JPH1090634A - Semiconductor optical switching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new semiconductor switching device utilizing a photonic band by allowing the device to have a means irradiating the control light of a circularly polarized light on cyclic structures on a two dimensional flat plane along an optical path which does not orthogonally cross optical paths of lights to be controlled and switching passing rates of the lights to be controlled by the control light. SOLUTION: Light beams to be emitted from two lines of optical fibers 1a, 1b are made incident on two optical paths La, Lb via collimating lenses 2a, 2b. Moreover, polarizers 3a, 3b are arranged on the incident optical paths. Further, a two dimensional photonic band 4 is arranged on mid-courses of two optical paths La, Lb. The two dimensional band 4 is constituted by arranging a medium having a second complex index of refraction in cycles in a medium having a first complex index of refraction. Then, when it is irradiated with the control light of the circularly polarized light the band is changed. At this time, the band is changed to the state of transmission or reflection with respect to incident lights having the same circularly polarized light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical semiconductor device, and more particularly, to a semiconductor optical switch device capable of switching controlled light.

[0002]

2. Description of the Related Art In optical communication, a technique for optically switching for modulation or the like is required. The simplest optical switch would be a method of turning on and off the driving of a light source such as a semiconductor laser. However, if the driving current of the semiconductor laser is turned on / off, the oscillation wavelength is disturbed, which is not preferable for high-speed communication.

As a technique for switching incident light, a technique using the Franz-Keldysh effect (FK) for controlling the absorption band structure of a bulk semiconductor by an electric field, and an effective band by applying an electric field to a multiple quantum well (MQW) structure. One that uses the quantum confined Stark effect (QCSE) that shifts the gap red, one that uses the Wannier-Stark effect (WS) that causes a blue shift by discretizing the MQW quantum well, and one that uses the refractive index change due to current injection. Etc. are known.

Of these technologies, those using a bulk semiconductor are naturally strongly restricted by the characteristics of the bulk semiconductor. Those using a quantum confinement structure such as a quantum well include a well layer (well region) and a barrier layer (barrier region).
Has a degree of design freedom in combination with the above, but is still limited by the properties of the material used.

[0005] A photonic band has been proposed as a technique that allows more free design. Photonic bands create new optical properties by creating a periodic structure in media with different refractive indices.

A photonic band in which a medium having a high refractive index and a medium having a low refractive index are regularly arranged in a one-dimensional direction has already been put to practical use as a distributed Bragg reflector (DBR). Strong reflection occurs for incident light whose repetition period of the refractive index distribution is λ / 2 of the incident light. For example, by alternately arranging a high refractive index region having an optical length of λ / 4 and a low refractive index region having an optical length of λ / 4, a reflection band having a certain wavelength width is formed.

When a low refractive index region having an optical length of λ / 2 (or an integral multiple thereof) is sandwiched in the DBR structure, the structure becomes similar to that of a Fabry-Perot resonator, and a narrow pass band (narrow band) sandwiched between high reflectance bands is used. Pass band).

The periodic structure described above can be realized not only by the refractive index, which is the real part of the plurality of refractive indexes, but also by the extinction coefficient, which is the imaginary part of the complex refractive index. That is, it can be realized using two or more types of optical media having different complex refractive indices.

The photonic band is established even if the periodic structure is expanded from one dimension to two dimensions and three dimensions. When a basic unit (unit cell or primitive cell) having a predetermined symmetry is periodically and repeatedly arranged in one-dimensional, two-dimensional, and three-dimensional directions, a band structure (photonic) reflecting the symmetry and periodicity is obtained. Band) is obtained.

[0010]

When a photonic band is used, the same optical material as that of the related art can be used to realize optical properties that have been impossible in the related art. However, optical elements using photonic bands have not yet been sufficiently developed.

An object of the present invention is to provide a novel semiconductor optical switch device using a photonic band.

Another object of the present invention is to provide a novel semiconductor optical switch device for a plurality of incident beams using a photonic band of two or more dimensions.

[0013]

According to a first aspect of the present invention, there are provided two types of optical media having different complex refractive indices,
A photonic band layer that forms a periodic structure on a two-dimensional plane including at least one optical medium including two types of semiconductors that are semiconductors; an optical path of controlled light parallel to the two-dimensional plane; Means for irradiating the periodic structure on the two-dimensional plane with circularly polarized control light along an optical path that is not orthogonal to the optical path of the light, wherein the control light switches the transmittance of the controlled light with the control light. It is to provide.

By irradiating the photonic band layer with circularly polarized light, upward spin or downward spin can be selectively excited. The photonic band changes due to the change in the spin distribution in the photonic band layer.

By changing the photonic band, the transmission band for the controlled light can be changed to a reflection band or an absorption band, or the reflection band or the absorption band can be changed to a transmission band. Thus, an optical switch function can be realized.

The photonic band has a band structure depending on the incident direction of the controlled light due to its periodic structure. When the controlled light is incident on a plurality of optical paths having different symmetries, different optical switch functions can be realized according to the optical paths.

According to another aspect of the present invention, a periodic structure is formed on a two-dimensional plane including two types of optical media having different complex refractive indexes, at least one of which is a semiconductor. A photonic band layer to be controlled, an optical path of the controlled light parallel to the two-dimensional plane, and means for applying an electric stress to the periodic structure of the photonic band layer. Provided is a semiconductor optical switch device for switching a transmittance.

The photonic band can also be changed by electric stress. Switching of the controlled light can be performed based on the change of the photonic band. Using the symmetry of the photonic band,
It is also possible to realize an optical switch function of performing different switching depending on the direction of the optical path.

[0019]

FIG. 1 is a perspective view schematically showing a semiconductor optical switch device according to an embodiment of the present invention.

Light beams emitted from the two optical fibers 1a and 1b are incident on two optical paths La and Lb via collimator lenses 2a and 2b. Incidentally, the polarizers 3a and 3b are arranged on this incident optical path.

A two-dimensional photonic band 4 is arranged in the middle of the two optical paths La and Lb. The two-dimensional photonic band 4 is configured such that a medium having a second complex refractive index is periodically arranged in a medium having a first complex refractive index.

From above the two-dimensional photonic band 4,
The control light 5 enters through the circular polarizer 3c. Control light 5
Is set in a direction not orthogonal to the optical paths La and Lb of the controlled light. That is, the optical path Lc and the optical path L
The inner product of a and Lb takes a value other than 0. Polarizers 3a, 3b
Is a circular polarizer, there is no need to arrange a polarizer on the output side. When the polarizers 3a and 3b are linear polarizers, the optical path L
Linear polarizers (analyzers) 6a and 6b orthogonal to the polarizers on the incident side are arranged on the emission sides of a and Lb.

Next, the configuration and function of the two-dimensional photonic band 4 will be described with reference to FIG.

FIG. 2A is a perspective view schematically showing a two-dimensional photonic band. A medium having a second complex refractive index Ny is periodically embedded in a medium having a first complex refractive index Nx. A photonic band is formed by this complex refractive index periodic structure.

FIG. 2B is a schematic plan view of the photonic band structure. FIG. 2B shows a case of a triangular lattice having hexagonal symmetry. The periodic structure is not limited to the illustrated triangular lattice, and various periodic structures such as a square lattice, a rectangular lattice, and an oblique lattice can be adopted.

One of the two types of optical media having a complex refractive index may be vacuum or air, but when a photonic band is formed by a semiconductor structure, vacuum or air is relatively troublesome to handle. .

FIGS. 2C and 2D show two examples of forming a photonic band using two types of semiconductor optical materials. In FIG. 2C, the first semiconductor layer 4a
Is selectively etched to leave a columnar portion. In addition, although the figure shows a case where the lower portion of the first semiconductor layer 4a remains, the entire thickness of the first semiconductor layer 4a may be etched. The second semiconductor layer 4b is buried on the first semiconductor layer 4a leaving the columnar portions. In this way, a photonic band is formed by the first semiconductor layer 4a periodically arranged and the second semiconductor layer 4b embedded therein.

In FIG. 2D, the first semiconductor layer 4
A mask having openings periodically arranged is formed on a, and anisotropic etching is performed through the openings to form columnar recesses. The second semiconductor layer 4b is grown on the first semiconductor layer 4a having the column-shaped recess, and the recess is buried. The first semiconductor layer 4a having the concave portion and the second semiconductor layer 4b embedded in the concave portion form a two-dimensional structure periodically arranged.

The triangular lattice shown in FIG.
A Brillouin zone as shown in FIG. According to the hexagonal symmetry, a Brillouin zone of an equivalent hexagonal structure is formed. The vertex of the hexagon is the J point (J direction), and the midpoint of each side is the X point (X direction). The direction orthogonal to the two-dimensional periodic structure is indicated by 示 す.

FIG. 2 (F) shows an example of a band structure for the triangular lattice shown in FIG. 2 (B). The horizontal axis indicates the direction of the wave vector of the light, and the vertical axis indicates the photon energy of the incident light. Each curve shown in the figure indicates a transmission band through which light passes. The broken line indicates the transmission band when the photonic band changes. When circularly polarized light is used as the incident signal light for the photonic band 4, circularly polarized light in the same direction as the control light 5 is used. For example, when the incident light having the photon energy E1 is incident from the X direction, the state is the point P1 on the transmission band, and the incident light is transmitted as it is.

As shown in FIG. 1, when the two-dimensional photonic band 4 is irradiated with circularly polarized light as the control light 5, the spin distribution changes and the photonic band changes from a solid line to a broken line. That is, the position of the transmission band is from point P1 to point P
2 and the point P1 changes from the transmission state to the reflection state. Therefore, the transmitted light changes to the zero state.

As shown in FIG. 1, when two incident lights are incident from two directions, different switching can be performed by the same control light. For example, it is assumed that two optical paths La and Lb are arranged in the X direction and the J direction, respectively, and the photon energy of the incident light is E2. Then, the two incident lights correspond to the points P2 and P3. When the control light 5 of the circularly polarized light is not irradiated, the band is at the position indicated by the solid line, and is reflected at the point P2 and is transmitted at the point P3. When the circularly polarized control light 5 is irradiated, the band changes from a solid line to a broken line. At this time, for the incident light having the same circularly polarized light, the point P2 changes to a transmission state and the point P3 changes to a reflection state. In this manner, switching having a complementary function can be realized by the same control light.

When linearly polarized light is used as the incident light, when the spin distribution is changed by the control light 5, the polarization angle of the incident light is rotated by the spin distribution. Outgoing side polarizer 6
If a and 6b are arranged in a state orthogonal to the polarizers 3a and 3b on the incident side, the output light changes due to the rotation of the polarization angle.

FIG. 3 is a graph schematically showing a switching operation in a case where controlled light is incident in the J direction and the X direction and control light is selectively applied. 3 shows the waveform of the control light. FIG. 3 shows the input waveform and output waveform of the controlled light in the J direction in the second and third stages. 3 shows the input waveform and output waveform of the controlled light in the X direction in the fourth and fifth stages. In each graph, the horizontal axis represents time, and the vertical axis represents light intensity.

As shown in the second and fourth stages, it is assumed that the controlled light in the J and X directions is a pulse train with a fixed time interval.

The control light is, as shown in the first graph,
It is assumed that the photonic band is irradiated in synchronization with the second pulse. By the irradiation of the control light, the transmission state changes to the reflection state in the J direction. Therefore, while the control light is being irradiated, the incident light is not transmitted, and the second pulse disappears.

In the X direction, irradiation of control light causes
The reflection state changes to the transmission state. Therefore, when the control light is not irradiated, the output light disappears, and the incident light is transmitted only while the control light is irradiated. In this way,
Only the second pulse is transmitted and the first, third, and fourth pulses disappear.

As is clear from the third and fifth graphs, the switching in the J direction and the switching in the X direction are performed complementarily.

When the spin distribution is excited by using circularly polarized light, the relaxation time of the spin is significantly faster than other relaxation times. Therefore, extremely high-speed switching can be realized. Although FIG. 1 shows a case where two incident lights are incident, more incident lights can be used. When light is incident from the same symmetry direction, the same switching operation is obtained.

In the embodiment shown in FIG. 1, the case where optical switching is performed using a two-dimensional photonic band has been described. However, a three-dimensional photonic band can be used.

FIG. 4 shows an example of a configuration for realizing a three-dimensional photonic band. The basic unit is a cube, and a sphere having a first complex refractive index is arranged at the vertex of the cube.
These basic units are repeatedly arranged in a three-dimensional direction. The portion other than the sphere is filled with the second medium having the second complex refractive index. In the case of a three-dimensional photonic band, the three-dimensional photonic band is based on periodicity (symmetry) in three-dimensional space.
A dimensional band is obtained.

The band structure shown in FIG. 2F changes according to each parameter of the photonic band. The basic unit of the two-dimensional or three-dimensional periodic structure can be selected according to the wavelength of the incident light to be used. For example, when exciton absorption is used, it is preferable to select light having a wavelength slightly longer than the band edge as the incident light. The periodic structure of the photonic band is selected according to this wavelength. When the exciton absorption is used, the effect is more remarkable in a semiconductor structure using the quantum confinement effect than in a bulk semiconductor.

FIGS. 5A, 5B and 5C schematically show a semiconductor structure having a quantum confinement effect. FIG.
(A) shows a quantum well structure in which two types of semiconductors having different complex refractive indices are alternately stacked. In the case of such a multiple quantum well structure, periodicity occurs one-dimensionally in the stacking direction.

FIG. 5B shows quantum wire structures arranged regularly in parallel. In the case of a quantum wire having a limited degree of freedom in the two-dimensional direction, the quantum effect is further enhanced.

FIG. 5C shows a quantum box structure confined in a three-dimensional direction. Quantum boxes are regularly arranged in a two-dimensional plane.

FIGS. 5B and 5C show the case where quantum wires and quantum boxes are arranged in a two-dimensional plane.
The same structure may be periodically stacked in a direction orthogonal to the illustrated plane to form a three-dimensional periodic structure.

In the embodiment of FIG. 1, the case where the photonic band is changed by the control light has been described. However, it is not always preferable to control the signal light using light. For example, when the control signal is an electric signal, it is often desired to perform the control electrically. Hereinafter, an embodiment in which the photonic band is electrically controlled will be described.

FIG. 6 shows the configuration of the second embodiment. FIG.
6A is a schematic plan view showing a planar configuration, FIG. 6B is a perspective view schematically showing a photonic band structure, and FIG.
FIG. 3C is a cross-sectional view illustrating a stacked configuration of the switch device.
In this embodiment, the same structure as that of the 0.75 μm band semiconductor MQW amplifier is used.

As shown in FIG. 6C, the (001) plane is
Have n⁺The molecular beam epitaxy is formed on the surface of the
N-type layers 22, 23, 24, 2 by taxi (MBE)
5 and the i-type layer 25 are laminated. The n-type layer 22 has a thickness of about
500 nm, Si-doped carrier density about 1 × 10¹⁸c
m^-3Is a buffer layer formed of an n-type GaAs layer.
The n-type layer 23 on the GaAs layer has a thickness of about 15 nm,
Al about 15nm thick _0.5Ga_0.5As layer alternately
A superlattice layer having a carrier concentration of about 5 × 10
¹⁷cm^-3Si is doped so that

The n-type layer 24 thereon has a carrier density of 5 ×
10 ¹⁷ cm ^-3 doped with Si, about 1500 nm thick
Is a clad layer of n-type Al _0.5 Ga _0.5 As. The n-type layer 25 thereon has a carrier density of about 1 × 10 ¹⁷ cm ^−3.
Is about 50 nm thick and n-doped with Si.
It is a waveguide layer of type Al _0.4 Ga _0.6 As.

The i-type layer 26 is made of an i-type G having a thickness of about 2.8 nm.
an aAs layer and an i-type Al _0.4 Ga _0.6 layer having a thickness of about 4.0 nm.
An active layer in which 50 pairs of As layers are alternately stacked. In addition,
After laminating 50 pairs of superlattice layers, a mask pattern is formed on the surface, and a recess for realizing a two-dimensional photonic band as shown in FIG. 6B is etched. Ga
Selectively etching As and AlGaAs alternately;
The etching is stopped when the lower waveguide layer 25 is exposed.

After the etching is completed, the mask is removed and Ga is removed.
When As is grown, the concave portion is preferentially filled back, and a growth surface having a flat surface appears. After that, a p-type layer stack is grown by MBE on the active layer 26 that has realized the two-dimensional photonic band.

The first p-type layer 27 has a carrier density of about 1
X 10 ¹⁷ cm ^-3 Be doped to a thickness of about 5
It is a waveguide layer formed of 0 nm p-type Al _0.4 Ga _0.6 As. The p-type layer 28 thereon is a clad layer formed of p-type Al _0.5 Ga _0.5 As doped with Be so as to have a carrier density of about 5 × 10 ¹⁷ cm ⁻³ and having a thickness of about 1500 nm.

The upper p-type layer 29 is a contact layer formed of p-type GaAs having a thickness of about 500 nm and doped with Be so that the carrier density becomes about 5 × 10 ¹⁸ cm ⁻³ .

After forming such a laminated structure, GaAs
An n-side electrode 30a is formed on the lower surface of the s substrate 21, and a p-side electrode 30b is formed on the p-type contact layer.

Thereafter, the laminated portion is etched, and FIG.
A ridge structure having a width of about 5 μm as shown in FIG. Create the end face in the length direction of the waveguide by cleavage,
A rectangular waveguide structure having an optical path length of about 100 μm is formed. The antireflection films 12a and 12b are coated on the cleaved surfaces. The reflectance of the antireflection films 12a and 12b is, for example, 0.1% or less.

The photonic band is set so as to have a transmission band on the longer wavelength side than the band edge of the material of the active layer. The wavelength of the signal light is selected in accordance with the transmission band. The signal light is incident from the incident surface provided with the antireflection film toward the emission surface.

A reverse bias voltage is applied between the electrodes 30a and 30b, and a reverse bias electric field is applied to the active layer. The active layer 26 has a superlattice structure, and a quantum confined Stark effect (QCSE) occurs. The band edge is red-shifted by the QCSE, and the wavelength of the incident light changes from the transmission state to the absorption state. Due to this change, the complex refractive index of the active layer changes, and the transmission band and the reflection band (absorption band) of the photonic band also change. Due to this change, the transmitted light intensity of the signal light is reduced, and a switching operation occurs.

Although the case where the quantum well structure using the superlattice layer is used has been described, a bulk semiconductor, a quantum wire, or a quantum box may be used. Further, the case where a reverse bias voltage is applied has been described, but a forward bias voltage may be applied. In this case, a current flows through the photonic band due to the forward bias voltage, carriers are injected into the active layer, and the refractive index changes.

It should be noted that the etching using the mask
Although the case where a three-dimensional photonic band structure is formed has been described, it is unavoidable to affect crystallinity when a fine structure is formed by etching. As a method of realizing a periodic structure without using etching, a method using a vicinal substrate (for example, Y.
Nishikawa et al. Jpn. J. Appl. Phys. 34 , L915-L91
7 (1995)) etc. could be used. Also, a method of forming a quantum dot whose position is controlled by using strain (for example, K. Mukai et al. Jpn. J. Appl. Phys. 3
3 , L1710-L1712 (1994)), etc.

The photonic band can be formed by a one-dimensional, two-dimensional or three-dimensional periodic structure.
The material used is not limited to a semiconductor. At least one of the two types of optical media having different complex refractive indices (preferably, the one that forms a wider area) may be formed of a semiconductor.

FIG. 7 shows a surface emitting laser according to another embodiment of the present invention. FIG. 7A is a perspective view schematically showing a shape of a surface emitting laser, and FIG. 7B is a cross-sectional view showing a layered structure of the surface emitting laser. As shown in FIG. 7A, a surface emitting laser structure is formed inside the columnar projection 15, and a ring-shaped electrode 30b is formed on the upper surface. A photonic band layer 11 having a two-dimensional periodic structure is formed in a cylinder. Two incident lights are incident parallel to the plane of the two-dimensional photonic band.

Switching of incident light is performed using the oscillation state and non-oscillation state of the surface emitting laser. Between the laser oscillation state and the non-oscillation state, the carrier density in the active layer changes, and the photonic band changes.
Therefore, it is possible to switch the incident light using the change in the photonic band.

As shown in FIG. 7B, the surface emitting laser is formed using a semiconductor laminated structure. (001)
On the surface of the n ⁺ -type GaAs substrate 21 having a surface, n type DB
R layer 32, n-type cladding layer 33, i-type barrier layer 34, i
The active layer 35 is grown by MBE.

The n-type DBR layer 32 includes an n-type AlAs layer having a thickness of about 64.2 nm doped with Si so as to have a carrier density of about 2 × 10 ¹⁸ cm ⁻³ and an n-type AlAs layer having a thickness of 54.4 nm.
It is formed by alternately laminating 25.5 pairs with Al _0.25 Ga _0.75 As.

The n-type cladding layer 33 has a carrier density of about 1
It is formed of an n-type Al _0.51 Ga _0.49 As layer with a thickness of about 50 nm doped with Si so as to have a ^density of × 10 ¹⁸ cm ⁻³ .

The i-type guide layer 34 has an i-type guide layer of about 50 nm in thickness.
It is formed of a type Al _0.51 Ga _0.49 As layer.

First, the thickness of the i-type active layer 35 is about 2.8.
nm i-type GaAs layer and about 4.0 nm thick i-type Al
Five pairs of alternate stacks with _0.51 Ga _0.49 As are formed.

After growing the alternate stack, a mask pattern is formed on the surface, and a concave portion for selectively forming a photonic band in the alternate stack is etched. After the etching is completed, the mask is removed, and the GaAs is formed in the same manner as in the above embodiment.
Buried growth. After the flat surface is formed by the buried growth, the growth is stopped, and the i-type active layer 35 is completed.

Thereafter, an i-type guide layer 36, a p-type cladding layer 37, a p-type DBR layer 38, and a p-type contact layer 39 are grown on the i-type active layer 35 by MBE.

The i-type guide layer 36 has a thickness of about 46 nm.
It is formed by a type Al _0.51 Ga _0.49 As layer. The p-type cladding layer 37 is a p-type Al layer doped with Be so as to have a carrier density of 1 × 10 ¹⁸ cm ⁻³ and having a thickness of about 50 nm.
It is formed of a _0.51 Ga _0.49 As layer.

The p-type DBR layer 38 includes a p-type Al _0.51 Ga _0.49 As layer having a thickness of about 7.5 nm and a p-type DBR layer 38 having a thickness of about 47.0 nm.
AlAs layer, p-type Al _0.51 Ga with a thickness of about 15.0 nm
_0.49 As layer, about 40.1 nm thick p-type Al _0.25 Ga
It is formed of 22.5 pairs of _0.75 As layer and has a carrier density of about 2
Be is doped so as to be × 10 ¹⁸ cm ⁻³ .

The p-type contact layer 39 is formed of a Be-doped p-type GaAs layer having a thickness of about 53 nm so that the carrier density becomes about 1 × 10 ¹⁹ cm ⁻³ or more.

After forming such a laminated structure, a p-side annular electrode 30b is formed on the p-type contact layer 39, an n-side electrode 30a is formed on the back surface of the substrate 21, and an etching mask is formed on the front surface. Etching is performed in a columnar shape as shown. The electrons transported from the substrate 21 side flow intensively in the cylindrical portion due to the current confinement structure formed by the etching side wall.

A current based on a control signal is supplied between the n-side electrode 30a and the p-side electrode 30b to cause the surface emitting laser to perform pulse oscillation. The carrier density in the active layer changes between when the laser oscillates and when it does not oscillate, causing a change in the photonic band. The transmitted light intensity changes according to the change of the photonic band.

The laser oscillates based on the control signal and switches the incident light. At the same time, a clock light pulse is generated from the surface emitting laser in the vertical direction based on the control signal.

As described above, in this embodiment, the switching operation of the incident light is caused by the current injection, and the laser light corresponding to the control signal is secondarily generated.

When a plurality of incident lights are incident from the isotropic direction of the columnar projection 15 shown in FIG. 7A, the same switching operation is performed on the plurality of incident lights in response to the current injection.

The time-multiplexed optical pulse train is separated into only the multiplexed portions, and a time delay corresponding to all of the multiplexed portions is added, and the signal light is incident from the isotropic direction of the photonic band as signal light. When the optical switch is operated in this state, a signal can be extracted (clock extraction) at a certain period from the time-multiplexed optical pulse train.

The band structure used for the photonic band is determined depending on the incident direction of the signal light. The photonic band structure has a k-space region having a large effect and a k-space region having a small effect. In order to switch the signal light effectively, it is preferable to select the direction in which the band change is large.

In the embodiments shown in FIGS. 6 and 7, since the signal light can be controlled by the electric signal, the configuration of the optical switch device is simplified.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0083]

As described above, according to the present invention,
A semiconductor optical switch device that performs optical switching using a one-dimensional, two-dimensional, or three-dimensional photonic band is provided.

Since various switching characteristics can be realized by the structure of the photonic band, the degree of freedom in designing the optical switch device is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a configuration of a semiconductor optical switch device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a two-dimensional photonic band used in the embodiment of FIG. 2A is a perspective view, FIG. 2B is a plan view, FIGS. 2C and 2D are cross-sectional views, and FIG. 2E is a conceptual view showing a Brillouin zone.
(F) is a graph showing a photonic band structure.

FIG. 3 is a graph for explaining the operation of the semiconductor optical switch device shown in FIG. 1;

FIG. 4 is a perspective view schematically showing a three-dimensional photonic band.

5A and 5B are a cross-sectional view and a perspective view schematically showing a structure having a quantum confinement effect.

FIG. 6 is a plan view, a schematic perspective view, and a sectional view showing a semiconductor optical switch device according to another embodiment of the present invention.

FIG. 7 is a schematic perspective view and a sectional view showing a semiconductor optical switch device according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Collimator lens 3, 6 Polarizer (analyzer) 4 Two-dimensional photonic band 5 Control light 12 Antireflection film 21 Substrate 22 Buffer layer 23 Super lattice layer 24 Cladding layer 25 Waveguide layer 26 Active layer 27 Waveguide Layer 28 clad layer 29 contact layer 30 electrode 32 n-type DBR layer 33 clad layer 34 guide layer 35 active layer 36 guide layer 37 clad layer 38 p-type DBR layer 39 p-type contact layer

Claims (15)

[Claims] 1. A photonic band layer comprising two types of optical media having different complex refractive indices, wherein at least one of the optical media includes two types of semiconductors which are semiconductors and forms a periodic structure on a two-dimensional plane. Along an optical path of the controlled light parallel to the two-dimensional plane, and an optical path that is not orthogonal to the optical path of the controlled light.
Means for irradiating circularly polarized control light to a periodic structure on a two-dimensional plane, wherein the control light switches the transmittance of the controlled light. 2. The semiconductor optical switch device according to claim 1, wherein the controlled light has a plurality of optical paths, each of which is not orthogonal to the traveling direction of the control light. 3. The semiconductor optical switch device according to claim 2, wherein the optical paths of the plurality of controlled lights include a plurality of optical paths along directions in which the periodic structures of the photonic band layers have different symmetries. 4. The semiconductor optical switch device according to claim 1, wherein said photonic band layer has a three-dimensional periodic structure having a periodic structure also in a direction intersecting with said two-dimensional plane. 5. The semiconductor optical switch device according to claim 1, wherein the periodic structure of the photonic band layer includes a quantum confinement structure. 6. The controlled light is circularly polarized light.
6. The semiconductor optical switch device according to any one of 5. 7. The apparatus according to claim 1, wherein the controlled light is linearly polarized light, and further includes an analyzer disposed on an emission side of an optical path of the controlled light and having a polarization axis orthogonal to the incident linearly polarized light.
6. The semiconductor optical switch device according to any one of items 1 to 5, 8. A photonic band layer comprising two types of optical media having different complex refractive indices, wherein the photonic band layer includes two types of optical media, at least one of which is a semiconductor, and forms a periodic structure on a two-dimensional plane. A semiconductor optical switch including: an optical path of controlled light parallel to a two-dimensional plane; and means for applying an electrical stress to the periodic structure of the photonic band layer, wherein the optical stress switches a transmittance of the controlled light by the electrical stress. apparatus. 9. The semiconductor optical switch device according to claim 8, wherein said electric stress is a current or an electric field. 10. The semiconductor optical switch device according to claim 8, wherein the optical path includes a plurality of optical paths along directions in which the periodic structures of the photonic band layers have different symmetries. 11. The photonic band layer according to claim 2, wherein
9. The semiconductor optical switch device according to claim 6, having a three-dimensional periodic structure having a periodic structure also in a direction intersecting with the dimensional plane. 12. The semiconductor optical switch device according to claim 8, wherein the periodic structure of the photonic band layer includes a quantum confinement structure. 13. The semiconductor optical switch device according to claim 8, further comprising a pair of electrodes arranged above and below said photonic band layer. 14. An n-type semiconductor layer disposed between the photonic band layer and one of the pair of electrodes, and an n-type semiconductor layer disposed between the photonic band layer and the other of the pair of electrodes. 14. The semiconductor optical switch device according to claim 8, further comprising a p-type semiconductor layer. 15. The semiconductor device according to claim 1, wherein at least one of the n-type semiconductor layer and the p-type semiconductor layer has a distributed Bragg reflection structure.
5. The semiconductor optical switch device according to 4.