JP2002217488A - Element and system of surface emission laser, wavelength adjusting method, surface-emitting laser array, optical interconnection system, and local area network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-emitting laser element which can suppress leakage of electrons in the well layer of a multi-quantum structural part, when electric field is applied and obtain large refractive index variations in a high electric field. SOLUTION: This surface-emitting laser element is equipped with the multi- quantum well structure part 104 between an active layer 101 and a couple of distribution Bragg reflectors 102 and 103 facing each other across the active layer 101, and is provided with a pair (105, 106) of 1st electrodes for applying currents to the active layer 101 and a pair (106, 107) of 2nd electrodes for applying an electric field to the multi-quantum well structure part 104 independently of each other; and the electric field is applied to the multi-quantum well structure part 104 by the pair of the 2nd electrodes to vary the refractive index of the multi-quantum well structure part 104, thereby varying the oscillation frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface emitting laser device, a surface emitting laser system, a wavelength adjusting method, a surface emitting laser array, an optical interconnection system, and a local area network system capable of changing an oscillation wavelength.

[0002]

2. Description of the Related Art Conventionally, a surface emitting laser device that emits a laser beam perpendicularly to a semiconductor substrate has a small cavity volume and therefore has a low oscillation threshold current and can perform high-speed modulation. Further, the beam spread is narrow, the coupling with other optical devices is good, and it is easy to form a two-dimensional array, and there is great expectation as an array light source for optical transmission and optical interconnection.

In recent years, wavelength division multiplexing (WDM) communication has attracted attention as a system having an optical transmission rate exceeding 10 Gbps, and research and development have been carried out. At present, 4 Gigabit Ethernet with a transmission speed of 10 Gbps
Wavelength WDM communication has been proposed, and a system that further increases the number of wavelength divisions is required in the future. In such wavelength division multiplex communication, it is necessary to control the oscillation wavelength at minute wavelength intervals, and it is considered that a surface emitting laser having a wavelength variable mechanism is required.

[0004] In a surface emitting laser, the oscillation wavelength can be changed by changing the optical length of the resonator. Conventionally,
As a typical method for changing the optical length of the resonator, the following has been devised.

[0005] For example, the document "Appl. Phys. Le
tt. 62 1993 p. p. 219 ", a semiconductor layer that changes the refractive index by a plasma effect due to carrier injection is provided in the resonator, and the optical length of the resonator is variable.

In Japanese Patent Application Laid-Open No. 188518/1994, a multiple quantum well structure is provided in a resonator, and the refractive index is changed by applying a vertical electric field to make the optical length of the resonator variable.

In Japanese Patent Application Laid-Open No. Hei 10-27943, a cavity is formed in a resonator by a technique such as lamination of substrates by a micromachining technique, and the thickness of the cavity is mechanically controlled by electrostatic force to control the cavity length. Is changing.

[0008]

In the method using the plasma effect by carrier injection, the refractive index can be changed most greatly in electric modulation. However, there is a problem that the current density required for this is large, the power consumption is large, and the element generates heat.

In the method of mechanically modulating by micromachining, the manufacturing process is complicated, and there is a problem in the yield and reliability of the device.

On the other hand, when a multiple quantum well modulation layer is used, the power consumption is small because of the voltage drive type. No special process is required.

In the multiple quantum well structure, the refractive index modulation effect with higher efficiency can be obtained by the quantum confinement Stark effect based on the quantum size effect than in the case of using a conventional bulk. In a surface emitting laser based on this principle,
It is possible to obtain a wavelength tunable width of more than ten nm. The change in the refractive index in the multiple quantum well structure is an effect due to a long wavelength shift of the exciton absorption edge under the application of a vertical electric field.If the applied electric field is not relatively large and the well width is not too wide,
A change in energy occurs at the carrier level in the well in proportion to the square of the applied electric field and the fourth power of the well width, and as a result, the refractive index changes.

On the other hand, if the well width is too thick, the quantum effect and the exciton effect are weakened, and the characteristics approach the bulk characteristics. vice versa,
When the well width is small, since the quantum level is originally high, carrier leakage easily occurs, and excitons are dissociated.

Therefore, the width of the quantum well must be large enough to obtain the quantum effect, and the energy barrier of the barrier layer must be large enough to suppress carrier leakage under a high electric field. As described above, the amount of change in the refractive index greatly depends on the multiple quantum well structure, and in order to obtain a large change in the refractive index under a high electric field, the carrier (particularly, electrons)
It is important to prevent leaks.

The present invention relates to a surface emitting laser device and a surface emitting laser capable of suppressing the leakage of electrons from the well layer of the multiple quantum well structure when an electric field is applied and obtaining a large change in the refractive index under a high electric field. It is an object of the present invention to provide a system, a wavelength adjusting method, a surface emitting laser array, an optical interconnection system, and a local area network system.

[0015]

In order to achieve the above object, the present invention provides a multi-quantum well structure between an active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween. A first electrode for injecting a current into the active layer and a second electrode for applying an electric field to the multiple quantum well structure.
Are provided independently of each other, and an electric field is applied to the multiple quantum well structure by the second electrode, thereby changing the refractive index of the multiple quantum well structure and making the oscillation wavelength variable. Further, GaInNAs mixed crystal is used as a material of the well layer of the multiple quantum well structure.

The invention according to claim 2 provides an active layer and the active layer.
With a pair of distributed Bragg reflectors facing each other across the active layer
With multiple quantum well structure in between, current is injected into active layer
An electric field to the first electrode and the multiple quantum well structure for
Are provided independently of each other,
An electric field is applied to the multiple quantum well structure by the two electrodes.
Oscillation by changing the refractive index of the multiple quantum well structure
A surface emitting laser device capable of changing a wavelength, wherein
The well layer of the quantum well structure has a first Ga_x1In _1-x1N_z1
As_1-z1(0 <x1 ≦ 1, 0 ≦ z1 ≦ 1) layer and second G
a_x2In_1-x2N _z2As_1-z2(0 <x2 ≦ 1, 0 <z2 ≦
1) The first layer is composed of two layers having different compositions from the layer.
Ga_x1In_1-x1N_z1As_1-z1(0 <x1 ≦ 1,0 ≦ z
1 ≦ 1) The second Ga layer_x2In_1-x2N_z2As_1-z2(0
<X2 ≦ 1, 0 <z2 ≦ 1) compared to the conduction band energy
High energy and valence band energy
I have.

According to a third aspect of the present invention, in the surface emitting laser device according to the first or second aspect, the II-VI group semiconductor material is used for the barrier layer having the multiple quantum well structure. Features.

According to a fourth aspect of the present invention, in the surface emitting laser device according to any one of the first to third aspects, a GaInNAs semiconductor material is used for the active layer. I have.

According to a fifth aspect of the present invention, in the surface emitting laser device according to any one of the first to third aspects, the active layer includes GaInNAs or GaIn.
It is characterized in that a quantum dot structure made of an nAs semiconductor material is used.

According to a sixth aspect of the present invention, a multiple quantum well structure is provided between an active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, and a current is injected into the active layer. And a second electrode for applying an electric field to the multiple quantum well structure are provided independently of each other. By applying an electric field to the multiple quantum well structure by the second electrode, the multiple quantum well It is characterized by having a surface emitting laser element that varies the oscillation wavelength by changing the refractive index of the structure portion, and oscillation wavelength detecting means that detects the oscillation wavelength of the surface emitting laser element.

According to a seventh aspect of the present invention, in the surface emitting laser system according to the sixth aspect, the surface emitting laser element is so arranged that the oscillation wavelength detected by the oscillation wavelength detecting means becomes a desired oscillation wavelength. It is characterized in that voltage adjusting means for adjusting the voltage applied to the multiple quantum well structure is further provided.

According to a further aspect of the present invention, a multiple quantum well structure is provided between an active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, and a current is injected into the active layer. And a second electrode for applying an electric field to the multiple quantum well structure are provided independently of each other. By applying an electric field to the multiple quantum well structure by the second electrode, the multiple quantum well A surface emitting laser element main body that changes a refractive index of a structure portion to vary an oscillation wavelength; and a surface emitting laser element main body provided outside a resonator on a side opposite to a light emitting surface of the surface emitting laser element main body. And light detecting means for detecting light near the oscillation wavelength which has entered from the light emitting surface and transmitted through the surface emitting laser element body.

According to a ninth aspect of the present invention, there is provided a surface emitting laser element according to the eighth aspect, and a light incidence means for sweeping a wavelength to make monochromatic light incident on a light emitting surface of the surface emitting laser element. When the wavelength is swept by the light incident means on the light emitting surface of the surface emitting laser element and monochromatic light is incident, and light near the oscillation wavelength transmitted through the surface emitting laser element is detected by the light detecting means of the surface emitting laser element. Light amount detecting means for detecting the light amount of light detected by the light detecting means, voltage applying means for applying a voltage to the multiple quantum well structure of the surface emitting laser element, and light amount of light detected by the light amount detecting means Is characterized by having a storage means for storing the relationship between the wavelength of monochromatic light at that time and the voltage applied to the multiple quantum well structure of the surface emitting laser element at that time.

The invention described in claim 10 is the same as the claim 9.
In the above-described surface emitting laser system, when the surface emitting laser element is oscillated at a desired resonance wavelength, the voltage applying unit may determine the wavelength of the monochromatic light stored in the storage unit and the multiple quantum well structure of the surface emitting laser element. Based on the relationship with the voltage applied to the portion, the voltage applied to the multiple quantum well structure of the surface emitting laser device corresponding to the desired resonance wavelength is determined from the storage means and applied to the multiple quantum well structure of the surface emitting laser device. It is characterized by being adapted to.

The invention according to claim 11 is the same as the invention according to claim 8.
A wavelength adjusting method for adjusting a resonance wavelength of a surface emitting laser element according to claim 1, wherein a light emitting surface of the surface emitting laser element main body is applied while an applied voltage is applied to a multiple quantum well structure portion of the surface emitting laser element main body. The wavelength of the monochromatic light whose wavelength is continuously changed is made incident, and the resonance wavelength of the resonator of the surface emitting laser element main body is detected by detecting the amount of monochromatic light transmitted through the surface emitting laser element main body. Derive the relationship between the applied voltage applied to the multiple quantum well structure and the detected resonance wavelength, and adjust the applied voltage based on the derived relationship between the applied voltage and the resonance wavelength to adjust the resonance wavelength. It is characterized by.

The invention according to claim 12 is the first invention.
A plurality of the surface emitting laser elements according to any one of claims 5 to 8 are arranged in an array.

The invention according to claim 13 is the first invention.
The surface emitting laser device according to any one of claims 5 to 8, or claim 6, claim 7, claim 9, and claim 9.
An optical interconnection system using the surface emitting laser system according to claim 10 or the surface emitting laser array according to claim 12.

The invention according to claim 14 is the first invention.
The surface emitting laser device according to any one of claims 5 to 8, or claim 6, claim 7, claim 9, and claim 9.
A local area network system using the surface emitting laser system according to claim 10 or the surface emitting laser array according to claim 12.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of the surface emitting laser device of the present invention. The surface emitting laser device of FIG. 1 includes a multiple quantum well structure 104 between an active layer 101 and a pair of distributed Bragg reflectors 102 and 103 opposed to each other with the active layer 101 interposed therebetween. A first set of electrodes (105, 106) for injection and a second set of electrodes (106, 107) for applying an electric field to the multiple quantum well structure 104 are provided independently of each other.
By applying an electric field to the multiple quantum well structure 104 by the electrode set (106, 107), the refractive index of the multiple quantum well structure 104 is changed and the oscillation wavelength is made variable.

First Embodiment In a first embodiment of the present invention, in the surface emitting laser device as shown in FIG. 1, GaInNAs mixed crystal is used as a material of a well layer of the multiple quantum well structure 104. Features. That is, in the surface emitting laser device of the first embodiment, GaInNAs mixed crystal is used as the semiconductor material of the well layer of the multiple quantum well structure 104 that modulates the refractive index by applying an electric field.

In the GaInNAs mixed crystal, the energy mainly on the conduction band side is largely reduced by the addition of nitrogen.
A large conduction band discontinuity is obtained at a heterojunction interface with a semiconductor layer such as As. As a result, the electron confinement on the conduction band side of the multiple quantum well structure can be improved, and the leakage of electrons can be suppressed up to the application of a high electric field as compared with the conventional multiple quantum well structure of InGaAs / GaAs or the like.

[0032]Second embodiment Further, the second embodiment of the present invention employs a surface light emission as shown in FIG.
In the laser device, the well of the multiple quantum well structure 104
The layer comprises a first Ga_x1In_1-x1N_z1As_1-z1(0 <x1 ≦
1,0 ≦ z1 ≦ 1) layer and second Ga_x2In_1-x2N_z2As
_1-z2(0 <x2 ≦ 1, 0 <z2 ≦ 1)
The first Ga _x1In_1-x1N_z1
As_1-z1The (0 <x1 ≦ 1, 0 ≦ z1 ≦ 1) layer is the second layer.
Ga_x2In_1-x2N_z2As_1-z2(0 <x2 ≦ 1, 0 <z2
≦ 1) The conduction band energy and valence band energy
It is characterized by high energy.

That is, in the surface emitting laser device of the second embodiment, GaInN layers having different compositions are formed in the well layers of the multiple quantum well structure 104 which performs refractive index modulation by applying an electric field.
A quantum well having a staggered band structure is formed by using an As layer. FIG. 2A shows a band of a staggered quantum well structure in the absence of an electric field. Referring to FIG. 2A, a well portion is formed by a GaInNAs layer having a thickness d1 and a GaInNAs layer having a thickness d2 having a different composition. When the staggered quantum well layer is biased as shown in FIG. 2B, electrons and holes are affected by the confinement of the quantum wells formed by the GaInNAs layers having the thicknesses d1 and d2, respectively, at the initial stage of the electric field application. The change in the level is large. Therefore, a large change in the refractive index can be obtained at the initial stage of the electric field application. That is, in the staggered quantum well structure, since the effective well width at the initial stage of the electric field application can be reduced, a large change in the refractive index can be obtained with a small electric field. Further, since the well width does not have to be narrowed in order to increase the confinement effect, the quantum level is not increased unnecessarily, and carrier leakage does not occur even under a high electric field.

Conventionally, it has been difficult to obtain such a staggered junction from the viewpoint of materials. However, in the case of GaInNAs mixed crystal, the conduction band energy and the valence band energy can be controlled by the amount of nitrogen added. Becomes easier. This is because energy of the conduction band and the valence band can be reduced by adding nitrogen. Therefore, the amount of nitrogen added to one GaInNAs mixed crystal is increased, and the forbidden band width is increased by the other GaInNAs depending on the Ga composition.
When the adjustment is made to be substantially the same as that of the mixed crystal, a staggered quantum well structure can be easily obtained. That is, G
When aInNAs is used, a staggered quantum well structure can be easily manufactured by controlling the amount of added nitrogen.

As described above, in the multi-quantum well structure of the surface emitting laser device according to the second embodiment, the refractive index change rate is particularly large when a low electric field is applied, and the refractive index change rate is large at a bias voltage lower than the conventional one. Can be obtained, whereby a wavelength tunable surface emitting laser device with a reduced operating voltage can be obtained.

Third Embodiment In a third embodiment of the present invention, a multiplexed laser is used in a surface emitting laser device as shown in FIG. 1 (further, in the surface emitting laser device of the first or second embodiment). The barrier layer of the quantum well structure 104 is characterized by using a II-VI group semiconductor material. The group II-VI mixed crystal has a wider forbidden band width than the group III-V mixed crystal, and can obtain a multiple quantum well structure having a deep potential. For example, ZnS _0.06 Se _0.94 lattice-matched to a GaAs substrate has a bandgap of 2.6 eV or more, Cd _0.58 Zn _0.42 S has a bandgap of 2.8 eV or more, and MnS _0.88 Se _0.12 has a bandgap of 4.4 eV. The above forbidden band width is obtained. When such a II-VI group mixed crystal semiconductor is used as a barrier layer of a multiple quantum well structure, carrier confinement is very strong, and even when a high electric field is applied, leakage of carriers (eg, electrons) from the well can be effectively prevented. Therefore, a large amount of change in the refractive index can be obtained under the application of a high electric field, and a surface emitting laser device having a large wavelength variable amount can be obtained.

The surface emitting laser device shown in FIG.
In the surface emitting laser devices according to the third to third embodiments, the active layer 101 may be formed using a GaInNAs semiconductor material. When a GaInNAs mixed crystal is used as the material of the active layer 101, oscillation in the wavelength band longer than 0.9 μm (1.3 μm band, 1.55 μm band, and oscillation in the longer wavelength band) is obtained on the GaAs substrate. can get. In particular,
By using a laser element oscillating in the 3 μm band and a quartz fiber, high-speed communication becomes possible. Further, when the spacer layer of this surface emitting laser element is an (Al) GaAs spacer layer, GaInNAs mixed crystal and (Al) GaAs
Since the conduction band discontinuity with the spacer layer is large,
Electron overflow from the active layer 101 is suppressed,
Reactive current and element heat generation are reduced, and wavelength fluctuation due to temperature rise can be reduced (reduction of oscillation reactive current, lowering of threshold, and suppression of element temperature rise). For example, refer to the document “The 47th Lecture Meeting on Applied Physics, 3
1a-N-10 ", the differential temperature change rate of the oscillation wavelength is 0.39 nm / K in the 1.3 μm band end-face type laser,
The temperature change rate of the forbidden band width is 0.42 nm / K, which is
It is reported that the value is about half that of the GaAsP material. Therefore, when GaInNAs mixed crystal is also used for the active layer, it is possible to minimize the fluctuation of the oscillation wavelength. This simplifies bias voltage control of the multiple quantum well structure with respect to changes in the driving state of the device, operating environment temperature, and the like.

Alternatively, the active layer 101 may include GaI
A quantum dot structure made of nNAs or GaInAs semiconductor material can be used. When a GaInNAs or GaInAs quantum dot structure is used for the active layer 101, an oscillation wavelength of 1.2 μm to 1.55 μm is obtained on a GaAs substrate. Further, the threshold current and the operating current are reduced by the quantum size effect, the heat generation of the element is reduced, and the fluctuation of the wavelength due to the temperature rise can be reduced.

Fourth Embodiment FIG. 3 is a diagram showing a configuration example of a fourth embodiment (surface emitting laser system) of the present invention. Referring to FIG. 3, the surface emitting laser system includes an active layer 101 and the active layer 10.
A pair of distributed Bragg reflectors 102 facing each other
And a first set of electrodes (10) for injecting current into the active layer 101.
, 106) and a second set of electrodes (106, 107) for applying an electric field to the multiple quantum well structure 104 are provided independently of each other, and the second set of electrodes (106, 10
7) a surface emitting laser device 110 that changes the refractive index of the multiple quantum well structure 104 by applying an electric field to the multiple quantum well structure 104 to vary the oscillation wavelength;
Oscillation wavelength detecting means 120 for detecting the oscillation wavelength of the surface emitting laser element 110. FIG. 3 shows an example of the surface emitting laser element 110 having a structure for extracting light from the substrate side.

In this surface emitting laser system, the oscillation wavelength detecting means 120 for detecting the oscillation wavelength of the surface emitting laser element 110 is provided, so that the detected oscillation wavelength becomes a desired oscillation wavelength. Light emitting laser device 1
The applied voltage (bias voltage) to the ten multiple quantum well structure portions 104 can be adjusted.

FIG. 4 is a diagram showing another example of the configuration of the surface emitting laser system according to the present invention. In the surface emitting laser system of FIG. 4, in the surface emitting laser system of FIG. 3, the multiple quantum well structure of the surface emitting laser element 110 is set so that the oscillation wavelength detected by the oscillation wavelength detecting means 120 becomes a desired oscillation wavelength. Voltage adjusting means 130 for adjusting the voltage applied to 104 is further provided. Since the voltage adjusting means 130 for adjusting the voltage applied to the multiple quantum well structure 104 of the surface emitting laser device 110 is further provided, the voltage (bias voltage) applied to the multiple quantum well structure of the surface emitting laser device is provided. Is automatically adjusted.

Fifth Embodiment FIG. 5 is a diagram showing a configuration example of a fifth embodiment (surface emitting laser element) of the present invention. Referring to FIG. 5, the surface emitting laser device includes a multiple quantum well structure 104 between an active layer 101 and a pair of distributed Bragg reflectors 102 and 103 opposed to each other with the active layer 101 interposed therebetween. A first set of electrodes (105, 10) for injecting current into
6) and a second set of electrodes (106, 107) for applying an electric field to the multiple quantum well structure 104 are provided independently of each other. The surface emitting laser device main body 110 in which the refractive index of the multiple quantum well structure portion 104 is changed by applying an electric field to the structure portion 104 to change the oscillation wavelength, and the light emitting surface of the surface emitting laser device main body 110 are opposite. And a light detecting means 111 for detecting light near the oscillation wavelength which is incident from the light emitting surface of the surface emitting laser element main body 110 and transmitted through the surface emitting laser element main body. .

Here, as the light detecting means 111, a light detecting layer, a light detector, or the like can be used.

As described above, the oscillation wavelength that is incident on the outside of the cavity opposite to the light emitting surface of the surface emitting laser element main body 110 from the light emitting surface of the surface emitting laser element main body 110 and transmitted through the surface emitting laser element main body. Light detecting means 1 for detecting nearby light
When the light detecting means 11 is provided, the light detecting means 111 can detect optical information about the resonator structure such as the light intensity emitted from the resonator or the transmission characteristics of the resonator.

Sixth Embodiment FIG. 6 is a diagram showing a configuration example of a sixth embodiment (surface emitting laser system) of the present invention. Referring to FIG.
In the surface emitting laser system according to the fifth embodiment, the wavelength is swept and monochromatic light is incident on the light emitting surface of the surface emitting laser element of the fifth embodiment (the surface emitting laser element of FIG. 5) and the surface emitting laser element. A light incident means 140 for causing light to enter the monochromatic light by sweeping the wavelength by the light incident means 140 onto the light emitting surface of the surface emitting laser element, and light having an oscillation wavelength near the oscillation wavelength transmitted through the surface emitting laser element (element body 110). When the light is detected by the light detecting means 111 of the light emitting laser element, a voltage is applied to the light quantity detecting means 141 for detecting the light quantity of the light detected by the light detecting means 111 and the multiple quantum well structure 104 of the surface emitting laser element. When the light amount of the light detected by the voltage application unit 142 and the light amount detection unit 141 is maximized, the wavelength of the monochromatic light at that time and the multiple quantum well structure 104 of the surface emitting laser element
Storage means 143 for storing the relationship with the applied voltage.

In the surface emitting laser system shown in FIG. 6, while an applied voltage is applied to the multiple quantum well structure 104 of the surface emitting laser element, the wavelength is set by the light incident means 140 on the light emitting surface of the surface emitting laser element. The monochromatic light is swept and made incident, the light near the oscillation wavelength transmitted through the surface emitting laser element is detected by the light detecting means 111 of the surface emitting laser element, and the light amount of the light detected by the light detecting means is detected by the light amount detecting means 141. To detect. When the light amount of the light detected by the light amount detecting unit 141 becomes maximum, the relationship between the wavelength of the monochromatic light and the voltage applied to the multiple quantum well structure unit 104 of the surface emitting laser element at that time is stored. 143. Then, based on the relationship between the wavelength of the monochromatic light stored in the storage unit 143 and the voltage applied to the multiple quantum well structure 104 of the surface emitting laser element, the voltage application unit 142 adjusts the wavelength to a desired resonance wavelength. The voltage applied to the multiple quantum well structure 104 of the surface emitting laser device can be adjusted.

FIG. 7 is a diagram showing another configuration example of the surface emitting laser system according to the sixth embodiment. In the surface emitting laser system of FIG. 7, when the surface emitting laser element is oscillated at a desired resonance wavelength in the surface emitting laser system of FIG. The voltage applied to the multiple quantum well structure 104 is automatically determined from the storage means 143 and applied to the multiple quantum well structure 104 of the surface emitting laser device.

In the surface emitting laser system shown in FIG. 7, the voltage applying means 142 determines the voltage applied to the multiple quantum well structure 104 of the surface emitting laser element corresponding to a desired resonance wavelength from the storage means 143, and Since the voltage is applied to the multiple quantum well structure 104 of the device, the applied voltage can be automatically adjusted so that the surface emitting laser device body oscillates at a desired resonance wavelength.

As described above, in the surface emitting laser system of the sixth embodiment, the light emission of the surface emitting laser element main body 110 is performed while the applied voltage is applied to the multiple quantum well structure 104 of the surface emitting laser element. Monochromatic light whose wavelength is continuously changed is incident from the surface, and the amount of the monochromatic light transmitted through the surface emitting laser element main body 110 is detected, whereby the resonance wavelength of the resonator of the surface emitting laser element main body 110 (monochromatic light) is detected. Of the multiple quantum well structure 10 at this time.
4, the relationship between the applied voltage and the detected resonance wavelength (the incident wavelength of monochromatic light) is derived, and the applied voltage is adjusted based on the derived relationship between the applied voltage and the resonance wavelength to change the resonance wavelength. Can be adjusted.

The change in wavelength due to heat during laser operation is achieved by driving the element with a pulse close to the actual driving condition, synchronizing the injection current with the photodetection current, and detecting the transmitted light during non-current injection. Thus, calibration (adjustment) can be added to the operating temperature. In this method, since only collimated monochromatic light needs to be incident on the surface emitting laser array at a time, optical alignment is hardly required. In addition, since information on the cavity length of the surface emitting laser element can be electrically detected as a photocurrent flowing through the light receiving section, inspection can be performed easily and in parallel even on a surface emitting laser array with a large number of integrations. I can do it.

In other words, in the surface emitting laser system of the sixth embodiment, monochromatic light is incident on the light emitting surface of the surface emitting laser element main body 110 while continuously changing the wavelength. Light detecting means 11 provided on the opposite end face of the resonator
1, the transmitted light is detected, the resonance wavelength is checked, and the driving condition of the surface emitting laser device is determined from the voltage applied to the multiple quantum well structure at this time and the incident wavelength when the transmitted light is detected. Since the adjustment is performed, it is possible to easily adjust the driving conditions collectively.

Seventh Embodiment The seventh embodiment of the present invention is the same as the first, second and third embodiments described above.
Alternatively, this is a surface-emitting laser array using the surface-emitting laser element of the fifth embodiment. In the seventh embodiment, a wavelength-variable surface-emitting laser array capable of two-dimensional integration can be provided.

Eighth Embodiment The eighth embodiment of the present invention is directed to the surface emitting laser device of the first, second, third or fifth embodiment described above, or the fourth or sixth embodiment. This is an optical interconnection system using the surface emitting laser system according to the embodiment or the surface emitting laser array according to the seventh embodiment. In the eighth embodiment, the wavelength division range is wide, An optical interconnection system using multiplexing (WDM) can be easily provided.

Ninth Embodiment The ninth embodiment of the present invention is directed to the surface emitting laser device of the first, second, third or fifth embodiment, or the fourth or sixth embodiment. This is a local area network (LAN) system using the surface emitting laser system of the embodiment or the surface emitting laser array of the seventh embodiment. In the ninth embodiment, the usable wavelength bandwidth is wide. An optical LAN system using wavelength division multiplexing (WDM) can be easily provided.

[0055]

Embodiment 1 FIG. 8 is a view showing a specific configuration example of the surface emitting laser device of Embodiment 1. Referring to FIG. 8, the surface emitting laser device according to the first embodiment includes an AlAs / Ga
An n-DBR (distributed Bragg reflector) 3 having a laminated structure of 35 pairs of As, an undoped GaAs spacer layer 4, a GaInNAs / GaAs MQW active layer 5, an undoped GaAs spacer layer 6, and a p-AlAs layer 7
A p-GaAs contact layer 9, a multiple quantum well structure 11 made of GaInNAs / GaAs for refractive index modulation, an undoped DBR 12 having a stacked structure of 25 pairs of Al _0.8 Ga _0.2 As / GaAs, and p-GaAs.
The contact layers 13 are sequentially stacked. And n
The n-electrode 1 is formed on the back surface of the -GaAs substrate 2, the p-electrode 10 is formed on the p-GaAs contact layer 9, and the p-electrode 10 is formed on the p-GaAs contact layer 13.
An electrode 14 is formed.

In the first embodiment, Ga is used as the active layer 5.
A triple quantum well active layer made of an InNAs / GaAs mixed crystal was used. At this time, the thickness of the GaInNAs layer of the active layer 5 was set to 7 nm, and the thickness of the GaAs layer of the active layer 5 was set to 15 nm. The In composition of the GaInNAs mixed crystal is 0.1.
It was set to 3.

The p-GaAs contact layers 9 and 13
Is 100 nm, the thickness of the AlAs layer 7 is 30 nm, and the thickness of the resonance region including the GaAs spacer layers 4 and 6, the active layer 5, the contact layer 9, and the multiple quantum well structure 11 is The adjustment was performed so that the layer 5 was located at the center of the resonance region and constituted a two-wavelength resonator.

The undoped DBR12 Al _0.8 G
a _0.2 As layer with a thickness of 108 nm, undoped DB
The thickness of the GaAs layer of R12 was 95 nm. Also, n
-The thickness of the AlAs layer of DBR3 is 112 nm, and n-
The thickness of the GaAs layer of DBR3 was 95 nm.

The multiple quantum well structure 11 is made of AlG
The thickness of the aAs barrier layer was 10 nm, the thickness of the GaInNAs well layer was 10 nm, and 18 layers were stacked. In addition, the energy between the quantum levels of the multiple quantum well structure 11 in an unbiased state is set to be higher than the energy of the oscillation light by 60 meV or more in order to prevent light absorption.

The surface emitting laser device shown in FIG. 8 is manufactured by the following steps. That is, first, AlAs / GaAs is formed on the n-GaAs substrate 2 by MOCVD.
n-DBR (distributed Bragg reflector) 3 having a laminated structure of 35 pairs of s and undoped GaAs spacer layer 4
, GaInNAs / GaAs MQW active layer 5, undoped GaAs spacer layer 6, p-AlAs layer 7
A p-GaAs contact layer 9, a multiple quantum well structure 11 made of GaInNAs / GaAs for refractive index modulation, an undoped DBR 12 having a stacked structure of 25 pairs of Al _0.8 Ga _0.2 As / GaAs, and p-GaAs.
The contact layers 13 are sequentially laminated.

Thereafter, a post-shaped (columnar) resist pattern is formed by photolithography, and p-GaAs is removed from the p-GaAs contact layer 13 by dry etching.
Each layer up to the s-contact layer 9 is etched and removed in a post shape (column shape). Next, after removing the resist, a resist pattern is formed again, and the contact layer 9, the AlA
The etching removal of the s layer 7 is performed sequentially. Next, the AlAs layer 7 is selectively oxidized in a heated steam atmosphere to form a single transverse mode control structure which also serves as a current confinement by the selective oxidation region 8 under the contact layer 9. Next, the p electrode 10,
Each of the p-electrodes 14 is formed by using a resist lift-off method, and an n-electrode 1 having an opening for taking out light output (opening for a light emitting portion) is formed on the back surface of the substrate 2.

In the surface emitting laser device shown in FIG.
And applying a forward bias voltage between the n-electrode 1 and
By injecting a current into the active layer 5 and applying a voltage between the p-electrode 14 and the p-electrode 10, an electric field can be applied (voltage applied) to the multiple quantum well structure 11.

In the first embodiment, the use of a GaInNAs / GaAs mixed crystal as the material of the multiple quantum well structure 11 for performing the refractive index modulation increases the conduction band discontinuity and suppresses the electron leakage. Can be. As a result, a large change in the refractive index is obtained under the application of a high electric field, and the wavelength tunable width is larger than that of the conventional surface emitting laser device. Further, by using a GaInNAs mixed crystal as the well layer material of the multiple quantum well structure 11, the amount of lattice distortion of the multiple quantum well structure 11 can be reduced as compared with the related art. As a result, even after crystal growth of a DBR layer (distributed Bragg reflector) having a thickness of several μm, the surface condition of the device is good, and generation of lattice defects and deterioration of device characteristics can be suppressed.

In the first embodiment, the active layer 5 has GaIn
By using the mixed crystal of NAs, carrier overflow from the active layer 5 is reduced, and the oscillation threshold current and the heat generation of the element can be reduced. As a result, the wavelength change due to temperature is small, and the wavelength control becomes easy.

Embodiment 2 FIG. 9 is a diagram showing a specific configuration example of a surface emitting laser device of Embodiment 2. Referring to FIG. 9, the surface emitting laser device according to the second embodiment includes an AlAs / G substrate on an n-GaAs substrate 22.
n-DBR23 having a laminated structure of 35 pairs of aAs
A multiple quantum well structure portion 24 of GaInNAs / GaAs for refractive index modulation, a p-GaAs contact layer 25, an undoped GaAs spacer layer 27,
aInNAs / GaAs MQW active layer 28, undoped GaAs spacer layer 29, p-AlAs layer 30
An undoped DBR 32 of 25 pairs of Al _0.8 Ga _0.2 As / GaAs, and a p-GaAs contact layer 33
Are sequentially laminated. Then, the n-GaAs substrate 2
2 has an n-electrode 21 formed on the back surface thereof and p-GaAs
An n-electrode 26 is formed on the s-contact layer 25, and a p-electrode 34 is formed on the p-GaAs contact layer 33.

Here, in the surface-emitting laser device of Example 2 (the surface-emitting laser device of FIG. 9), the well layers of the multiple quantum well structure 24 for changing the refractive index by applying an electric field are composed of two layers having different compositions. It consists of two GaInNAs layers.

In the surface emitting laser device of the second embodiment, the resonator structure and the DBR structure are the same as those of the surface emitting laser device of the first embodiment.

In the surface emitting laser device of Example 2, the thickness of the GaAs barrier layer of the multiple quantum well structure 24 was 10 nm. The thicknesses of the two types of GaInNAs layers constituting the well layers of the multiple quantum well structure 24 were each set to 5 nm. Also, two types of Ga forming the well layer
The InNAs layer is made to have the same forbidden band width by adjusting the composition of nitrogen (N) and In.
The conduction band energy of the As layer was set to be lower by about 30 meV than the other conduction band energy.

When nitrogen is added, the forbidden band width decreases, the energy of the conduction band and the valence band decreases, and the lattice constant decreases. On the other hand, when the In composition is increased, the forbidden band width decreases, the energy of the conduction band decreases, and the energy of the valence band increases.
Also, the lattice constant increases. Therefore, nitrogen and In
By adjusting the composition, a highly flexible design is possible.

The energy between the quantum levels of the entire multiple quantum well structure 24 is 6 to the energy of the oscillation light.
The energy was made higher than 0 meV.

The surface emitting laser device shown in FIG. 9 is manufactured by the following steps. That is, first, AlAs / Ga is formed on the n-GaAs substrate 22 by MOCVD.
An n-DBR 23 having a stacked structure of 35 pairs of As,
Multi-quantum well structure section 24 of GaInNAs / GaAs for refractive index modulation and p-GaAs contact layer 2
5, undoped GaAs spacer layer 27, GaI
nNAs / GaAs MQW active layer 28 and undoped G
aAs spacer layer 29, p-AlAs layer 30,
An undoped DBR 32 of 25 pairs of l _0.8 Ga _0.2 As / GaAs and a p-GaAs contact layer 33 are sequentially laminated. Thereafter, similarly to the surface emitting laser element of FIG. 8, each layer up to the p-GaAs contact layer 25 is etched and removed in a post shape by dry etching, and the AlAs layer 30 is selectively oxidized in a heated steam atmosphere. A single transverse mode control structure also serving as current confinement by the selective oxidation region 31 is provided. Next, the n-electrode 26 and the p-electrode 3
4 are sequentially formed, and an n-electrode 21 having an opening for a light emitting portion is formed on the back surface of the substrate 22.

In the surface emitting laser device shown in FIG.
A current is injected into the active layer 28 by applying a bias voltage between the n-electrode 26 and the n-electrode 2.
By applying a voltage between the first and n-electrodes 26, an electric field can be applied (voltage applied) to the multiple quantum well structure 24.

In the surface emitting laser device of the second embodiment, since the multiple quantum well structure portion 24 is provided between the active layer 28 and the n-DBR 23, only one etching step is required, and the manufacture becomes easy.

In the surface emitting laser device of the second embodiment,
Since the well layer of the multiple quantum well structure portion 24 has a staggered structure made of two kinds of GaInNAs mixed crystals having different compositions, the well layer is compared with a rectangular potential quantum well structure having a single composition having the same well width and the same number of wells. In addition, the change amount of the oscillation wavelength is large with respect to the same applied voltage to the multiple quantum well structure, so that a low voltage operation can be performed. Also,
The variable width of the wavelength also increases.

In Example 2, both Ga and the composition of nitrogen (N) were adjusted to obtain Ga having the same forbidden band width.
Although the staggered structure quantum well is formed by the InNAs mixed crystal, the band gap of each GaInNAs layer may be different. Moreover, the one produced by adjusting only the nitrogen composition may be used.

Also, in the surface emitting laser device of the second embodiment, similarly to the first embodiment, by using a GaInNAs mixed crystal for the active layer, carrier overflow from the active layer is reduced, and the oscillation threshold current and the heat generation of the device are reduced. Can be reduced. As a result, the wavelength change due to temperature is small, and the wavelength control becomes easy.

Embodiment 3 FIG. 10 is a view showing a specific configuration example of a surface emitting laser device of Embodiment 3. Note that, in the example of FIG. 10, the basic structure of the element is the same as that of the element of FIG. 8, and in FIG. 10, portions corresponding to FIG. 8 are denoted by the same reference numerals.

In the surface emitting laser device of the third embodiment, the barrier layer of the multiple quantum well structure 11 is made of Cd _0.58 Zn _0.42 S which is a II-VI group mixed crystal semiconductor, and the material of the well layer is GaInNA.
s. For the active layer 5, GaInAs quantum dots grown in SK mode are used. The resonator structure and the DBR structure are the same as in the first embodiment. During the crystal growth of the multiple quantum well structure 11, the growth temperature was set as low as possible to suppress the interdiffusion at the heterojunction surface.

The surface emitting laser device shown in FIG. 10 is manufactured by the following steps. That is, crystal growth, processing, and electrode formation are performed in the same manner as in the surface emitting laser element of FIG. Thereafter, an insulating film 15 such as SiO ₂ is formed on the entire surface of the element, and the insulating film is removed from the electrode portion. Thereafter, the conductive resin 16 is spin-coated to bury the post portion. Thus, it can be easily mounted on the submount on which the electrode pattern is formed, with the p-electrode surface facing down, for example, by using solder reflow.

In the surface emitting laser device according to the third embodiment,
Cd is added to the barrier layer of the subwell structure 11._{0. 58}Zn_0.42II such as S
Up to high electric field application by using -VI group mixed crystal semiconductor
A wavelength change is obtained, and the amount of change is large. In addition,
In the surface emitting laser device according to the third embodiment, the active layer 5 has a quantum dot structure.
The oscillation threshold voltage due to the quantum size effect.
Flow and element heat generation can be reduced. This
Therefore, wavelength change due to temperature is small and wavelength control is easy.
Become.

Fourth Embodiment FIG. 11 is a view showing a specific configuration example of a surface emitting laser system according to a fourth embodiment. The surface emitting laser system of FIG. 11 is a specific example of the surface emitting laser system of the fourth embodiment. That is, the surface emitting laser system of FIG. 11 detects the surface emitting laser element 110 of the first, second, or third embodiment and the wavelength of the oscillation state light of the surface emitting laser element 110, and Control circuit 42 for adjusting the voltage applied to the multiple quantum well structure of the surface emitting laser device so that the oscillation wavelength of the laser beam becomes a desired oscillation wavelength.
The oscillation wavelength of the surface emitting laser element 110 is dynamically controlled by the bias control circuit 42. As can be understood from this, the bias control circuit 42 is provided with the oscillation wavelength detecting unit 12 of the fourth embodiment.
It has a function of 0 and the voltage adjusting means 130.

According to the surface emitting laser system shown in FIG.
Since the bias voltage can be changed according to the operation state, a laser system using the surface emitting laser device of the first, second or third embodiment having a wide wavelength tunable range and high wavelength stability is provided. be able to.

Fifth Embodiment FIG. 12 is a view showing a specific configuration example of the surface emitting laser device of the fifth embodiment. In the example of FIG. 12, the basic structure of the element is the same as that of the elements of FIGS.
In FIG. 2, portions corresponding to those in FIGS. 8 and 10 are denoted by the same reference numerals.

The surface emitting laser element of FIG. 12 has the same surface emitting laser element body as the surface emitting laser element of FIG. 10, and the p-GaAs of the surface emitting laser element of FIG.
On the contact layer 13, the light detecting means 1 of the fifth embodiment
A pin diode 17 as 11 is formed,
On the diode 17, an n-GaAs contact layer 18,
An n-electrode 19 is formed.

In the surface emitting laser device of the fifth embodiment, the crystal is grown up to the p-GaAs contact layer 13 in the same manner as in the first and third embodiments in the same manner as in the first embodiment.
Pin diode 17 made of GaInNAs material, n
Crystal growth of the GaAs contact layer 18 is performed, and post formation, selective oxidation, and electrode formation are performed using the same method as in the first and third embodiments. The light emitting surface of this surface emitting laser element is on the substrate 2 side, and the pin diode 17 is provided at the end of the resonator opposite to the light emitting surface. Also, p
On the in diode 17, an n electrode 19 for applying a voltage to the pin diode 17 independently is provided.

In the surface emitting laser device of the fifth embodiment, current can be injected into the active layer 5 by forward biasing the n-electrode 1 and the p-electrode 10, and the multiple quantum well can be formed by the p-electrode 10 and the p-electrode 14. An electric field can be applied to the structure 11 to change the refractive index, and photodetection can be performed by reversely biasing the pin diode 17 with the p-electrode 14 and the n-electrode 19.

In the surface emitting laser device shown in FIG. 12, it is possible to monitor the light output during oscillation and the light transmission characteristics of the device. Further, as the material of the pin diode 17, any material having light receiving sensitivity in the oscillation wavelength band may be used, and other materials may be used. In the above-described example, the light detecting means 111 is manufactured by crystal growth on the surface emitting laser element main body. However, the light detecting means 111 may be formed by bonding or bonding to the surface emitting laser element main body.
The other electronic component which becomes 1 may be provided.

In the surface emitting laser device of the fifth embodiment, the monochromatic light is made incident from the light emitting surface of the surface emitting laser device to sweep the wavelength, so that the light detecting means 1 provided on the opposite end face of the resonator is provided.
11 (pin diode 17 in the example of FIG. 12), the transmission characteristics of the resonator can be obtained, and the resonance wavelength can be checked. By storing information such as the applied voltage to the multiple quantum well structure and the device temperature together with the resonance wavelength in a storage means such as a flash memory at this time, the bias setting necessary for oscillation for each device (setting of applied voltage) It can be performed. The wavelength of the surface emitting laser element whose wavelength has been adjusted in this manner can select a wavelength with high accuracy. Also,
Since data necessary for wavelength adjustment can be obtained electrically in a lump of the array, high-precision optical alignment is not required.

Sixth Embodiment FIG. 13 is a diagram showing a specific configuration example of a multi-wavelength light source system using the surface emitting laser array of the sixth embodiment. FIG.
In the multi-wavelength light source system, the surface emitting laser device according to the first, second, third or fifth embodiment, or the surface emitting laser system according to the fourth or sixth embodiment is used. A surface-emitting laser array (multi-wavelength array) 42 in which (n) surface-emitting laser elements are arranged in an array is used as a multi-wavelength light source) for controlling a voltage applied to a multiple quantum well structure. The bias control circuit 43 controls so that different oscillation wavelengths λ ₁ , λ ₂ ,..., Λ _n are obtained for each of the n surface emitting laser elements in the array 42. The shape of the array may be a two-dimensional array other than the one-dimensional array.

At this time, the signal serving as the control source of the bias voltage for setting the oscillation wavelength for each surface emitting laser element may be a signal obtained by directly monitoring the oscillation light, or a signal as described in the fifth embodiment. Data adjusted for each element may be used.

The surface emitting laser array (multi-wavelength array) 42 of the sixth embodiment can vary the oscillation wavelength for each surface emitting laser element, so that it can be applied to a wide range of applications. By using the surface emitting laser device of the second, third, or fifth embodiment, the variable width of the wavelength is wide.

Seventh Embodiment FIG. 14 is a diagram showing a configuration example of an optical interconnection system according to a seventh embodiment. The optical interconnection system of FIG. 14 is configured to transmit and receive an optical signal between the chip 1 and the chip 2 via an optical fiber.
Here, a surface emitting laser array light source as shown in FIG. 13 is used for the chips 1 and 2 (first, second, and second).
The surface emitting laser device according to the third or fifth embodiment, or the surface emitting laser system according to the fourth or sixth embodiment is used). That is, the chip 1 is provided with the surface emitting laser array 42-1, the bias control circuit 43-1, the multiplexing / demultiplexing means 44-1 and the light receiving means 45-1 such as a PD. Similarly, the chip 2 is provided with a surface emitting laser array 42-2, a bias control circuit 43-2, a multiplexing / demultiplexing unit 44-2, and a light receiving unit 45-2 such as a PD. .

In the optical interconnection system shown in FIG. 14, surface emitting laser arrays (multi-wavelength arrays) 42-1, 42 controlled to different oscillation wavelengths for each surface emitting laser element.
On the transmitting side, light of different wavelengths is guided to one optical fiber by a multiplexing means 44-1 or 44-2 such as an optical coupler, and on the receiving side, a demultiplexing means such as a grating is used. After demultiplexing the light for each wavelength by 44-2 or 44-1, a signal is received by light receiving means 45-2 or 45-1 such as a PD.

In the optical interconnection system of FIG. 14, the bias control circuits 43-1 and 43-2 control the voltage applied to the multiple quantum well structure of the surface emitting laser device by directly detecting the wavelength of the oscillation light. It is carried out. In addition, as described above, it is also possible to adopt a system configuration for performing wavelength adjustment in accordance with information stored in advance.

In the optical interconnection system shown in FIG. 14, the surface emitting laser device of the first, second, third or fifth embodiment or the surface emitting laser system of the fourth or sixth embodiment is used. By using this, a large wavelength variable width can be used at a minute wavelength interval, so that a large amount of information can be transmitted at a higher speed than in the past.

Eighth Embodiment FIG. 15 shows a local area network (LA) of an eighth embodiment.
N) is a diagram illustrating a configuration example of a system. LAN of FIG.
The system is configured by connecting an optical cable between a terminal and a server according to a protocol such as Ethernet (registered trademark). For example, each terminal is connected to a switch for each floor, and then connected to a server via a core switch. Since the surface emitting laser device of the first, second, third or fifth embodiment, or the surface emitting laser system of the fourth or sixth embodiment can continuously change the oscillation wavelength, The desired wavelength can be easily obtained, and the variable wavelength range is wide, so that the usable wavelength band is wide. Therefore, it is possible to transmit a large amount of information at a higher speed than before.

[0097]

As described above, according to the first aspect of the present invention, the GaInNAs mixed crystal is used for the well layer of the multiple quantum well structure in which the refractive index is changed by applying an electric field. It is possible to provide a surface emitting laser element capable of suppressing the leakage of electrons from the well layer of the multiple quantum well structure at the time and obtaining a large change in the refractive index under a high electric field.

That is, when an attempt is made to fabricate a refractive index modulation region having a multiple quantum well structure in a surface emitting laser having a wavelength of 1 to 1.3 μm, for example, InGaAs or the like is used as a conventional III-V mixed crystal semiconductor material. One of the materials for the well layer. However, when the GaInNAs mixed crystal is used as the well layer of the multiple quantum well structure, the conduction band energy is largely reduced mainly by band gap bowing due to nitrogen addition, and when compared with the InGaAs material having the same forbidden width, the conduction band side is reduced. A deep potential well can be created. Accordingly, a strong confinement effect is obtained particularly for electrons that easily leak from the well layer when an electric field is applied, excitons are less likely to be dissociated, and a large change in the refractive index can be obtained under the application of a stronger electric field than before. by this,
A tunable surface emitting laser device having a wider tunable width than the conventional one can be obtained.

The GaInNAs mixed crystal has a reduced lattice constant by adding nitrogen, and has the same forbidden band width.
The degree of lattice misalignment with the substrate can be reduced as compared with the GaAs mixed crystal. In a wavelength tunable surface emitting laser device, a multi-quantum well structure for performing refractive index modulation requires about 10 pairs or more, and a DBR having a thickness of several μm is formed on the multi-quantum well structure.
Need to be grown. When the lattice irregularity of the multiple quantum well structure is large, crystal defects such as transition occur during the crystal growth of the multiple quantum well structure and the DBR layer, and the device characteristics are deteriorated. In a surface emitting laser device requiring such a thick reflecting mirror, it is very important to reduce the amount of lattice distortion of the multiple quantum well structure.

When the well layer of the multiple quantum well structure is made of GaInNAs mixed crystal as in the first aspect of the present invention, the degree of lattice mismatch in the multiple quantum well can be made very small, and the multiple quantum well structure and the number A DBR having a thickness of μm can be grown with good crystallinity. As a result, an element having good characteristics can be obtained.

According to the second aspect of the present invention, a well layer having a multiple quantum well structure in which a refractive index is changed by application of an electric field is formed of GaInNAs layers having different compositions to form a staggered junction. Therefore, the rate of change in the refractive index when a low electric field is applied is large, and a large change in the refractive index can be obtained with a bias voltage lower than in the past, whereby a wavelength tunable surface emitting laser device with a reduced operating voltage can be obtained. .

According to the third aspect of the present invention, in the surface emitting laser device according to the first or second aspect, a II-VI group semiconductor material is used for a barrier layer having a multiple quantum well structure. Therefore, carrier confinement is very strong, and leakage of carriers (for example, electrons) from a well can be effectively suppressed even under the application of a high electric field.
A large amount of change in refractive index can be obtained under high electric field application,
A surface emitting laser device having a large wavelength variable amount can be obtained.

According to a fourth aspect of the present invention, in the surface emitting laser device according to any one of the first to third aspects, a GaInNAs semiconductor material is used for the active layer. 1.3 μm on GaAs substrate
Band, 1.55 μm band, longer wavelength, etc.
A surface emitting laser element having a wavelength band longer than 0.9 μm can be obtained. In addition, high quality AlG
Since an aAs / AlAsDBR or a current confinement structure by selective oxidation of AlAs can be used, excellent device characteristics can be obtained. In the case of GaInNAs mixed crystal, the amount of band discontinuity in the conduction band is large, and carrier overflow is effectively suppressed. Therefore, the oscillation reactive current is reduced, the threshold value is lowered, and the rise in element temperature is suppressed. For example, refer to the document “The 47th Lecture Meeting on Applied Physics, 3
1a-N-10 ", the differential temperature change rate of the oscillation wavelength is 0.39 nm / K in the 1.3 μm band end-face type laser,
The temperature change rate of the forbidden band width is 0.42 nm / K, which is
It is reported that the value is about half that of the GaAsP material. Therefore, when GaInNAs mixed crystal is also used for the active layer, it is possible to minimize the fluctuation of the oscillation wavelength. This simplifies the control of the bias voltage of the multiple quantum well structure with respect to changes in the driving state of the device, the operating environment temperature, and the like.

According to a fifth aspect of the present invention, in the surface emitting laser device according to any one of the first to third aspects, the active layer includes a quantum well made of a GaInNAs or GaInAs semiconductor material. Since the dot structure is used, an oscillation wavelength in a band of 1.2 μm to 1.55 μm can be obtained on a GaAs substrate, and excellent element characteristics can be obtained. Further, in the quantum dot structure, the oscillation threshold current can be further reduced by the quantum size effect, and the reduction in the wavelength tunable width and the efficiency of the element can be suppressed by reducing the heat generation of the element.

According to the present invention, a multiple quantum well structure is provided between the active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, and a current is injected into the active layer. And a second electrode for applying an electric field to the multiple quantum well structure are provided independently of each other, and the second electrode applies an electric field to the multiple quantum well structure to perform multiplexing. A surface emitting laser element that changes the refractive index of the quantum well structure to vary the oscillation wavelength, and an oscillation wavelength detecting unit that detects the oscillation wavelength of the surface emitting laser element. The oscillation wavelength of the device is detected, and the bias current of the multiple quantum well structure can be appropriately adjusted according to the operation and the oscillation state of the device, so that the desired oscillation wavelength is obtained and the stability of the oscillation wavelength is improved. .

According to a seventh aspect of the present invention, in the surface emitting laser system according to the sixth aspect, the surface emitting laser is set so that the oscillation wavelength detected by the oscillation wavelength detecting means becomes a desired oscillation wavelength. Since the voltage adjusting means for adjusting the voltage applied to the multiple quantum well structure of the device is further provided, the oscillation wavelength can be automatically adjusted so that the oscillation wavelength of the device becomes a desired oscillation wavelength.

According to the present invention, a multiple quantum well structure is provided between the active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, and a current is injected into the active layer. And a second electrode for applying an electric field to the multiple quantum well structure are provided independently of each other, and the second electrode applies an electric field to the multiple quantum well structure to perform multiplexing. A surface emitting laser element main body that changes the refractive index of the quantum well structure to vary the oscillation wavelength; and a surface emitting laser provided outside the cavity on the side opposite to the light emitting surface of the surface emitting laser element main body. Light detecting means for detecting light near the oscillation wavelength that has entered from the light emitting surface of the element body and transmitted through the surface emitting laser element body, so that the light output of the element body during laser oscillation or the light emission Element when light enters from the surface Transmission characteristics can be detected, APC control and, it is possible to examine the optical characteristics such as the resonant wavelength of the element.

According to a ninth aspect of the present invention, there is provided a surface emitting laser device according to the eighth aspect, and a light incident means for causing a monochromatic light to enter the light emitting surface of the surface emitting laser device by sweeping a wavelength. The wavelength is swept by the light incident means on the light emitting surface of the surface emitting laser element, and monochromatic light is incident thereon, and light near the oscillation wavelength transmitted through the surface emitting laser element is detected by the light detecting means of the surface emitting laser element. When detecting the amount of light detected by the light detecting means, a voltage applying means for applying a voltage to the multiple quantum well structure of the surface emitting laser device, and a light detected by the light amount detecting means. Storage means for storing the relationship between the wavelength of monochromatic light at that time and the voltage applied to the multiple quantum well structure of the surface emitting laser element at the time when the amount of light is maximized. Divide the applied voltage corresponding to the oscillation wavelength Out, by applying the applied voltage to the multiple quantum well structure of the surface emitting laser element, it is possible to oscillate the laser device at a desired oscillation wavelength.

According to a tenth aspect of the present invention, in the surface emitting laser system according to the ninth aspect, when the surface emitting laser element is oscillated at a desired resonance wavelength, the voltage applying means is stored in the storage means. Based on the relationship between the stored wavelength of monochromatic light and the voltage applied to the multiple quantum well structure of the surface emitting laser device, the voltage applied to the multiple quantum well structure of the surface emitting laser device corresponding to the desired resonance wavelength Is determined from the storage means and applied to the multiple quantum well structure of the surface emitting laser device, so that the oscillation wavelength can be automatically adjusted so that the oscillation wavelength of the device becomes a desired oscillation wavelength.

According to an eleventh aspect of the present invention, there is provided the wavelength adjusting method for adjusting the resonance wavelength of the surface emitting laser element according to the eighth aspect, wherein the method is applied to the multiple quantum well structure of the surface emitting laser element body. In a state where a voltage is applied, monochromatic light whose wavelength is continuously changed is made incident from the light emitting surface of the surface emitting laser element main body, and the amount of monochromatic light transmitted through the surface emitting laser element main body is detected. The resonance wavelength of the resonator of the surface emitting laser element body is detected by using the equation, the relationship between the applied voltage applied to the multiple quantum well structure and the detected resonance wavelength is derived, and the derived applied voltage and resonance wavelength are derived. Based on the relationship, the resonance wavelength is adjusted by adjusting the applied voltage, so that the oscillation wavelength of the element becomes a desired oscillation wavelength,
The oscillation wavelength can be automatically adjusted.

According to the twelfth aspect of the present invention, there is provided a surface on which a plurality of the surface emitting laser elements according to any one of the first to fifth and eighth aspects are arranged in an array. Since it is a light emitting laser array, it is possible to continuously adjust the wavelength for each element, and to obtain a wavelength tunable surface emitting laser array having a wide wavelength tunable width and optimal for two-dimensional integration for wavelength multiplex communication.

According to the thirteenth aspect of the present invention, the first aspect
The surface emitting laser device according to any one of claims 5 to 8, or claim 6, claim 7, claim 9, and claim 9.
Since the surface-emitting laser system according to any one of claims 10 or 10, or the optical interconnection system is configured using the surface-emitting laser array according to claim 12,
An optical interconnection system using WDM having a wide wavelength bandwidth can be easily obtained, and a large amount of data can be transmitted at high speed. In the system according to claim 13,
It is possible to control the wavelength at minute wavelength intervals.

According to the fourteenth aspect of the present invention, the surface emitting laser device according to any one of the first to fifth and eighth aspects, or the sixth, seventh, and seventh aspects. Since the LAN system is configured using the surface emitting laser system according to any one of claims 9 and 10, or the surface emitting laser array according to claim 12, the wavelength bandwidth that can be used is wide. An optical LAN system using WDM can be easily obtained, and a large amount of data can be transmitted at high speed. In the first gigabit Ethernet of 10 Gbps or later, a WDM system using four wavelengths is used, and it is considered that the number of wavelength multiplexing will further increase with the speeding up of the network in the future. Further, in the system according to the fourteenth aspect, it is possible to control the wavelength at a minute wavelength interval.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a surface emitting laser device of the present invention.

FIG. 2 is a diagram showing a staggered band structure.

FIG. 3 is a diagram showing a configuration example of a surface emitting laser system according to the present invention.

FIG. 4 is a diagram showing another configuration example of the surface emitting laser system according to the present invention.

FIG. 5 is a diagram showing a configuration example of a surface emitting laser device according to the present invention.

FIG. 6 is a diagram showing another configuration example of the surface emitting laser system according to the present invention.

FIG. 7 is a diagram showing another configuration example of the surface emitting laser system according to the present invention.

FIG. 8 is a diagram illustrating a specific configuration example of the surface emitting laser element according to the first embodiment.

FIG. 9 is a diagram illustrating a specific configuration example of a surface emitting laser element according to a second embodiment.

FIG. 10 is a diagram illustrating a specific configuration example of a surface emitting laser element according to a third embodiment.

FIG. 11 is a diagram illustrating a specific configuration example of a surface emitting laser system according to a fourth embodiment.

FIG. 12 is a diagram showing a specific configuration example of a surface emitting laser element according to a fifth embodiment.

FIG. 13 is a diagram illustrating a specific configuration example of a multi-wavelength light source system using a surface emitting laser array according to a sixth embodiment.

FIG. 14 is a diagram illustrating a configuration example of an optical interconnection system according to a seventh embodiment.

FIG. 15 is a diagram illustrating a configuration example of a LAN system according to an eighth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Active layer 102,103 Distributed Bragg reflector 104 Multiple quantum well structure part 105,106,107 Electrode 110 Surface emitting laser element 120 Oscillation wavelength detection means 130 Voltage adjustment means 140 Light incidence means 141 Light quantity detection means 142 Voltage application means 143 Storage Means 1, 26, 21, 19 n electrode 2, 22 n-GaAs substrate 3, 23 n-DBR (distributed Bragg reflector) 5, 28 GaInNAs / GaAs MQW
Active layer 4,6,27,29 undoped GaAs spacer layer 7,30 p-AlAs layer 8,31 selective oxidation region 9,13,25,33 p-GaAs contact layer 11,24 multiple quantum well structure part 12,32 undoped DBR 10, 14, 34 p electrode 15 insulating film 16 conductive resin 17 pin diode 18 n-G
aAs contact layer 42 surface emitting laser array 43 bias control circuit 44-1 and 44-2 multiplexing / demultiplexing means 45-1 and 45-2 light receiving means

Claims (14)

[Claims] A multi-quantum well structure is provided between an active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, and a first electrode for injecting current into the active layer and a multi-quantum well structure are provided. A second electrode for applying an electric field to the well structure is provided independently of each other, and the refractive index of the multiple quantum well structure is changed by applying an electric field to the multiple quantum well structure by the second electrode. A surface emitting laser device having a variable oscillation wavelength, wherein GaInNAs mixed crystal is used as a material of a well layer of the multiple quantum well structure. 2. An active layer and a pair facing each other across the active layer.
Multiple quantum well structure between the distributed Bragg reflector
And a first electrode for injecting current into the active layer and a large weight.
The second electrode for applying an electric field to the subwell structure is
Provided independently of each other, and a multiple quantum well
Multiple quantum well structure by applying an electric field to the structure
Surface emitting laser with variable oscillation wavelength by changing the refractive index of the part
The device, wherein the well layer of the multiple quantum well structure portion includes:
First Ga_x1In_1-x1N_z1As _1-z1(0 <x1 ≦ 1,0
≦ z1 ≦ 1) layer and second Ga_x2In_1-x2N_z2As
_1-z2(0 <x2 ≦ 1, 0 <z2 ≦ 1)
The first Ga_x1In_1-x1N_z1
As_1-z1The (0 <x1 ≦ 1, 0 ≦ z1 ≦ 1) layer is the second layer.
Ga_x2In_1-x2N_z2As_1-z2(0 <x2 ≦ 1, 0 <z2
≦ 1) The conduction band energy and valence band energy
A surface emitting laser device having high energy. 3. The surface emitting laser device according to claim 1, wherein the barrier layer having a multiple quantum well structure includes:
A surface emitting laser device using a II-VI group semiconductor material. 4. The surface emitting laser device according to claim 1, wherein the active layer includes
A surface-emitting laser device using an aInNAs semiconductor material. 5. The surface emitting laser device according to claim 1, wherein the active layer includes
A surface emitting laser device using a quantum dot structure made of aInNAs or GaInAs semiconductor material. 6. A multi-quantum well structure portion between an active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, wherein a first electrode for injecting current into the active layer and a multi-quantum well structure are provided. A second electrode for applying an electric field to the well structure is provided independently of each other, and the refractive index of the multiple quantum well structure is changed by applying an electric field to the multiple quantum well structure by the second electrode. A surface emitting laser system comprising: a surface emitting laser element that makes an oscillation wavelength variable; and an oscillation wavelength detecting unit that detects an oscillation wavelength of the surface emitting laser element. 7. The surface emitting laser system according to claim 6, wherein the oscillation wavelength detected by the oscillation wavelength detecting means is applied to the multiple quantum well structure of the surface emitting laser element such that the oscillation wavelength becomes a desired oscillation wavelength. A surface emitting laser system further comprising a voltage adjusting unit for adjusting a voltage. 8. A multi-quantum well structure between an active layer and a pair of distributed Bragg reflectors opposed to each other with the active layer interposed therebetween, wherein a first electrode for injecting current into the active layer and a multi-quantum well structure are provided. A second electrode for applying an electric field to the well structure is provided independently of each other, and the refractive index of the multiple quantum well structure is changed by applying an electric field to the multiple quantum well structure by the second electrode. A surface-emitting laser element main body having a variable oscillation wavelength, and a surface which is provided outside the resonator on the side opposite to the light-emitting surface of the surface-emitting laser element body and which is incident from the light-emitting surface of the surface-emitting laser element main body. And a light detecting means for detecting light near the oscillation wavelength transmitted through the light emitting laser element body. 9. A surface emitting laser device according to claim 8, light emitting means for sweeping a wavelength to make monochromatic light incident on a light emitting surface of the surface emitting laser device, and light emitting of the surface emitting laser device. When the wavelength is swept by the light incident means and monochromatic light is incident on the surface and light near the oscillation wavelength transmitted through the surface emitting laser element is detected by the light detecting means of the surface emitting laser element, the light is detected by the light detecting means. Light amount detecting means for detecting the light amount of light, voltage applying means for applying a voltage to the multiple quantum well structure of the surface emitting laser element, and when the light amount of the light detected by the light amount detecting means is maximum, A surface emitting laser system comprising: storage means for storing a relationship between a wavelength of monochromatic light and a voltage applied to a multiple quantum well structure of a surface emitting laser element at that time. 10. The surface emitting laser system according to claim 9, wherein when oscillating the surface emitting laser element at a desired resonance wavelength, the voltage applying means is configured to control the wavelength of the monochromatic light stored in the storage means and the surface. Based on the relationship between the voltage applied to the multiple quantum well structure of the light emitting laser device and the voltage applied to the multiple quantum well structure of the surface emitting laser corresponding to the desired resonance wavelength, the surface emitting laser device A surface emitting laser system characterized in that the voltage is applied to the multiple quantum well structure of (1). 11. A wavelength adjusting method for adjusting a resonance wavelength of a surface emitting laser device according to claim 8, wherein a surface of the surface emitting laser device is applied with an applied voltage to a multiple quantum well structure portion. By emitting monochromatic light whose wavelength is continuously changed from the light emitting surface of the light emitting laser element main body and detecting the amount of monochromatic light transmitted through the surface emitting laser element main body, the cavity of the surface emitting laser element main body is detected. Detect resonance wavelength,
At this time, the relationship between the applied voltage applied to the multiple quantum well structure and the detected resonance wavelength is derived, and the resonance wavelength is adjusted by adjusting the applied voltage based on the derived relationship between the applied voltage and the resonance wavelength. Wavelength adjusting method. 12. A surface emitting laser array, wherein a plurality of the surface emitting laser elements according to any one of claims 1 to 5 are arranged in an array. 13. The surface-emitting laser device according to claim 1, or any one of claims 6, 7, 9, and 10. 13. An optical interconnection system using the surface emitting laser system according to claim 12 or the surface emitting laser array according to claim 12. 14. The surface-emitting laser device according to claim 1, or any one of claims 6, 7, 9, and 10. 13. A local area network system using the surface emitting laser system according to claim 12 or the surface emitting laser array according to claim 12.