JP2000214497A - Light amplifying gate circuit and optical gate switch and wavelength selective filter which use the circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost, a small-loss, and a high-speed optical amplifying gate circuit, and an optical gated switch and wavelength selection filter which use it. SOLUTION: The optical gate circuit can be constituted small in size by monolithically constituting a light amplifying-light branching-light amplifying part and a light amplifying-light branching-light absorbing part in a light amplifying and a light absorption regions, and it is possible for this circuit to amplify a signal light input and gate-output from one of the output ends, and make the other output end absorb the signal light to fully attenuate it for preventing it from being outputted, and is also possible for the circuit to electrically control output ends N2, N3 from which to gate-output, for high-speed switching. A high efficiency optical coupling to optical fibers to be coupled to input/output ends N1, N2, N3 can be performed by providing spot size conversion parts 18-1, 18-2 in the neighborhood of the signal light input end and output end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical amplification type gate circuit, an optical gate type switch using the same, and a wavelength selection filter.

[0002]

2. Description of the Related Art With the development of optical network technology, the need for a matrix optical switch for dynamic traffic control and detour in the event of a failure has increased. Matrix optical switches include 1) low loss, 2) low crosstalk,
3) High-speed switching, 4) Low power consumption, 5) Small size, 6) Low cost, etc. are required. As a matrix optical switch that may satisfy such requirements, semiconductor optical amplifiers are arranged as optical gates on each output side of the optical branch circuit, and the output is controlled by controlling the injection current to these optical gates. Attention has been paid to a matrix optical switch of a system in which an optical gate is selected and an optical path is switched, that is, a gate type matrix optical switch using a semiconductor optical amplifier.

FIG. 8 shows a conventional example of an optical switch constituting a matrix optical switch.

The optical switch shown in FIG. 1 is a 1 × 2 type optical switch having one input and two outputs, and has one input port and two input ports.
Output ports 2-2, 2- of an optical branching circuit 2 (hereinafter referred to as a 1-input 2-output optical branching circuit) having two output ports.
3 and semiconductor optical amplifiers 3-1 and 3-2 forming an optical gate
Are connected to each other.

In the optical switch shown in FIG.
Is input to the input port 2-1 of the optical branching circuit 2, is substantially equally distributed to the output ports 2-2 and 2-3, and outputs the signal light 1-1 and
1-2, and each output port 2-2, 2
-3 are connected to the semiconductor optical amplifiers 3-1 and 3-2.

Here, for example, when a signal light is output in the direction of the arrow 5-1, a forward current I _k1 is injected into the semiconductor optical amplifier 3-1 from the current injection terminal 4-1. _No. 2 is not injected with the forward current I _k2 .
Thus, the amplified signal light is extracted from the output terminal of the semiconductor optical amplifier 3-1.

On the other hand, since the forward current I _k2 is not injected into the semiconductor optical amplifier 3-2, the signal light 1-2 is attenuated by being absorbed by the semiconductor optical amplifier 3-2. Almost no signal light is output from the output terminal of 3-2. That is, the crosstalk between both output terminals is suppressed low.

In such a configuration, the optical branching circuit 2 is realized using a glass waveguide or an optical fiber, and the semiconductor optical amplifiers 3-1 and 3-2 are mounted in a hybrid structure with the optical branching circuit.

[0009]

The conventional optical switch shown in FIG. 8 is realized by hybrid mounting a glass waveguide type or optical fiber type optical branching circuit and a semiconductor optical amplifier. Therefore, there are the following problems.

(1) Since a large amount of time is required for assembling and mounting and costs for mounting jigs, adjustment parts, and the like, optical parts are expensive.

(2) There is a large refractive index error between the refractive index (about 1.46) of the glass waveguide type or optical fiber type optical branch circuit and the refractive index (about 3.3) of the semiconductor optical amplifier. Because of the matching, coupling loss and reflection loss at the connection part of the optical component are large.

(3) Since the optical branching circuit of the glass waveguide type or the optical fiber type has a low refractive index, the dimensions are at least several tens mm in length and several mm in width, and the dimensions (length,
(The width is about 1 mm), which is too large.

(4) For the reason (2) above, in order to realize a lossless optical switch, it is necessary to greatly increase the injection current in the semiconductor optical amplifier, which results in an optical switch that consumes a large amount of power. become.

(5) For the purpose of miniaturization, it has been studied to monolithically configure the optical branch circuit and the semiconductor optical amplifier on an InP (or GaAs) substrate.
When a passive optical component such as an optical branch circuit is formed on a P (or GaAs) substrate, the loss increases. Lossless,
Alternatively, in order to realize an optical switch having a gain, an excessive injection current must be passed, and it has not yet been realized as a practical optical switch.

An object of the present invention is to solve the above problems and provide a low-cost, low-loss, high-speed optical amplification type gate circuit, an optical gate type switch using the same, and a wavelength selection filter.

[0016]

In order to achieve the above object, an optical amplification type gate circuit according to the present invention comprises a slab-shaped lower cladding layer, an active layer and an upper first cladding layer formed on a substrate in this order. An upper second clad layer having a substantially rectangular cross-sectional shape is formed on the first clad layer so as to be branched into at least two branches from one end of the substrate to the other end, and a side surface of the upper second clad layer and the upper first clad layer The exposed upper surface is covered with an oxide layer and a polymer film, the upper second cladding layer is formed on the upper first cladding layer with at least two upper electrodes via a contact layer, and formed on the upper electrode and the lower surface of the substrate. Current is separately injected between the lower electrode and
A signal is incident from one end of the upper second cladding layer, and the amplified signal light is output from one of the upper second cladding layers on the branch side.

In addition to the above configuration, the optical amplification type gate circuit of the present invention preferably has an anti-reflection coating layer formed on the incident end face and the outgoing end face of the signal light.

In addition to the above configuration, the selection of the output terminal for outputting the amplified signal light of the optical amplification type gate circuit of the present invention is performed by applying a current to one of the upper electrodes on the upper side of the upper second cladding layer on the branch side. It is preferable to control by injecting.

In addition to the above configuration, it is preferable that the upper second cladding layer of the optical amplification type gate circuit of the present invention is formed so that the width is tapered toward one end and the other end.

In addition to the above configuration, the branch side of the upper second cladding layer of the optical amplification type gate circuit of the present invention is preferably patterned to the other end so as to include a curved pattern.

In addition to the above structure, one end of the upper second cladding layer of the optical amplification type gate circuit of the present invention is formed in two tapered shapes arranged at a narrow interval, and spreads radially toward the other end. It is preferably formed as follows.

In addition to the above configuration, in the optical amplification type gate circuit of the present invention, the refractive index between the lower cladding layer and the active layer has a value between the refractive index of the lower cladding layer and the refractive index of the active layer. It is preferable to provide a slab-shaped buffer layer.

In addition to the above configuration, the optical amplification type gate circuit according to the present invention may be arranged such that the incident end face and the output end face of the signal light have an angle of 2 ° to 10 °.
Is preferably formed at an angle of.

The optical amplification type gate circuit of the present invention has N inputs and M outputs (N ≧ 1,
M ≧ 2).

The wavelength selection filter of the present invention is a filter having an Add / Drop function using the optical amplification type gate circuit having the above configuration.

According to the present invention, the optical gate circuit can be formed by forming the optical amplification, light branching, and light amplifying unit and the light amplification, light branching, and the light absorbing unit into a monolithic shape in the light amplifying and light absorbing region. It can be configured in a small size, amplify the signal light input and output it to the gate at one output terminal, and absorb the signal light at the other output terminal so that it is sufficiently attenuated and not output. At the same time, it is possible to perform high-speed switching by electrically controlling which output terminal outputs the gate. Further, by providing a spot size converter near the signal light input terminal and the output terminal side, highly efficient optical coupling with an optical fiber connected to the input / output terminal can be performed.

[0027]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1A is a sectional view of a signal light input side showing an embodiment of an optical amplification type gate circuit according to the present invention.
1B is a top view, FIG. 1C is a cross-sectional view taken along line AA of FIG. 1A, and FIG. 1D is a cross-sectional view taken along line BB of FIG. 1B.

The characteristics of the present optical amplification type gate circuit are as follows.
The optical amplifying / branching / optical amplifying unit and the optical amplifying / branching / optical absorbing unit are configured in a monolithic shape in the light absorbing region. With such a configuration, the optical gate circuit can be configured in a small size, and the signal light input is amplified and gate-outputted to one output terminal, while the other output terminal absorbs the signal light to absorb light sufficiently. The output can be attenuated so as not to be output, and at the same time, which output terminal is to be gated can be electrically controlled to perform high-speed switching. Further, by providing a spot size converter near the signal light input terminal and the output terminal side, highly efficient optical coupling with an optical fiber connected to the input / output terminal can be performed.

Hereinafter, the present optical amplification type gate circuit will be described in detail.

In the present optical amplification type gate circuit, the signal light input 1 is bifurcated and spread at an angle ψ (preferably in the range of 3 ° to 30 °) in the direction of arrow 5-1 or arrow 5-2. One of them is optically amplified, branched, and output through an optical amplification unit, and the other end is electrically controlled so as not to be output through optical amplification, optical branching, and a light absorption unit, and is output in any direction. The optical path can be switched at high speed by electrical control.

For example, when it is desired to optically amplify and output the signal light input 1 in the direction of arrow 5-1, the current I _k1 is supplied to the terminal 4-1.
And inject the current I _k2 into the terminal 4-2. Conversely, when it is desired to optically amplify and output the signal light input 1 in the direction of arrow 5-2, the terminal 4-1 The current I _k1 may be injected, and the current I _k3 may be injected into the terminal 4-3.

In the region where the current is injected as described above, the signal light is optically amplified, and in the region where the current is not injected, the signal light is absorbed and attenuated.

The light amplification type gate circuits shown in FIGS. 1A to 1D are 1.5 μm band light amplification type gate circuits.
6 is an InP (n ⁺ ) substrate, 7 is a slab-shaped InP (n)
A lower clad layer, 8 a slab-shaped InGaAsP active layer, 9 a slab-shaped InP (p) upper first clad layer,
Reference numeral 10 denotes a ridge structure and an upper second cladding layer 10-1.
An upper second cladding layer having a two-branch structure such as 10-3 and made of InP (p), 11 being an InGaAsP contact layer formed on the upper second cladding layer 10,
12-1, 12-2 and 12-3 are upper surface electrodes, 13 is a lower surface electrode, 14 is an electrode separation groove, 15-1 and 15-2 are non-reflective coating layers formed on light input / output end faces, 17
Is a SiO ₂ layer (low dielectric constant layer) formed on the side surface of the upper second cladding layer 10 of the ridge structure and the upper surface of the upper first cladding layer 9, and 16-1 and 16-2 cover the SiO ₂ layer 17. Polyimide film or fluorinated polyimide film (low dielectric constant layer), 18-1, 18-2 and 1
8-3 is the second upper part of the ridge structure for spot size conversion.
Reference numeral 19 denotes a tapered portion of the cladding layer 10, and reference numeral 19 denotes a branch portion for splitting the signal light into two.

The input terminal N ₁ side to the connected optical fiber signal light propagating through the inside (not shown) 1 reaches the input terminal N _1, activity immediately below the ridge of the upper second clad layer 10-1 Coupled within layer 8 and confined to propagate. Since the current I _k1 is injected from the terminal 4-1 into the upper electrode 12-1 on the upper second cladding layer 10-1, the signal light 1
Is amplified in this region, reaches the branching portion 19, and is branched into two at the branching portion 19. One of the branched signal lights propagates in the active layer 8 immediately below the ridge-type upper second cladding layer 10-2 while being guided by the upper second cladding layer 10-2, and the other signal light propagates in the ridge-type upper cladding layer 10-2. The inside of the active layer 8 directly below the upper second cladding layer 10-3 is formed by the upper second cladding layer 1.
It propagates while being guided by 0-3.

Here, for example, the current I _k2 is connected to the terminal 4-2.
If the current I _k3 is not injected into the terminal 4-3, the signal light propagating in the active layer 8 directly below the upper second cladding layer 10-2 while being guided by the upper second cladding layer 10-2 further increases It is optically amplified in the region of the second cladding layer 10, and output is optically amplified by the high gain from the output terminal N ₂ in the arrow 5-1 direction. Conversely, the upper second cladding layer 10
While being guided by -3 signal light propagating in the active layer 8 directly below the receives the light absorption significantly attenuated in the region of the upper second clad layer 10-3 arrow from the terminal N ₃ 5
Almost no signal light is output in the -2 direction. Moreover the signal light terminal N ₃ side from the optical fiber diameter (125 [mu] m) long as the input side away to the extent of terminal N ₁ in the Y-direction position and the terminal N ₃ in the Y direction, for example, an optical fiber (not shown) It hardly leaks into the connected optical fiber (not shown).

That is, the upper second cladding layer 1 on the branch side
Since one side of O-2 and 10-3 performs optical amplification and the other side absorbs light, the ON / OFF extinction ratio of the optical gate circuit can be made very large. Another feature of this structure is that the side surface of the upper second cladding layer 10 has a low dielectric constant SiO ₂ layer 17 and polyimide films 16-1 and 16-2.
Therefore, the switching speed at which the optical signal is switched to either the direction of arrow 5-1 or the direction of arrow 5-2 to perform gate output can be increased. The spot size converter of the present invention is formed by making the vicinity of the end faces of the upper second cladding layers 10-1 to 10-3 at the input end and the output end into a tapered shape like 18-1 to 18-3. The optical amplification type gate circuit can efficiently make the signal light 1 that has propagated in the optical fiber enter the active layer immediately below the upper second cladding layer, propagate the signal light, and branch the signal light in two directions. The split signal light can be efficiently coupled and propagated in the optical fiber connected to the terminal N ₂ (N ₃ ).

That is, the tapered input and tapered output structure is such that unnecessary radiation loss in the optical amplification type gate circuit of the present invention is minimized.

FIG. 2A is a sectional view on the signal light input side showing another embodiment of the optical amplification type gate circuit of the present invention.
2 (b) is a top view, FIG. 2 (c) is a cross-sectional view taken along line CC of FIG. 2 (a), and FIG. 2 (d) is a cross-sectional view taken along line DD of FIG. 2 (b).

The difference from the embodiment shown in FIG.
nP (n) lower cladding layer 7 and InGaAsP active layer 8
This is the point that the buffer layer 20 is formed between these two. This buffer layer 20 is for minimizing the polarization dependence of the present optical amplification type gate circuit. The refractive index of the buffer layer 20 is equal to the refractive index of the InP (n) lower cladding layer 7 (3.
163) and smaller than the refractive index (3.375) of the InGaAsP active layer 8 (3.2 to 3.25).
It is preferable to select The thickness of the buffer layer 20 is InP
(N) It is preferable that the thickness is substantially equal to the thickness (about 3 μm) of the lower cladding layer 7.

Spot size converters 18-1 and 18-
2, 18-3, the width W ₁ = 0 μm and the width W ₂ =
3 μm, L ₁ = 50 μm, InGaAsP active layer 8 thickness 0.25 μm, InP (P) upper first cladding layer 9 thickness 70 nm, refractive index 3.163, InP (p) upper second cladding layer 10 Assuming that the refractive index is 3.163 and the thickness is 3 μm, the half width of the light intensity distribution in the width direction in the active layer 8 at the entrance / exit end face is about 3.3 μm, which is about 1 μm compared to the half width at the width W _2. .2 times larger. Further, the half width of the light intensity distribution in the thickness direction of the active layer 8 at the incident / exit end face is also about 1.5 μm, which is about 1.5 times as large as the half width at the width W ₂ ,
It was found that the spot size conversion effect was sufficiently obtained. This is obtained by inserting the buffer layer 20 and optimizing its refractive index and its thickness.

FIG. 3 shows another embodiment of the optical amplification type gate circuit according to the present invention, which corresponds to FIG. 2 (c) and corresponds to FIG.
FIG. 4 is a sectional view taken along line C of FIG.

The difference from the embodiment shown in FIG. 2 is that the InP (p) upper second cladding layer 10-2 of the ridge structure has a
10-3 is constituted by S curve patterns 21-1 and 21-2. By providing the S curve pattern 21-1 and 21-2, it is possible to increase the distance S between the output terminal N ₂ and the output terminal N _3, it is possible to improve the extinction ratio and crosstalk characteristics. Also, the S curve patterns 21-1, 2
Unnecessary scattering loss of signal light confined and propagated in the active layer 8 directly below 1-2 can be suppressed, and as a result, signal light that has been optically amplified with a high gain can be extracted.
Further, since L ₂ is longer, the gain medium length and the light-absorbing medium length becomes longer, a higher extinction ratio, it is possible to realize high gain characteristics.

FIG. 4A is a sectional view on the signal light input side showing another embodiment of the light amplification type gate circuit of the present invention.
4B is a top view, FIG. 4C is a sectional view taken along line EE of FIG. 4A, and FIG. 4D is a sectional view taken along line FF of FIG. 4B.

The difference from the embodiment shown in FIG. 3 is that a wedge 22 is provided on the upper electrode 12-1 and the ridge type InP
(P) by an upper similar to the electrode pattern to the pattern of the second cladding layer 10, the injection current upper first cladding layer 9 to confine I _k1 to the upper second cladding layer 10, active layer 8 , Lower cladding layer 7, InP (n
⁺ ) It can flow to the lower electrode 13 through the substrate 6.
As a result, light can be efficiently confined in the active layer 8 immediately below the upper second cladding layer 10-1, and the light can be amplified. If the input / output end faces are formed at an angle θ (preferably in the range of 2 ° to 10 °), propagation of reflected light from the input / output end faces into the optical amplification type gate circuit can be suppressed. it can.

Here, it goes without saying that the formation of the oblique end face is also effective for the embodiment shown in FIGS. 1 (a) to 1 (d) to FIG.

FIG. 5A is a cross-sectional view on the signal light input side showing another embodiment of the light amplification type gate circuit of the present invention.
5B is a top view, FIG. 5C is a sectional view taken along line GG of FIG. 5A, and FIG. 5D is a sectional view taken along line HH of FIG. 5B.

The difference from the embodiment shown in FIG. 4 is that the upper ridge-shaped second cladding layers 10-2 and 10-3 have a width d.
Is a point separated by.

In the embodiment shown in FIGS. 1 to 4, the signal light input is made to enter the active layer 8 immediately below the optical converging portion of the upper second cladding layer 10-1, and thereafter, the upper second cladding layer 1
The configuration is such that the light is branched and propagated in the active layer 8 immediately below 0-2 and 10-3.

[0050] The configuration shown in FIG. 5 contrast, it is incident on the terminal N ₁₁ and the terminal N ₁₂ very close to the signal light 1,
Thereafter, the upper second cladding layers 10-2 and 10-2 gradually spread at an angle ψ (ψ: preferably in the range of 3 ° to 30 °).
In this case, the light is branched and propagated in the active layer 8 immediately below the area -3.

Here, the value of the interval d is preferably as small as possible, and is set to the minimum dimension (about 1 μm) that can be realized in the process. With this configuration, the signal light from the optical fiber connected to both the input and output end faces has a mode field diameter of the optical fiber in the range of 5 μm to 8 μm. Therefore, the signal light is transmitted to the two terminals N ₁₁ and N _12. And the upper second cladding layers 10-2 and 10-3 are separated and the currents I _k2 and I _k3 can be independently injected from the terminals 4-2 and 4-3. Therefore, for example, when it is desired to amplify and output the signal light 1 in the direction of arrow 5-1, it is sufficient to inject only the current I _k2 (do not inject the current I _k2 ), and conversely, in the direction of arrow 5-2 When the signal light 1 is to be amplified and output in the direction, only the current I _k3 may be injected (the current I _k2 is not injected).

With such a configuration, a higher extinction ratio and lower crosstalk characteristics can be obtained.

In the embodiments shown in FIGS. 1 to 5, the case where the number of signal light input terminals 1 is one and the number of signal light output terminals is two has been described. Is two or more, the number of signal light output terminals is three or more (4, 6,
8, ...).

FIG. 6 is a block diagram showing an embodiment of an optical gate type switch using the optical amplification type gate circuit of the present invention. FIG. 6 (a) shows a 1 × 2 type optical gate switch. 6 (b) shows a 2 × 2 optical gate switch.

These optical gate switches can be made small, and can obtain amplified signal light (signal light with gain). In addition, these optical gate switches can obtain a characteristic of a high extinction ratio between the output light 1 and the output light 2, and can obtain a low crosstalk characteristic. further,
These optical gate switches have features such as a reduction in connection loss between optical components and a reduction in injection current as a result (because connection loss is low).

FIG. 7 is a block diagram of a wavelength selection filter using the optical amplification type gate circuit of the present invention.
It has an op function.

This wavelength selection filter splits the wavelength-multiplexed signal light (wavelengths λ _{1 to} λ ₄ ) by the optical splitter 24-1 and converts the split signal light of each wavelength into an optical amplification type gate. Circuit 2
3-1, 23-2, and 23-4. Optical amplification type gate circuits 23-1, 23-2, 23-3, 23
-4, one is input to the optical demultiplexer 24-2 as indicated by arrows 27-1, 27-2, 27-3, and 27-4, and the other is output to the DROP receiving circuit 25 by the arrow 28-.
1, 28-2, 28-3, and 28-4. The optical signal from the ADD transmission circuit 26 is indicated by an arrow 29-1,
29-2, 29-3, and 29-4, the signal light of each wavelength is input to the optical demultiplexer 24-2,
-2, a signal light having a desired wavelength is output.

As described above, in the embodiment shown in FIGS. 1 to 5, an InP substrate is used as the substrate 6 and the wavelength is 1.5 μm.
Although an optical circuit in the m band has been described, the present invention is not limited to this, and an optical circuit in the 1.3 μm wavelength band may be configured using a GaAs substrate as the substrate 6. That is, various compound semiconductor substrates can be used as the substrate 6.

The SiO ₂ layer 17 may contain a dopant for controlling the refractive index, such as F, B or P.

Further, in the embodiment shown in FIGS. 1 to 5, the upper second cladding layer 10-2 divided into two branches.
A groove is formed in the portion of the polyimide film 16-3 between the upper second cladding layer 10-3 and the light absorbing agent (carbon, metal fine particles, dye, pigment, etc.) in the film. , The extinction ratio and the crosstalk characteristics may be further improved.

The optical amplification type gate circuits shown in FIGS. 1 to 5 are arranged in an array on the same substrate, and have N inputs and M outputs (N ≧ 1, M ≧ 2). May be configured. With such a configuration,
A highly integrated optical device can be realized with small size and high performance.

In the optical amplification type gate circuit shown in FIGS. 1 to 5, a current is injected into the upper electrode of the upper second cladding layer to be gate-outputted, but a terminal on the so-called light-absorbing side which does not output a gate. If a reverse voltage is applied instead of injecting a current into the device, more light absorption can be generated, and a higher extinction ratio and low crosstalk characteristics can be obtained.

In the optical amplification type gate circuit shown in FIGS. 1 to 5, the InP (p) upper first cladding layer (not shown) (not shown) 9 and the InP (p) upper second cladding layer (not shown) An etch stop layer (InGaAsP) of about 15 nm is formed between the upper second clad layer 10 and the upper second clad layer 10 in a ridge shape so that the etching is stopped at the etch stop layer. Is configured. As a specific composition example of the active layer 8, Ga _0.27 In _0.73 As _0.5 P _0.43 is used, and the wavelength is 1.
It can be operated as a 55 μm band. As a specific composition example of the contact layer 11, P ⁺ -In _0.53 Ga
C doping of _0.47 As (10 ¹⁹ ) is used.

As described above, according to the present invention, (1) by providing an optical amplification / optical branching / optical amplification section and an optical amplification (or optical absorption) / optical branching / optical absorption section on one substrate, It is possible to realize an optical amplification type gate circuit that can switch the signal light incident on one input terminal to one of the two output terminals and output the signal light at high speed.

(2) The present optical amplification type gate circuit can be realized with a small size and a monolithic structure.

(3) The extinction ratio of the two output terminals can be increased, and the crosstalk characteristics can be reduced.

(4) The connection loss between the optical components is extremely small because they are monolithically integrated.

(5) By making the spot size conversion section and the branch section have a tapered structure, the signal light incident on the input terminal of the present optical amplification type gate circuit is efficiently coupled and propagated in the active layer, Thereafter, the light can be efficiently branched and propagated in two directions.

(6) If this optical amplification type gate circuit is used,
N × M type (N ≧ 1, M ≧ 2) optical gate switch such as × 2 type, 2 × 2 type, 1 × 4 type, 1 × 6 type, wavelength selective filter, wavelength selective filter with Add / Drop function Etc. can be realized with small size and high performance.

(7) Since it is an integrated part, the cost of assembly and mounting as in the conventional case can be greatly reduced.

(8) After amplifying the signal light, it is branched into two, one is optically amplified, and the other is a monolithically integrated optical device that propagates while absorbing light.
An optical device having a monolithically integrated optical device for propagating signal light while amplifying it and splitting the signal light while absorbing the other light is obtained. This optical device is not a combination of conventional single-function components such as a branching component and an amplification component, but an optical device having a plurality of functions integrally formed in a monolithic manner.

(9) The crystal is grown on an InP (n ⁺ ) substrate.
InP (n) lower cladding layer 7, InGaAsP active layer 8, InP (p) upper first cladding layer 9, InGaAs
A P-etch stop layer (not shown), an InP (p) upper second cladding layer 10, and an InGaAsP contact layer 11 are sequentially crystal-grown. The contact layer 11 and the upper second cladding layer 10 are processed into a ridge shape by dry etching. Next, an SiO ₂ layer 17 and a polyimide film 16 are formed. Thereafter, by forming an electrode pattern, an optical amplification type gate circuit can be produced. Since it is a simple process, cost reduction can be achieved.

(10) Since the active layer 8 through which the signal light propagates is made of a slab, and the upper first clad layer and the lower clad layer having a low refractive index are formed above and below the slab, the ridge-shaped upper clad layer is formed. Even if the propagation path of the signal light is guided by the curved pattern or the discontinuous pattern of the second cladding layer, the signal light in the active layer 8 propagates relatively smoothly and has no unnecessary scattering properties, so that a high gain is obtained. An optical device is obtained.

[0074]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide a low-cost, low-loss, high-speed optical amplification type gate circuit, an optical gate type switch using the same, and a wavelength selection filter.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view on the signal light input side showing one embodiment of an optical amplification type gate circuit of the present invention, FIG. 1B is a top view,
(C) is a sectional view taken along the line AA of (a), and (d) is a sectional view of B of (b).
FIG. 4 is a cross-sectional view taken along line B.

2A is a cross-sectional view on the signal light input side showing another embodiment of the optical amplification type gate circuit according to the present invention, FIG. 2B is a top view, and FIG. 2C is CC in FIG. Line cross-sectional view, (d) is (b)
FIG. 4 is a sectional view taken along line DD of FIG.

FIG. 3 is a cross-sectional view showing another embodiment of the light amplification type gate circuit of the present invention.

4A is a cross-sectional view on the signal light input side showing another embodiment of the optical amplification type gate circuit of the present invention, FIG. 4B is a top view, and FIG. 4C is EE in FIG. Line cross-sectional view, (d) is (b)
FIG. 4 is a sectional view taken along line FF of FIG.

5A is a sectional view on the signal light input side showing another embodiment of the optical amplification type gate circuit of the present invention, FIG. 5B is a top view, and FIG. 5C is GG in FIG. Line cross-sectional view, (d) is (b)
FIG. 3 is a sectional view taken along line HH of FIG.

FIG. 6 is a block diagram showing one embodiment of an optical gate type switch using the optical amplification type gate circuit of the present invention;
(A) shows a 1 × 2 type optical gate switch, and (b) shows a 2 × 2 type optical gate switch.
A × 2 type optical gate switch is shown.

FIG. 7 is a block diagram of a wavelength selection filter using the optical amplification type gate circuit of the present invention.

FIG. 8 is a conventional example of an optical switch constituting a matrix optical switch.

[Explanation of symbols]

Reference Signs List 6 InP (n ⁺ ) substrate 7 InP (n) lower cladding layer 8 InGaAsP active layer 9 Slab-shaped InP (p) upper first cladding layer 10-1, 10-2, 10-3 upper second cladding layer 12- 1, 12-2, 12-3 Upper electrode 13 Lower electrode 18-1, 8-2 Spot size converter (taper) 19 Branch

Claims (10)

[Claims] A slab-shaped lower cladding layer, an active layer and an upper first cladding layer are sequentially formed on a substrate.
An upper second clad layer having a substantially rectangular cross-sectional shape is formed on the clad layer so as to be branched into at least two branches from one end to the other end of the substrate, and the side surfaces of the upper second clad layer and the upper first clad layer are formed. The exposed upper surface was covered with an oxide layer and a polymer film, and the upper second cladding layer was formed on the upper first cladding layer with at least two upper electrodes via a contact layer, and formed on the upper electrode and the lower surface of the substrate. Currents are separately injected between the lower electrode and the lower electrode, a signal is input from one end of the upper second cladding layer, and an amplified signal light is output from one of the upper second cladding layers on the branch side. An optical amplification type gate circuit characterized by the above-mentioned. 2. The optical amplification type gate circuit according to claim 1, wherein a non-reflection coating layer is formed on an incident end face and an output end face of the signal light. 3. The selection of an output terminal for outputting the amplified signal light is controlled by injecting a current into one of the upper surface electrodes on the upper side of the upper second cladding layer on the branch side. Item 3. An optical amplification type gate circuit according to item 1 or 2. 4. The optical amplification type gate circuit according to claim 1, wherein the upper second cladding layer is formed so as to have a tapered width toward one end and the other end. 5. The optical amplification type gate circuit according to claim 1, wherein the branch side of the upper second cladding layer is patterned to the other end so as to include a curved pattern. 6. One end of the upper second cladding layer is formed in two tapered shapes arranged at a narrow interval, and is formed so as to expand radially toward the other end. The optical amplification type gate circuit according to any one of the above. 7. A slab-shaped buffer layer having a refractive index between the lower clad layer and the active layer having a refractive index between the refractive index of the lower clad layer and the refractive index of the active layer. The optical amplification type gate circuit according to claim 1. 8. The optical amplification type gate circuit according to claim 1, wherein the incident end face and the output end face of the signal light are formed obliquely at an angle of 2 ° to 10 °. 9. An N-input M-output (N ≧ 1, M ≧ 1) using the optical amplification type gate circuit according to any one of claims 1 to 8.
2) The optical amplification type gate circuit. 10. A wavelength selection filter having an Add / Drop function using the optical amplification type gate circuit according to claim 1.