JPH10104670A - Optical logic device using polarization - Google Patents

Abstract

(57) [Problem] To provide an optical logic element using a distributed Bragg-type semiconductor laser and to enable higher-speed operation. SOLUTION: Two types of active layers 104 and 105 are provided adjacent to a common waveguide 103. Further, the common waveguide 1 before and after the active layers 104 and 105 are formed.
03 on the grating 113 along the amplification region.
Gratings 114 are formed, which together form a resonator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an all-optical logic operation of signal light by switching the polarization plane of output light with input signal light in the fields of optical communication, optical switching, optical information processing and the like. The present invention relates to a polarization-based optical logic device of the distributed Bragg reflector semiconductor laser type utilizing polarization.

[0002]

2. Description of the Related Art An all-optical logic operation element is indispensable for controlling an optical signal in an all-optical system expected to be realized. FIG. 9 shows an example of a conventional optical logic device (Reference 1: H. Kawaguchi, "Optical bistability and c.
haos in a semiconductor laser with saturable absor
ber "Applied Physics Letter, 45, 12, pp. 1264-1266, 198
9, Reference 2: "Introduction to Optical Switching Technology", supervised by Hiroshi Ishikawa
Kenichi Yukimatsu, Telecommunications Association, pp.76-78, 1993.)

This optical logic element is composed of a distributed Bragg type semiconductor laser and has a sectional structure shown in FIG. This configuration will be described below. As shown in FIG.
A cladding layer 902 made of n-type InP is formed on a substrate 901 made of n-type InP. On top of this, InG of a composition having a band gap wavelength of 1.6 μm is formed.
An active layer 903 made of aAsP is formed. On the active layer 903, a clad layer 904 made of p-type InP is formed, and a cap layer 905 is formed thereon. Then, the electrode 90 is formed on the cap layer 905.
6a and 906b are formed, and an electrode 90
7 are formed.

Here, as shown in FIG. 9, this optical logic element comprises a region under the electrode 906a and a region under the electrode 906b, and each region depends on the state of current injected into the electrodes 906a and 906b. Can be set to different operation states. This optical logic element is connected to the electrode 9
By setting a predetermined relationship between currents to be injected into the respective electrodes 06a and 906b, for example, bistable operation is achieved, and FIG.
Optical input / output characteristics as shown in FIG.

The operation will be described. In FIG. 10, the electrodes 906a and 906b are set so that the state shown by the point A when a predetermined bias light is input is obtained.
The current to be injected into each is adjusted. From this state, when the input pulse light 1001 is newly added as the light input, the light output immediately increases, and even if the input pulse light 1001 is no longer input, the light output is maintained in the state shown by the point B. That is, as shown in FIG. 11B, a memory operation in which an optical output is held with respect to the input pulse of FIG. 11A is possible.

[0006] Further, as shown in FIG.
The currents injected into the electrode 906b and the electrode 906b are set in a predetermined relationship, and the system of the optical logic element is maintained at the point A. Then, by adding two input signals 1201 and 1202 to the optical logic element in this state, FIG.
An AND operation is obtained as shown in FIG. FIG.
As shown in FIG. 4, the currents injected into the electrodes 906a and 906b are set to have a predetermined relationship, and the system of the optical logic element is maintained at the point A. Then, by adding two input signals 1401 and 1402 to the optical logic element in this state, as shown in FIGS.
Operation is obtained.

[0007]

As described above, according to the optical logic device using the distributed black semiconductor laser, the memory, AND,
A logical operation such as OR becomes possible. However, in the above-described conventional optical logic element, the ON / OFF operation of the optical output is performed by the ON / OFF of the optical input. That is, the operation speed of turning on and off the optical output is limited by the carrier lifetime of the semiconductor laser when the injection current is converted into light. For this reason, the conventional optical logic element has a problem that there is a limit in increasing the speed of its operation.

For example, when a large-capacity data transfer is required and a transfer rate of at least 10 Gbit / s is required, the optical switching speed needs to be at least 10 GHz. Nowadays, a larger data transfer capacity is required, and an optical switching operation exceeding 40 GHz is required. However, in the related art, the optical switching speed is about 1 GHz on average, and the operation at a maximum of 2 to 3 GHz is the limit even at the highest state, which is far from the above requirement.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to enable an optical logic device using a distributed Bragg semiconductor laser to operate at higher speed. .

[0010]

According to the present invention, there is provided a polarization utilizing optical logic element comprising: a lower cladding layer formed on a semiconductor substrate; a waveguide layer having a predetermined wavelength reflected thereon; A first waveguide including a common waveguide on which a transmitting first grating is formed, an upper cladding layer formed thereon, a cap layer formed thereon, and a first electrode formed thereon; Was prepared. A first active layer formed on a lower clad layer formed on the semiconductor substrate following the first region, an upper clad layer formed thereon, a cap layer formed thereon; A second region including the second electrode formed thereon was provided. A second active layer formed on the lower clad layer formed on the semiconductor substrate following the second region, an upper clad layer formed thereon, a cap layer formed thereon; A third region including a third electrode formed thereon was provided. A second grating formed on a lower cladding layer formed on the semiconductor substrate following the third region and reflecting a guided light having a predetermined wavelength and transmitting the rest; A fourth region including a waveguide, an upper clad layer formed thereon, a cap layer formed thereon, and a fourth electrode formed thereon was provided. In addition, a fifth electrode formed on the back surface of the semiconductor substrate is provided. The first active layer amplifies polarized light in the horizontal direction with respect to the semiconductor substrate more than the second active layer, and the second active layer vertically amplifies light with respect to the semiconductor substrate as compared with the first active layer. The first grating reflects the polarized light in the horizontal direction with respect to the semiconductor substrate more than the second grating, and the second grating reflects the first grating more than the first grating. Polarized light perpendicular to the semiconductor substrate is more reflected. With this configuration,
A first grating, first and second active layers, and
The second grating has a resonator structure. And
For example, the active layer 1 and the active layer 2 are operated in a bistable operation, and the polarized light in the horizontal direction is input to the semiconductor substrate and amplified in the first active layer. When wave light is input, the output of polarized light in the horizontal direction from the semiconductor substrate from the first active layer is attenuated, and the output of polarized light in the direction perpendicular to the semiconductor substrate from the second active layer becomes dominant.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a sectional view showing a configuration of a polarization-use optical logic element according to an embodiment of the present invention. Hereinafter, the configuration of this polarization utilizing optical logic element will be described. As shown in FIG. 1, first, an n-side electrode 101 is formed on a substrate 10 made of n-type InP.
2 formed on the back surface. In addition, a common waveguide (common waveguide layer) 103 made of InGaAsP having a band gap wavelength of 1.3 μm is formed on the surface of the substrate 102. This common waveguide 103 also has a function as a cladding layer. An active layer 104 and an active layer 105 having different characteristics are formed on the common waveguide 103.

First, the active layer 104 has a thickness of 0.1 μm.
InGa having a composition having a band gap wavelength of 1.6 μm
It is composed of AsP. Then, as shown in the plan view of FIG. 1B, the active layer 104 has a width of 1 μm and a length of 300 μm.
μm. On the other hand, the active layer 105 has a thickness of 0.
It is formed of InGaAsP having a composition of 5 μm and a band gap wavelength of 1.6 μm. Also,
As shown in FIG. 1B, the active layer 105 has a width of 0.5 μm.
The length m is 300 μm. And FIG.
As shown in FIG. 1B as viewed from the light output surface of FIG. 1A and FIG. 1A, a cladding layer 106 is formed on the active layers 104 and 105 described above.

On the common waveguide 103 before and after the active layers 104 and 105 are formed, gratings 113 and 114 are formed along the amplification region, and these constitute a resonator. Grating 1
Reference numerals 13 and 114 are such that a part of incident light is transmitted and a part is reflected. Then, a p-InP layer 107 is formed thereon, and the electrodes 109 to 1 are interposed via a cap layer 108.
12 are formed. As described above, the first embodiment is characterized in that two types of active layers 104 and 105 are provided adjacent to the common waveguide 103.

Next, the active layer 104 and the active layer 105 will be described. First, in a region where the active layer 104 is formed, a laser oscillation operation is performed by injecting a current between the electrode 110 and the electrode 101. Here, this active layer 1
04 is TE (transver
se electric) The confinement coefficient of light with respect to light is TM (tra
nsverse magnetic) larger than light. Note that TE light is polarized light in a direction horizontal to the substrate 102, and TM light is polarized light in a direction perpendicular to the substrate 102. On the other hand, the active layer 10
The region where 5 is formed performs a laser oscillation operation by injecting a current between the electrode 111 and the electrode 101. As is clear from the structure, the active layer 105 has a larger light confinement coefficient for TM light than TE light.

That is, in the first region under the electrode 109, the second region under the electrode 110, and the fourth region under the electrode 112, a distributed Bragg reflection type semiconductor laser in which TE light mainly oscillates is formed. I have. Then, in the second region, the TE light that has been optically input is more efficiently amplified. In the first region and the third and fourth regions below the electrode 111, a distributed Bragg reflection type semiconductor laser that mainly oscillates TM light is configured. Then, in the third region, the light input TM light is more efficiently amplified.

By adjusting the amount of current injected into the electrodes 109 and 112, the gain of the TE light in the second region and the gain of the TM light in the third region can be controlled. Then, for example, as a whole, a bistable operation state in which the TE light and the TM light compete with each other can be achieved. For example, in the bistable operation, in a state where TE light is oscillated from the active layer 104 in a state where there is no light input, oscillation of TM light from the active layer 105 is suppressed. Further, in the state where TM light is oscillated from the active layer 105, the oscillation of TE light from the active layer 104 is suppressed, and the TM light is output.

Then, for example, TM
When TE light is input in a state where light is oscillated and TM light is output, the active layer 105 that oscillates TM light does not amplify TE light much, but the active layer 104 does not amplify TE light.
The E light is more effectively amplified to be in the TE light oscillation state.
As a result, the oscillation of the TM light of the active layer 105 is suppressed, and the output state of the TE light is changed by the oscillation of the active layer 104. That is, as the above-mentioned bistable operation state, TM
By turning on and off the input of the TE light while the light is being output, the output state of the TE light and the output state of the TM light can be switched.

The mode competition (bistable operation) between the polarizations of the TE light and the TM light is performed while the optical output is constant. Therefore, in switching between the output state of the TE light and the output state of the TM light, the operation of converting the injection current to the optical output is not switched. As a result, the switching between the output state of the TE light and the output state of the TM light can be performed at a very high speed without the operating speed being limited by the carrier life inside the element. The on / off of the input light (TE light) is, for example, 40
The operation can be performed at GHz, and when the polarization-use optical logic element of the first embodiment is used, a high-speed operation of 40 GHz can be performed while compensating the optical output of the modulator.

The operation of the polarization-use optical logic element according to the first embodiment will be described below. First, FIG.
Operation characteristics having a memory function as shown in FIG. For example, the wavelength of the TE light oscillated by the active layer 104 is 1550 nm, the wavelength of the TM light oscillated by the active layer 105 is 1560 nm, and the wavelength interval between them is 10 nm. This is controlled by the amount of current injected into the electrodes 109 and 112. Further, the current to be injected into each of the second region and the third region is set so that the gain difference between the TE light and the TM light becomes 0.6 dB (TE <TM). Then, the input TE light is set in the state of point A in FIG.
In this state, when the optical input pulse 21 is input, the TE optical output from the polarization-use optical logic element changes as shown in FIG.
The state at the point B in FIG.

On the other hand, this time, by inputting the TM light,
The E light output attenuates, changes to the TM light output state, and returns from the state at point B to the state at point A. That is, according to the polarization-based optical logic element of the first embodiment, the TE optical input and T
By focusing on the TE light output by switching the M light input, the characteristics shown in FIG. 2A can be obtained. Then, for example, as shown in FIGS.
By switching between optical pulse input and TM optical pulse input,
This polarization utilizing optical logic element can switch between TE light output and TM light output shown in FIGS. 2 (d) and 2 (e).

Second, as shown in FIG. 3, an AND or NAND operation can be obtained. For example, the wavelength interval between the oscillation wavelengths of the active layer 104 and the active layer 105 is 3 nm, and the gain difference between them is 1.0 dB (TE <TE <
TM). That is, from the state of the point A in FIG.
When 2 is input, the state shifts to the TE light output state for the first time. As a result, as shown in FIGS. 3B and 3C, by using two TE optical inputs, this polarization utilizing optical logic element can be used as the TE optical input shown in FIGS. 3D and 3E. Output and TM light output can be switched. That is, two T
With the E light input, an AND operation can be obtained by focusing on the TE light output, and a NAND operation can be obtained by focusing on the TM light output.

Third, as shown in FIG. 4, an OR or NOR operation can be obtained. For example, the active layer 10
The wavelength interval between the oscillation wavelength 4 and the active layer 105 is 3 nm, and the gain difference is 0.1 dB (TE <TM). That is, when the TE light input 41 is input from the state of the point A in FIG. 4A where there is almost no TE light output, the state is shifted to the TE light output state for the first time. In addition, even if the TE light input 42 is input, the TE light output state is maintained. As a result, as shown in FIGS. 4B and 4C, by using two TE optical inputs, the polarization utilizing optical logic element can be used as the TE optical input shown in FIGS. 4D and 4E. Output and TM light output can be switched. That is, with two TE light inputs, an OR operation can be obtained by focusing on the TE light output, and a NOR operation can be obtained by focusing on the TM light output. Note that a single input with one TE input is a NOT operation.

Second Embodiment In the first embodiment, an active layer mainly for amplifying TE light and an active layer mainly for amplifying TM light are arranged adjacent to each other. However, the present invention is not limited to this. is not. As shown in FIG. 5, the active layer 104 and the active layer 105 may be arranged so as to sandwich the grating 116. In the polarization-based optical logic element according to the second embodiment, a current is injected into the region of the grating 116 by the electrode 115. The polarization-use optical logic element is connected to the first
Area, a second area under the electrode 110, a third area under the electrode 115, a fourth area under the electrode 111, and an electrode 1
12 and a fifth area below the fifth area.

In this polarization-use optical logic element, the region where the active layer 104 is formed
A laser oscillation operation is performed by injecting a current between the electrode and the electrode 101. On the other hand, in a region where the active layer 105 is formed, a laser oscillation operation is performed by injecting a current between the electrode 111 and the electrode 101. That is, the first region and the second region
In the region and the third region, a distributed Bragg reflection type semiconductor laser that mainly oscillates TE light is configured. In the third region, the fourth region, and the fifth region, a distributed Bragg reflection type semiconductor laser that mainly oscillates TM light is configured.

The oscillation wavelength of the active layer 104 is in the region 1
And the oscillation wavelength of the active layer 105 is controlled by the current injected into the region 5. For this reason,
In the second embodiment, the oscillation wavelength of the active layer 104 and the oscillation wavelength of the active layer 105 can be individually controlled more easily. In the polarization-based optical logic element according to the second embodiment, in addition to the above, the amount of current injected into each of the regions 2 and 4 also
By adjusting the gain in the active layers 104 and 105, it is possible to obtain the same effect as that of the polarization utilizing optical logic element according to the second embodiment.

Embodiment 3 Hereinafter, a third embodiment of the present invention will be described.
FIG. 5 is a sectional view showing the configuration of the polarization-use optical logic element according to the third embodiment. As shown in FIG. 5, in this polarization-use optical logic element, a semiconductor layer 120 is newly provided. The semiconductor layer 120 is formed on the active layer 104, and is continuously formed on the lower active layer 105a. Then, the active layer 15 in the first and second embodiments is used.
However, in the third embodiment, the lower active layer 150a, a part of the semiconductor layer 120, and the upper active layer 150b are included. The rest is the same as FIG.

With this configuration, as described below, it becomes easier to manufacture this polarization utilizing optical logic element. Hereinafter, an outline of the manufacturing method will be described. First, as shown in FIG. 7A, a common waveguide 103 is formed on a substrate 102, and a semiconductor film 701 made of InGaAsP, which is a material of the active layers 104 and 105, is deposited thereon. Next, as shown in FIG. 7B, an InP film 702 to be the semiconductor layer 120 is formed thereon. Next, as shown in FIG. 7C, the active layer 105 is formed thereon.
A semiconductor film 703 made of InGaAsP is deposited.

Next, as shown in FIG. 7D, by selectively etching using a resist mask 704,
An upper active layer 105b is formed. This is performed by wet etching using an etching solution obtained by diluting a stock solution of sulfuric acid: hydrogen peroxide: water 1: 10: 1 with water 10-fold.
In wet etching using this etching solution, In
P film 702 is hardly etched, and InGaAs
The semiconductor film 703 made of P is selectively etched.

Next, as shown in FIG. 7E, a P-type InP film 705 is deposited thereon, and as shown in FIG. 7F, the resist mask 706 is sequentially etched using the resist mask 706 as an etching mask. Layer 106, semiconductor layer 120,
An active layer 104 and a lower active layer 105a are formed. Next, as shown in FIG.
The gratings 113 and 114 are formed at predetermined positions of No. 3, a p-InP layer 107 is formed thereon, and a cap layer 108 is formed.

Then, as shown in FIG. 8H, electrodes 109 to 112 are formed on the cap layer 108 and the substrate 10
2. An electrode 101 is formed on the back surface. As described above, in the third region below the electrode 111, the lower active layer 105a and the upper active layer 105b sandwiching the semiconductor layer 120 are formed.
An active layer in which the confinement coefficient of light with respect to M light is larger than that with TE light is formed. This is because in FIG.
Corresponding to 5. An active layer 104 is formed in a second region below the electrode 110. In this region, a light confinement coefficient for TE light is larger than that for TM light.

As described above, in the third embodiment, unlike the active layers 104, 105a, and 105b, the materials constituting the active layers are different from those which are selectively etched under predetermined etching conditions. Semiconductor layer 1
20 (InP film 702). As a result, according to the third embodiment, the thickness of the active layer 104 can be controlled by forming the semiconductor film 701. As a result, compared to controlling the film thickness by etching,
The accuracy of controlling the thickness of the active layer 104 is further improved. The operation of the polarization-use optical logic element according to the third embodiment is the same as the operation of the polarization-use optical logic element described in the first embodiment, and the effect is the same. Needless to say, the above-described configuration using the semiconductor layer can be applied to the polarization-use optical logic element described in Embodiment 2.

In the above-described first to third embodiments, n-type InP is used as the substrate. However, the present invention is not limited to this, and a substrate made of p-type InP may be used. Further, another semiconductor may be used. Further, although InGaAsP is used for the active layer, the present invention is not limited to this, and it is possible to use InGaAlAs (T
E), InAlAs-based (TE), or AlGa
The same is true even when a material system such as an As (TM) is used.

Further, a quantum well structure or a strained quantum well structure may be used for the active layer. In this case, in the active layer using the quantum well structure and the compressive strain quantum well structure, the light confinement coefficient for TE light is larger than that for TM light. In the extensional strain quantum well structure,
The light confinement coefficient for the TM light is larger than that for the TE light. However, in the first to third embodiments, the two active layers are made of the same material, so that the first to third embodiments can more easily manufacture a polarization-use optical logic element.

The present invention is not limited to the configuration shown in the first to third embodiments. For example, an isolation groove may be provided as an isolation between electrodes for injecting current into each of the first to fourth regions. An insulating region may be provided. Also, in order to control the width of the active layer, light or current is confined by a buried structure using a ridge structure or a PN junction, a buried structure using an insulating layer, or a buried structure using a rib. Needless to say good things.

[0035]

As described above, according to the present invention, the first and second active layers are provided, and the first and second gratings which reflect the waveguide light of a predetermined wavelength before and after the first and second active layers and transmit the rest are provided. It was configured to be arranged. The first active layer amplifies polarized light in the horizontal direction with respect to the semiconductor substrate more than the second active layer, and the second active layer vertically amplifies light with respect to the semiconductor substrate as compared with the first active layer. Is further amplified. Further, the first grating reflects polarized light in the horizontal direction with respect to the semiconductor substrate more than the second grating,
The second grating reflects polarized light in a direction perpendicular to the semiconductor substrate more than the first grating.

With this configuration, the first grating, the first and second active layers, and the second grating have a resonator structure. For example, the active layer 1 and the active layer 2 are operated in a bistable operation, and the polarized light in the horizontal direction is input to the semiconductor substrate and amplified in the first active layer. When the input of the polarized light is turned on and off, the output of polarized light in the horizontal direction with respect to the semiconductor substrate from the first active layer and the output of polarized light in the vertical direction with the semiconductor substrate from the second active layer are switched.

The switching of the polarized light is not limited by the carrier lifetime in the first and second active layers.
For example, the output of one polarized light can be turned on and off at 40 GHz using a modulator. As a result, according to the present invention,
While compensating for the optical output of the modulator, a high-speed operation of 40 GHz becomes possible, and a higher-speed operation becomes possible as compared with a conventional optical logic element. Further, in addition to the above, according to the present invention, NOT, NAN which could not be achieved by the prior art.
Negative logic such as D and NOR can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a polarization-use optical logic element according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing operation characteristics of the polarization-use optical logic element of FIG.

FIG. 3 is an explanatory diagram showing another operation characteristic of the polarization-use optical logic element of FIG. 1;

FIG. 4 is an explanatory diagram showing another operation characteristic of the polarization-use optical logic element of FIG. 1;

FIG. 5 is a cross-sectional view illustrating a configuration of a polarization-use optical logic element according to a second embodiment of the present invention.

FIG. 6 is a sectional view illustrating a configuration of a polarization-use optical logic element according to a third embodiment of the present invention.

7 is a cross-sectional view for explaining a manufacturing process of the polarization-use optical logic element of FIG.

8 is a cross-sectional view following FIG. 7 for explaining the manufacturing process of the polarization-use optical logic element of FIG. 6;

FIG. 9 is a sectional view showing an example of a conventional optical logic element.

FIG. 10 is an explanatory diagram showing operation characteristics of the optical logic element of FIG. 9;

FIG. 11 is an explanatory diagram showing another operation characteristic of the optical logic element in FIG. 1;

FIG. 12 is an explanatory diagram showing another operation characteristic of the optical logic element in FIG. 1;

FIG. 13 is an explanatory diagram showing another operation characteristic of the optical logic element in FIG. 1;

FIG. 14 is an explanatory diagram showing another operation characteristic of the optical logic element in FIG. 1;

FIG. 15 is an explanatory diagram showing another operation characteristic of the optical logic element in FIG. 1;

[Explanation of symbols]

101 n-side electrode, 102 substrate, 103 common waveguide (common waveguide layer), 104, 105 active layer, 106 cladding layer, 107 p-InP layer, 108 cap layer, 109, 110, 111, 112 ... electrodes, 113,
114 ... Grating.

Claims (4)

[Claims] 1. A common waveguide on which a first cladding layer is formed on a lower cladding layer formed on a semiconductor substrate, the first cladding layer is formed on the lower cladding layer to reflect guided light of a predetermined wavelength and transmit the rest. An upper cladding layer formed thereon, a cap layer formed thereon, a first region including a first electrode formed thereon, and a first region formed on the semiconductor substrate following the first region. A first active layer formed on the lower clad layer, the upper clad layer formed thereon, the cap layer formed thereon, and a second electrode formed on the second electrode. Region 2, a second active layer formed on a lower cladding layer formed on the semiconductor substrate subsequent to the second region, the upper cladding layer formed on the second active layer, Said cap layer, formed thereon A third region formed of a third electrode formed on the lower clad layer formed on the semiconductor substrate subsequent to the third region, and reflects a guided light having a predetermined wavelength and transmits the rest. The common waveguide on which a second grating is formed, the upper cladding layer formed thereon, the cap layer formed thereon, and a fourth electrode formed on the fourth electrode. And a fifth electrode formed on the back surface of the semiconductor substrate, wherein the first active layer amplifies the polarized light in the horizontal direction with respect to the semiconductor substrate more than the second active layer. The second active layer amplifies the polarized light in a direction perpendicular to the semiconductor substrate more than the first active layer, and the first grating has a higher semiconductor light intensity than the second grating. More polarized light in the horizontal direction with the substrate The second grating reflects polarized light in a direction perpendicular to the semiconductor substrate more than the first grating, and the first to fourth electrodes respectively include the first to fourth regions. An optical logic device utilizing polarization, wherein the optical logic device is formed so as to allow a current to flow therethrough. 2. The polarization-use optical logic element according to claim 1, wherein said polarization-use optical logic element is formed on said upper cladding layer between said second region and said third region, and reflects the guided light having a predetermined wavelength to remain. Is the common waveguide on which the transmitting third grating is formed, the upper cladding layer formed thereon, the cap layer formed thereon, and the sixth waveguide formed thereon.
A polarization utilizing optical logic element, comprising: a fifth region comprising: 3. The polarization-use optical logic element according to claim 1, wherein the first active layer has a width in the direction of the input and output optical waveguides greater than its thickness, and the second active layer has A polarization utilizing optical logic element, the thickness of which is greater than the width in the direction of the input and output optical waveguides. 4. The polarization-use optical logic element according to claim 1, wherein the second active layer is formed to have the same thickness as an upper active layer and the first active layer. Polarization comprising: a lower active layer; and a semiconductor layer formed on the first active layer and the lower active layer, the semiconductor layer being made of a material that is less likely to be etched than the upper active layer. Use optical logic element.