JP2007071615A - Surface plasmon resonance angle spectrum measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize and weight-reduce surface plasmon resonance measuring device having a highly-integrated/parallel detection mechanism. <P>SOLUTION: In this surface plasmon resonance angle spectrum measuring device, a material onto the metal surface is detected by surface plasmon polariton resonance. The device is characterized by having an angle measuring mechanism 4 for measuring a resonance coupling angle from the locus of a beam in an imaged image by combining a two-dimensional plane waveguide 6 comprising one or more layers of metal films and one or more layers of dielectric films with an imager. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention was developed by applying optical waveguide and optical circuit fabrication technology, enables small, light and highly integrated parallel analysis, and analyzes electrochemical reactions such as interactions between biomolecules such as DNA, proteins, sugar chains, etc. / It relates to a surface plasmon resonance angle spectrum measuring apparatus for measuring surface plasmon resonance used for gas component analysis.

  Surface plasmon polariton is a surface wave mode of light generated on a metal surface, and the light wave is localized as an evanescent field in the immediate vicinity of the metal surface due to the resonance phenomenon of conduction electron density wave and incident light on the metal surface. (See, for example, Non-Patent Document 1). The state of the light wave that has become surface plasmon polariton, such as phase and field distribution, changes sensitively if the surface state changes, so that sample substances (molecules, etc.) are adsorbed and desorbed near the metal surface, or on the metal surface. Selective binding / dissociation with a fixed binding species can be detected (see, for example, Non-Patent Document 2).

  Therefore, surface plasmon resonance can sensitively detect changes in the state near the metal surface, and can measure physiological, biochemical, chemical or physical measurements without changing the physiological state by labeling or the like. It is applied to the measurement of adsorption / desorption or bonding / dissociation of substances, phase transitions and structural changes (see, for example, Patent Document 1).

  The basic structure of a conventional surface plasmon resonance sensor is as shown in FIG. 1. A prism coupling portion having a dimension of about 0.5 to 10 cm and an arrangement surrounding the prism coupling portion are attached with a light source, and a light beam is incident. Then, surface plasmon polariton is generated in the sensor detection part on the surface of the metal thin film. When the phase between the incident light and the surface plasmon polariton is matched, the incident light is converted into the surface plasmon polariton and distributed on the metal surface, so that the reflected light intensity decreases accordingly. This decrease in reflected light intensity is called total reflection attenuation (ATR). If the sample part is adsorbed / detached or bound / dissociated in the detection part, the equivalent refractive index in the vicinity of the detection part changes, so the phase matching condition between the incident light and the surface plasmon polariton also changes, and the ATR intensity changes. appear. In detail, spectrum measurement is performed to detect changes in ATR intensity, real-time measurement of attenuation peak change in the spectrum, adsorption / desorption, binding / dissociation from sample detector, or structural changes such as phase transition and molecular orientation. And the speed coefficient thereof can be obtained.

  In a conventional surface plasmon resonance sensor, a prism coupling portion and an angle measuring mechanism that determines an incident angle and a detection angle occupy a large proportion of the volume and weight of the entire apparatus. In order to realize highly accurate measurement, it is necessary to sweep the incident angle and detection angle with an accuracy of 0.01 ° or less without causing the light incident position and defocusing. The basic configuration alone cannot avoid increasing the volume and weight of the device. In addition, when performing measurement at the same time with sensor detectors arranged in parallel on the substrate in order to investigate the characteristics of the sample under multiple conditions at high speed, such as screening measurement, light incidence / measurement via the prism coupling part is performed. Since it becomes a corner, it is difficult to adjust the measurement so that the same irradiation condition is measured at an arbitrary position on the substrate, and the measurement includes a difference due to variation in the light irradiation condition such as the irradiation beam diameter at each measurement position. Therefore, it is difficult to implement highly integrated and parallel measurement in which the validity of analysis results is guaranteed.

JP 2005-98788 A Fukui Manjuo and Otsu Motoichi Basics of Optical Nanotechnology Ohmsha 2003 Rokusha Hitoshi Introduction to Biosensor Corona Corporation 2003 D. F. Pile and D. K. Gramotnev, Channelplasmon &#8211; polarito in a triangular groove on a metal surface, Optics Letters, Vol. 29 No. 10 (2004) p.1069 Hiroshi Nishihara, Masamitsu Haruna, Toshiaki Sugawara Optical Integrated Circuits (Revised Supplement) Ohmsha 1993

  In view of the above-described problems, the surface plasmon resonance measuring apparatus is required to have a limited number of places where the apparatus can be placed without taking up volume and weight in order to expand the application area of ATR angle spectrum measurement. In order to perform measurement under a large number of conditions in parallel on the same substrate, it is required that a plurality of sensor detection units that can be measured under the same conditions can be arranged on the substrate in a highly integrated manner.

  Therefore, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a surface plasmon resonance measurement apparatus having a small and light surface plasmon resonance measurement apparatus and a highly integrated / parallel detection mechanism.

The features of the present invention, which is a means for solving the above problems, are listed below.
The surface plasmon resonance angle spectrum measuring apparatus of the present invention is a surface plasmon resonance angle spectrum measuring apparatus for measuring surface plasmon polariton resonance of a substance on a metal surface, wherein one or more dielectric films are provided on one or more metal films. The dielectric film includes an input optical coupling unit, a two-dimensional planar waveguide, and a detection unit, and an angle measuring mechanism that measures a resonance coupling angle from a ray trajectory in the dielectric film. .
Furthermore, the surface plasmon resonance angle spectrum measuring apparatus of the present invention is characterized in that the detection unit has a groove or hole structure arranged in a straight line, and the detection is performed on the bottom and side surfaces thereof.
Furthermore, the surface plasmon resonance angle spectrum measuring apparatus of the present invention is characterized in that a linear shape of a groove or hole structure arranged in a straight line is used as a reference line at the time of angle measurement.
Furthermore, in the surface plasmon resonance angle spectrum measuring apparatus of the present invention, in order to bend the propagation direction of the guided light beam in the planar waveguide in a specific direction, a dielectric region having a different refractive index is formed in the dielectric film surface. These are arranged so that their interfaces are represented as quadratic curves, and the waveguide light bent by the refraction phenomenon has a mechanism for converging on a part of the detection unit.
Further, the surface plasmon resonance angle spectrum measuring apparatus according to the present invention employs a mechanism that functions as a coupling portion on the side end face of the structure composed of a dielectric and a groove as an input optical coupling portion for coupling a guided light beam into a two-dimensional waveguide. It is characterized by that.
Further, the surface plasmon resonance angle spectrum measuring apparatus of the present invention, a dielectric core structure adjacent the groove considered pair, the phase matching condition for binding to guided _{light: K + k illum · sinθ ≒} n ave · k illum (where, K is 2 [pi / (a set of grooves and the dielectric value of the cross-section sum of the width), k _illum at wave number of the external incident light from the sum of the product of n _ave respective refractive index and the volume fraction It is characterized by satisfying the relationship of a value obtained by multiplying the obtained average refractive index by a correction term (0.9 to 1.1).
Furthermore, the surface plasmon resonance angle spectrum measuring apparatus of the present invention is characterized in that the beam diameter of the input coupled light beam to the input optical coupling unit is 1 to 10 times the interaction length of the input optical coupling unit.
Further, in the surface plasmon resonance angle spectrum measuring apparatus according to the present invention, the metal film is mainly composed of elements of Ag, Cu, Au, and Pt, and the dielectric film is a transparent dielectric, which is an oxide, fluoride, or It is an organic polymer.

  As described above, according to the surface plasmon resonance angle spectrum measuring apparatus of the present invention, the two-dimensional in-plane arrangement of the sensor optical system is achieved by using the bottom surface and side surface of the groove or hole in the planar waveguide core as the detection unit. Is possible, and a simple configuration can be obtained. For this reason, the effect of facilitating the design and manufacture of the waveguide control of the light beam and the input light coupling portion with the outside can be obtained. In the conventional ATR angle spectrum detection method as shown in FIG. 1, if the optical axis of the incident light is not on the vertical section of the detector plane, the polarization or spot size of the incident light changes when the incident angle is changed, When the optical axis deviates from the reflected light detector, it becomes an error factor for peak angle detection. However, by adopting a planar waveguide, the optical axis is always kept parallel to the planar waveguide. An effect that does not occur is obtained. In addition, since it can be easily combined with a channel formed on a substrate, the present invention can be used in various fields such as a chemical chip and a biological chip. The spot size of the light beam is suppressed to about the thickness of the waveguide. Further, by realizing a sensitivity distribution below the diffraction limit of light, such as one-dimensional plasmon polaritons, an improvement in sensitivity for detecting a very small amount of sample can be expected.

  Further, according to the surface plasmon resonance angle spectrum measuring apparatus of the present invention, the deflection angle is built in the planar waveguide, so that the incident angle to the detection unit can be swept without changing the incident angle of the external incident light. It becomes. This eliminates the need for using a large angle measuring instrument, so that the effect of developing a smaller and lighter device can be obtained.

Further, according to the surface plasmon resonance angle spectrum measuring apparatus of the present invention, the input optical coupling unit 3 is formed in the planar waveguide, so that it is highly efficient without using a large prism coupling unit or a waveguide alignment mechanism. Guided light can be coupled. Since the lower surface of the core is made of metal, there is no coupling diffraction toward the substrate side, and the effect of increasing the coupling efficiency of light input / output from the upper surface of the core can be obtained as compared with the case where there is no metal film. In addition, by making the difference in refractive index between the groove and the dielectric structure large, it is possible to make a coupling part with a short interaction length, which makes it possible to make a compact coupling part, and because the groove is thinner than the wavelength of light, external incidence An effect of relaxing the condition for the incident angle of optical coupling can be obtained.
Since the light is input from the upper surface of the core, the coupling portion can be arranged at an arbitrary position in the planar waveguide. Therefore, the degree of freedom in designing the angular spectrum measurement mechanism can be increased as compared with the prism coupling and end surface coupling mechanisms. Since the dimension is only about 1 μm to 1 mm per side per coupling portion, the effect of facilitating sensor integration and parallelization can be obtained.

Moreover, according to the surface plasmon resonance angle spectrum measuring apparatus of the present invention, the angle spectrum information can be obtained by directly reading the locus of the light beam. The conventional ATR angle spectrum detection method using a prism coupler requires precise adjustment of the optical system such as the position and tilt of the measurement surface. In the present invention, an effect of reducing adjustment at the time of measurement can be obtained by strictly designing and producing a deflection mechanism and a coupling portion at the time of manufacture.
In addition, since the irradiation spot size and the irradiation position at the time of measurement can be directly observed and evaluated while checking their influence on the ATR peak angle fluctuation, an effect of improving the reliability of the measurement result can be obtained.
There is an effect that it is possible to combine with other microspectroscopic techniques such as measurement only in combination with image processing or image measurement technology by a computer, and distribution measurement of fluorescence, absorption, and surface enhanced Raman scattering signals.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 2 is a perspective view showing an embodiment of the present invention. FIG. 3 is a cross-sectional view showing an embodiment of the present invention. According to the surface plasmon resonance angle spectrum measuring apparatus of the present invention, the arrangement of the surface plasmon resonance detection unit and the coupling unit and the method for detecting the ATR angle spectrum are shown in FIG. It comprises a metal 5-dielectric planar waveguide 6 as shown in a perspective view, a detection unit 1, an in-plane bending mechanism 2 and an input optical coupling unit 3 incorporated therein, and further a surface plasmon resonance angle spectrum measuring apparatus. It comprises a microscope and an imager and includes an angle measuring mechanism 4.
The outline of the measurement by the surface plasmon resonance angle spectrum measuring apparatus is as follows. In order to detect the adsorption / desorption or binding / dissociation of the sample at the detection unit 1 in FIGS. Light) 7 is converted into a guided light beam by the input light coupling unit 3, and the light beam is converted into a specific incident angle by the in-plane bending mechanism 2 and irradiated to the detection unit 1. The incident position of the externally incident light beam (mainly laser light) 7 is swept horizontally along the coupling unit 3, and the response characteristics of the light beam such as reflection and transmission at the detection unit 1 for each incident angle are observed by the angle measuring mechanism 4. Then, the resonance coupling angle is measured.

In the surface plasmon resonance angle spectrum measuring apparatus of the present invention, the arrangement configuration of the structure functioning as the detection unit 1 in the structure of the two-dimensional planar waveguide 6 has been invented. Here, the surface plasmon resonance angle spectrum measuring apparatus means that one or more transparent dielectrics (SiO ₂ , MgF ₂ , etc.) are formed on the metal film 5 on which one or more metals (Ag, Au, Cu, Al, etc.) are deposited. A planar waveguide 6 made of an organic material such as an inorganic compound or a polymer is deposited, and guides light using a transparent dielectric as a waveguide core. The metal film may be one or more layers. Similarly, the dielectric film 6 may have one or more layers. In particular, in order to function as the planar waveguide 6, a waveguide mode cutoff is selected depending on the refractive index and thickness of the dielectric film 6, and the thickness and refractive index distribution suitable for each measurement can be adjusted. . When the polarization of the waveguide mode excited in the waveguide 6 is defined, a TM mode having an electric field component perpendicular to a TE mode having an electric field component parallel to the plane of the waveguide 6 can be considered. In the present invention, it is preferable to use the lowest order mode of each polarization of TE and TM. The polarization of the waveguide mode can be controlled by the polarization state of the incident light.

A groove or hole structure is formed in the planar waveguide 6, and the side and bottom surfaces thereof are used as the detection unit 1. The detection unit 1 is open so that the sample can be adsorbed / detached or combined / dissociated, and the measurement itself can be performed on a solid, but fills a gas or liquid containing the sample. FIG. 4 is a plan view and a cross-sectional view showing an embodiment of the detection unit of the present invention. As shown in FIG. 4, a linear groove 1 structure is formed in the planar waveguide 6, and the sample solution is put into the groove 1 for use.
Moreover, FIG. 5 is the top view and sectional drawing which show one Embodiment of the detection part of this invention. As shown in FIG. 5, the gas sample is detected and adsorbed / separated by being arranged in a number of detection units 1 having a fine pore structure. The propagation constant and field distribution of the surface plasmon polariton generated in the detector 1 are different depending on the polarization component of the waveguide mode, and the detection sensitivity and sensitivity distribution are different. When the waveguide mode is a TM component, the TM lowest order mode has the same field distribution and propagation constant as the surface plasmon polariton due to the metal film 5 on the lower surface of the core.・ Leaving will be observed.
Moreover, FIG. 6 is the top view and sectional drawing which show one Embodiment of the detection part of this invention. When the guided mode is a TE component, a metal (Au, Ag, etc.) film thinner than the skin thickness (1 to 60 nm) is deposited on the side surface of the detection unit 1 as shown in FIG. Measurement configuration. In this case, the adsorption / detachment of the sample in the vicinity of the side end face film is detected. Further, when the metal films 5 on the side end surfaces and the lower surface are used as the detection unit 1 as shown in FIG. 6, there is also a one-dimensional plasmon polariton mode having a field distribution localized one-dimensionally at the corners of the detection unit 1.
By selecting the form of the detector 1 to be used and the waveguide mode, the detection sensitivity and the size of the sensitivity distribution can be adjusted.

Furthermore, in the surface plasmon resonance angle spectrum measuring apparatus of the present invention, a mechanism for easily executing the incident angle sweep to the detector 1 in the planar waveguide surface 6 is used for the angle spectrum measurement. Different refractive index regions in the waveguide 6 with a shape of a part of a quadratic curve (elliptic arc, parabola, hyperbola, etc.), or a shape close to a quadratic curve modified for dispersion correction and beam shape correction And using the light refraction phenomenon, the direction of travel of the light beam is changed and guided to the detection unit 1 at an arbitrary incident angle. As shown in FIG. 6, the guided light beam bends at the interface where the refractive index changes, satisfying the relationship of the following equation based on Snell's law.
n ₁ sinθ ₁ = n ₂ sinθ ₂ (1) (where n ₁ is the equivalent refractive index on the interface incident side, θ ₁ is the incident angle, n ₂ is the equivalent refractive index on the interface exit side, and θ ₂ is the exit angle) .)
By utilizing this phenomenon and arranging the detector 1 in the vicinity of the focal point of the quadratic curve in the planar waveguide, angular spectrum measurement can be performed with the incident angle of the external incident light source 7 fixed.

Furthermore, in the surface plasmon resonance angle spectrum measuring apparatus of the present invention, about 1 to 100 input optical coupling portions 3 having a groove-dielectric structure are provided for optical coupling of the metal 5-dielectric into the planar waveguide 6. By arranging them side by side, it is possible to obtain highly efficient incident light. In the present invention, this is referred to as the input optical coupling unit 3 for coupling from the side end face of the dielectric structure.
As shown in FIG. 2 or 3, a groove whose depth reaches the vicinity of the metal surface is formed at an arbitrary position in the planar waveguide 6, or a dielectric structure is fabricated with a material different from that of the planar waveguide 6. Thus, the input optical coupling unit 3 is used. Waveguide light (surface plasmon polariton when p-polarized light is incident) can be generated by making light incident at an appropriate beam diameter and incident angle on the side end of the dielectric core structure formed by the groove. It is assumed that the groove portion is occupied by a gas, liquid, or solid whose refractive index is smaller than that of the dielectric structure, such as vacuum or air. Normally, the groove portion is occupied by air having a refractive index close to 1 so that the refractive index difference between the groove and the dielectric core structure is as large as possible in order to make the coupling portion small and highly efficient.

External when the thickness of the dielectric core structure of the input optical coupling part 3 is sufficient (wavelength / [4 × refractive index of core material] or more) and the bottom of the groove reaches or is close to the metal layer A method for analyzing the phase matching condition between incident light and guided light is described. The groove and the adjacent dielectric core structure are considered as one set, and the average refractive index is obtained by the following equation using the volume fraction δ of the groove and the dielectric in the set.
n _ave = a [(δ−1) × n ₀ + δ × n ₁ ] (2) Equation (where δ = groove volume / (groove volume + dielectric volume), n ₀ is the material occupying the groove) N ₁ is the refractive index of the dielectric structure, a is a correction term for the equivalent refractive index, and is about 0.9 to 1.1 depending on the thickness of the core, the type of metal, the measurement wavelength, the mode, and the polarization. Using this, the incident light is converted into guided light by setting the incident angle, the groove and the length of the dielectric so as to meet the following phase matching relationship.
K + k _illum sin θ = n _ave k _illum (3) where K is 2π / (cross-sectional width of a pair of grooves and dielectric: refer to 8 in FIG. 3) and corresponds to the reciprocal lattice constant. _killum is the wave number of the external incident light, θ is the incident angle of the external incident light, and the right side represents the propagation constant of the guided light. Here, in the case where a plurality of grooves and dielectric core structures are arranged, the cross-sectional width and the arrangement interval are not necessarily constant, and the average refractive index obtained for one set of the grooves and the dielectric structures is expressed by Equation (3). A random structure satisfying this relationship may be used. Further, although the efficiency is inferior, only a pair of grooves and a dielectric core structure can be used as the input optical coupling unit 3. Furthermore, the end surface of the groove and the dielectric core structure may not be vertical, but the end surface may have an inclination. In particular, when the same structure is arranged at a constant period, it can be regarded as a diffraction grating coupler (grating coupler), and in this case, higher-order phase matching conditions can be similarly analyzed from the relationship of equation (3).
When the groove is shallower than the wavelength of the incident light, coupling with the guided light occurs even if the relationship of the expression (3) is not strictly satisfied, and the tolerance of each parameter at the time of implementation can be relatively large with respect to the design value. .

In order to improve the coupling efficiency, it is necessary to optimize the field distribution of the incident beam in combination with the phase condition (3), which is carried out by adjusting the beam diameter of the incident beam.
The optimum condition of the incident beam field distribution is a spatial distribution that is congruent with the field distribution of the outgoing light from the coupling portion 3, and the beam diameter of the incident light has the same size as the interaction length of the input optical coupling portion 3. By adjusting in this way, an input coupling efficiency of about 80% can be realized. Assuming that the radiation loss coefficient of the waveguide mode in the input optical coupling unit 3 at the time of output coupling is α _rad [μm ⁻¹ ], the incident light with a Gaussian distribution is obtained if the metal loss coefficient α _abs << α _rad due to metal absorption In this case, the maximum efficiency is obtained when the beam diameter is 1.3 to 1.4 × α _rad ⁻¹ . These relationships are the same as the diffraction grating coupling portion of the dielectric waveguide. Even for the matching of the electric field distribution, the incident light can be coupled to the guided light even if the above optimum conditions are not met. Rather, by using light rays that are slightly thicker than the optimum distribution, the effects of fluctuations in irradiation position due to vibration and creep due to incident light sweep drive, and the inclination of the substrate plane from the horizontal are alleviated, and measurement stability is maintained.

In the general usage of the coupling portion of the present invention, the linear input optical coupling portion 3 is arranged and used in a planar waveguide as shown in FIG. FIG. 7 is a plan view showing an embodiment of the in-plane bending mechanism and the input optical coupling portion of the present invention.
In this case, if the external incident light is swept linearly, the in-plane bending mechanism 2 can deflect the guided light beam to an arbitrary incident angle. FIG. 8 is a perspective view showing an embodiment of the in-plane bending mechanism 2 and the input light coupling portion of the present invention. The input light coupling portion 3 is arranged in a quadratic curve shape and also has the function of the bending mechanism 2. In order to bend the propagation direction of the guided light beam in the planar waveguide 6 in a specific direction, the in-plane bending mechanism 2 is configured to form dielectric regions having different refractive indexes in the surface of the dielectric film 6 and their interfaces. Are arranged so as to be expressed as a quadratic curve. With this arrangement, a refraction phenomenon of incident light occurs, and the bent guided light beam can be converged on a part of the detection unit 1.
As shown in FIG. 8, there is a method in which the input light coupling portion 3 is arranged in a quadratic curve shape so that both functions of the guided light input light coupling portion 3 and the incident angle bending are performed. In this case, the fabrication becomes easy and the angular spectrum measurement mechanism becomes smaller. However, it is necessary to sweep the external input light along a quadratic curve or to perform a raster scan in the plane including the input light coupling unit 3. It becomes. Specific examples of the quadratic curve shape include a circular arc shape, an elliptical shape, a parabolic shape, and a hyperbolic shape.

  In addition, in order to obtain angular spectrum information of the ATR intensity, a configuration in which the trajectory of the light beam in the planar waveguide 6 is detected by the angle measuring mechanism 4 is provided. The angle measuring mechanism 4 uses a CCD camera, a CMOS camera, a photodiode array, or the like. When the fine beam is propagated into the planar waveguide 6, bright lines are observed when observed from above the core surface of the planar waveguide. The bright lines are generated by scattering due to the surface roughness of the metal film 5 and the refractive index fluctuation in the core, and the metal mirror surface on the lower surface of the core makes it easy to observe the bright lines from the upper surface. With the configuration shown in FIGS. 2 and 3, an enlarged image is observed using a lens, and the angle spectrum analysis is performed by measuring the emission line intensity of the resonance coupling light component and the reflected / transmitted light component generated in the detection unit 1. Can be done. In this case, if there is a structure serving as a reference when measuring the incident angle and the transmission / reflection angle, such as the detection unit 1 arranged in a straight line, the analysis becomes easy.

FIG. 9 is a perspective view showing an embodiment of the present invention. The direction of the input light coupling unit 3 is adjusted so that the vicinity of the surface plasmon polariton resonance coupling angle can be measured in detail with respect to the detection unit 1. FIG. 10 is a perspective view showing an embodiment of the present invention. The direction of the input light coupling unit 3 is adjusted so that the vicinity of the surface plasmon polariton resonance coupling angle can be measured in detail with respect to the detection unit 1.
In addition to the above, a more practical form of the surface plasmon resonance angle spectrum measuring apparatus is shown in FIGS. 9 and 10 with respect to the incident light coupling unit 3, the detection unit 1, and the in-plane bending mechanism 2 in the planar waveguide 6. In addition, the shape and arrangement position of the coupling portion 3 are designed according to the predicted coupling resonance angle, and the angular spectrum near the resonance angle can be measured in more detail.

Example 1
First, examples of design and operation verification of a device including a waveguide using a metal-dielectric core, an input optical coupling unit, and an angle measuring mechanism will be described.
An Ag thin film having a thickness of 150 nm is deposited on a quartz glass substrate by sputtering, and 10 nm of SiO ₂ is deposited thereon as a protective layer. A transparent polymer (resist ZEP520 for electron beam lithography manufactured by Nippon Zeon Co., Ltd., refractive index 1.54) was deposited thereon by a spin coating method to produce a two-dimensional planar waveguide 6. The dimensions and shape of the input optical coupling part 3 were designed by predicting the characteristics by the equation (3) or computer simulation of electromagnetic field numerical analysis. The designed pattern was transferred by an electron beam drawing apparatus, and the resist film pattern remaining after development was used as it is as the dielectric film 6 of the two-dimensional planar waveguide. The angle measuring mechanism 4 is a commercially available 1/4 inch 260,000 pixel interline CCD camera, and was observed using a 20 × objective lens.

As an example, a case in which the volume fraction of the groove and the dielectric is 1: 1 and the input coupling unit 3 is an edge (diffraction grating) coupling unit having a constant pitch, which is the simplest form, will be described. FIG. 11 is a photograph showing an example of the input optical coupling unit of the present invention. As shown in FIG. 11, a pattern of a linear waveguide having a width of 4 μm and a length of 250 μm and the input optical coupling portion 3 at both ends thereof was produced. The coupling efficiency is evaluated by using one as an input coupling unit and the other as an output coupling unit. As a result of detecting the intensity from the output coupling portion for each incident angle using incident light having a wavelength of 780 nm and a beam diameter of 30 mm in the case of the lattice constant Λ1200 nm, 1500 nm, and 2000 nm and the total length of the coupling portion of 75 mm, as shown in FIG. I asked for it. FIG. 12 is a graph of an example of the coupling efficiency evaluation of the input optical coupling unit of the present invention.
At this time, the average refractive index n _ave is 1.24, and the lattice constant Λ and the peak angle satisfy the relationship of the expression (3). FIG. 13 is a graph of an example of computer simulation of the coupling efficiency analysis of the input optical coupling unit of the present invention. As shown in FIG. 13, in the result of the simulation by the time domain finite difference method, the characteristics such as the peak angle coincide with the experimental result. From the above, it was confirmed that the guided light beam was coupled and guided by the mechanism used in the present invention, and it was confirmed that it has a function close to the design. However, although the coupling efficiency estimated from the simulation is required to be 80% at maximum, in the experiment, the incident beam diameter was not optimized and was about 20%.

(Example 2)
An embodiment of ATR angle measurement by surface plasmon polariton resonance is shown in FIG. FIG. 14 is a photograph of the present invention. This is a surface plasmon resonance measuring apparatus of the form shown in FIG. In the same manufacturing method as above, the input optical coupling portion 3 is formed in a semicircular shape with a radius of 100 μm, and holes having a lattice constant of 500 nm and a diameter of 250 nm are arranged in a hexagonal lattice pattern in the vicinity of the focal point of the circular arc over a width of 3.5 μm and length of 200 μm. Yes. An attempt was made to detect changes in the amount of water adsorbed on the surface of the holes (bottom surface: SiO ₂ , side surface: polymer) that had been opened in large numbers due to humidity.

FIG. 15 is a photograph of an implementation result of the present invention at a humidity of 25%. FIG. 16 is a photograph of an implementation result of the present invention when the humidity is 80% or more. As shown in FIGS. 15 and 16, the results of the resonance angle measurement are shown. The p-polarized light, the wavelength of 780 nm, and the beam diameter of 30 μm are incident on the arcuate coupling portion from the incident angle of 45 °, and the response at the detector 1 is measured. Observed by angular mechanism 4. The sample is placed in an environment where the room temperature is 25 ° C. and the relative humidity is 25% and 80% or more, respectively. The results of detecting the difference between the case where the incident angle is fixed and the case where no sample is adsorbed are shown below. In accordance with the relationship of the expression (1), the guided light beam is incident on the detector 1 at an incident angle of 29 ° when irradiated at a position of 48 ° on the arc. Using the detection units 1 arranged in a straight line as a reference for angle measurement, the incident angle was determined with the angle taken by the straight line passing through the center of the emission line of the incident light as the incident angle.
In FIG. 15, when the incident angle to the detection unit is adjusted to 28 °, the incident light is combined with the diffraction radiation mode by the hole structure of the detection unit 1 to become the peak angle of the ATR. While scattered radiation is strongly generated, it is confirmed that the components of transmitted light and reflected light are weak. On the other hand, FIG. 16 shows the observation result at an incident angle of 29 °. Since the ATR peak angle is shifted to the wide-angle side due to the increase in the amount of adsorbed water on the detector 1, the light beam that is not coupled with the radiation mode is transmitted and guided. A strong wave was observed. In this way, it was confirmed that the ATR characteristics changed according to the humidity, and changes in the moisture and the amount of adsorbed water in the atmosphere could be detected.

  The surface plasmon resonance detection mechanism characterized by the small and light weight and integrated / parallel arrangement obtained by the present invention enables large capacity, ultra-high speed, measurement / It is thought that effects such as improved reliability of analysis and cost reduction due to improvement of mass productivity by chip implementation are expected. Thereby, for example, it can be expected to be used as a biochip for screening measurement such as antigen-antibody interaction and protein function analysis in the medical and pharmaceutical fields. In addition, it is expected to be used in many industries as an on-chip sensor, such as pathogen identification in health and environmental fields, water / air component analysis, ion current analysis by electrode reactions of fuel cells and rechargeable batteries, and battery life monitoring. Is done. Taking advantage of its small size and light weight, it can be used outdoors as a portable surface plasmon resonance sensor or as an embedded device. It can be used in the field.

It is a perspective view which shows a prior art. It is a perspective view which shows one Embodiment of this invention. It is sectional drawing which shows one Embodiment of this invention. It is the top view and sectional drawing which show one Embodiment of the detection part of this invention. It is the top view and sectional drawing which show one Embodiment of the detection part of this invention. It is the top view and sectional drawing which show one Embodiment of the detection part of this invention. It is a top view which shows one Embodiment of the in-plane bending mechanism and input light coupling part of this invention. It is a perspective view which shows one Embodiment of the in-plane bending mechanism and input light coupling part of this invention. The input light coupling portion is arranged in a quadratic curve shape and also has a function of a bending mechanism. It is a perspective view which shows one Embodiment of this invention. The direction of the input light coupling unit is adjusted so that the vicinity of the surface plasmon polariton resonance coupling angle can be measured in detail with respect to the detection unit. It is a perspective view which shows one Embodiment of this invention. The direction of the input light coupling unit is adjusted so that the vicinity of the surface plasmon polariton resonance coupling angle can be measured in detail with respect to the detection unit. It is a photograph which shows one Example of the input optical coupling part of this invention. It is a graph of one Example of coupling efficiency evaluation of the input optical coupling part of this invention. It is a graph of one Example of the computer simulation of the coupling efficiency analysis of the input optical coupling part of this invention. It is a photograph of the present invention. It is a photograph of one implementation result of the present invention when the humidity is 25%. It is a photograph of one implementation result of the present invention when the humidity is 80% or more.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection part 2 Bending mechanism 3 Input light coupling part 4 Angle measuring mechanism 5 Metal film 6 Dielectric film 7 External incident light source

Claims (8)

In a surface plasmon resonance angle spectrum measuring apparatus that measures surface plasmon polariton resonance by irradiating a material on a metal surface with light,
The surface plasmon resonance angle spectrum measuring device is:
One or more dielectric films are provided on one or more metal films, and the dielectric film includes an input optical coupling unit, a two-dimensional planar waveguide, and a detection unit, and
An apparatus for measuring a surface plasmon resonance angle spectrum, comprising an angle measuring mechanism for measuring a resonance coupling angle from a locus of light rays in a dielectric film. In the surface plasmon resonance angle spectrum measuring apparatus according to claim 1,
The surface plasmon resonance angle spectrum measuring apparatus, detecting section is a groove or pore structure are arranged linearly, surface plasmon resonance angle spectrum measuring apparatus and detecting at the bottom and side surfaces. In the surface plasmon resonance angle spectrum measuring apparatus according to claim 1 or 2,
The surface plasmon resonance angle spectrum measurement apparatus uses a linear shape of a groove or hole structure arranged in a straight line as a reference line at the time of angle measurement. In the surface plasmon resonance angle spectrum measuring apparatus according to any one of claims 1 to 3,
The surface plasmon resonance angle spectrum measuring apparatus is designed to place dielectric regions having different refractive indexes in the dielectric film surface in order to bend the propagation direction of the guided light beam in the planar waveguide in a specific direction. The surface plasmon resonance angle spectrum measuring device is characterized in that a waveguide light beam arranged so as to be expressed as a quadratic curve and bent by a refraction phenomenon converges on a part of the detection unit. In the surface plasmon resonance angle spectrum measuring apparatus according to any one of claims 1 to 4,
The surface plasmon resonance angle spectrum measuring apparatus employs a mechanism that functions as a coupling portion on a side end face of a structure formed by a dielectric and a groove as an input optical coupling portion for coupling a guided light beam into a two-dimensional waveguide. A surface plasmon resonance angle spectrum measuring apparatus. In the surface plasmon resonance angle spectrum measuring apparatus according to claim 5,
The surface plasmon resonance angle spectrum measuring apparatus considers a dielectric core structure adjacent to a groove as a set, and a phase matching condition for coupling to guided light: K + k _illum · sin _{θ≈n ave} · k _illum (where, the value of K 2 [pi / (sum of the cross-sectional width of the pair of grooves and the dielectric), k _illum at wave number of the external incident light, the average refractive determined from the sum of the products of n _ave respective refractive index and the volume fraction The surface plasmon resonance angle spectrum measuring apparatus characterized by satisfying the relationship of the correction term (0.9 to 1.1) multiplied by the rate). In the surface plasmon resonance angle spectrum measuring apparatus according to claim 5 or 6,
The surface plasmon resonance angle spectrum measuring apparatus characterized in that the input coupled light beam to the input optical coupling unit has a beam diameter that is 1 to 10 times the interaction length of the input optical coupling unit. In the surface plasmon resonance angle spectrum measuring device according to any one of claims 1 to 7,
The surface plasmon resonance angle spectrum measuring device is:
The metal film is composed mainly of Ag, Cu, Au, and Pt elements.
The surface plasmon resonance angle spectrum measuring apparatus characterized in that the dielectric film is composed mainly of a transparent oxide, fluoride or organic polymer.