JP3302088B2 - Integrated optical device and optical communication network using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated optical device used for optical communication and the like, particularly to an integrated optical coupler and a semiconductor optical amplifier, and further to an optical communication network using this device.

[0002]

2. Description of the Related Art Among optical devices used for optical communication, particularly for an optical local area network, the importance of an optical amplifier has been rapidly increasing in recent years. Optical amplifiers are broadly divided into fiber amplifiers and semiconductor amplifiers, and are properly used depending on the application.

[0003] A semiconductor amplifier (hereinafter also referred to as LDA) has a great advantage that it is excellent in integration because it has the same structure as a semiconductor laser. As an example in which LDA is mainly integrated, K.K. Y. "M" by LIOU et al.
onoliticallyIntegrated G
aInAsP / InP Optical Amplif
ear with Low Loss Y-brach
ing Waveguides and Monito
ring Photodetector "(Confe
rence on Laser and Electr
oOptics '90, lecture number CDF7). FIG. 14 is a schematic diagram of this.

[0004] The optical amplifier section 801 on the InP substrate 800,
It has a structure in which a Y branch portion 802 and a PIN light receiving portion 803 are integrated. The layer configuration has a structure in which an optical guide layer (wavelength 1.1 μm) is provided below an active layer (wavelength 1.3 μm). The active layer is common to the optical amplifier unit 801 and the light receiving unit 803. The Y branch 802 has a structure in which the active layer is removed, and the end faces of the optical amplifier 801 and the light receiving unit 803 are coated with anti-reflection. It is characterized in that the waveguide loss and the coupling loss of the waveguide of each part are extremely small, and the Y-branch 802 branches in two directions and can be monitored separately.

[0005]

However, this configuration has significant drawbacks. That is, the signal light must be LDA
Therefore, if a trouble occurs in the LDA, the signal light is seriously damaged. It is considered that the semiconductor optical amplifier has a higher carrier injection amount than the LD, and the probability of internal deterioration is higher than the LD. Therefore, a fail-safe function against the deterioration is indispensable. For this purpose, it is conceivable to provide ordinary optical switches before and after the LDA. For example, in Japanese Patent Publication No. 4-64044, an optical component such as a lens or a prism is externally used, but this method has to be externally mounted. However, the advantages of integration are lost. That is,
LDA-specific advantages are lost.

The present invention has been devised in view of the above problems, and has as its object to provide an integrated optical device, particularly
It is an object of the present invention to provide an integrated optical coupler and a semiconductor optical amplifier having a configuration in which an LDA has a fail-safe function by integrating an all-open semiconductor optical switch, and an optical communication network using the device. .

[0007]

[0008]

[0009]

Gist of the present invention, in order to solve the problem] has, on a semiconductor substrate, at least a first conductivity type first cladding layer of the first core layer of a first conductivity type, a second cladding layer of a first conductivity type ,
What is claimed is: 1. A waveguide type optical device having a double optical waveguide structure in which a second core layer and a second conductive type third clad layer are laminated, wherein the optical device is divided into a plurality of regions in a waveguide direction, and out at least in one region have a periodic refractive index modulation layer, or both in the second cladding layer or the third cladding layer, the said periodic refractive index modulation layer
Controlling the light distribution of the double waveguide, and
The modulation layer has the same refraction as the cladding layer adjacent to it
And the conductivity type of the material is
Periodically having a different region and the same region as that of the
An integrated optical device having means for independently injecting carriers into the plurality of regions .

At this time, the second core layer may be a gain medium for incident light .

Further, the gist of the present invention is that a semiconductor substrate comprises:
At least a first clad layer of the first conductivity type, a first core layer of the first conductivity type, a second clad layer of the first conductivity type, a second core layer and a third clad layer of the second conductivity type laminated on each other. A waveguide type optical device having an optical waveguide structure, wherein the optical device is divided into a plurality of regions in a waveguide direction, and at least one of the divided regions in the second clad layer or the third clad layer or Both of them have a periodic refractive index modulation layer, and no carrier is injected into the periodic refractive index modulation layer.
Sometimes, the light incident on the waveguide type optical device is output as it is
The integrated optical device is characterized in that the light distribution of the double waveguide is controlled so that the second core layer is a gain medium for incident light.

As a specific application, an optical communication network characterized in that the integrated optical device is arranged on a bus-type optical transmission line having a plurality of terminal stations,
There is an optical communication network in which this integrated optical device is arranged on a star-type optical transmission line having a plurality of terminal stations.

[0013]

An optical device having a structure in which two waveguides are brought close to each other is generally well known as a directional coupler. At this time, if the respective propagation constants are β ₁ and β ₂ , Δβ = β ₂
The power branching ratio is determined by −β _{1, the} waveguide interval d, and the coupling length L, so that a function of a coupler or a switch can be provided. Furthermore, by introducing a layer that modulates the propagation constant between the two waveguides, that is, a refractive index modulation layer (typically, there are two types described below), the degree of freedom in design and the tolerance in fabrication are increased. Or add a new function, for example, an optical filtering function.

On the other hand, by injecting carriers into the core layer of the waveguide, not only can it be used as an optical amplifier or a semiconductor laser as a gain medium in a wavelength range determined by the material of the core, but also the refractive index of the core layer decreases. Therefore, the light intensity distribution can be changed.

At this time, when the carrier is injected into the core,
By setting the carrier density to differ periodically,
Simultaneously perform the two actions (light amplification and light intensity distribution change)
Can be satisfied. For example, the first core layer and
And the second core layer form a directional coupler, while
For example, when carriers are periodically injected only into the first core layer
think of. 1 × 10¹⁸ cm^-3When carrier injection
Folding rate is 10^-3Decrease in order (Casey and
Panish; Heterostructure L
asers (Academic Press, 19
78)). Therefore, it is necessary to inject carriers periodically.
Is equivalent to forming a variable refractive index grating.
It is.

A directional coupler is formed by the first core layer and the second core layer (in this case, a variable refractive index grating is formed). For example, only the first core layer is formed. A carrier may be injected.

In both of the above cases, if the grating vector is K, the Bragg condition (phase matching condition) is β ₂ = β ₁ + K (1). Here _{Δ = β 2 - (β 1} + K) When ..... (2), the power transfer rate eta is η = 1 / (1+ (Δ / κ) 2) · (sinβ c z) 2 ·· ... (3) Here, κ is the coupling efficiency between the two waveguides, z is the coordinate in the traveling direction, and β _c = (κ ² + Δ ² ) ^1/2 (4)

From this, the maximum power transfer rate η _max is η _max = 1 / (1+ (Δ / κ) ² ) (5), and the maximum perfect coupling length L is L = π / 2β _c. ... (6)

When a variable refractive index grating is formed, the effective refractive indices of the waveguides 1 and 2 are set to n ₁ and n ₂
When the carrier is injected at about 1 × 10 ¹⁸ cm ⁻³ , the refractive index decreases to the order of 10 ⁻³ . As a result, the propagation constant decreases and κ increases.

When carrier injection is performed only on waveguide 1
Is the propagation constant of waveguide 1 and the coupling efficiency with waveguide 2 is β
_{1, inj}And κ_injThen β_{1, inj}= Β₁−Δβ₁(Δβ₁> 0). At this time, Δ at the time of carrier injection is Δ_injExpressed as
From equation (2), Δ_inj= Δ + Δβ₁ And the power transfer rate is η_intIs η from equation (3)_int= 1 / (1+ (Δ / κ)_inj+ Δβ_{1, inj}/ Κ_inj)^Two) ・ (Sinβ_{c, inj}z) ^Two Becomes

Therefore, since κ increases during carrier injection, ≫1... When no carrier is injected Δ / κ: (7) ≪1... When carrier is injected The layer configuration can be set as described above. In this way, it is possible to prevent η _int from increasing at the time of carrier injection and causing a power transition, and to prevent power transition at the time of non-injection.

At this time, when there is no grating, κ
Since ≪1, Δ / κ ≫1 ············· (8)

Particularly, in the case of a high injection device such as an optical amplifier, the carrier injection effect of the refractive index is large, which is advantageous in design.

On the other hand, when carriers are injected periodically,
During carrier non-injection K = 0 Since Δ _c = β ₂ -β ₁ uninjected time _{Δ inj = β 2, inj -} (β 1, inj + K) at injection = Δ _c -K.

By selecting κ at the time of carrier non-injection as κ≪1, ≪1... At the time of non-carrier injection Δ / κ: (7 ′) ≪1... At the time of carrier injection. In this way, it is possible to prevent the power transfer from occurring during the carrier injection and from the power transfer during the non-injection.

When there is no periodic current confinement layer,
The layer configuration can be set so that Δ / κ≫1 (8 ′) always holds, and power transition can be prevented.

Particularly, in the case of a high injection device such as an LDA, the carrier injection effect of the refractive index is large, which is advantageous in design.

Since the refractive index differs depending on the amount of injected carriers, the effective grating pitch changes. As a result, a filtering effect appears, but the filter band can be set wider or narrower depending on the purpose by controlling the shape of the grating.

[0029]

FIG. 1 is a sectional view of a first embodiment of the present invention. The configuration is such that three regions are connected in series with respect to the traveling direction of light. Regions 1 and 3 are coupler regions,
Region 2 is a gain region or an optical amplifier. The layer configuration was designed so that Expression (7) holds in regions 1 and 3, and Expression (8) holds in region 2.

For example, in FIG.
An As substrate 11 is an n-type first cladding layer (Al _0.5 Ga _0.5
As, thickness 1.5 μm), 12 is an n-type first core layer (Al
_0.08 Ga _0.92 As, thickness 0.1 μm), 13 is an n-type second
Cladding layer (Al _0.5 Ga _0.5 As, thickness 0.5 μm),
Reference _numeral 14 denotes an n-type third cladding layer (Al _0.3 Ga _0.7 As, thickness 0.5 μm), and reference numeral 15 denotes an undoped second core layer (Al _0.08
Ga _0.92 As, thickness 0.05 μm), 16 is a p-type fourth cladding layer (Al _0.5 Ga _0.5 As, thickness 1.5 μm), 1
7 is a contact layer (GaAs). 18 and 19
Denotes a positive electrode and a negative electrode, and 20 denotes a grating for modulating the refractive index. In the case of this example, the wavelength of the guided light was 860 nm, and the grating 20 was set to a sine curve with a pitch of 8.5 μm and a depth of 1.2 nm.

The device length of the regions 1 and 3 is a perfect coupling length (500 μm in this embodiment) determined by the equation (4), and the device length of the region 2 (amplifying section) is 600 μm. Further, an anti-reflection (AR) coat 22 is applied to the input / output end face. Reference numeral 21 denotes a spherical fiber.

The operation principle will be described with reference to FIG.
For example, consider a case where light having a wavelength of 860 nm is guided only to the first core layer 12.

1) When no carriers are injected into the entire region In FIG. 2, since the refractive index does not change, the light 26 input to the optical waveguide 25 does not couple with the waveguide mode of the second waveguide 24 at all. Therefore, the light passes through the area 2 and the area 3 and is output to the outside.

2) When Carrier is Injected into All Regions In FIG. 3, light 31 guided to the first waveguide 25 is
Modulated by the grating 20 and the second
Coupling with the waveguide 24. Since the transfer rate is set to be 100% with respect to the injected carrier density, when the light is guided by the complete coupling length, the light moves to the waveguide 24 at the transfer rate of 100% (the electric field distribution is indicated by 32). Since the region 2 is a gain region, only light amplification is performed and the light intensity increases (the electric field distribution is indicated by 33). Next, in the region 3 where the guided light 34 travels, the waveguide 24 is
, And is output to the outside through the non-reflection end face 22. In region 2, regardless of carrier injection,
Since there is no coupling, it is possible to select a carrier injection amount and a device length to perform desired optical amplification.

[0035]

Second Embodiment In the first embodiment, bulk AlGaAs is used for the core 15 of the optical amplifier, but a quantum well layer (QW) may be used. FIG. 6 shows the Al content of each layer in an example of the layer configuration in this case. The second core layer is made of Al _0.2 Ga _0.8 As
The multi-quantum well structure 15a includes five pairs of (barrier layer) and GaAs (well layer). As a result, the gain spectrum can be narrowed as compared with the first embodiment, and the magnitude of the gain can be increased. FIG. 11 shows a gain spectrum 701 of a bulk and a gain spectrum 702 of a multiple quantum well when carrier injection levels are equalized.
Is schematically represented.

[0036]

Embodiment 3 FIG. 5 is a sectional view of a third embodiment of the present invention. Similarly, three regions are connected in series in the light traveling direction. Regions 1 and 3 are optical coupler units, and region 2 is an optical amplifier unit. The layer configuration was designed so that the expression (7 ′) was satisfied in the regions 1 and 3, and the expression (8 ′) was satisfied in the region 2.

For example, in FIG.
aAs substrate, 101 is an n-type first cladding layer (Al _0.5 G
a _0.5 As, thickness 1.5 μm), 102 is an n-type first core layer (Al _0.08 Ga _0.92 As, thickness 0.1 μm), 103
Denotes an n-type second cladding layer (Al _0.5 Ga _0.5 As, thickness of
5 μm), 104 is an undoped second core layer (Al _0.08 G
a _0.92 As, thickness 0.05 μm), 105 is a p-type third cladding layer (Al _0.5 Ga _0.5 As, thickness 1.5 μm), 1
06 is a contact layer (GaAs). 107 and 108 are a positive electrode and a negative electrode, and 109 is a periodic current confinement layer for modulating the refractive index. In the case of this embodiment, the wavelength of the guided light is 860 nm, and the grating of the periodic current confinement layer 109 is set to a rectangular shape with a pitch of 8.5 μm and a duty of 50%.

The device length of the regions 1 and 3 is a perfect coupling length (500 μm in this embodiment) determined by the equation (4), and the device length of the region 2 (amplifying portion) is 600 μm. In addition, on the input / output end face facing the spherical optical fiber 110,
An anti-reflection (AR) coat 111 is applied.

Next, the manufacturing method of the third embodiment will be briefly described.

For example, a conventional metal organic chemical vapor deposition method (M
OCVD) and molecular beam epitaxial growth (MBE)
First, a (100) n-type GaAs substrate 10
The first core layer 101 grows from the first cladding layer 101 to the second core layer 104. After growing the second core layer 104, p-type Al
_0.5 Ga _0.5 As layer (thickness 0.3 μm, carrier concentration p ~
3 × 10 ¹⁷ cm ⁻³ ) and an n-type Al _0.5 Ga _0.5 As layer (thickness 0.5 μm, carrier concentration n〜3 × 10 ¹⁷ cm ⁻³ ), and a pitch 8.5 μm as described above. The grating pattern has a depth of p-type Al _0.5 Ga _0.5 As
Etch to reach the layer. After this, M
P-type Al _0.5 Ga _0.5 As layer (0.7 μm thick) by OCVD
m and a carrier concentration of p〜3 × 10 ¹⁷ cm ^-3 ).

The reason why the carrier concentration is set to ３3 × 10 ¹⁷ cm ^-3 is to prevent a difference in refractive index from being generated in this region when carriers are not injected. As a result, a periodic current confinement layer 109 is formed. Thereafter, the contact layer 106
Grow.

The present embodiment is completed by forming a buried structure and the like and forming electrodes 107 and 108 for controlling the transverse mode. FIG. 8 is a schematic view of the cross section of FIG.
In the figure, reference numeral 401 denotes an Al _0.5 Ga _0.5 As high resistance buried layer. The structure for controlling the transverse mode is the same for the other embodiments.

Next, the operation principle of the third embodiment will be described with reference to FIG. For example, consider a case where light having a wavelength of 860 nm is guided only to the first core layer 102.

1) When Carriers Are Not Injected into All Regions In FIG. 6, since the refractive index does not change near the periodic current confinement layer 109 as described above, the light 201 input to the optical waveguide 205 is It does not couple at all with the guided mode. Therefore, the light passes through the area 2 and the area 3 and is output to the outside (fail-safe function).

2) When Carriers are Injected Independently into All Regions Carriers injected from the positive electrode 107 have their carrier distribution modulated by the periodic current confinement layer 109, so that carrier distribution occurs in the second core layer 104. , An equivalent refractive index distribution corresponding to this is formed.

Therefore, the light 30 guided to the waveguide 205
1 is coupled to the waveguide 204 by the periodic current confinement layer 109, as shown in FIG. Since the transition rate is set to be 100% with respect to the injected carrier density, the waveguide moves to the waveguide 204 at the transition rate of 100% when guided by the complete coupling length (the electric field distribution is indicated by 302). The carriers that have passed through the second core layer 104
However, the refractive index is not modulated in the first core layer 102 because of the low carrier diffusion effect and low carrier injection efficiency (because the first core layer 102 has no pn junction).

Since the region 2 is a gain region, only light amplification is performed and the light intensity is increased (the electric field distribution is 303
). Next, in the region 3 where the guided light 304 travels, the light travels from the waveguide 204 to the waveguide 205 similarly to the region 1, and is output to the outside via the non-reflective end face 111. Since the region 2 does not couple regardless of the carrier injection, the carrier injection amount and the device length can be selected for a desired optical amplification.

In this embodiment, the n-substrate is used, but since the diffusion length varies depending on the carrier, it may be more advantageous to use the p-substrate.

[0049]

Embodiment 4 FIG. 9 is a schematic view of a fourth embodiment of the present invention. The periodic current confinement layer 109 ′ is
The difference between the third embodiment and the third embodiment is that they are set in.

As a result, 1) the carrier distribution in the second core layer 104 at the time of carrier injection is the third even if the same grating pattern is used.
Different from the embodiment, that is, the effective grating is different. 2) Carrier distribution is induced also in the first core layer 102 depending on the position of the periodic current confinement layer 109 '. 3) Regrowth in manufacturing. Third to form the gain layer 104
It requires a more advanced manufacturing technique than the embodiment, and the like.

By positively utilizing 2), the first core layer 102
Although the coupling can be further increased by using the gain medium as a gain medium, it may become a loss medium at the time of non-carrier injection. The operating principle is the same as in the third embodiment.

[0052]

Embodiment 5 In the third and fourth embodiments, bulk AlGaAs is used for the core layer 104 of the optical amplifier section, but a quantum well layer (QW) may be used. FIG. 10 shows the Al content of each layer in an example of the layer configuration in this case. The second core layer is made of Al _0.2
The multiple quantum well structure 104a includes five pairs of Ga _0.8 As (barrier layer) and GaAs (well layer). As a result, the gain spectrum can be narrowed as compared with the third and fourth embodiments, and the magnitude of the gain can be increased. FIG. 11 schematically shows a gain spectrum 701 of a bulk and a gain spectrum 702 of a multiple quantum well when carrier injection levels are equalized.

Further, by using a strained quantum well layer as the second core layer, it is possible to provide a gain equal to the TE mode and the TM mode (polarization independent LDA).

Next, an embodiment in which the device of the present invention is applied to an optical communication network will be described. In an optical communication network of a bus type, a star type or a loop type, when light is branched and information is extracted, an optical amplifier corresponding to the branching method and the number of branches is required.

[0055]

Embodiment 6 FIG. 12 shows an application example in which the device of the present invention is used as an optical booster amplifier. 400 is a bus line, 401 and 402 are optical repeaters, 403 to 406
Is an optical node, and 407 to 410 are active optical switches. Optical repeaters 401 and 402 contain the apparatus of the present invention and are used to compensate for the power lost per branch. Normally, the optical repeaters 401 and 402 and the optical switches 407 to 410 are linked, and amplification according to the number of branches is performed by the optical repeaters 401 and 402. When amplification is performed, the switches are always opened to the node side. I have.

When a trouble occurs in the optical amplifier for some reason, the power supply to the optical amplifier is cut off and
The active optical switch is also closed, and the optical signal on the bus line 400 passes without loss. That is, the fail-safe function operates.

[0057]

[Embodiment 7] FIG. 13 shows a device according to the present invention in which a booster amplifier +
This is an application example when used as a switch. 500 is an optical transmission line, 501 is an optical amplifier / optical switch including the device of the present embodiment, 502 is a star type optical switch, and 503 to 50
7 is an optical node.

The function as a booster amplifier is the same as that of the sixth embodiment. When each terminal station transmits, the current is simply turned off by turning off the current of the optical amplifier / switch 501. Therefore, for example, a ping-pong communication network in which transmission and reception are alternately performed can be easily formed.

[0059]

The effects of the present invention are as follows.

1) Since the optical switch, the optical amplifier, the optical modulator, and the optical multiplexing / branching device can be monolithically integrated, the device can be small in size and high in function. 2) When an active device such as an optical amplifier fails, fail-safe operation is automatically performed. 3) Easy integration with other devices.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a first embodiment of the apparatus of the present invention.

FIG. 2 is a schematic diagram illustrating the operation principle of the first embodiment.

FIG. 3 is a schematic diagram illustrating the operation principle of the first embodiment.

FIG. 4 is a diagram illustrating a layer configuration of a second embodiment of the device of the present invention.

FIG. 5 is a schematic sectional view of a third embodiment of the device of the present invention.

FIG. 6 is a schematic diagram illustrating the operation principle of the third embodiment.

FIG. 7 is a schematic diagram illustrating the operation principle of the third embodiment.

FIG. 8 is a cross-sectional view of the third embodiment.

FIG. 9 is a schematic sectional view of a fourth embodiment of the device of the present invention.

FIG. 10 is a diagram illustrating a layer configuration of a fifth embodiment of the device of the present invention.

FIG. 11 is a schematic diagram of a gain spectrum according to the second and fifth embodiments.

FIG. 12 is a diagram showing an embodiment of an optical communication system to which the device of the present invention is applied.

FIG. 13 is a diagram showing an embodiment of an optical communication system to which the device of the present invention is applied.

FIG. 14 is a perspective view showing a conventional example.

[Explanation of symbols]

 10, 100 Substrate 11, 101 First cladding layer 12, 102 First core layer 13, 103, 103 'Second cladding layer 14, 105 Third cladding layer 15, 15a, 104, 104a Second core layer 16 Fourth cladding Layer 17, 106 Contact layer 18, 107 Positive electrode 19, 108 Negative electrode 20 Grating 21, 110 Spherical optical fiber 22, 111 Non-reflective film 24, 25, 204, 205 Optical waveguide 109, 109 'Periodical current confinement layer 350 High resistance buried layer 400 Optical bus line 401, 402 Optical repeater 403-406, 503-507 Optical node 407-410 Active optical switch 500 Optical transmission line 501 Optical amplifier / optical switch 502 Star coupler

Continuation of the front page (56) References JP-A-2-248097 (JP, A) JP-A-2-63012 (JP, A) JP-A-2-2631491 (JP, A) JP-A-3-174503 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 2/00 H01S 5/30

Claims (7)

(57) [Claims] 1. A double optical waveguide structure in which at least a first clad layer, a first core layer, a second clad layer, a third clad layer, a second core layer, and a fourth clad layer are laminated on a semiconductor substrate. A waveguide type optical device, which is divided into a plurality of regions in a waveguide direction, and has a refractive index modulation layer between the second clad layer and the third clad layer in at least one of the regions. An integrated optical device having means for injecting carriers into the first core layer or the second core layer in each of the plurality of regions is arranged on a bus-type optical transmission path having a plurality of terminal stations; An optical communication network, wherein, when carriers are not injected into a core layer or the second core layer, light incident on the integrated optical device is output as it is. 2. A double optical waveguide structure in which at least a first clad layer, a first core layer, a second clad layer, a third clad layer, a second core layer, and a fourth clad layer are laminated on a semiconductor substrate. A waveguide type optical device, which is divided into a plurality of regions in a waveguide direction, and has a refractive index modulation layer between the second clad layer and the third clad layer in at least one of the regions. An integrated optical device having means for injecting carriers into the first core layer or the second core layer in each of the plurality of regions is disposed on a star-type optical transmission path having a plurality of terminal stations; An optical communication network, wherein, when carriers are not injected into a core layer or the second core layer, light incident on the integrated optical device is output as it is. 3. A semiconductor device, comprising: a first conductive type first clad layer, a first conductive type first core layer, a first conductive type second clad layer, a second core layer, and a second conductive type. The third
What is claimed is: 1. A waveguide type optical device having a double optical waveguide structure in which a clad layer is laminated, wherein the optical device is divided into a plurality of regions in a waveguide direction, and at least one of the divided regions is formed in the second clad layer. Alternatively, the periodic refractive index modulation layer is provided in the third cladding layer or both, and the periodic refractive index modulation layer controls the light distribution of the double waveguide, and the periodic refractive index modulation layer has Means made of a substance having the same refractive index as that of the adjacent cladding layer and having a region different in conductivity type from that of the cladding layer and the same region periodically, and injecting carriers into the plurality of regions independently. An integrated optical device, comprising: 4. The integrated optical device according to claim 3, wherein said second core layer is a gain medium for incident light. 5. A semiconductor substrate having at least a first cladding layer of a first conductivity type, a first core layer of a first conductivity type, a second cladding layer of a first conductivity type, a second core layer, and a second conductivity type. The third
What is claimed is: 1. A waveguide type optical device having a double optical waveguide structure in which a clad layer is laminated, wherein the optical device is divided into a plurality of regions in a waveguide direction, and at least one of the divided regions is formed in the second clad layer. Alternatively, a periodic refractive index modulation layer is provided in the third cladding layer or both, and when the carrier is not injected into the periodic refractive index modulation layer , the waveguide type optical device is not used.
An integrated optical device, wherein the light distribution of the double waveguide is controlled so that light incident on the chair is output as it is, and the second core layer is a gain medium for the incident light. 6. The integrated optical device according to claim 3, 4 or 5, wherein the integrated optical device is arranged on a bus-type optical transmission line having a plurality of terminal stations, and when no carrier is injected into the periodic refractive index modulation layer,
An optical communication network wherein light incident on the integrated optical device is output as it is. 7. An integrated optical device according to claim 3, which is arranged on a star-type optical transmission line having a plurality of terminal stations, and wherein no carrier is injected into said periodic refractive index modulation layer.
An optical communication network wherein light incident on the integrated optical device is output as it is.