiment of this invention, and the operation | movement of pixel selection, and is a figure corresponding to AA sectional drawing of FIG. It is a schematic diagram which shows the structure of the holography apparatus which concerns on one Embodiment of this invention. It is a schematic diagram which shows the structure of the hologram recording apparatus which concerns on one Embodiment of this invention. 1 is a block diagram illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. FIG. 11 is a schematic diagram for explaining the configuration of the imaging apparatus and the pixel selection operation shown in FIG. It is a graph which shows the film thickness dependence of the coercive force in the magnetization inversion layer by the light modulation element of an Example, (a) is Co film, (b) is based on the film thickness of Pd film. It is a graph which shows the film thickness dependence of the Kerr rotation angle in the magnetization inversion layer by the light modulation element of an Example, (a) is Co film, (b) is based on the film thickness of Pd film.

  Hereinafter, embodiments for realizing a light modulation element, a spatial light modulator, and an imaging apparatus according to the present invention will be described with reference to the drawings.

[Light modulation element]
(First embodiment)
As shown in FIG. 1, the light modulation element 5 according to the first embodiment of the present invention has a configuration in which a magnetization fixed layer 51, an intermediate layer 52, a magnetization inversion layer 53, and a protective layer 54 are laminated in this order. The upper electrode 2 and the lower electrode 3 that are electrodes are connected in the vertical direction, and current is supplied perpendicular to the film surface. The light modulation element 5 includes a magnetization fixed layer 51 in which magnetization is fixed in one direction and a magnetization inversion layer 53 in which the magnetization direction can be rotated, with a nonmagnetic or insulating intermediate layer 52 interposed therebetween, CPP-GMR Spin injection magnetization reversal elements such as (Current Perpendicular to the Plane Giant MagnetoResistance) elements and TMR (Tunnel MagnetoResistance) elements, which protect these layers from damage in the manufacturing process For this purpose, a protective layer 54 is provided as the uppermost layer. Each layer constituting the light modulation element 5 is continuously formed and laminated by a known method such as a sputtering method or a molecular beam epitaxy (MBE) method, and a desired plane is formed by an electron beam lithography or an ion beam milling method. Processed into a visual shape.

  Here, the magnetization reversal operation of the light modulation element 5 will be described with reference to FIG. In FIG. 2, the protective layer 54 is not shown. The light modulation element 5, which is a spin-injection magnetization reversal element, inverts the magnetization direction of the magnetization reversal layer 53 by injecting electrons having spins in the opposite direction, that is, by supplying current in the opposite direction (spin-injection magnetization). Reversal, hereinafter referred to as magnetization reversal as appropriate), so that the magnetization direction of the magnetization fixed layer 51 is the same or 180 ° different. Specifically, as shown in FIG. 2A, when a current is supplied from the magnetization switching layer 53 side to the magnetization fixed layer 51 with the upper electrode 2 set to “+” and the lower electrode 3 set to “−”, the magnetization is changed. The magnetization of the inversion layer 53 is the same as the magnetization direction of the magnetization fixed layer 51. Hereinafter, this state is referred to as that the magnetization of the light modulation element 5 is parallel (P: Parallel). On the other hand, as shown in FIG. 2B, when the upper electrode 2 is set to “−” and the lower electrode 3 is set to “+” and a current is supplied from the magnetization fixed layer 51 side to the magnetization switching layer 53, the magnetization switching layer The magnetization of 53 is opposite to the magnetization direction of the magnetization fixed layer 51. Hereinafter, this state is referred to as anti-parallel (AP) where the magnetization of the light modulation element 5 is antiparallel.

  If the light modulation element 5 exhibits either parallel or antiparallel magnetization, the magnetization is retained by the coercive force Hcf of the magnetization reversal layer 53 until a current for reversing the magnetization is supplied. As described above, since the magnetization is held in the light modulation element 5, the current supplied to the light modulation element 5 is a current that temporarily reaches a current value that reverses the magnetization direction, such as a pulse current. Can do. However, when the coercive force Hcf of the magnetization reversal layer 53 increases and approaches the coercive force Hcp of the magnetization fixed layer 51, the current required for magnetization reversal (magnetization reversal current) increases, and more than the coercive force Hcp of the magnetization fixed layer 51 Then, the magnetization reversal operation by current supply cannot be performed. Therefore, the magnetization fixed layer 51 and the magnetization inversion layer 53 are configured as described later so that the coercive forces Hcf and Hcp satisfy Hcf <Hcp, and preferably the difference is 500 Oe or more.

  When light incident on the light modulation element 5 is reflected by the magnetization reversal layer 53 that is a magnetic material and emitted, the direction of polarization of the incident light changes (rotation) due to the Kerr effect (magnetic Kerr effect). Further, as shown in FIGS. 2 (a) and 2 (b), the lights incident on the light modulation elements 5 having the parallel and antiparallel magnetizations have the same magnitude because the magnetization direction of the magnetization reversal layer 53 differs by 180 °. The optical rotation angle, that is, the Kerr rotation angles + θk and −θk of the magnetization reversal layer 53 (hereinafter, “θk” indicates only the size but does not indicate the direction) are rotated in opposite directions and emitted. The emitted light from the light modulation element 5 functions as a pixel of a later-described spatial light modulator or the like by changing the polarization direction according to the direction of the supplied current. It is desirable that the Kerr rotation angle θk of the magnetization reversal layer 53 that is the difference between the two is large.

  The magnitude of the Kerr effect is proportional to the scalar product of the wave number vector of incident light and the magnetization vector of the magnetic material. That is, the Kerr rotation angle θk of the magnetization switching layer 53 becomes larger as the incident angle of light is closer to the magnetization direction of the magnetization switching layer 53. Here, if the magnetization reversal layer 53 (and the magnetization fixed layer 51) has magnetization in the film plane direction (in-plane magnetic anisotropy), the light modulation element 5 has a structure that approaches the magnetization direction in parallel with the light. It is difficult to make it incident. On the other hand, if the magnetization switching layer 53 has magnetization in a direction perpendicular to the film surface, that is, perpendicular magnetic anisotropy, light can be easily incident in parallel to the magnetization direction, and a large Kerr effect can be applied. A rotation angle θk is obtained. In the light modulation element 5 according to this embodiment, the magnetization fixed layer 51 and the magnetization reversal layer 53 are configured as follows, thereby having perpendicular magnetic anisotropy and a large Kerr rotation angle θk. Hereinafter, with reference to FIG. 1, the detail of each layer which comprises the light modulation element 5 is demonstrated.

  As shown in FIG. 1, in the light modulation element 5 according to the present embodiment, the magnetization fixed layer 51 and the magnetization inversion layer 53 are each composed of a multilayer film in which Pd films and Co films are alternately stacked (see FIG. 1). (The Pd film is indicated as “Pd”, and the Co film is indicated as “Co”.) Co is a ferromagnetic material, and can constitute a magnetization fixed layer and a magnetization reversal layer independently. However, by forming a multilayer film alternately laminated with nonmagnetic Pd (hereinafter referred to as a Co / Pd multilayer film), As a single unit, the coercive force is increased. Furthermore, since the Co / Pd multilayer film has a strong perpendicular magnetic anisotropy energy Ku, the light modulation element 5 having a perpendicular magnetic anisotropy, a stable magnetization reversal operation, and a small variation can be obtained. In addition, the Co / Pd multilayer film has good process resistance, specifically oxidation resistance, heat resistance, acid resistance, alkali resistance, chemical resistance, and the like. For example, when the light modulation element 5 is manufactured, ion beam milling is performed. When it is molded into a desired shape by a method or the like, even if the side surface (end surface) is exposed and exposed to the atmosphere, it hardly oxidizes, and the deterioration of magnetic properties and the like is small. Further, by configuring the magnetization fixed layer 51 and the magnetization inversion layer 53 with a common material (Pd and Co), the productivity of the light modulation element 5 is improved, and the correlation between the coercive forces Hcp and Hcf is described later. It becomes easy to control. Furthermore, since the Co / Pd multilayer film contains Co, the Kerr rotation angle and the Faraday rotation angle are large. Therefore, by forming the magnetization reversal layer 53, the difference in optical rotation angle due to the magnetization reversal of the light modulation element 5 is increased. can do. The Co / Pd multilayer film can be formed by a known method such as a DC magnetron sputtering method or an ion beam sputtering method.

  Here, in the present specification, as shown in FIG. 2, the light that has entered from the upper side of the magnetization switching layer 53 (light modulation element 5) and exited again is reflected by the magnetization switching layer 53 (Co / Pd multilayer film). ) And the light that has reached only the inside of the layer (the deepest and the interface with the intermediate layer 52) is expressed as “reflected by the magnetization switching layer 53”. On the other hand, for example, light incident from above the magnetization switching layer 53 is emitted below the magnetization switching layer 53, passes through the intermediate layer 52, and further enters at least the surface of the magnetization fixed layer 51. This case is expressed as “transmitting through the magnetization switching layer 53”.

The magnetization fixed layer 51 preferably has a total thickness of 3 to 20 nm. The film thickness t _Co p of the single _Co film layer (one layer) is preferably in the range of 0.1 to 1 nm, and the film thickness t _Pd p of the single Pd film layer is in the range of 0.1 to 2 nm. It is preferable. Further, the number of Co films and Pd films is not particularly limited, and the Co films and the Pd films may be alternately and repeatedly stacked so as to have the entire thickness. In addition, the uppermost layer and the lowermost layer of the Co / Pd multilayer film may be either a Co film or a Pd film, respectively, but it is preferable to stack a Co film on the uppermost layer serving as an interface with the intermediate layer 52. Since the Co film is disposed at the interface with the intermediate layer 52, the spin polarization at the interface is increased, and the spin torque caused by the spin injected into the magnetization switching layer 53 through the intermediate layer 52 is increased. The current required for inversion can be reduced, and the effect is particularly great when the light modulation element 5 is a TMR element.

The entire thickness of the magnetization switching layer 53 is preferably 1.5 to 10 nm. Further, the thickness t Cof of the single _Co film layer (one layer) is preferably in the range of 0.1 to 1 nm, and the Kerr rotation angle θk of the magnetization switching layer 53 can be increased as the film thickness is further increased. preferable. On the other hand, the thickness t _Pd f Pd film single layer is preferably in a range of 0.1 to 2 nm. Further, like the Co / Pd multilayer film in the magnetization fixed layer 51, the number of Co films and Pd films is not particularly defined, and the Co film and the Pd film are alternately and repeatedly stacked so as to have the total thickness described above. That's fine. Further, the uppermost layer and the lowermost layer of the Co / Pd multilayer film may be either a Co film or a Pd film, respectively, but it is preferable to stack a Co film on the lowermost layer that becomes an interface with the intermediate layer 52. By arranging the Co film at the interface with the intermediate layer 52, the spin polarization rate at the interface is increased, and the spin torque due to the spin injected into the magnetization switching layer 53 through the intermediate layer 52 is increased. The current required for the magnetization reversal of the light modulation element 5 can be reduced, and the effect is particularly great when the light modulation element 5 is a TMR element.

In the light modulation element 5, the coercive force Hcf of the magnetization reversal layer 53 is made smaller than the coercive force Hcp of the magnetization fixed layer 51 as described above in order to reduce the magnetization reversal current. Therefore, it is preferable to make the magnetization switching layer 53 thinner than the magnetization fixed layer 51 as the total thickness of each. Further, as described above, the Co / Pd multilayer film has a large coercive force, but within the range of the thickness of the single layer, the thickness of the single layer of Co film increases as the thickness of the single layer of Co film increases. The thinner the Co / Pd multilayer film, the smaller the coercivity. Therefore, the film thickness t _Cof of the Co film single layer of the magnetization switching layer 53 is made larger than the film thickness t _Cop of the Co film single layer of the magnetization fixed layer 51 (t _Cof > t _Co p), or the magnetization switching layer The film thickness t _Pd f of the Pd film single layer 53 is made smaller than the film thickness t _Pd p of the Pd film single layer of the magnetization fixed layer 51 (t _Pd f <t _Pd p), or both (t _Cof > t _Co p, t _Pd f <t _Pd p). As described above, the light modulation element 5 according to the present embodiment can easily control the correlation between the film thicknesses of the Co film and the Pd film in the magnetization fixed layer 51 and the magnetization switching layer 53, thereby easily changing the magnetization switching layer 53. Can be made smaller than the coercive force Hcp of the magnetization fixed layer 51.

The intermediate layer 52 is provided between the magnetization fixed layer 51 and the magnetization switching layer 53. If the light modulation element 5 is a TMR element, the intermediate layer 52 is made of an insulator such as MgO, Al ₂ O ₃ , HfO ₂ or a laminated film containing an insulator such as Mg / MgO / Mg. The thickness is preferably 0.5 to 2 nm. If the light modulation element 5 is a CPP-GMR element, the intermediate layer 52 is preferably made of a nonmagnetic metal such as Cu, Au, or Ag, and its thickness is preferably 2 to 6 nm.

  The protective layer 54 is composed of a single layer of Ta, Ru, Cu, or two layers of Cu / Ta, Cu / Ru. In addition, when setting it as the said 2 layer structure, all make Cu inside (lower layer). If the thickness of the protective layer 54 is less than 1 nm, it is difficult to form a continuous film. On the other hand, even if the thickness exceeds 10 nm, the effect of protecting the magnetization switching layer 53 and the like in the manufacturing process is further improved. In addition, the transmitted light amount of incident light from above the light modulation element 5 is attenuated. Therefore, the thickness of the protective layer 54 is preferably 1 to 10 nm.

  By configuring each layer constituting the light modulation element 5 according to the first embodiment in such a configuration, as shown in FIGS. 2A and 2B, the magnetization reversal layer 53 (and the magnetization fixed layer 51) The magnetization becomes perpendicular to the film surface, and light (incident polarized light) can be easily incident at an incident angle parallel to or close to the magnetization direction. Thereby, the light reflected by the magnetization reversal layer 53 is optically rotated by the polar Kerr effect. Further, the magnetization reversal layer 53 is further rotated by making it a Co / Pd multilayer film having a large Kerr rotation angle and Faraday rotation angle. Therefore, the difference in the polarization direction (2θk) of each outgoing light (outgoing polarized light) is large between FIGS. 2A and 2B where the magnetization of the magnetization switching layer 53 differs by 180 °, and the degree of light modulation is excellent. The light modulation element 5 is obtained. In addition, the difference in coercive force between the magnetization fixed layer 51 and the magnetization switching layer 53 can be easily controlled, whereby the magnetization switching current can be reduced. The light modulation element 5 may be stacked in the order of the magnetization reversal layer 53, the intermediate layer 52, the magnetization fixed layer 51, and the protective layer 54 by switching the positions of the magnetization fixed layer 51 and the magnetization reversal layer 53 as described later. In this case, however, since the lowermost layer of the magnetization fixed layer 51 and the uppermost layer of the magnetization switching layer 53 are interfaces with the intermediate layer 52, a Co film is preferably disposed at this position.

  As described above, according to the light modulation element according to the first embodiment, the spin modulation magnetization reversal element capable of high-definition and high-speed response is applied to the light modulation degree by applying the Co / Pd multilayer film. An improved light modulation element can be obtained.

(Second Embodiment)
Next, an optical modulation element according to the second embodiment of the present invention will be described with reference to FIG. The same elements as those in the first embodiment (see FIG. 1) are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 3A, the light modulation element 5A according to the second embodiment of the present invention is laminated in the order of a magnetization fixed layer 51A, an intermediate layer 52, a magnetization inversion layer 53, and a protective layer 54, and has a single layer structure. The spin-injection magnetization reversal element has the same configuration as that of the light modulation element 5 according to the first embodiment except that the magnetization fixed layer 51A is provided, and the magnetization reversal operation and the rotation of incident light are the same. Therefore, in the light modulation element 5A, only the magnetization switching layer 53 is formed of a Co / Pd multilayer film. As described above, since the Co / Pd multilayer film has strong perpendicular magnetic anisotropy, even if only one of the magnetization fixed layer and the magnetization inversion layer is formed of the Co / Pd multilayer film as described above, it is sufficiently perpendicular magnetic anisotropic. Thus, an optical modulation element that exhibits high performance and small operational variation can be obtained. Particularly in the second embodiment, since the magnetization reversal layer 53 is formed of a Co / Pd multilayer film having a large Kerr rotation angle θk, the difference in optical rotation angle due to magnetization reversal is similar to that of the light modulation element 5 according to the first embodiment. A large light modulation element 5A is obtained.

  When only the magnetization switching layer 53 is formed of a Co / Pd multilayer film, the magnetization pinned layer 51A is known as a magnetization pinned layer such as a CPP-GMR element or a TMR element having perpendicular magnetic anisotropy other than the Co / Pd multilayer film. The magnetic material can be a single layer, and the thickness is preferably 2 to 20 nm. Specific examples include transition metals such as Fe, Co, Ni and alloys containing them, and in particular, transition metals selected from Fe, Co, Ni and rare earth metals selected from Sm, Eu, Gd, Tb. Alloys are preferred. Such an alloy has a low saturation magnetization Ms, a magnetic field leaking from the magnetization fixed layer 51A to the magnetization reversal layer 53 is reduced, and the phenomenon that the spin injection magnetization reversal characteristic shifts in one direction of the current axis direction can be suppressed. In the light modulation element 5A, a stable spin injection magnetization reversal operation can be obtained with the positive magnetization reversal current and the negative magnetization reversal current substantially equal to each other.

Parameters such as the thickness of the Co / Pd multilayer film constituting the magnetization switching layer 53 are the same as those in the first embodiment. Here, as described above, the coercive force of the Co / Pd multilayer film decreases as the thickness of the Co film single layer increases or as the Pd film single layer decreases. Furthermore, the Kerr rotation angle θk can be increased by increasing the thickness of the single Co film. Therefore, the film thickness t _Cof and the Pd film of the single Co film are set so that the coercive force Hcf of the magnetization reversal layer 53 is smaller than the coercive force Hcp of the magnetization fixed layer 51A and exhibits a sufficient Kerr rotation angle θk. The film thickness t _Pd f of the single layer is designed.

  As described above, according to the light modulation element according to the second embodiment, the spin injection magnetization reversal element capable of high-definition and high-speed response is optically modulated in the same manner as the light modulation element according to the first embodiment. Therefore, the light modulation element can be further improved in the magnetization reversal operation.

(Third embodiment)
Next, with reference to FIG.3 (b), the light modulation element which concerns on 3rd Embodiment of this invention is demonstrated. The same elements as those in the first embodiment (see FIG. 1) are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 3B, the light modulation element 5B according to the third embodiment of the present invention is laminated in the order of the magnetization fixed layer 51, the intermediate layer 52, the magnetization inversion layer 53A, and the protective layer 54, and has a single layer structure. The spin reversal magnetization reversal element has the same configuration as that of the light modulation element 5 according to the first embodiment except that the magnetization reversal layer 53A is provided. Therefore, in the light modulation element 5B, only the magnetization fixed layer 51 is configured by a Co / Pd multilayer film, compared to the second embodiment (see FIG. 3A) in which the magnetization switching layer 53 is configured by a Co / Pd multilayer film. Is done.

Parameters such as the thickness of the Co / Pd multilayer film constituting the magnetization fixed layer 51 are the same as those in the first embodiment. Here, it is necessary to make the coercive force Hcf of the magnetization switching layer 53 </ b> A smaller than the coercive force Hcp of the magnetization fixed layer 51. That is, the film thickness t _Co p of the Co film single layer is made thin and the film thickness t _Pd p of the Pd film single layer is made thick so that the coercive force Hcp of the magnetization fixed layer 51 is larger than the coercivity Hcf of the magnetization switching layer 53A. design.

  When only the magnetization fixed layer 51 is formed of a Co / Pd multilayer film, the magnetization switching layer 53A is known as a magnetization switching layer such as a CPP-GMR element or a TMR element having perpendicular magnetic anisotropy other than the Co / Pd multilayer film. The magnetic material can be a single layer, and the thickness is preferably 1.5 to 15 nm. Specifically, similarly to the magnetization fixed layer 51A of the second embodiment, transition metals such as Fe, Co, Ni, and alloys containing them are mentioned, and in particular, transition metals selected from Fe, Co, Ni and Sm Alloys with rare earth metals selected from Eu, Gd, Tb are preferred. As described above, since such an alloy has a low saturation magnetization Ms, it is possible to reduce the magnetization reversal current by reducing the magnetization reversal current density Jc of the light modulation element 5B. Further, the magnetization switching layer 53A may be formed of a Co / Pt multilayer film in which Co films and Pt films are alternately stacked, or an Fe / Pt multilayer film in which Fe films and Pt films are alternately stacked. Since these multilayer films also have a Kerr rotation angle and a Faraday rotation angle and a coercive force smaller than that of the Co / Pd multilayer film, the coercive force Hcf of the magnetization reversal layer 53A can be made smaller than the coercive force Hcp of the magnetization fixed layer 51. Easy.

  As described above, according to the light modulation element according to the third embodiment, the spin modulation magnetization reversal element capable of high-definition and high-speed response is improved in the degree of light modulation by the polar Kerr effect, and further the magnetization reversal. A light modulation element with reduced current can be obtained.

(Fourth embodiment)
Next, with reference to FIG. 4, a light modulation element according to the fourth embodiment of the present invention will be described. The same elements as those in the first embodiment (see FIG. 1) are denoted by the same reference numerals, and description thereof is omitted. As illustrated in FIG. 4, the light modulation element 5 </ b> C according to the fourth embodiment of the present invention includes a magnetization fixed layer 51 </ b> B, an intermediate layer 52, a magnetization inversion layer 53 </ b> B, and a protective layer 54 stacked in this order. Further, the magnetization fixed layer 51B includes a Co / Pd multilayer film and a transition metal film (metal film) 511 laminated at the interface with the intermediate layer 52. The magnetization switching layer 53B includes a Co / Pd multilayer film and an intermediate layer. And a transition metal film (metal film) 531 laminated at the interface with 52. The Co / Pd multilayer film provided in each of the magnetization fixed layer 51B and the magnetization reversal layer 53B has the same configuration as the magnetization fixed layer 51 and the magnetization reversal layer 53 in the light modulation element 5, and parameters such as the thickness thereof are the same as those in the first embodiment. Since it is the same as that of a form, description is abbreviate | omitted. Therefore, in the light modulation element 5C, in the light modulation element 5 according to the first embodiment, the transition metal films 511 and 531 are inserted between the magnetization fixed layer 51 and the intermediate layer 52 and between the magnetization switching layer 53 and the intermediate layer 52, respectively. The spin injection magnetization reversal element having the above-described configuration is the same as that of the first embodiment in the magnetization reversal operation and the rotation of incident light.

The transition metal films 511 and 531 are each made of at least one transition metal selected from Fe, Co, and Ni or an alloy containing the transition metal, and preferably have a thickness in the range of 0.1 to 1 nm. Examples of the alloy containing a transition metal include CoFe, CoFeB, NiFe, and CoFeSi. In both of the magnetization fixed layer 51B and the magnetization switching layer 53B, a film containing such a transition metal is provided at the interface between the metal film and the intermediate layer 52, thereby increasing the spin polarization at the interface, Since the spin torque due to the spins injected into the magnetization switching layer 53 via the layer 52 increases, the current required for the magnetization switching of the light modulation element 5C can be reduced. This effect is particularly great when the light modulation element 5C is a TMR element. Further, when MgO is applied to the intermediate layer 52, the magnetization reversal current can be reduced by flowing a coherent tunnel current in combination with this MgO. CoFeB, Fe, and Co are preferably applied to the transition metal films 511 and 531. In the Co / Pd multilayer film, the layers in which the transition metal films 511 and 531 are stacked and in contact with each other may be either a Co film or a Pd film, but is preferably a Pd film. In the case of using the Co in the transition metal layer 511 and 531, its thickness may be in the range of the 0.1 to 1 nm, Co / Pd necessarily the same thickness as the Co film in the multilayer film (t _Co p, t _Co f) is not necessary.

  The light modulation element 5C according to the fourth embodiment is configured to include the transition metal films 511 and 531 in both the magnetization fixed layer 51B and the magnetization switching layer 53B. However, the effect can be obtained even if only one of them is provided. Therefore, as a modification of the fourth embodiment, as a light modulation element (not shown) in which the magnetization switching layer 53B provided with the transition metal film 531 is combined with the magnetization fixed layer 51 composed only of the Co / Pd multilayer film. Also good. The effects can be obtained even when the transition metal films 511 and 531 are stacked on the magnetization fixed layer and the magnetization inversion layer formed of other than the Co / Pd multilayer film. For example, as a modification of the second embodiment, a light modulation element in which the transition metal film 531 is added to the light modulation element 5A (see FIG. 3A), that is, the magnetization reversal layer 53B is combined with the magnetization fixed layer 51A. Further, the transition metal film 511 may be laminated on the magnetization fixed layer 51A (not shown). On the other hand, as a modification of the third embodiment, a light modulation element in which the transition metal film 511 is added to the light modulation element 5B (see FIG. 3B), that is, the magnetization fixed layer 51B is combined with the magnetization switching layer 53A. Further, a transition metal film 531 may be stacked on the magnetization switching layer 53A (not shown).

  As described above, according to the light modulation element according to the fourth embodiment, the spin injection magnetization reversal element capable of high definition and high-speed response is equivalent to the light modulation element according to the first to third embodiments. It is possible to obtain a light modulation element that improves the degree of light modulation and further reduces the magnetization reversal current.

[Spatial light modulator, display device]
(First Embodiment of Spatial Light Modulator)
Next, embodiments of the spatial light modulator including the light modulation element according to the first to fourth embodiments of the present invention and the modification thereof in a pixel, and a display device using the spatial light modulator will be described. Since these light modulation elements have the same magnetization reversal operation and rotation of incident light as described above, in this specification, the light modulation element 5 (see FIG. 1) according to the first embodiment is provided in a pixel. Will be described. In addition, the pixel in this specification refers to a means for displaying information (bright / dark) in the minimum unit of display by the spatial light modulator.

  The spatial light modulator 1 according to the first embodiment of the present invention includes a pixel array 40 including pixels 4 arranged in a two-dimensional array on a substrate 7 (see FIG. 6), as shown in FIG. A current control unit 80 that selects and drives one or more pixels 4 from the array 40 is provided. The plane (upper surface) in this specification is a light incident surface of the spatial light modulator, and the spatial light modulator 1 reflects light incident on the pixel 4 (pixel array 40) from above and modulates the light. Thus, the reflective spatial light modulator is emitted upward.

  As shown in FIG. 5, the pixel array 40 includes a plurality of upper electrodes 2, 2... Striped in plan view, and a plurality of lower electrodes 3, 3 that are also striped and orthogonal to the upper electrode 2 in plan view. ,..., And one pixel 4 is provided at each intersection of the upper electrode 2 and the lower electrode 3. Therefore, the pixels 4 are arranged in a two-dimensional array on the light incident surface of the spatial light modulator 1 to form the pixel array 40. In the present embodiment, the pixel array 40 is exemplified by a configuration including 25 pixels 4 of 5 rows × 5 columns. The upper electrode 2 and the lower electrode 3 are collectively referred to as electrodes 2 and 3 as appropriate. As shown in FIGS. 5 and 6, the pixel 4 includes an upper electrode 2 and a lower electrode 3 as a pair of electrodes in the pixel 4, and a light modulation element 5 sandwiched between the electrodes 2 and 3 from above and below. Is provided. In FIG. 6, the protective layer 54 (see FIG. 1) of the light modulation element 5 is not shown. Further, the insulating members 6 are buried between the adjacent upper electrodes 2 and 2, between the light modulation elements 5 and 5, and between the lower electrodes 3 and 3.

  As shown in FIG. 5, the current control unit 80 controls the upper electrode selection unit 82 that selects the upper electrode 2, the lower electrode selection unit 83 that selects the lower electrode 3, and the electrode selection units 82 and 83. A pixel selection section (pixel selection means) 84 and a power supply (current supply means) 81 that supplies current to the electrodes 2 and 3 are provided. These may be known ones, and appropriate voltages and currents are supplied to reverse the magnetization of the light modulation element 5.

  The upper electrode selection unit 82 selects one or more of the upper electrodes 2, and the lower electrode selection unit 83 selects one or more of the lower electrodes 3, and each supplies a predetermined current from the power source 81. The pixel selection unit 84 selects one or more specific pixels 4 of the pixel array 40 based on, for example, an external signal (not shown), and connects the electrodes 2 and 3 connected to the selected pixel 4 to the electrode selection units 82 and 83. To select. The power supply 81 supplies an appropriate voltage / current to reverse the magnetization of the light modulation element 5 provided in the selected pixel 4. With such a configuration, a specific pixel 4 is selected, and a predetermined current is supplied to the light modulation element 5 of this pixel 4 to reverse the magnetization. In FIG. 5, the power supply 81 is connected to one end of each of the electrodes 2 and 3 via the electrode selection units 82 and 83, but may be connected to both ends. By connecting to both ends, the response speed can be increased and the operation variation between pixels can be reduced.

  Details of the configuration of the pixel 4 of the spatial light modulator 1 will be described with reference to FIGS. The upper electrode 2 is disposed on the light modulation element 5 as shown in FIG. 6 and extends in a strip shape in the lateral direction as shown in FIG. One upper electrode 2 supplies current to each of the light modulation elements 5 of the plurality of pixels 4, 4,... Arranged in one horizontal row. On the other hand, the lower electrode 3 is arranged under the light modulation element 5 and extends in a strip shape in the vertical direction. One lower electrode 3 supplies a current to each of the light modulation elements 5 of the plurality of pixels 4, 4,... Arranged in one vertical column. The upper electrode 2 is made of a transparent electrode material so as not to block incident light and outgoing light of the light modulation element 5. On the other hand, the lower electrode 3 is made of an electrode metal material having excellent conductivity.

  As shown in FIG. 5, the light modulation element 5 is arranged in a portion where the upper electrode 2 and the lower electrode 3 overlap in a plan view, and is sandwiched and connected to the electrodes 2 and 3 from above and below. The planar view shape of the light modulation element 5 is a square in the present embodiment, but is not limited to this. In addition, one light modulation element 5 is arranged for one pixel 4. For example, a plurality of light modulation elements such as (1 × 3), (2 × 2), and the like are provided in one pixel 4 in the surface direction. An element 5 may be provided.

The upper electrode 2 is made of a transparent electrode material so that light can pass therethrough. Transparent electrode materials include, for example, indium zinc oxide (IZO), indium tin oxide (ITO), tin oxide (SnO ₂ ), antimony oxide-tin oxide system (ATO), oxidation zinc (ZnO), fluorine-doped tin oxide (FTO), consisting of a known transparent electrode material such as indium oxide (in ₂ O _3). In particular, IZO is most preferable in terms of specific resistance and ease of film formation. These transparent electrode materials are formed into a film by a known method such as a sputtering method, a vacuum deposition method, or a coating method.

  When the electrode (wiring) is made of a transparent electrode material, it is preferable to provide a metal film between the electrode and the light modulation element 5 connected to the electrode. That is, in the upper electrode 2 made of a transparent electrode material, it is preferable to laminate a metal film as a base layer between the light modulation element 5 (not shown). By interposing a metal film between the light modulation element 5 and the upper electrode 2 made of a transparent electrode material having a resistance higher than that of the electrode metal material, the contact resistance between the upper electrode 2 and the light modulation element 5 is reduced. To increase the response speed.

  As the metal constituting the underlayer, for example, Au, Ru, Ta, or an alloy composed of two or more of these metals can be used, and these metals are formed by a known method such as a sputtering method. The Then, in order to further reduce the contact resistance by improving the adhesion between the underlayer and the layer above it, that is, the transparent electrode, the metal film serving as the underlayer is continuously formed in the vacuum processing chamber with the transparent electrode material. It is preferred that If the thickness of the underlayer is less than 1 nm, it is difficult to form a continuous film, while if it exceeds 10 nm, the amount of transmitted light is reduced. Therefore, the preferable thickness of the underlayer is 1 to 10 nm.

  The lower electrode 3 is made of a general electrode metal material such as a metal such as Cu, Al, Au, Ag, Ta, Cr, or an alloy thereof. Then, it is processed into a stripe shape by a known method such as a sputtering method, by film formation, photolithography, etching, lift-off method, or the like.

As the substrate 7, for example, a known substrate such as a Si substrate whose surface is thermally oxidized can be applied. The insulating member 6 is disposed between the adjacent upper electrodes 2 and 2 (not shown in FIG. 6), between the light modulation elements 5 and 5, and between the lower electrodes 3 and 3, and is made of, for example, SiO ₂ or Al ₂ O _3. Become.

(Spatial light modulator manufacturing method)
Next, an example of a method for manufacturing the pixel 4 (pixel array 40) of the spatial light modulator 1 shown in FIGS. 5 and 6 will be described.
First, the lower electrode 3 is formed. A metal electrode material is formed on the surface of the substrate 7 by a sputtering method or the like, and formed into a stripe shape by photolithography or the like to form the lower electrode 3. Then, an insulating film such as SiO ₂ (which becomes the insulating member 6) is deposited between the lower electrodes 3 and 3.

  Next, the light modulation element 5 is formed. A magnetization fixed layer 51, an intermediate layer 52, a magnetization switching layer 53, and a protective layer 54 are continuously formed on the upper surface of the lower electrode 3 (and the insulating member 6), for example, a known method such as sputtering or molecular beam epitaxy (MBE). In this way, the film is continuously formed and laminated. These layers are formed and processed into the shape in plan view by electron beam lithography, ion beam milling, or the like to obtain the light modulation element 5. With the resist used as a mask in the molding process left, an insulating film is formed and deposited between the light modulation elements 5 and 5 (including those between adjacent pixels 4 and 4). The insulating film 6 is removed (lifted off) to form the insulating member 6. Alternatively, after forming the light modulation element 5, the resist is removed, an insulating film is formed and deposited between the light modulation elements 5 and 5, and light is etched or etched by CMP (Chemical Mechanical Polishing). The insulating film on the modulation element 5 may be removed.

  Next, the upper electrode 2 is formed. A metal film as a base layer and a transparent electrode material are continuously formed on the upper surfaces of the light modulation element 5 and the insulating member 6 and formed into a stripe shape orthogonal to the lower electrode 3 to form the upper electrode 2. Finally, the insulating member 6 is deposited between the upper electrodes 2 and 2 to form the pixel 4 (pixel array 40).

(First embodiment of display device, pixel selection operation of spatial light modulator)
Next, the pixel selection operation of the spatial light modulator 1 will be described as a display device 10 using the spatial light modulator 1 with reference to FIG. The electrodes 2 and 3 are connected to the current control unit 80 as described above. As shown in FIG. 6, in the display device 10 according to the present embodiment, a light source 91 that emits light toward the pixel array 40 above the pixels 4 (pixel array 40) of the spatial light modulator 1 and , An incident polarizing filter PF1 that converts light emitted from the light source 91 into polarized light before entering the pixel array 40, and an outgoing polarizing filter PF2 that transmits only polarized light in a specific direction from the light reflected and emitted from the pixel array 40. And a detector (image display means) 93 for detecting light transmitted through the output polarization filter PF2.

  The light source 91 includes, for example, a laser light source, a beam expander that is optically connected to the laser light source to expand the laser light, and a lens that converts the expanded laser light into parallel light (see FIG. 8). Since the laser light emitted from the light source 91 includes various polarization components, the laser light is transmitted through the incident polarization filter PF1 in front of the pixel array 40 to obtain light of one polarization component. Hereinafter, light of one polarization component is referred to as polarization. This polarized light (incident polarized light) is incident on all the pixels 4 of the pixel array 40 at a predetermined incident angle. In each pixel 4, the incident polarized light passes through the upper electrode 2 and enters the light modulation element 5, is reflected by the magnetization reversal layer 53 of the light modulation element 5, is emitted as outgoing polarization, and is transmitted through the upper electrode 2 again. Then, the light is emitted from the pixel 4. All the outgoing polarized light emitted from each pixel 4 reaches the outgoing polarization filter PF2. The outgoing polarization filter PF2 transmits only specific polarized light, here, polarized light whose angle θap is rotated with respect to the incident polarized light, and this transmitted outgoing polarized light is incident on the detector 93. The polarizing filters PF1 and PF2 are polarizing plates, respectively, and the detector 93 is an image display means such as a screen. Alternatively, the detector 93 may be imaging means such as a camera.

  As described above, the light modulation element 5 is a spin-injection magnetization reversal element, and the polarizations that have undergone magnetization reversal according to the direction of the current supplied from the electrodes 2 and 3 and reflected by the magnetization reversal layer 53 are opposite to each other. (See FIGS. 2A and 2B). If the optical rotation angles in the light modulation element 5 in which the magnetization is parallel and antiparallel are respectively expressed as θp and θap, and the Kerr rotation angle of the magnetization reversal layer 53 is θk, then θp = + θk and θap = −θk. The difference in the polarization direction of the light emitted from the light modulation element 5, that is, the difference in optical rotation angle | θp−θap |

  Alternatively, the polarized light incident on the light modulation element 5 is transmitted through the magnetization switching layer 53, the intermediate layer 52, and the magnetization fixed layer 51, reflected on the upper surface of the lower electrode 3, and again, the magnetization fixed layer 51, the intermediate layer 52, and the magnetization The structure which permeate | transmits and inject | emits the inversion layer 53 may be sufficient. In this case, by passing through the magnetization reversal layer 53 and the magnetization fixed layer 51 which are magnetic materials, the direction of polarized light depends on the respective predetermined angles (optical rotation) of the magnetization reversal layer 53 and the magnetization fixed layer 51 due to the Faraday effect. Rotate (rotate) to (angle). However, since the magnetization direction of the magnetization fixed layer 51 is constant, the change in the polarization of the emitted light from the light modulation element 5 is determined by the Faraday rotation angle θF of the magnetization switching layer 53. Since the emitted light passes through the magnetization switching layer 53 twice, the difference in optical rotation angle | θp−θap | is 4θF.

  The respective outgoing polarizations from the pixels 4 and 4 at the left and right ends of FIG. 6 that have been rotated by the angle θap with respect to the incident polarized light pass through the outgoing polarization filter PF2 and reach the detector 93, so that the pixel 4 is bright (white). ) Is displayed on the detector 93. On the other hand, since the outgoing polarized light from the central pixel 4 is blocked by the outgoing polarizing filter PF2, the pixel 4 is dark (black) and displayed on the detector 93. Thus, light / dark (white / black) can be separated for each pixel, and light / dark can be switched by switching the direction of the current. As an initial state of the spatial light modulator 1, for example, all the upper electrodes 2 are “-” so that the magnetizations of the light modulation elements 5 of all the pixels 4 are anti-parallel so that the whole is displayed white. All of the lower electrode 3 may be set to “+” to supply an upward current.

  Here, the Kerr rotation angle θk and the Faraday rotation angle θF of the magnetization switching layer 53 are larger as the incident angle of light is closer to the magnetization direction of the magnetization switching layer 53 as described above. Accordingly, it is desirable that the incident angle be perpendicular to the film surface, that is, 0 °, in order to maximize the difference in optical rotation angle | θp−θap |. In this case, the optical path of the outgoing polarized light coincides with the optical path of the incident polarized light. . Therefore, the incident angle is slightly inclined so that the outgoing polarization filter PF2, the detector 93, the light source 91, and the incoming polarization filter PF1 are arranged so as not to block the optical paths of the incident polarized light and the outgoing polarized light, respectively. Specifically, the incident angle of polarized light is preferably 5 ° to 30 °. Alternatively, a half mirror may be disposed between the incident polarizing filter PF1 and the pixel array 40 with an incident angle of 0 °, and only the outgoing polarized light may be reflected to the side. In this case, the output polarization filter PF2 and the detector 93 are arranged on the side of the pixel array 40.

(Second Embodiment of Spatial Light Modulator and Display Device)
In another embodiment (second embodiment), the spatial light modulator according to the present invention may be a reflective spatial light modulator that is incident from the substrate side as a configuration in which the top and bottom are switched (not shown). That is, the lower electrode is made of a transparent electrode material, and the upper electrode is made of an electrode metal material, so that light incident from below passes through the lower electrode and is reflected by the light modulation element 5 or the upper electrode. Transmits and exits. In this case, as in the case where the upper electrode is made of a transparent electrode material, the lower electrode is preferably provided with a base layer, which is a metal film, between the light modulation element 5 and the contact resistance is reduced. Further, the light modulation element 5 is laminated with the positions of the magnetization fixed layer 51 and the magnetization inversion layer 53 interchanged. Further, the substrate is made of a transparent substrate material such as SiO ₂ , Al ₂ O ₃ , MgO or the like so that light enters the pixel 4 from below and light emitted from the pixel 4 is irradiated again downward. Consists of. The spatial light modulator according to the second embodiment is arranged on the display device 10 (see FIG. 6) by inverting the top and bottom (front and back) of the pixel array 40 and arranging the substrate side facing the light source 91 and the like. Can be used.

(Third embodiment of spatial light modulator and display device)
In the spatial light modulator according to the present invention, as yet another embodiment (third embodiment), as shown in FIG. 7, the upper electrode 2 and the lower electrode 3A are both made of a transparent electrode material, and the transmission type The spatial light modulator 1A may be used. At this time, the substrate 7A is made of the transparent substrate material described in the second embodiment so that light transmitted through the pixel 4A from above is further irradiated downward. Further, the light modulation element 5 may be stacked by switching the positions of the magnetization fixed layer 51 and the magnetization switching layer 53. In the display device 10A using such a spatial light modulator 1A, the light source 91 and the incident polarization filter PF1 are disposed immediately above the pixel array 40A, and the output polarization filter PF2 and the detector 93 are disposed immediately below the pixel array 40A. The incident angle can be 0 °. Further, the spatial light modulator 1A may be arranged in the display device 10A by inverting the top and bottom of the pixel array 40A.

(Modification of Embodiment of Spatial Light Modulator)
Further, as respective modifications of the spatial light modulators according to the first to third embodiments, the upper electrode and the lower electrode that are made of a transparent electrode material and transmit light, and the wiring portion is a light modulation element as an electrode metal material. A hole may be formed in a region overlapping with 5 in plan view, and a transparent electrode material may be provided only inside the hole (not shown). By using such an electrode, light can be incident on the light modulation element 5 using a low-resistance metal material, so that voltage drop due to wiring resistance can be suppressed to save power and reduce variation in operation between pixels. it can.

  As described above, according to the spatial light modulators according to the embodiments of the present invention and the modifications thereof, pixel selectivity can be achieved using a spin-injection magnetization reversal element capable of high-definition and high-speed response as a light modulation element. An excellent spatial light modulator. The display device according to the embodiment of the present invention using such a spatial light modulator can display a high-definition and clear image at a high display speed.

[Holography device]
Next, a holography apparatus according to an embodiment of the present invention will be described with reference to FIG. The holography device according to the embodiment of the present invention is obtained by changing a part of the configuration of the display device 10 (see FIG. 6) according to the embodiment of the present invention so as to project a hologram. The same elements as those of the display device 10 are denoted by the same reference numerals, and the description thereof is omitted.

  A holography device 11 according to an embodiment of the present invention includes a signal generation unit including an imaging unit such as a CCD camera 94 that images an interference fringe formed by reference light and object light of a subject and converts the image into an image signal. The image reproduction unit includes the spatial light modulator 1 according to the first embodiment of the present invention, which receives the image signal and reproduces the image (hologram) of the subject. The image reproducing unit further includes a light source 91 and polarizing filters PF1 and PF2 on the light incident / exit side of the pixel array 40 of the spatial light modulator 1. That is, the image reproducing unit has a configuration in which the detector 93 (image display means) is removed from the display device 10, and, similar to the display device, the spatial light modulator according to the second and third embodiments (see FIG. 7). Can also be applied. On the other hand, the signal generation unit further includes a light source 92 for obtaining interference fringes, half mirrors HM1 and HM2, and a mirror for reflecting light in a predetermined direction. The light source 92 is configured using a laser light source similar to that used in the display device 10 together with the light source 91 of the image reproduction unit.

  The holography device 11 according to an embodiment of the present invention divides the light emitted from one light source 92 into two systems of illumination light for the subject and reference light by the half mirror HM1, in the signal generation unit, Interference fringes are formed by superimposing the object light, which is reflected light from the subject of the illumination light, and the reference light on the half mirror HM2. The interference fringes are imaged by the CCD camera 94 and converted into an interference fringe pattern image signal (image signal), and this image signal is input to the pixel selector 84 (see FIG. 5) of the spatial light modulator 1. In the image reproducing unit, the spatial light modulator 1 optically modulates incident light from the light source 91 (further incident polarized light via the incident polarization filter PF1) based on the image signal, thereby outputting outgoing light (further outgoing polarized light). The light transmitted through the filter PF2) becomes a hologram. The holography device according to the embodiment of the present invention can perform light modulation corresponding to the interference fringe pattern image signal by using the spatial light modulator according to each embodiment of the present invention capable of high-speed response.

[Hologram recording device]
Next, a hologram recording apparatus according to an embodiment of the present invention will be described with reference to FIG. The same elements as those of the display device 10 (see FIG. 6) and the holography device 11 (see FIG. 8) are denoted by the same reference numerals, and the description thereof is omitted.

  The hologram recording apparatus 12 according to an embodiment of the present invention includes a light source 92, a spatial light modulator that optically modulates each of the half mirror HM1 and the two light beams that divide the light emitted from the light source 92 into two light beams. A CMOS camera (imaging means) that detects phase information by imaging disturbance of the wavefront when the hologram recording medium (recording medium) M is irradiated with the light emitted from the spatial light modulators 1a and 1b and the spatial light modulators 1a and 1b. 95. In the present embodiment, the spatial light modulators 1a and 1b have the same configuration as the spatial light modulator 1 according to the first embodiment of the present invention, respectively, or the spatial light modulators according to the second and third embodiments ( (See FIG. 7). The hologram recording medium M is made of, for example, a photopolymer material that is held between two glass plates.

  In the hologram recording device 12, one of the two systems of light divided in the same manner as in the holography device 11 is optically modulated into signal light by using the two-dimensional page data from the outside as an input signal by the first spatial light modulator 1a. The other reference light is optically modulated by the second spatial light modulator 1b using the phase information as an input signal, and the hologram recording medium M is simultaneously irradiated with the light-modulated reference light and the signal light for recording. Further, the hologram recording device 12 outputs the wavefront disturbance in the hologram recording medium M as phase information by the CMOS camera 95, and inputs this phase information to the second spatial light modulator 1b in real time to influence the disturbance of the wavefront. Feedback to cancel is possible.

[Imaging device]
Next, an imaging apparatus according to an embodiment of the present invention will be described with reference to FIG. The imaging apparatus according to the embodiment of the present invention is obtained by applying the spatial light modulator 1 (see FIGS. 5 and 6) according to the first embodiment of the present invention to the imaging apparatus. The same elements as those of the spatial light modulator 1 and the display device 10 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 10, the imaging device 13 according to an embodiment of the present invention includes a pixel array 40 including a plurality of pixels 4 including the light modulation elements 5 according to the first embodiment of the present invention, and a pixel array 40. A current control unit 80 that selects and drives one or more pixels 4 from the above, an output polarization filter (polarizer) PF2 that transmits polarized light in a specific direction, and a photoelectric conversion unit (photoelectric conversion means) that converts light into charges ) 96, a charge storage unit (charge storage unit) 97 for storing charges, and a charge / video signal conversion unit 98 for converting charges into signals. That is, the imaging device 13 includes a pixel array 40 and a current control unit 80 that constitute the spatial light modulator 1 according to the first embodiment of the present invention, and these configurations are the same as those of the spatial light modulator 1 shown in FIG. A schematic plan view can be referred to.

  The pixel array 40 (pixel 4) and the current control unit 80 have the same configurations as those in the spatial light modulator 1 shown in FIG. The outgoing polarization filter PF2 is a filtering means that receives light emitted from the pixel array 40 and transmits only the light emitted from the selected pixel 4, and is polarized in the same manner as that used in the spatial light modulator 1. It consists of a plate. The photoelectric conversion unit 96 converts light that has passed through the output polarization filter PF2 into electric charges, and includes a photodiode or the like. The charge storage unit 97 stores the charge converted by the photoelectric conversion unit 96 and includes a capacitor and the like. In addition, the charge storage unit 97 is connected to the pixel selection unit 84 of the current control unit 80 and stores information for specifying the pixel 4 corresponding to the stored charge. The charge / video signal conversion unit 98 converts the charge released by the charge storage unit 97 into an electrical signal (video signal) in association with the information specifying the pixel 4. The outgoing polarization filter PF2, the photoelectric conversion unit 96, the charge storage unit 97, and the charge / video signal conversion unit 98 may be respectively by known means. As described above, the pixel 4 in the imaging device 13 according to the embodiment of the present invention includes only the light receiving unit, and like a conventional pixel (imaging device) made of CMOS or the like, the photoelectric conversion unit and the charge storage unit are respectively provided. It is not necessary to provide further. The pixel selection in the imaging device 13 scans the pixel 4 that performs imaging, that is, photoelectric conversion of the emitted light. For example, the pixel 4 is shifted in the pixel array 40 and selection and deselection are repeated. The pixel selection method performed by the current control unit 80 is the same as that in the spatial light modulator 1 according to the first embodiment, and a description thereof will be omitted.

  Next, details of the configuration of the imaging apparatus according to an embodiment of the present invention will be described with reference to FIG. As illustrated in FIG. 11, the imaging device 13 further transmits the incident polarization filter PF1 that polarizes the light (incident light) before entering the pixel 4 and the output polarization filter PF2 in addition to the block diagram illustrated in FIG. 10. A condensing lens 99 that collects light so as to enter the photoelectric conversion unit 96 is provided. The imaging device 13 is a reflection type like the spatial light modulator 1, and these elements are arranged above the pixel array 40. In the imaging device 13, a subject (imaging target) is arranged on the light incident surface instead of the light source 91 of the display device 10. In FIG. 11, the charge storage unit 97, the charge / video signal conversion unit 98, and the protective layer 54 (see FIG. 1) of the light modulation element 5 are not shown.

  The pixel selection operation of the imaging device 13 will be described with reference to FIG. Since the reflected light from the subject, ie, the subject light contains various polarization components, it is transmitted through the incident polarization filter PF1 to be incident polarization of one polarization component. Incident polarized light enters the pixel 4 at a predetermined incident angle, passes through the upper electrode 2, reflects off the surface of the light modulation element 5 or the lower electrode 3, passes through the upper electrode 2 again, and exits the polarization filter PF 2. To reach. The outgoing polarization filter PF2 transmits only the outgoing polarized light from the selected pixel 4 shown in the center in FIG. 11, that is, the polarized light whose angle θap is rotated with respect to the incident polarized light, and the transmitted outgoing polarized light is condensed by the condenser lens 99. Then, it enters the photoelectric conversion unit 96 and is converted into electric charge. The rotation of the polarized light emitted from the pixel 4 (light modulation element 5) is as described in the first embodiment of the light modulation element 5. As described above, since the light incident on the photoelectric conversion unit 96 is light emitted only from the pixel 4 selected at that time, one photoelectric conversion unit 96 may be provided in the imaging device 13. There is no need to prepare for. The incident polarizing filter PF1 is composed of a polarizing plate or the like, like the outgoing polarizing filter PF2. Further, the condensing lens 99 only needs to be able to condense light emitted from any pixel 4 of the pixel array 40 so as to enter the photoelectric conversion unit 96, and may be configured by a plurality of lenses.

  Although the imaging apparatus 13 according to the present embodiment is shown as a reflective imaging apparatus that includes the spatial light modulator 1 according to the first embodiment and captures the upper subject light, it will be described as a second embodiment of the display apparatus. As described above, when the spatial light modulator according to the second embodiment is provided, the pixel array 40 of the spatial light modulator may be arranged upside down. Furthermore, as described in the third embodiment of the display device, a transmissive imaging device including the transmissive spatial light modulator 1A according to the third embodiment may be provided. In this case, similarly to the display device 10A (see FIG. 7), the output polarization filter PF2 is disposed immediately below the pixel array 40A, and further, the condenser lens 99 and the photoelectric conversion unit 96 are disposed immediately below (not shown). ). Moreover, although the imaging device 13 includes the light modulation element 5 according to the first embodiment as an image pickup element, similarly to the pixels of the spatial light modulator, the light modulation elements 5A, 5B, and 5B according to the second to fourth embodiments. Any of 5C and variations thereof can be applied.

  As described above, according to the imaging apparatus according to the embodiment of the present invention, since the difference in the optical rotation angle is large between selection and non-selection of the pixel, the imaging apparatus is excellent in pixel scanning performance.

  As mentioned above, although each embodiment for implementing the light modulation element, the spatial light modulator, the display device, the holography device, the hologram recording device, and the imaging device of the present invention has been described, the present invention is limited to these embodiments. However, various modifications are possible within the scope of the claims.

  In order to confirm the effect of the present invention, a sample of the light modulation element (see FIG. 1) according to the first embodiment of the present invention shown in Example 1 of Table 1 was prepared, and its Kerr rotation angle θk and coercive force Hcf , Hcp was evaluated. The unit of film thickness shown in Table 1 is nm. On the magnetization reversal layer, Ru was laminated as a protective layer (see FIG. 1) with a thickness of 3 nm, Cu was applied to the lower electrode, and IZO was applied to the upper electrode. In addition, in order to evaluate by measuring the angle of rotation of the reflected light, processing by photolithography or the like was not performed, and a film was continuously formed from the lower electrode to the upper electrode by a DC magnetron sputtering method. Similarly, as a comparative example, a sample of a light modulation element having the configuration shown in Table 1 was produced. Comparative Example 1 has the same perpendicular magnetic anisotropy as Example 1, and Comparative Example 2 has in-plane magnetic anisotropy, both of which have a GMR structure.

  By applying a uniform magnetic field from the outside to the manufactured sample, the magnetization direction of the magnetization fixed layer and the magnetization inversion layer was set to one direction. Then, blue laser light having a wavelength of 405 nm was incident at an incident angle of 30 °, and the optical rotation angle of the reflected light from the sample was measured with a vertical magnetic field micro-Kerr effect measuring device (manufactured by Neoarc Corporation). Next, while continuing the measurement of the optical rotation angle of the reflected light, a magnetic field in the direction opposite to the applied magnetic field is applied while increasing the magnitude, thereby reversing the magnetization of the magnetization reversal layer and reflecting from the sample. The optical rotation angle at which the light changed was measured. Table 1 shows the difference in optical rotation angle due to magnetization reversal as the change amount 2θk of the Kerr rotation angle. In Example 1, the magnetic field was continuously increased and applied until the optical rotation angle of the reflected light changed again, that is, until the magnetization of the magnetization fixed layer was reversed.

  As shown in Table 1, in Example 1, which is a sample of the light modulation element 5 according to the first embodiment of the present invention, the magnetization reversal layer 53 is formed of a Co / Pd multilayer film, so that in-plane magnetic anisotropy is achieved. As a matter of course, a larger Kerr rotation angle θk than that of Comparative Example 1 having the same perpendicular magnetic anisotropy was obtained.

Further, for Example 1, the coercive forces Hcf: 750 Oe and Hcp: 1700 Oe were obtained from the magnitudes of the applied magnetic fields when the magnetizations of the magnetization switching layer 53 and the magnetization fixed layer 51 were reversed. As described above, the magnetization reversal layer 53 is thinner than the magnetization fixed layer 51 as a whole, the Co film single layer is thick, and the Pd single layer is thin (t _Cof > t _Co p, t _Pd f <t _Pd p) is configured so that the coercive force Hcf of the magnetization reversal layer 53 is sufficiently smaller than the coercive force Hcp of the magnetization fixed layer 51, and the light can be reversed in magnetization at a low current. The modulation element 5 was obtained.

  Furthermore, in order to confirm the conditions for further enhancing the effect of the present invention, with respect to the sample of Example 1 shown in Table 1, each of the Pd film and the Co film in the Co / Pd multilayer film constituting the magnetization switching layer 53 is shown. Samples with different single layer thicknesses were prepared, and their coercive force and Kerr rotation angle were measured.

The magnetization fixed layer 51 and the intermediate layer 52 are the same as those in Example 1 shown in Table 1, and the Co / Pd multilayer film constituting the magnetization switching layer 53 is laminated by repeating the Co film and the Pd film five times. did. Incidentally, Co film single layer of thickness t _Co film thickness of f Pd film single layer in the sample with varying t _Pd f: 0.8 nm in fixed, by changing the thickness t _Pd f Pd film monolayer In the sample, the thickness of the single Co film layer was fixed at t _Cof : 0.3 nm.

With respect to the manufactured sample, the magnetization reversal optical rotation angle was measured in the same manner as in Example 1, and the Kerr rotation angle θk and the coercive force Hcf of the magnetization reversal layer 53 were measured. Coercivity Hcf and Kerr rotation angle θk of the magnetization reversal layer 53, the thickness t _Pd f dependency graph thickness t _Co f dependence and Pd film of the Co film 12, shown in FIG. 13.

FIG. 12 (a), the (b), the coercive force Hcf of the magnetization reversal layer 53, as the thickness t _Co f of the Co film monolayer thick, also has a film thickness t _Pd f Pd film monolayer The thinner, the smaller. On the other hand, as shown in FIGS. 13A and 13B, the Kerr rotation angle θk increases as the Co film single layer thickness t _Cof increases and the Pd film single layer thickness t _Pd f decreases. It ’s bigger. When the film thickness t _Pd f of the single Pd film layer is thin, the Kerr rotation angle θk increases because the Pd film having a high reflectivity becomes thin and more light is transmitted to the Co film below it. This is considered to be incident. As described above, the light modulation element 5 according to the first embodiment of the present invention controls the magnetization inversion layer 53 and the magnetization by controlling the thickness of each of the Co film and the Pd film of the Co / Pd multilayer film. It is easy to make the difference in coercive force with the fixed layer 51 preferable and increase the Kerr rotation angle θk.

DESCRIPTION OF SYMBOLS 1,1A Spatial light modulator 10, 10A Display apparatus 11 Holography apparatus 12 Hologram recording apparatus 13 Imaging apparatus 40, 40A Pixel array 4, 4A Pixel 2 Upper electrode 3, 3A Lower electrode 5, 5A, 5B, 5C Light modulation element 51 , 51A, 51B Magnetization fixed layer 511 Transition metal film (metal film)
52 Intermediate layer 53, 53A, 53B Magnetization inversion layer 531 Transition metal film (metal film)
54 Protective layer 6 Insulating member 7, 7A Substrate 80 Current control unit 81 Power supply (current supply means)
84 Pixel selection unit (pixel selection means)
91, 92 Light source 93 Detector (image display means)
94 CCD camera (imaging means)
95 CMOS camera (imaging means)
96 Photoelectric conversion part (photoelectric conversion means)
97 Charge storage unit (charge storage means)
PF1 incident polarizing filter PF2 outgoing polarizing filter (polarizer)

Claims (12)

A magnetization pinned layer, an intermediate layer, and a magnetization reversal layer having a coercivity smaller than that of the magnetization pinned layer are stacked in this order, and current is supplied from electrodes connected to the top and bottom of the magnetization reversal layer. A light modulation element that changes the magnetization direction and emits incident light by changing its polarization direction,
At least one of the magnetization fixed layer and the magnetization switching layer is a multilayer film in which Pd films and Co films are alternately stacked. The magnetization fixed layer and the magnetization switching layer are multilayer films in which Pd films and Co films are alternately stacked,
The light modulation element according to claim 1, wherein the Co film in the magnetization switching layer is thicker than the Co film in the magnetization fixed layer. The magnetization fixed layer and the magnetization switching layer are multilayer films in which Pd films and Co films are alternately stacked,
3. The light modulation element according to claim 1, wherein the Pd film in the magnetization switching layer has a smaller thickness than the Pd film in the magnetization fixed layer. 4.   One of the magnetization fixed layer or the magnetization switching layer is a multilayer film in which Pd films and Co films are alternately stacked, and the other is a transition metal selected from Fe, Co, Ni, and Sm, Eu, Gd, Tb. The light modulation element according to claim 1, wherein the light modulation element is made of an alloy with a rare earth metal selected from the group consisting of:   At least one of the magnetization fixed layer and the magnetization switching layer is a multilayer film in which Pd films and Co films are alternately stacked, and the Co film is stacked at an interface with the intermediate layer. The light modulation element according to any one of claims 1 to 4.   At least one of the magnetization fixed layer and the magnetization switching layer further includes a metal film made of at least one transition metal selected from Fe, Co, and Ni or an alloy containing the transition metal at an interface with the intermediate layer. The light modulation element according to any one of claims 1 to 4, further comprising: A plurality of pixels arranged two-dimensionally, pixel selection means for selecting one or more pixels from the plurality of pixels, and current supply means for supplying a predetermined current to the pixels selected by the pixel selection means. A spatial light modulator that reflects and changes the polarization direction of the light incident on the pixel selected by the pixel selection means in a specific direction,
The pixel includes the light modulation element according to any one of claims 1 to 6, and an upper electrode and a lower electrode that supply current to the light modulation element,
One of the upper electrode and the lower electrode includes a transparent electrode material and transmits light incident on the pixel and light emitted from the light modulation element, and the other is formed of a metal electrode. . A plurality of pixels arranged two-dimensionally, pixel selection means for selecting one or more pixels from the plurality of pixels, and current supply means for supplying a predetermined current to the pixels selected by the pixel selection means. A spatial light modulator that changes the polarization direction of light incident on the pixel selected by the pixel selection means to a specific direction and transmits the light;
The pixel includes the light modulation element according to any one of claims 1 to 6, and an upper electrode and a lower electrode that supply current to the light modulation element,
The upper electrode and the lower electrode include a transparent electrode material, and one of the upper electrode and the lower electrode transmits light incident on the pixel, and the other transmits light emitted from the light modulation element. A featured spatial light modulator.   A display device comprising: the spatial light modulator according to claim 7 or 8; and image display means for projecting light emitted from the spatial light modulator.   The imaging unit according to claim 7 or 8, wherein an imaging unit that images an interference fringe formed by the object light and the reference light and converts the image into an image signal, and the light that is input and emitted from the image signal is used as a reproduced image. And a spatial light modulator. A hologram recording apparatus for recording information on a recording medium using signal light and reference light,
Imaging means for detecting, as phase information, a state change in the recording medium when the signal light and the reference light are incident on the recording medium; and at least one of the signal light and the reference light based on the phase information A hologram recording apparatus comprising: the spatial light modulator according to claim 7, which performs light modulation.   The spatial light modulator according to claim 7 or 8, further comprising: a polarizer that transmits light emitted from a pixel selected by the pixel selection unit; and a photoelectric that converts light transmitted through the polarizer into an electric charge. An imaging apparatus comprising: a converting unit; and a charge accumulating unit that accumulates the electric charge, and images subject light incident on the two-dimensionally arranged pixels.

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