JPH0983087A - Polarization controllable and wavelength controllable semiconductor optical device and optical network using the same - Google Patents

Abstract

(57) Abstract: A semiconductor optical device such as a semiconductor laser capable of suppressing chirping at the time of high-speed modulation and capable of wavelength control, and a semiconductor optical filter having transmission characteristics independent of polarization and capable of wavelength control. Is. A semiconductor optical device having optical waveguides (103, 104) that allow polarization modes independent of each other and a Bragg reflection type or distributed feedback type resonator. A semiconductor optical device has a gain region that gives different gains depending on the polarization state of the polarization mode, a loss region that gives different loss depending on the polarization state of the polarization mode independently of the gain region, and an independent polarization region. It has means for arbitrarily selecting one of the wave modes and means for controlling the wavelength independently of the gain and loss regions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor optical device such as a light source and an optical filter used for optical communication and optical information processing, and more particularly to a semiconductor laser or a semiconductor laser capable of controlling polarization and wavelength. The present invention relates to a semiconductor optical device such as a semiconductor filter and an optical network using the same.

[0002]

2. Description of the Related Art At present, one of the problems in optical communication is increasing the capacity. One approach is a wavelength-multiplexed optical LAN that simultaneously increases the capacity of the time axis (speedup and time multiplexing) and the capacity of the space axis (wavelength multiplexing). The optical device used here, for example, a semiconductor laser, has severe requirements for lowering the chirp and controlling the wavelength (tuning wavelength and stabilizing wavelength). Effective proposals have been made for low chirp and wavelength control. For example, in order to reduce the chirp, a semiconductor laser is driven by CW (continuous operation), intensity modulation is performed by a modulator made of a dielectric or a semiconductor, or a method of switching a polarization plane of oscillated light according to a signal, so-called There is a polarization modulation method. For example, Japanese Patent Laid-Open No. Sho 2
-42593 or JP-A-62-144426
No. 6,086,045. Regarding wavelength control,
It is disclosed in Japanese Patent Laid-Open No. 2-246393. However, no example has been reported in which low chirp and wavelength control are simultaneously solved.

Further, as a wavelength tunable optical filter to be combined with a wavelength division multiplex light source, only a semiconductor optical filter having a large polarization dependency or a non-semiconductor type filter having a wide pass band has been proposed, so that the capacity can be increased. What can be dealt with has not been proposed yet.

[0004]

SUMMARY OF THE INVENTION To summarize the above, the following can be said. (1) There was no light source that simultaneously realized low chirp and wavelength control. (2) There is no variable wavelength optical filter that can be used in combination with the above light source. (3) There is no wavelength multiplexing LAN that can be realized with a simple configuration.

Therefore, a first object of the present invention (claims 1 to 6, claim 15 and 16) is to suppress the chirping at the time of high-speed modulation and to control the wavelength of the semiconductor laser and the transmission characteristics to be biased. An object of the present invention is to provide a semiconductor optical device such as a semiconductor optical filter that is wave-independent and capable of wavelength control with substantially the same structure.

A second object of the present invention (claims 7 to 11 and 13) is to provide a semiconductor optical device such as a semiconductor laser having wavelength controllability which is excellent in polarization modulation characteristics.

A third object of the present invention (claims 12 and 1)
4) is to provide a semiconductor optical device such as a semiconductor laser capable of polarization modulation having excellent wavelength tunability and a semiconductor optical filter having excellent wavelength tunability.

A fourth object of the present invention (claim 17) is to provide a high-density wavelength division multiplexing optical network which can be realized with a simple structure.

[0009]

A semiconductor optical device of the present invention which achieves the first object is a semiconductor optical device having an optical waveguide and a Bragg reflection type resonator which allow polarization modes independent of each other. Gain control means for giving a different gain depending on the polarization state of each polarization mode; loss control means for giving a different loss depending on the polarization state of each polarization mode independently of the gain control means; It is characterized by comprising means for arbitrarily selecting one of the independent polarization modes and means for controlling the wavelength independently of the gain and loss control means. In this configuration, the following modes are possible. A gain region having an active layer, a loss region having a loss layer, and a wavelength control region having a wavelength tuning layer are formed in series along the optical waveguide. Further, a phase control region is formed.

The first object is also achieved by the following semiconductor optical device. That is, it is a semiconductor optical device having an optical waveguide and a distributed feedback resonator that allow polarization modes independent of each other, and gain control means for giving different gains depending on the polarization state of each polarization mode. A loss control means for giving a different loss depending on a polarization state of a polarization mode independently of the gain control means, a means for arbitrarily selecting one of the independent polarization modes, and the gain and loss control means. And a means for controlling the wavelength independently. In this configuration, the following modes are possible.
A plurality of gain regions each having an active layer and a loss region each having a loss layer are formed in series along the optical waveguide. A wavelength tuning layer is formed in parallel with the plurality of gain regions and loss regions.

In the semiconductor optical device of the present invention which achieves the second object, in the above structure, the gain control means has a structure of an active layer formed in a gain region provided along the optical waveguide. It has a multiple quantum well structure. Further, in the gain control means, the structure of the active layer in the gain region has a multiple quantum well structure, and at least one of the layer thickness and composition of the well layer and the barrier layer of the quantum well and the strain stress which compose the quantum well structure is different from the other. It is different from the quantum well (asymmetric strain quantum well). The loss control means uses a superstructure represented by a quantum well structure having a quantum confined Stark effect in a part of an optical waveguide in a loss region provided along the optical waveguide. Further, the means for arbitrarily selecting the polarization mode controls the voltage applied to the loss layer formed in the loss region provided along the optical waveguide, and the gain provided along the optical waveguide. At least one of controlling the density of carriers injected into the active layer formed in the region is performed. Also, the means for controlling the wavelength is characterized in that the effective refractive index of the optical waveguide in the region where the Bragg reflection type resonator is formed is changed by carrier injection or voltage application. Further, the means for controlling the wavelength includes the gain control means in the wavelength tuning layer provided in parallel with the active layer and the loss layer formed respectively in the gain region and the loss region provided along the optical waveguide. And carrier injection or voltage application independently of the loss control means.

In the semiconductor optical device of the present invention which achieves the third object, in the above structure, a multiple quantum well is used for the tuning layer forming the optical waveguide in the region where the Bragg reflection type resonator is formed. Is characterized by. The wavelength tuning layer is provided in parallel with the active layer and the loss layer, and multiple quantum wells are used.

In the above configuration, for example, 1) by controlling the polarization dependence of both the gain region and the loss region, it is possible to satisfy the following expressions (1) to (3) without difficulty. 2) It is possible to control the wavelength to be determined by the following formula (2) by changing the refractive index by the wavelength control region provided independently of the polarization control.

The optical network of the present invention which achieves the fourth object is a wavelength division multiplexing optical network (for example, having a bus type or ring type) having a plurality of terminal stations on an optical transmission line, The semiconductor laser having the above-mentioned configuration is used for the transmitting section which constitutes the terminal station, and a polarizer is arranged on the emission surface thereof to send out only light of a specific polarization, and the receiving section which constitutes the terminal station has the above-mentioned constitution. A semiconductor optical filter is used to select the wavelength of light of arbitrary polarization and receive the light.

Here, the conditions required for the wavelength tunable polarization modulation laser will be briefly described. The oscillation wavelength of the semiconductor laser is determined by the following oscillation conditional expression.

Γ · g _th = Γ · α _in + α _M + α _sc (1) where α _M = l / 2L _eff · ln (1 / R ₁ · 1 / R ₂ ) exp (i · (2n _eff・ L _eff / λ ten φ)) = 0 (2) where Γ: optical confinement coefficient in active layer g _th : threshold gain α _in : internal loss α _M : reflection loss α _sc : other loss (scattering loss) , Coupling loss, etc.) R _i : Effective reflectance in two directions viewed from one point in the resonator n _eff : Effective refractive index of waveguide L _eff : Effective resonator length λ: Oscillation wavelength φ: In addition to this, the semiconductor laser for direct polarization modulation has, as another condition, polarization modes independent of each other, for example, a TE mode and a TM mode, and their threshold gains are substantially equal, that is, , Γ _TE · g _thTE = Γ _TM · g _thTM (3) is required.

The threshold gain is obtained in (1), and the wavelength is obtained in (2).
The polarization switching condition is determined in (3). Since the selection of the threshold gain and the polarization mode is apparent from the description of the embodiment, the wavelength variable function will be described here. In the case of a DFB laser, n _eff can be controlled by carrier injection or voltage application. Therefore, in the conventional DFB laser, the cavity direction is multi-divided and the carrier distribution (= gain distribution) is controlled to control the gain and the wavelength. In this method, since gain and wavelength control are not independent, it is not desirable from the standpoint of wavelength control alone. The essence of the present invention is that the wavelength control means (tuning layer for wavelength control) is provided separately from the independent control gain control means (gain region) and loss control means (loss region) introduced to stably operate polarization modulation. ) Is provided separately from the former to independently control the wavelength.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a sectional view in the resonator direction of a first embodiment of the present invention. It is divided into four in the resonator direction, and each of them is a gain region, a loss region, a phase control region, and a wavelength control region.
FIG. 2 is a sectional view in a direction perpendicular to the resonator direction. Each region is electrically independent, but is optically coupled via the common light guide layer 103 and the like. The specific layer configuration is as follows.

In FIG. 1, 101 is an n-type InP substrate,
102 is an n-type InP clad layer, 103 is an n-type InGa
AsP light guide layer, 104a is undoped GaInAs
P active layer 104b undoped GaInAsP loss layer 104c InGaAsP tuning layer 105
Is a p-type InP cladding layer, 106 is a p-type InGaAsP
It is a cap layer. Further, in FIG. 2, 110 is a high resistance InP buried layer.

Reference numeral 107 denotes the n-type cladding layer 102 and n.
The gratings are formed on the boundary of the mold light guide layer 103, and 108a to 108d and 109 are electrodes. Reference numeral 111 is a λ / 2 coat, and 112 is an antireflection (AR) coat. The pitch of the grating 107 is set so that the TM mode of the Bragg wavelength has a gain peak. The structures of the active layer 104a and the loss layer 104b are the same in this embodiment.

FIG. 3 is a schematic diagram of a band structure of the active layer 104a and the loss layer (also referred to as an absorption layer) 104b. FIG.
, The well layer 121 is made of InGaAs (tensile strain 1.0%) and has a thickness of 10 nm, the barrier layer 122 is made of InGaAsP (wavelength of 1.1 μm composition) and has a thickness of 10 nm, and the SCH layer 123 is In
100 nm consisting of GaAsP (wavelength 1.2 μm composition)
Is the thickness of. The number of wells was 5 cycles.

Next, the operating principle of the first embodiment will be described. FIG. 4 shows gains (correctly Γ · g) for TE mode and TM mode when a carrier (-10 ¹⁸ cm ⁻³ ) is injected into the gain region by passing a current from the electrode 108a to the electrode 109. The relationship with the resonator loss (Γ · α _in + α _M + α _sc ) is shown (axis is wavelength). The difference in the gain spectrum between TE and TM is due to the change in the band structure of the strained quantum well of the active layer 104a. The reason why the resonator loss spectrum has two minimum values is that the effective refractive index differs for one Bragg wavelength due to the difference in polarization. As shown in FIG. 4, it is difficult to select the TM mode and the TE mode in the oscillation of the DFB laser only by changing the gain profiles of the TE mode and the TM mode.

FIG. 5 shows not only the injection of carriers into the gain region but also the electrodes 108b and 109 in the loss region.
The same relationship is shown when a reverse bias (for example, -5V) is applied in between to optimize the resonator spectrum.
The reason why the peak value of the resonator loss vector is smaller in TM is due to the polarization dependence of the loss of the quantum confinement effect (QCSE). In this way, by controlling not only the gain spectrum but also the resonator loss spectrum,
Expression (3) can be easily satisfied.

While maintaining the expression (3), a current is made to flow from the electrode 108d to the electrode 109 to change the carriers injected into the wavelength control (tuning) region.
By changing _eff , the oscillation wavelength can be swept by the equation (2) (FIG. 6). At this time, the phase (φ in the equation (2)) may shift, so that the phase can be controlled by causing a current to flow from the electrode 108c in the phase adjustment region to the electrode l09 and injecting carriers into the tuning layer 104c. .

After adjusting the current in the gain region and the applied voltage in the loss region so that the equation (3) holds in a steady state, there are several modulation methods. (1) A signal is applied as a voltage to the loss region. The advantage of this method is that high-speed modulation by QCSE is possible,
The line width can be extremely narrowed because the carrier distribution in the resonator is kept constant. (2) The signal is superimposed on the gain region as a current. The advantage of this method is that the modulation circuit is simple.

Next, the present invention is applied to a wavelength tunable filter (hereinafter referred to as T
The case of operating as WF) will be described. It demonstrates using FIG. 4 thru | or 6 again. In this case, λl
And λ2 are the TM component and TE of the light incident on the TWF.
I will consider it as an ingredient. The basic operation of the TWF is as follows.

(1) The Bragg wavelength is controlled near the gain peak by using the wavelength tunable mechanism described above (standby state). (2) Light of a plurality of wavelengths including light of a desired wavelength (polarization direction is random) is made incident on the TWF end face. (3) A desired light (or a light that seems to be so) is specified from a plurality of lights by using the above-mentioned wavelength tunable mechanism or other wavelength selection means. Since the light incident on the TWF is generally circularly polarized light with a gradual change in time, the TE
It has a component and a TM component. 4 to 6 show the TE component (λ2) and the TM component (λ1) when one wavelength is selected. (4) The carriers or voltages in the gain region and the loss region are controlled so that the intensity in the one polarization direction becomes stronger. (5) Since the polarization direction changes with the lapse of time, the gain region and the loss region are controlled while monitoring the TWF output with a light receiver or the like arranged after the filter.

As described above, in this embodiment, it is possible to always select the TE mode light or the TM mode light with the maximum sensitivity even if the polarization changes gently. This is a great improvement in consideration of the fact that a polarization analyzer or the like is indispensable for stabilizing the polarization when wavelength selection is usually performed using one semiconductor laser type optical filter.

The structure of the variable wavelength optical filter may be almost the same as that of the first embodiment (the λ / 2 coat 111 is replaced with an AR coat). In this case, there is a great advantage that it is suitable for integration because the structures of the transmitting unit and the receiving unit do not change. It is also advantageous in terms of cost. However, in the case of an optical filter, it is more important to reduce the polarization dependence than to reduce the line width. You may make changes for that purpose. For example, in the case of an ordinary optical filter, it is better that the coupling parameter of the grating (so-called κ · L, κ is the coupling coefficient, L is the coupling length) is larger, so that the ratio of the gain region to the loss region that changes the resonator length is It is possible to change the depth of the grating, change the electric field distribution, and so on.

Further, two of these optical filters are arranged in parallel, the signal light is branched and made incident on each of them, and one of them is TE.
Polarization diversity can be easily realized by receiving light in the TM mode and the other in the TM mode.

[0031] Example 2 Next, a second embodiment will be described. In the structure of the first embodiment, the performance of the gain region and the loss region can be further optimized by independently optimizing the structure. The structure is the same as that of the first embodiment except the active layer and the loss layer.
FIG. 7 shows the structure of the active layer 104a, and FIG. 8 shows the loss layer 104b.
Represents the structure of. The active layer 104a is InGaAs
And an asymmetric strained quantum well structure using InGaAsP as well layers 171 and 172 (the barrier layer 173 is GaInA
sP).

In this embodiment, the InGaAs well layer 17 is used.
1% (thickness 10 nm), a tensile strain of 1.0% was introduced, and the InGaAsP well layer 172 (λ = 1.65 μ
m, thickness 10 nm)) and InGaAsP barrier layer 1
73 (λ = 1.3 μm, thickness 10 nm) has no distortion 2
A gravitational well structure was used. Further, as shown in FIG. 8, in the structure of the loss region, the well layer 121 has a composition of InGaAs (tensile strain 1.7%) and a thickness of 10 nm, and the barrier layer 122 has a structure of InGaAsP (composition of wavelength 1.2 μm). Is 10 nm thick, and the SCH layer 123 is 100 nm thick with InGaAsP (wavelength 1.2 μm composition).
The thickness is nm. The number of wells was 2 cycles.

FIG. 9 shows the relationship between gain and loss vector when carriers are injected into the gain region and voltage is applied to the loss region for control. The difference from the first embodiment is that 1) the operating current becomes lower, 2) the modulation efficiency becomes higher (polarization modulation can be performed with a smaller current or voltage change), and 3) the line width is 4) The polarization modulation possible range (the current in the gain region and the applied voltage in the loss region must be adjusted before the polarization modulation, but the adjustment range becomes wider) It will be even wider.

The wavelength variable characteristic is the same as that of the first embodiment. The operation of the wavelength tunable optical filter is also the same as in the first embodiment.

Embodiment 3 Next, an example in which the wavelength variable range is widened will be described. The difference from the first and second embodiments is that the tuning layer 104c
Is an MQW structure. FIG. 10 is a band structure diagram of the tuning layer.

The well layer 141 is 10 nm thick with a composition of InGaAs (tensile strain 1.0%), the barrier layer 142 is 10 nm thick with a composition of InGaAsP (wavelength 1.2 μm composition), and SCH. Layer 143 is I
nGaAsP (wavelength 1.2 μm composition) 100 n
The thickness is m. The number of wells was 5 cycles. Since the tensile strain is introduced, the electron density in the conduction band increases, so that the effective change in the refractive index of the tuning layer 104c increases. As a result, it is possible to obtain a wavelength variable range that is twice as large as that of the first embodiment. As for the operation of the wavelength tunable optical filter, it is possible to obtain a wavelength tunable range that is about twice that of the first embodiment.

Embodiment 4 FIG. 11 is a sectional view in the resonator direction of the fourth embodiment of the present invention. FIG. 12 is a sectional view in a direction perpendicular to the resonator direction. It is divided into three parts in the direction of the resonator, which are a gain region 1, a gain region 2 and a loss region, respectively. Each region is electrically independent, but is optically common to the light guide layer 203.
And the tuning layer 206 and the like. The specific layer configuration is as follows.

Reference numeral 201 is a p-type InP substrate, and reference numeral 202 is an n-type I substrate.
nP cladding layer, 203 n-type InGaAsP optical guide layer, 204a undoped GaInAsP active layer, 20
4b is an undoped GaInAsP loss layer, 205 is an n-type InP spacer layer, 206 is an InGaAsP tuning layer, 207 is a p-type InP cladding layer, 208 is a p-type buried layer, and 209 is a p-type InGaAsP contact layer. 216 is an n-type InP lateral contact layer. Further, 210 is a grating having a λ / 4 phase shift formed at the boundary between the n-type cladding layer 202 and the n-type light guide layer 203, and 212a to 212c, 21.
3 and 214 are electrodes. No reflection on both ends (A
R) Coat 215 is applied. Grating 210
The pitch is set so that the TM mode of the Bragg wavelength becomes a gain beak. Active layer 204a and loss layer 2
The structure of 04b is the same in this example, and their band structure is the same as in FIG.

Next, the operation principle will be described. Since this is also essentially the same as the first embodiment, it will be described with reference to FIGS. FIG. 4 shows the electrode 213 of the fourth embodiment.
When a current is flown from the electrode to the electrode 214 to uniformly inject carriers (-10 ¹⁸ cm ^-3 ) into the gain regions 1 and 2,
Gain for TE mode and TM mode (exactly Γ ·
g) and the resonator loss (Γ · α _in + α _M + α _sc ) are also shown (the axis is the wavelength). The difference in gain spectrum between TE and TM is due to the change in the band structure of the strained quantum well of the active layer 204a. The reason why the resonator loss spectrum has two minimum values is that the effective refractive index differs for one Bragg wavelength due to the difference in polarization. As shown in FIG. 4, it is difficult to select the TM mode and the TE mode in the oscillation of the DFB laser only by changing the gain profiles of the TE mode and the TM mode. These are substantially the same as in the first embodiment.

FIG. 5 shows the gain regions 1 and 2 of the fourth embodiment.
The gain profile is optimized by nonuniformly injecting carriers into the loss region, and a reverse bias (for example, ~-
The same relationship when 5 V) is applied is also shown. The reason why the peak value of the resonator loss vector is smaller in TM is due to the polarization dependence of the loss of the quantum confinement effect (QCSE). As described above, also in the fourth embodiment, the expression (3) can be easily satisfied by controlling not only the gain spectrum but also the resonator loss spectrum. still,
At this time, the phase is also adjusted by non-uniform carrier injection into the gain regions 1 and 2.

While maintaining the expression (3), the electrode 212 (21
2a and / or 212b) causes a current to flow to the electrode 214 to change carriers injected into the gain regions 1 and / or 2 to change n _eff ,
The oscillation wavelength can be swept by the equation (2) (FIG. 6). At this time, the phase (φ in equation (2)) is also controlled.

After adjusting the currents in the gain regions 1 and 2 and the applied voltage in the loss region so that the equation (3) is established in the steady state, there are several methods for the modulation method as in the first embodiment. is there. (1) A signal is applied as a voltage to the loss region. The advantage of this method is as described in the first embodiment. (2) The signal is superposed on one or both of the gain regions 1 and 2 as a current. The advantage of this method is also as described in the first embodiment.

The case of operating this embodiment as a wavelength tunable filter is also as described in the first embodiment.

Embodiment 5 The fourth embodiment can also be modified to have the structure as described in the second and third embodiments. The operation and advantages of the modified example are as described above.

Embodiment 6 Next, an example in which the device of the present invention is applied to an optical network will be described. 13 and 14 are application examples to a bus type optical network and a ring type optical network,
The above devices are mounted on the optical nodes 401 to 406. By disposing a polarizer on the emission surface of the semiconductor laser described in the first to fifth embodiments, only specific polarized light (for example, TE light) can be taken out and sent to the transmission line. Reference numeral 400 is an optical bus line, and 411 to 416 are terminal devices.

On the other hand, the wavelength tunable mechanism described in the first embodiment is used in the semiconductor optical filter described in the above embodiment to receive incident light in an arbitrary polarization state from the transmission line. Although this polarization state changes with the passage of time, it is possible to always receive light with maximum efficiency by controlling the gain region and the loss region.

Further, two of these optical filters are arranged in parallel, the signal light is branched and made incident on each of them, and one of them is TE.
Polarization diversity can be easily realized by receiving light in the TM mode and the other mode.

The semiconductor laser of the present invention has a narrow line width and is stable even at high speed modulation. The optical filter of the present invention is
The pass band is narrow and the tunable range is wide. Since the semiconductor laser and the semiconductor optical filter of the present invention have almost the same structure, it is easy to integrate the nodes and the cost can be reduced.

Further, since light of different polarizations can be transmitted at the same time without using a polarizer, it is possible to make the network multifunctional by using the above device. For example, in a wavelength multiplexing system using a wavelength tunable laser and a wavelength tunable filter, the wavelength tunable filter can be used as a light source for polarization diversity with a very simple structure by providing polarization dependency.

Although the above description has been made for the L5 μm band, the same holds true for other wavelength bands and material systems.

[0051]

The effects of the present invention are as follows:
The light source and the optical filter for N or the like are provided with a simple configuration. Specifically, it is as follows.

(1) It is possible to realize a semiconductor laser that simultaneously realizes low chirp and wavelength control. (2) It is possible to realize a wavelength tunable optical filter which can be used in combination with the above light source and whose transmission characteristic is polarization independent and wavelength tunable. (3) A high-density wavelength division multiplexing optical LAN or the like can be realized with a simple configuration. (4) Since the semiconductor laser and the semiconductor optical filter can be realized with almost the same structure, it is advantageous for high functionality represented by integration and cost reduction.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment.

FIG. 2 is a transverse sectional view of the first embodiment.

FIG. 3 is a schematic diagram of band structures of an active layer and a loss layer of the first example.

FIG. 4 is an explanatory diagram of an operation principle of the first embodiment.

FIG. 5 is an explanatory diagram of an operation principle of the first embodiment.

FIG. 6 is an explanatory diagram of an operation principle of the first embodiment.

FIG. 7 is a schematic diagram of a band structure of an active layer of a second embodiment.

FIG. 8 is a schematic diagram of a band structure of a loss layer of a second example.

FIG. 9 is an explanatory diagram of an operation principle of the second embodiment.

FIG. 10 is a schematic diagram of a band structure of a tuning layer of a third embodiment.

FIG. 11 is a vertical sectional view of a fourth embodiment.

FIG. 12 is a transverse sectional view of the fourth embodiment.

FIG. 13 is a block diagram illustrating a bus type optical network of the present invention.

FIG. 14 is a block diagram illustrating a ring type optical network of the present invention.

[Explanation of symbols]

 101, 201 Substrate 102, 105, 202, 207 Clad layer 103, 203 Optical guide layer 104a, 204a Active layer 104b, 204b Loss layer 104c, 206 Tuning layer 106, 209 Cap layer 107, 210 Grating 108, 109, 212, 213 , 214 electrode 110, 208 buried layer 111 λ / 2 coat 112, 215 AR coat 121, 141 well layer 122, 142 barrier layer 123, 143 SCH layer 171 InGaAs strain well layer 172 InGaAs well layer 173 InGaAsP barrier layer 216 lateral contact Layer 400 Optical bus line 401-406 Optical node 411-416 Terminal device

Claims (17)

[Claims] 1. A semiconductor optical device having an optical waveguide that allows polarization modes independent of each other and a Bragg reflection type resonator, wherein the gain control means gives different gains depending on the polarization states of the respective polarization modes. A loss control means for giving a different loss depending on the polarization state of each polarization mode independently of the gain control means, a means for arbitrarily selecting one of the independent polarization modes, and the gain and loss. A semiconductor optical device having a control means and a means for controlling a wavelength independently. 2. A wavelength control region having a gain tuning region having an active layer, a loss region having a loss layer, and a wavelength tuning layer are formed in series along the optical waveguide. The semiconductor optical device described. 3. The semiconductor optical device according to claim 2, further comprising a phase control region. 4. A semiconductor optical device having an optical waveguide that allows polarization modes independent of each other and a distributed feedback resonator, wherein the gain control means gives a different gain depending on the polarization state of each polarization mode. A loss control means for giving a different loss depending on the polarization state of each polarization mode independently of the gain control means, a means for arbitrarily selecting one of the independent polarization modes, and the gain and loss. A semiconductor optical device having a control means and a means for controlling a wavelength independently. 5. The semiconductor optical device according to claim 4, wherein a plurality of gain regions each having an active layer and a loss region each having a loss layer are formed in series along the optical waveguide. . 6. The semiconductor optical device according to claim 5, wherein a wavelength tuning layer is formed in parallel with the plurality of gain regions and loss regions. 7. The gain control means according to claim 1, wherein the structure of the active layer formed in the gain region provided along the optical waveguide has a multiple quantum well structure. The semiconductor optical device according to any one of 1. 8. In the gain control means, the structure of the active layer in the gain region has a multiple quantum well structure, and at least one of the layer thickness and composition of the well layer and barrier layer of the quantum well and strain stress constituting the quantum well structure is formed. 8. The semiconductor optical device according to claim 7, wherein one of them is different from the other quantum well. 9. The loss control means uses a superstructure represented by a quantum well structure having a quantum confined Stark effect in a part of an optical waveguide in a loss region provided along the optical waveguide. 7. The semiconductor optical device according to claim 1, wherein 10. The means for arbitrarily selecting one of the polarization modes is to control a voltage applied to a loss layer formed in a loss region provided along the optical waveguide, and to the optical waveguide. 7. The semiconductor optical device according to claim 1, wherein at least one of controlling the density of carriers injected into an active layer formed in a gain region provided along the semiconductor optical device is performed. 11. The means for controlling the wavelength is to change the effective refractive index of the optical waveguide in the region where the Bragg reflection resonator is formed by carrier injection or voltage application. The semiconductor optical device according to any one of claims 1 to 3. 12. The semiconductor optical device according to claim 1, wherein a multiple quantum well is used in a tuning layer forming an optical waveguide in a region where the Bragg reflection type resonator is formed. 13. The means for controlling the wavelength comprises: an active layer formed in the gain region and a loss region provided along the optical waveguide, and a wavelength tuning layer provided in parallel with the loss layer, 7. The semiconductor optical device according to claim 4, wherein carrier injection or voltage application is performed independently of the gain control means and the loss control means. 14. The semiconductor optical device according to claim 13, wherein multiple quantum wells are used for the wavelength tuning layer. 15. The semiconductor optical device according to claim 1, wherein the device is configured as a semiconductor laser. 16. The semiconductor optical device according to claim 1, wherein the device is configured as a semiconductor optical filter. 17. In a wavelength division multiplexing optical network having a plurality of terminal stations on an optical transmission line, the semiconductor laser according to claim 15 is used for a transmitting section constituting the terminal station, and a polarizer is arranged on an emission surface thereof. And transmitting only the light of a specific polarization, and using the semiconductor optical filter according to claim 16 in the receiving section which constitutes the terminal station to select and receive the light of the arbitrary polarization. Optical network characterized by.