JPH06308560A - Optical semiconductor element utilizing polarization - Google Patents

Abstract

PURPOSE:To provide the optical semiconductor element utilizing polarization which is capable of executing resetting of a memory with a light signal and easily obtaining negative logic by utilizing the mode competition between a TE mode and TM mode with which the rate determination of the operating speed by a carrier life does not arise. CONSTITUTION:This optical semiconductor element utilizing polarization includes a directional coupler 12 with which the light input of a TE polarized wave outputs light to a cross and the light input of a TM polarized wave outputs light to a bar and cross or only to the bar, semiconductor optical amplifiers 21 to 24 which are disposed in arbitrary two ports, not diagonal to each other, among the four ports of this directional coupler 12 and amplify light signals and reflectors 31 to 34 which reflect a part or the whole of the light signals coming from the directional coupler 12 to the respective ports of the directional coupler 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization-utilizing optical semiconductor device which performs logical operation of signal light by switching the polarization plane of output light according to an input optical signal.

[0002]

2. Description of the Related Art An optical logic operation element, which is a kind of optical semiconductor element, is indispensable for controlling an optical signal in an all-optical system expected to be realized in the future. FIG. 11 is a side view showing an example of a conventional optical logic device. This optical logic device 1 is obtained by dividing an upper electrode 7 of a semiconductor laser composed of a substrate 2, a clad layer 3, an active layer 4, a clad layer 5, and electrodes 6 and 7 into two electrodes 7a and 7b. The light input / output characteristics as shown in FIG. 12 can be obtained by adjusting the currents injected into 7a and 7b.

For example, when the system is held at the position of point A in FIG. 12A and the pulsed input light p ₁ is incident on this system, the output light p ₂ becomes point B, and this state is maintained. That is, the memory operation is possible (see FIG. 13A). Further, when the system is held at the position of the point A in FIG. 12B and two input lights p ₃ and p ₄ are made incident on this system, the output light p ₂ becomes as shown in FIG.
It becomes like 3 (b). That is, the AND operation is possible. When the system is held at the position of point A in FIG. 12C and two input lights p ₅ and p ₆ are incident on this system, the output light p ₂
Is as shown in FIG. That is, the OR operation is possible. As described above, the optical logic element 1 can perform the logical operations of memory, AND, and OR by adjusting the injected current.

In addition, the output light p of a semiconductor laser is generally used.
_As shown in FIG. 14, ₂ has a TE wave in the horizontal direction and a TM wave in the vertical direction with respect to this semiconductor element. Since these two lights compete with each other, when the TE wave is output, the TM wave is suppressed, and conversely, when the TM wave is output, the TE wave is output.
The feature is that the waves are suppressed, and this mode competition between the polarizations is performed while the light intensity remains constant, so that the injection current does not need to be converted into the optical output, and therefore, the carrier lifetime inside the device depends on the operating speed. Is never rate-controlled.

[0005]

However, in the conventional optical logic device 1, the on / off operation speed of the output light p ₂ is limited by the carrier life inside the device, and the memory is reset. It has a drawback that it cannot be performed with an optical signal and must be performed with an electric pulse, and that it cannot perform negative logic operations such as NOT, NAND, and NOR. is there. Further, in the conventional semiconductor laser used for the optical logic element 1, the reflectance at the end face and the gain in the waveguide are larger in the TE wave than in the TM wave, so that the laser oscillation by the TM wave is less likely to occur. There was a problem.

The present invention has been made in view of the above circumstances, and the operation speed is not limited by the carrier life.
An object of the present invention is to provide a polarization-utilizing optical semiconductor device that can use the mode competition between the mode and the TM mode to reset the memory with an optical signal and can easily obtain the negative logic.

[0007]

In order to solve the above-mentioned problems, the present invention employs the following polarization-utilizing optical semiconductor device. That is, in the optical semiconductor device using polarization according to claim 1, the TE polarized light optical input is a cross, the TM polarized light input is a bar, and a directional coupler that outputs light to the cross or only the bar, and the direction. A semiconductor optical amplifier for amplifying an optical signal, which is provided in at least two arbitrary ports out of the four ports of the directional coupler, and a light coming from the directional coupler for each port of the directional coupler. And a reflector that reflects part or all of the signal.

A polarization-utilizing optical semiconductor device according to claim 2 is the polarization-utilizing optical semiconductor device according to claim 1, wherein
The directional coupler is characterized by being provided with one or more electrodes for injecting a current or applying a voltage.

A polarization-utilizing optical semiconductor device according to claim 3 is the polarization-utilizing optical semiconductor device according to claim 1 or 2, wherein the semiconductor optical amplifier is a wavelength tunable semiconductor optical amplifier. I am trying.

A polarization-utilizing optical semiconductor device according to a fourth aspect is the polarization-utilizing optical semiconductor device according to the first or second aspect, in which at least any of the four ports of the directional coupler is not on a diagonal line. The feature is that a variable wavelength filter is provided at two ports.

[0011]

In the optical semiconductor device using polarization according to the first aspect of the present invention, the optical input of TE polarization is crossed and the optical input of TM polarization is light on the bar and the cross or only the bar by the directional coupler. By outputting, the polarization plane of the output light is switched to perform a logical operation for one or more input lights, and N
Negative logic optical logic operations such as OT, NAND, NOR are performed.

Further, in the optical semiconductor device using polarization according to a second aspect of the present invention, the directional coupler is provided with one or more electrodes for injecting current or applying voltage. A current is injected or a voltage is applied to the optical coupling portion through this electrode to change the path of light.

In the optical semiconductor device using polarization according to a third aspect of the present invention, the wavelengths of the TE wave and the TM wave are adjusted to different wavelengths by using the semiconductor optical amplifier as a wavelength tunable semiconductor optical amplifier. Convert wavelength between optical input and output.

Further, in the optical semiconductor device using polarization according to a fourth aspect of the present invention, by providing a tunable wavelength filter at any two ports out of the four ports of the directional coupler that are not on a diagonal line, TE wave and The wavelength of each TM wave is adjusted to a different wavelength, and the wavelength between the optical input and output is converted.

[0015]

Embodiments of the present invention will be described below. (Embodiment 1) FIG. 1 is a configuration diagram showing a polarization-utilizing optical semiconductor element (hereinafter, simply referred to as an optical semiconductor element) 11 of Embodiment 1 of the present invention. In the figure, reference numeral 12 denotes a 2 × 2 directional coupler that outputs light to TE polarized light as a cross, and TM polarized light input outputs to a bar and a cross. Reference numerals 21 to 24 denote 4 of the directional coupler 12. The semiconductor optical amplifiers 31 to 34 optically joined to the two ports are semiconductor optical amplifiers 21 to 2 respectively.
4 is optically bonded to each of the four directional couplers 12
It is a total reflection mirror (reflector) that reflects a part or all of the optical signal coming from. These total reflection mirrors 31 to 34
May be a half mirror, and these total reflection mirrors 3
1 to 34 make the system a resonator.

Next, the operation of the optical semiconductor element 11 will be described. Here, a case where the input light p ₁₁ is made incident on the optical semiconductor element 11 from the semiconductor optical amplifier 21 side will be described. Here, when a sufficient current is injected into the semiconductor optical amplifier 21 to output light, the TE wave 4 of the input light p ₁₁
1 is amplified while propagating crosswise through the directional coupler, and finally reaches oscillation and is output as output light p ₁₂ . This T
Since the TM wave 42 has a different coupling length from the E wave 41, the TM wave 42 does not cross and propagates through the directional coupler 12 to the bar and the cross.

The gain of the semiconductor optical amplifier 21 and the reflectance at the mirror are smaller in the TM wave 42 than in the TE wave 41, and therefore the TM wave 42 tends to hardly oscillate. Semiconductor optical amplifier 2
It is possible to adjust the TM wave 42 to oscillate by amplifying it by 2, 23. In this case, mode competition occurs in the semiconductor optical amplifiers 21 and 24, and
An optical logic device as shown in FIG. 2 can be obtained.

For example, when the system is held at the position of point A in FIG. 2A and the pulsed TE input light p ₁₃ is incident on this system, the TE output light becomes point B and this state is maintained. .
That is, memory operation is possible. Here, since the TE input light and the TM input light compete with each other, the TM input light may be used for resetting (see FIG. 3A). Also,
When the system is held at the position of the point A in FIG. 2B and two TE input lights p ₁₄ and p ₁₅ are incident on this system, the TE output light is as shown in FIG.
It becomes like (b). That is, the AND operation is possible. At this time, the TM output light becomes NAND. Also, FIG.
When the system is held at the position of (c) and two TE input lights p ₁₆ and p ₁₇ are incident on this system, the TE output light becomes as shown in FIG. 3 (c). That is, the OR operation is possible. At this time, T
The M output light becomes NOR operation. However, when the TE input light is a single input, the NOT operation is performed.

As described above, according to the optical semiconductor device 11 of the first embodiment, the TE polarized light optical input is crossed, and the TM polarized light input is 2 × 2 direction in which light is output to the bar and the cross. Directional coupler 12 and semiconductor optical amplifiers 21 to 2 optically joined to the four ports of the directional coupler 12, respectively.
4 and total reflection mirrors 31 to 34 which are optically joined to the semiconductor optical amplifiers 21 to 24 and reflect a part or all of the optical signal coming from the directional coupler 12. , The polarization plane of the output light can be switched so as to perform a logical operation for one or more input lights, and thus a negative logical optical logic operation such as NOT, NAND, NOR can be performed.

Incidentally, it is possible to omit either one of the semiconductor optical amplifiers 21 and 24 or one of the semiconductor optical amplifiers 22 and 23. Furthermore, the total reflection mirrors 31 to 34 (or half mirrors) can be omitted by providing high reflection coating on the side of the semiconductor optical amplifiers 21 to 24 far from the directional coupler 12.

FIG. 4 is a block diagram showing an optical semiconductor element 35 which is a modified example of the optical semiconductor element 11.
The directional coupler 12 is simplified by replacing it with a directional coupler 36 that outputs TE waves for cross and TM waves only for a bar. Also in this optical semiconductor element 35, the polarization plane of the output light can be switched so as to perform the logical operation for one or more input lights, and thus the negative logical optical logic operation can be performed.

(Embodiment 2) FIG. 5 is a block diagram showing an optical semiconductor element 51 of Embodiment 2 of the present invention. This optical semiconductor element 51 is obtained by adding electrodes 52 and 53 to the directional coupler 12 of the optical semiconductor element 11 of the above-described first embodiment, and the same components as those of the above-described optical semiconductor element 11 are the same. The reference numerals are given and the description is omitted.

Next, the operation of the optical semiconductor element 51 will be described. Here, a case where the input light p ₁₁ is made incident on the optical semiconductor element 51 from the semiconductor optical amplifier 21 side will be described. Here, when a sufficient current is injected into the semiconductor optical amplifier 21 to output light, the TE wave 4 of the input light p ₁₁
1 is amplified while propagating crosswise through the directional coupler, and finally reaches oscillation and is output as output light p ₁₂ . This T
Since the TM wave 42 has a different coupling length from the E wave 41, the TM wave 42 does not cross and propagates through the directional coupler 12 to the bar and the cross. The characteristics of the directional coupler 12 can be adjusted through the current injected through the electrodes 52 and 53 and the applied voltage. Further, in order to properly adjust the directional coupler 12, it is possible to increase the number of the electrodes 52 and 53 (for example, four) or omit one of them.

Also in the optical semiconductor element 51, the TM wave 4
By amplifying the gain of 2 by the semiconductor optical amplifiers 22 and 23, the TM wave 42 can be adjusted to oscillate. In this case, mode competition is caused by the semiconductor optical amplifier 2
Therefore, it is possible to obtain an optical logic device which has the same operations as those of the optical semiconductor device 11 of the first embodiment.

For example, when the system is held at the position of point A in FIG. 2 (a) and the pulsed TE input light p ₁₃ is incident on this system, the TE output light becomes point B, and this state is held, Memory operation is possible. Here, since the TE input light and the TM input light compete with each other, the TM input light may be used for resetting (see FIG. 3A). In addition, FIG.
When the system is held at the position of point A and the two TE input lights p ₁₄ and p ₁₅ are incident on this system, the TE output light is as shown in FIG. 3B, and the AND operation is possible. At this time, the TM output light becomes NAND. Further, when the system is held at the position shown in FIG. 2C and two TE input lights p ₁₆ and p ₁₇ are made incident on this system, the TE output light becomes as shown in FIG. 3C and the OR operation is possible. is there. At this time, the TM output light becomes NOR operation. Also, the point that the NOT operation is performed when the TE input light is a single input is similar to the optical semiconductor element 11 of the first embodiment.

As described above, also in the optical semiconductor device 51 of the second embodiment, the optical semiconductor device 11 of the first embodiment is also used.
Similarly, the polarization plane of the output light can be switched so as to perform the logical operation for one or more input lights, and thus the negative logical optical logic operation can be performed.

FIG. 6 is a block diagram showing an optical semiconductor element 54 which is a modified example of the optical semiconductor element 51.
The directional coupler 12 is simplified by replacing it with a directional coupler 36 that outputs TE waves for cross and TM waves only for a bar. The optical semiconductor element 54 can also achieve the same actions and effects as those of the optical semiconductor element 51.

(Embodiment 3) FIG. 7 is a block diagram showing an optical semiconductor element 61 of Embodiment 3 of the present invention. This optical semiconductor device 61 is obtained by changing the wavelengths of the semiconductor optical amplifiers 21 to 24 of the optical semiconductor device 11 of the first embodiment described above.
In the optical semiconductor element 61, the polarization plane of the output light is switched so as to perform a logical operation for one or more input light in this optical semiconductor element 61 as in the optical semiconductor element 11 of the first embodiment. Therefore, it is possible to perform a negative logic optical logic operation.

Moreover, the wavelength tunable semiconductor optical amplifiers 62-
By using 65, the wavelengths of the TE wave and the TM wave can be adjusted to be equal or different by adjusting these wavelengths, and it is possible to match the optimum conditions.

Further, wavelength tunable semiconductor optical amplifiers 62 to 6 are used.
The optical semiconductor element 61 can be used as a wavelength conversion element by adjusting the wavelengths of the TE wave and the TM wave according to 5. For example, as is apparent from FIGS. 3B and 3C, the optical semiconductor element 61 described above can obtain a TM light output from one or a plurality of TE light inputs. Further, by adjusting the TE wave and the TM wave to different wavelengths, it is possible to convert the wavelength between the optical input and output. The wavelength tunable semiconductor optical amplifiers 62 to 65 are connected to the semiconductor optical amplifier 21.
The same effect can be obtained even if the configuration is changed to a configuration in which ˜24 and the variable wavelength filter are optically coupled.

FIG. 8 is a block diagram showing an optical semiconductor device 67 which is a modified example of the optical semiconductor device 61.
The directional coupler 12 is simplified by replacing it with a directional coupler 36 that outputs TE waves for cross and TM waves only for a bar. This optical semiconductor element 67 can also achieve the same actions and effects as those of the optical semiconductor element 61.

(Embodiment 4) FIG. 9 is a block diagram showing an optical semiconductor device 71 according to Embodiment 4 of the present invention. The optical semiconductor device 61 includes a variable wavelength filter 72 (73) between the semiconductor optical amplifier 21 (22) and the total reflection mirror 31 (32) of the optical semiconductor device 11 of the first embodiment, and the semiconductor optical device 61. A variable wavelength filter 74 (75) is provided between the amplifier 23 (24) and the total reflection mirror 33 (34), and this optical semiconductor element 71 is also the same as the optical semiconductor element 11 of the first embodiment. Similarly, the polarization plane of the output light can be switched so as to perform the logical operation for one or more input lights, and thus, the negative logical optical logic operation can be performed.

Moreover, by adjusting the wavelengths of the wavelength tunable filters 72 to 75 so that the wavelengths of the TE wave and the TM wave are equal or different, the optimum conditions can be met. In addition, the wavelength variable filter 72
By adjusting the wavelength of TE wave and TM wave by ~ 75,
The optical semiconductor element 71 described above can be used as a wavelength conversion element. For example, as is apparent from FIGS. 3B and 3C, the above-described optical semiconductor device 71 can obtain a TM light output from one or a plurality of TE light inputs.
Also, by adjusting the TE and TM waves to different wavelengths,
The wavelength between the optical input and output can be converted. It should be noted that either one of the variable wavelength filters 72 and 75, or one of the variable wavelength filters 73 and 74 can be omitted.

FIG. 10 is a block diagram showing an optical semiconductor device 77 which is a modified example of the optical semiconductor device 71. The directional coupler 12 outputs the TE wave to the cross and the TM wave to the bar only. The directional coupler 36 is replaced by a simplified one. This optical semiconductor element 77 can also achieve the same actions and effects as those of the optical semiconductor element 71.

In each of the above embodiments, the input is a TE wave,
The output was TE / TM wave, but conversely the input was TM wave,
The output can be TM / TE waves.

[0036]

As described above, according to the first aspect of the present invention.
According to the optical semiconductor device using polarization described above, a TE polarization light input is cross, a TM polarization light input is a bar, and a directional coupler that outputs light to only the cross or the bar, and the directional coupler. Of the four optical ports of at least two that are not on a diagonal line, and a semiconductor optical amplifier for amplifying an optical signal, and one of the optical signals coming from the directional coupler with respect to each port of the directional coupler. Since it has a reflector that reflects a part or all of it, it is possible to switch the polarization plane of the output light so as to perform a logical operation on one or more input lights, and to output a negative logic light such as NOT, NAND, or NOR. Can perform logical operations.

According to the optical semiconductor device using polarization of the present invention, since the directional coupler is provided with one or more electrodes for injecting current or applying voltage, the directional coupler is provided. A current can be injected or a voltage can be applied to the optical coupling part of this through this electrode, and thus the optical path can be changed.

According to the optical semiconductor device using polarization in the third aspect, since the semiconductor optical amplifier is a wavelength tunable semiconductor optical amplifier, the wavelengths of the TE wave and the TM wave are adjusted to different wavelengths. It is possible to convert the wavelength between the optical input and output.

Further, according to the optical semiconductor device using polarization in the fourth aspect, the variable wavelength filter is provided at any two ports out of the four ports of the directional coupler that are not on the diagonal line. The wavelength of each wave and the TM wave can be adjusted to different wavelengths from each other, and thus the wavelength between the optical input and output can be converted.

As described above, the polarization-based optical semiconductor in which the mode competition between polarizations whose operation speed is not limited by the carrier life is used, the memory can be reset by the optical signal, and the negative logic can be easily obtained. The device can be realized. Further, by adjusting the wavelengths of the TE wave and the TM wave, it is possible to realize a polarization-use optical semiconductor element capable of converting the wavelength between the optical input and output.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a polarization-utilizing optical semiconductor device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing characteristics of a polarization-utilizing optical semiconductor device of Example 1 of the present invention.

FIG. 3 is an explanatory diagram showing the characteristics of the polarization-based optical semiconductor device of Example 1 of the present invention.

FIG. 4 is a configuration diagram showing a modified example of the optical semiconductor device using polarization according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram showing a polarization-based optical semiconductor device of Example 2 of the present invention.

FIG. 6 is a configuration diagram showing a modified example of the polarization-based optical semiconductor device of Example 2 of the present invention.

FIG. 7 is a configuration diagram showing a polarization-based optical semiconductor device of Example 3 of the present invention.

FIG. 8 is a configuration diagram showing a modified example of a polarization-utilizing optical semiconductor device of Example 3 of the present invention.

FIG. 9 is a configuration diagram showing a polarization-utilizing optical semiconductor device of Example 4 of the present invention.

FIG. 10 is a configuration diagram showing a modified example of the optical semiconductor device using polarization according to the fourth embodiment of the present invention.

FIG. 11 is a configuration diagram showing a conventional optical logic element.

FIG. 12 is an explanatory diagram showing characteristics of a conventional optical logic element.

FIG. 13 is an explanatory diagram showing characteristics of a conventional optical logic element.

FIG. 14 is a configuration diagram showing a conventional semiconductor laser.

[Explanation of symbols]

11 Optical Semiconductor Device Utilizing Polarization 12 Directional Coupler 21-24 Semiconductor Optical Amplifier 31-34 Total Reflection Mirror (Reflector) 35 Optical Semiconductor Element 36 Directional Coupler 51 Optical Semiconductor Element 52, 53 Electrode 54 Optical Semiconductor Element 61 Optical semiconductor element 62 to 65 Wavelength variable semiconductor optical amplifier 67 Optical semiconductor element 71 Optical semiconductor element 72 to 75 Variable wavelength filter 77 Optical semiconductor element 41 TE wave 42 TM wave p ₁₁ input light p ₁₂ output light p ₁₃ TE input light p ₁₄ TE input light p ₁₅ TE input light p ₁₆ TE input light p ₁₇ TE input light

Claims (4)

[Claims] 1. A TE-polarized light optical input is a cross, and a TM-polarized light optical input is a bar and a directional coupler that outputs light only to the cross or the bar, and at least four ports of the directional coupler. A semiconductor optical amplifier that is provided on any two ports that are not on a diagonal line and that amplifies an optical signal, and a reflection that reflects a part or all of the optical signal coming from the directional coupler to each port of the directional coupler. And an optical semiconductor device using polarization. 2. The polarization-based optical semiconductor device according to claim 1, wherein the directional coupler is provided with one or more electrodes for injecting a current or applying a voltage. Utilized optical semiconductor device. 3. The polarization-based optical semiconductor element according to claim 1, wherein the semiconductor optical amplifier is a wavelength tunable semiconductor optical amplifier. 4. The polarization-based optical semiconductor device according to claim 1, wherein a tunable wavelength filter is provided at least at any two ports out of the four ports of the directional coupler that are not on a diagonal line. A polarization-based optical semiconductor device.