JP2003140206A - Optical switch and optical demultiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical switch and an optical demultiplexer with which the problems such as a limited operation speed due to the passing time of light, a large optical circuit size and a polarized wave dependency can be simultaneous ly solved, in which a more practical function of an optical interference type device can be realized, whose structure and control are simple, whose operation is stabilized, and which are suitable to a long distance and large capacity optical communication or the like. SOLUTION: Two refractive index varying regions 13 composed of an SOA are symmetrically provided in a multi-mode interferometer (MMI) 1 which has two optical input ports 11A and 11B and two optical output ports 12A and 12B, and the refractive index varying regions 13 are so arranged to include two points on which the light in the MMI 1 is once concentrated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch and an optical demultiplexer used mainly in optical communication technology.

[0002]

2. Description of the Related Art In recent years, WD has been used as a large capacity optical communication system.
M (wavelength division multiplex) optical communication has been developed, and OTDM (optical time division multiplex) optical communication system or TWDM (time wavelength division multiplex) optical communication system aiming at large-capacity optical communication has been proposed and research progresses. Has been.

While WDM optical communication is a technique for improving signal density by wavelength-multiplexing signal light,
The time division method such as OTDM and TWDM is a technique (for example, a signal density of 160 Gbit / s or more) intended to improve the signal density of pulsed light having a very narrow spectrum width of the same wavelength. However, the response speed of the electric signal is limited by the moving time of the carrier and is slower than the response speed of the light. For example, at present, the speed limit of electric signals is 40 Gbit.
It is considered to be about / s, and in order to process an OTDM signal at a speed higher than this, it is necessary to divide the optical signal by high-speed optical signal processing and drop (demux) it to a bit rate that can be electrically processed. .

Based on such a background, recently, a device for converting the wavelength of an optical signal as it is without converting it to an electric signal or for demaxing has been studied.
Interference devices, which are all-optical systems such as a non-linear loop mirror (NOLM), a Mach-Zehnder type, and a polarization splitting type, have been proposed so far. These interference type devices will be described with reference to FIG.

In the NOLM type device (FIG. 10 (a)), first, a signal light is split into two directions in an optical fiber loop, and a nonlinear refractive index change (hereinafter referred to as a nonlinear waveguide) is placed at an asymmetric position. That is, a differential phase shift is generated by the shift of the timing of passing through, and switching is performed by the phase difference when it is multiplexed.
This NOLM type device has several drawbacks. For example, in order for it to work, in principle the first pulse must pass through the gain medium, the control light must pass through, and then the second pulse must pass through the medium, but the transit time of this loop is The bit rate that can be processed by the switch is limited. Further, there is a limit to downsizing of the device as long as a general optical fiber loop of NOLM type is used.

Mach-Zehnder type device (see FIG.
(B)) has a configuration in which two nonlinear waveguides are arranged in each arm of the Mach-Zehnder interferometer.
The signal light is branched and introduced into the nonlinear waveguide of each arm, while the control light is input to the nonlinear waveguide of each arm at different timings to generate a differential phase shift, and the phase difference produces a signal. Are switched by determining the optical path when they are multiplexed. In this system, the operating speed is not limited by the light transit time unlike the NOLM, but two parallel-arranged arms incorporating a nonlinear waveguide are required, and the control light is provided on each arm. Since there is a need for a component for multiplexing, there is a drawback that the device configuration tends to be large.

The polarization separation type device is shown in FIG.
As shown in (c), one specific polarization component is delayed by a birefringent crystal (polarization separation delay circuit), and two polarization components are simultaneously phase-shifted by a nonlinear waveguide on the same optical axis. It is restored by the polarization separation delay circuit again, and only the pulse whose phase is different depending on the polarization component is taken out by the polarizer.

Unlike the Mach-Zehnder type device, this system has an advantage that it has one arm and has a simple structure, but the light passing through the optical fiber in actual optical communication has random polarization components. Therefore, there is a problem that it is not suitable for practical use.

[0009]

As described above, various optical interference type devices that perform wavelength conversion or signal division in the state of an optical signal without converting it into an electrical signal do not require electrical processing, and therefore can be processed at high speed. While it is possible to secure the speed, the problem of being subject to various new technical restrictions as described above is caused.

Therefore, the present invention solves the above-mentioned problems of the respective optical interference type devices, namely, the limitation of the operation speed due to the light transit time, the large size of the optical circuit, and the polarization dependence at the same time, and it is more practical. It is an object of the present invention to provide an optical switch and an optical demultiplexer suitable for long-distance and large-capacity optical communication that realizes the functions of a typical optical interference device, has a simple configuration and control, and has stable operation.

[0011]

As a result of intensive studies, the present inventor has come up with various aspects of the invention described below.

In the optical switch of the present invention, a refractive index change is optically induced between one or more optical input ports and two or more optical output ports, and the optical input port and the optical output port. A multimode interferometer having one or more refractive index change regions, the first incident light from the optical input port;
Is configured to be emitted from the light output port, the second light having a second wavelength is allowed to pass through the refractive index change region, and the change in the refractive index causes the second light to pass therethrough. The optical path distribution of one light inside the multi-mode interferometer is changed, and the first light having different light intensity is emitted from each of the light output ports.

In the optical switch of the present invention, a refractive index change is optically induced between one or more optical input ports and two or more optical output ports, and the optical input port and the optical output port. A multi-mode interferometer having one or more refractive index changing regions, wherein at least a part of the light incident from the optical input port is passed through the refractive index changing regions to change the light intensity, and the respective optical outputs are provided. It is characterized in that lights having different light intensities are emitted from the port.

That is, according to the present invention, a new optical switch which operates in response to the change in the refractive index is provided by providing a region in the predetermined portion inside the multimode interferometer which causes the change in the refractive index by light. To be realized. This optical switch is a compact, polarization-independent optical switch capable of high-speed push-pull operation. Furthermore, there is a practical advantage that all semiconductor materials can be monolithically manufactured.

Further, the optical demultiplexer of the present invention is for dividing the signal light of a predetermined information amount into a plurality of signals, and has a signal light input waveguide having a signal light input section on which the signal light is incident and a control. The optical switch includes a control light input waveguide having a control light input section on which light is incident, and an optical switch having the same number as the desired division number of the signal light, the optical switch including a signal light input port on which the signal light is incident and the A control light input port on which control light is incident, a signal light output port from which the desired divided signal lights are emitted, and an optical refractive index change is induced optically between the light input port and the light output port. And a multi-mode interferometer having one or more refractive index changing regions, wherein each of the optical switches causes the control light to pass through the refractive index changing region, and the change in the refractive index causes the signal light of the signal light to change. Optical path distribution By reduction, it is characterized in that for emitting the said respective signal light the desired split from the optical output port.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments to which the present invention is applied will be described below in detail with reference to the drawings.

-Principle Configuration of the Optical Switch of the Present Invention- FIG. 1 is a schematic diagram for explaining the principle configuration of the optical switch of the present invention. This optical switch comprises a multimode interferometer (MMI) 1 having an optical input port 11 (here one) and an optical output port 12 (here two), as shown in FIG. The basic configuration is that the refractive index changing region 13 is provided at a predetermined portion in the MMI 1.

This optical switch is constructed so that the light incident from the light input port 11 is emitted from the light output port 2 according to the refractive index distribution inside the MMI 1, and at least one of the light incident from the light input port 11 is output. The light passes through the refractive index changing region 13 to change the light intensity, and the light output ports 12 emit light with different light intensities.

Here, as a comparative example of the present invention, an optical path inside the MMI 1 when the refractive index changing region 13 is not provided is shown in FIG.
An example is shown in (b). Light propagates inside the MMI 1 in a plurality of modes, which appear as the density of the optical field inside the MMI. In this case, for example, as shown in the figure, the light is evenly output from the two light output ports 12. On the other hand, in the present invention, as shown in FIG. 1A, the refractive index changing region 13 is provided in advance in an important portion of the optical path, and the refractive index is changed by exciting this with light, so that the optical output The light output from the port 12 is no longer equally split into two. As described above, in the present invention, the refractive index change region 13
The optical output port 12 can be switched at a high speed at an arbitrary light intensity ratio by designing in consideration of the arrangement and efficiency.

A method of electrically changing the refractive index inside the MMI, not optically, as in the present invention, is, for example, 200
26th.ECOC (European Conference on Optica)
Communication. Proceeding, P. 177) (see FIG. 11). Here, it is shown that the output balance from the optical output port can be manipulated by applying or not applying a voltage to a part inside the MMI. However, as described above, since this is an electrical operation, the speed of this method is significantly slower than that of an optical operation.

Further, according to the present invention, as will be described later, when the refractive index changing region 13 is composed of a semiconductor amplifier (SOA), there is a new effect that amplification of an optical signal can be realized at the same time.

-Specific Embodiment of Optical Switch of the Present Invention- Based on the above-described principle structure of the optical switch of the present invention, a specific embodiment of the present invention will be described.

(First Embodiment) FIG. 2 is a schematic view showing the main structure of an optical switch according to the first embodiment. This optical switch has two optical input ports 11A and 11B.
And an MMI having two optical output ports 12A, 12B
Two refractive index change regions 13 are symmetrically installed inside 1. The refractive index change region 13 can be manufactured by, for example, SOA. The refractive index change region 13 is arranged so as to include two points where the light inside the MMI 1 once concentrates. Less than,
This optical switch function operation will be described.

The operation of the optical switch function will be described below. In the case of the present embodiment, the refractive index of the refractive index changing region 13 is set to be larger than the refractive index inside the MMI 1, so that light is guided inside the refractive index changing region 13. As described above, the method of guiding light to the refractive index change region 13 is an effective means for efficiently reflecting the change in the refractive index on the switching.

In this optical switch, since the two refractive index changing regions 13 are symmetrically arranged inside the MMI 1, as shown in FIG. 2A, when only the signal light is incident from the optical input port 11A, The light that has passed through the refractive index changing region 13 is condensed at one point which is centrally symmetric, and eventually the signal light is selectively emitted from one of the two light output ports 12A and 12B, here 12A.

Next, one of the refractive index changing regions 13 is excited by light. Refractive index changing region 13 by optical excitation
Carriers are generated inside the matrix, which causes a change in the refractive index. This change in the refractive index causes a change in the phase rotation number of light in the guided wave. For example, considering the case where the phase shift due to light is p as the case where the switching effect appears most, as shown in FIG. 2B, the interference pattern inside the MMI 1 is inverted after passing through the refractive index change region 13. The light output port for emitting the signal light is completely switched from 12A to 12B.

Here, the case where the signal light is emitted from the optical output port 12A is in the OFF state (FIG. 2A), and the case where the signal light is emitted from the optical output port 12A is the ON state (FIG. 2B). ). In this configuration, since the signal light is amplified when passing through the refractive index change region 13, switching and signal amplification are performed at the same time.

Further, if it is desired to change from the ON state of FIG. 2B to the OFF state, then the other refractive index changing region 13 may be optically excited to restore the balance. Such an ON / OFF switching operation is called a push-pull operation.

The push-pull operation will be described in more detail with reference to FIG. Consider the case where one of the four signal pulsed lights is taken out. This is, for example, 160 Gbi
This corresponds to demaxing t / s to 40 Gbit / s. In this case, control pulse light that enters at a bit rate of 1/4 of the signal pulse light is used.

The refractive index changing region 13 and the control pulse light intensity are set so that the optical phase amplitude in the refractive index changing region 13 synchronized with the control pulse light is about p. pull
The control pulse timing is push for one signal pulse.
It is delayed from the control pulse so that the phase rotation number has the characteristics shown in the figure. Then, a situation can be realized in which the phase difference between the push side and the pull side is p at the timing of the signal pulse immediately after the incidence of the push control pulse, and the phase difference disappears almost completely at other timings. In other words, this method makes it possible to repeatedly extract the required 1/4 signal light in an almost ideal form.

(Second Embodiment) Next, a specific embodiment of an optical switch for selectively changing the refractive index of a plurality of refractive index changing regions will be described. In particular, an optical switch capable of switching faster than the electrical method will be illustrated.

FIG. 4 is a schematic diagram showing a schematic configuration of the optical switch according to the second embodiment. This optical switch has a front stage MMI2 having control light input ports 21D and 21E.
1 and two MMIs of the rear stage MMI 22 having the signal light output ports 22B and 22C, both of which are two.
3, 24, and the signal light is connected to the signal light input port 24A.
Is configured to enter one of the waveguides 24.

The MMI 22 is similar to the MMI 1 described above,
Two refractive index change regions 25 made of, for example, SOA are provided inside.
Are symmetrically installed, and have the same size and composition (semiconductor material) from the control light input ports 21D and 21E of the MMI 21 to the refractive index change region 25. Here, the MMI 22 is the main part of the optical switch,
21 is provided for selective excitation of the refractive index change region 25. This embodiment is excellent in that all optical circuits can be formed in the plane.

The operation of the optical switch function will be described below. First, in the initial state of FIG. 4A, the optical switch is in the OFF state, and the signal light incident from the signal light input port 24A is emitted only from the signal light output port 22B.

Next, for switching, control light is input from the control light input port 21E. In this case, the structure sandwiching the central waveguides 23 and 24 has, for example, the configuration shown in FIG. 2A, and the control light has an upper refractive index change region 25.
Will be incident only on. As a result, as shown in FIG. 4B, the balance of the refractive index in the nonlinear waveguide portion is lost, and the signal light is emitted from the signal light output port 22C. That is, the push operation is realized.

Next, as shown in FIG. 4C, control light is made incident from the control light input port 21D. Then this time,
The control light is incident only on the lower refractive index change region 25 through the optical path symmetrical to the case of FIG. 4B. As a result, the symmetry of the refractive index changing region 25 is restored, the signal light is emitted only from the signal light output port 22B, and the pull operation is realized.

In the case of such an optical switch, as shown in FIG. 4, it is desirable that the signal light and the control light have different wavelengths. Since both lights pass through the inside of the optical switch, it is necessary to remove the control light after switching, but if the wavelengths of the two are different, they can be easily separated by the wavelength filter. Further, it is preferable that the signal light has a wavelength in a transparent region with respect to the refractive index change region 25.
When the signal light has a gain in the refractive index changing region 25, the presence or absence of a signal changes the carrier density inside the refractive index changing region 25, which hinders stable switching operation. In the refractive index change region 25, the amplified spontaneous emission light (Am
pleasing spontaneous emission (ASE) occurs and causes noise, but since the ASE has a wavelength in the gain region of the refractive index change region 25, if the signal light is a transparent wavelength, remove this along with the control light using a wavelength filter. You can

Even if the signal light has a transparent wavelength, as shown in FIG. 5, a change in the carrier causes a change in the refractive index also in that wavelength region, which is practically acceptable. This Figure 5
Is a characteristic diagram reported in Physical review Letter vol.57, p.2446, where the horizontal axis is the gain range in the positive range, the transparent range is the negative range, and the vertical axis is the refractive index change. . In addition, Index 1 to 7 have carrier densities of 1) to 1.
0 × 10 ¹⁵ , 2) 8.0 × 10 ¹⁶ , 3) 2.0 × 1
0 ¹⁷ , 4) 5.0 × 10 ¹⁷ , 5) 8.0 × 10 ¹⁷ , 6)
The variation is 1.0 × 10 ¹⁸ , 7) 1.5 × 10 ¹⁸ (cm ⁻³ ). Further, Eg means a band gap of a semiconductor material (GaAs in this case), and Er means exciton energy. As shown in the figure, it can be seen that the refractive index changes according to the carrier density change even in the transparent wavelength range.

FIG. 6 is a characteristic diagram showing a simulation by the beam propagation method in this embodiment. The optical switch used here has a structure in which a core part having a refractive index of 3.25 is surrounded by a material having a refractive index of 3.18, and a refractive index changing region composed of two SOAs is installed inside the MMI. Has been done. The size of the core part is 15μ in the horizontal direction.
m, and 1160 μm in the light incident direction (that is, in the illustrated example, the light incident direction is reduced).

The size of the refractive index changing region made of SOA is 1 μm in the lateral direction and 500 μm in the incident direction of light, but the simulation results are substantially the same even when the length is extended to sufficiently modulate the phase. . The wavelength of light is 1.55 μm, and TE mode polarization is assumed.

FIG. 6A shows the optical path in the optical switch in the switch OFF state. In this case, the refractive index of the refractive index changing region is 3.28. It can be confirmed that the light incident from the lower light input port passes through the two refractive index changing regions and is emitted only to the upper light output port.

FIG. 6B shows a simulation result when only the upper refractive index changing region is excited to have a refractive index of 3.31. This corresponds to the push operation. This time, it can be confirmed that light is emitted only to the lower optical output port.

Further, FIG. 6C shows a simulation result when the lower refractive index changing region is also excited to have a refractive index of 3.31. This corresponds to the pu11 operation. This time, again, we can confirm that light is passing through the boat above. It can be seen that continuous switching operation is realized under the above conditions.

Although not shown here, it is necessary for the light inside the MMI to be sufficiently guided to the refractive index changing region when the length of the refractive index changing region is 2000 μm in the light incident direction. The refractive index difference between the MMI and the refractive index change region was examined. As a result, light is not evenly input to the two refractive index changing regions up to a refractive index difference of 0.02,
It was also found that when the refractive index difference is up to 0.04, light leaks to the MMI while advancing in the refractive index change region, and ideal waveguide is possible when the refractive index difference is 0.05 or more.

Excitation of the refractive index changing region in this embodiment can be realized by an optical switch structure as shown in FIG. The configuration of the optical switch in this case is, as already described, the MMI.
The same size and composition (semiconductor material) may be used from the control light input port to the refractive index changing region. That is, a core portion having a refractive index of 3.25 is surrounded by a material having a refractive index of 3.18, and the size of the core portion is 15 μm in the lateral direction and 330 μm in the incident direction of light. The optical switch having this configuration can easily perform the push-pull operation.

(Third Embodiment) Next, a specific embodiment of an optical switch for generating a drop signal whose optical intensity is reduced from signal light using a plurality of MMIs will be described.

FIG. 7A is a schematic diagram showing a schematic structure of the optical switch according to the third embodiment. This optical switch is configured to include three MMIs 31 to 33 in the front stage and an MMI 34 in which two refractive index change regions 35 made of, for example, SOA are symmetrically installed in the rear stage.
All are monolithically made of the same semiconductor material, and the demultiplexing and multiplexing of light are all performed by MMI.

In this optical switch, in order to automatically and alternately enter light into the two optical input ports of the MMIs 31 to 33 for realizing push-pull, the optical input port of the control light is made one, and this is changed. A delay circuit 36 is provided on one side by branching into two waveguides. In addition, since three (31 to 33) of the four MMIs 31 to 34 forming the circuit can be exactly the same, there are few uncertain factors at the time of manufacture, and high production stability can be obtained.

FIG. 7B shows a conceptual configuration in which this optical switch is formed into a black box. As described above, the optical switch is configured to have two inputs and two outputs, and when the control light and the signal light are incident, the through signal light (light having the same intensity as the original incident light) and the drop signal light (the original light) are input. This is a 2-input 2-output configuration in which the light of which the intensity is reduced from the incident light) is emitted. When used, the wavelengths of the signal light and control light are changed, and only the control light is cut by the wavelength filter at the output end.
It is possible to improve the / N ratio.

-Specific Embodiment of the Optical Demultiplexer of the Present Invention-Hereinafter, the optical demultiplexer (optical signal separation device) of the present invention
Specific embodiments will be described.

(First Embodiment) This optical demultiplexer is formed by connecting a plurality of optical switches described in the third embodiment. FIG. 8 is a schematic diagram showing the main configuration of the optical demultiplexer according to the first embodiment.
The case where (a) is parallel connection and the case where 8 (b) is series connection are shown, respectively. In this case, the signal light is used as a pulse train and the control light is used as a periodic pulse train having a bit rate lower than that of the signal light, and these lights are synchronized with each other, whereby the optical demultiplexer using the optical switch of the third embodiment is used. Is realized.

The optical demultiplexer shown in FIG.
There are a plurality of optical switches 41 shown in FIG.
Connected in parallel and having a function of demultiplexing (signal separation) one signal light (for example, a signal light having a bit rate of 160 Gbit / s) into four signal lights (for example, a signal light of 40 Gbit / s) Is.

On the other hand, in the optical demultiplexer shown in FIG. 8B, a plurality of optical switches 41 shown in FIG. 7B, four in this case, are connected in series, and one optical signal (eg bit rate) is used. Has a function of demultiplexing 160 Gbit / s signal light into four signal lights (for example, 40 Gbit / s signal light).

The signal light demultiplexed to 40 Gbit / s can be electrically processed after being optoelectrically (OE) converted by the OE converter 37. The light source of the control light input to each optical switch 41 is single in the case of this example, and the timing of incidence on each optical switch 41 is adjusted and used. The operation of the entire circuit is the same in the case of serial connection and the case of parallel connection. However, in the case of serial connection, since the through signal is further incident on the optical switch 41 of the next stage to perform signal processing, signal light to be processed later is used. Since the purity of the signal light decreases to a greater extent, waveform deterioration and the like are likely to occur, but this does not occur in the case of parallel, and in this respect the parallel is more advantageous. On the contrary, in parallel, the waveguides cross each other as shown in the figure, so care must be taken in designing, but in series there is no such concern, and in this respect the series is more advantageous.

If all the waveguides of the optical demultiplexer are made of the same semiconductor material, all of these circuits can be monolithically formed on the semiconductor, so that compactness is possible and there is an advantage in practical use.

A conceptual configuration of this optical demultiplexer in a black box is shown in FIG. 8 (c). As described above, the optical demultiplexer is configured in the form of two inputs and four outputs, and for example, four signal lights of 160 Gbit / s are output to four signals.
This is a device for demuxing to 0 Gbit / s signal light.

(Second Embodiment) This optical demultiplexer has substantially the same configuration as that of the first embodiment, but is different in that the connection mode of each optical switch is different. Figure 8
As is apparent from (a), if the light is branched by the MMI of the 2-input 2-output type, the signal light is half wasted.
The present embodiment is configured to prevent such waste from occurring in the entire device.

FIG. 9 is a schematic diagram showing the main structure of the optical demultiplexer according to the second embodiment. Here, an MM for demultiplexing the control light and the signal light is used when the device configuration for integrating a plurality of optical switches 41 to extract all the signal light is performed.
It is demultiplexed by I42 and introduced into each MMI 43 having a refractive index change region made of SOA. At that time, all of the demultiplexing MMIs 42 have a 1-input 2-output or 2-input 2-output port configuration, and the whole is in parallel. It has a circuit. Control light,
It can be seen that there is no useless output of the signal light without being input to each optical switch.

In the optical demultiplexers of the first and second embodiments, the demux ratio can be arbitrarily changed depending on the number of optical switches to be installed and the setting of the timing of control light. Therefore, it is clear that the specific configuration of the optical demultiplexer realized by the present invention is not limited to that of this embodiment.

Further, it is obvious to those skilled in the art that the principle of the present invention is realized without being limited to the material of its constituent members, and various material systems can be applied without being limited to the above-mentioned material system. is there. If you don't care about monolithic integration, for example, a waveguide is an optical fiber, a coplanar waveguide,
A photonic crystal or the like can be used.

Various aspects of the present invention will be collectively described below as supplementary notes.

(Supplementary Note 1) One or more optical input ports and 2
A multi-mode interferometer having one or more light output ports and one or more refractive index change regions in which a refractive index change is optically induced between the light input port and the light output port, The first light having a first wavelength, which is incident from the light input port, is configured to be emitted from the light output port, and the second light having a second wavelength is passed through the refractive index change region. , The optical path distribution of the first light inside the multi-mode interferometer is changed by the change in the refractive index, and the first light having different light intensity is emitted from each of the optical output ports. switch.

(Supplementary Note 2) At least two refractive index changing regions are provided, and the second light is allowed to pass through each of the refractive index changing regions with a time lag to sequentially induce a refractive index change. The optical switch according to appendix 1.

(Supplementary Note 3) A pre-stage multi-mode interferometer having one or more pre-stage optical input ports and two or more pre-stage optical output ports is further provided, and the pre-stage optical output is provided to the optical input port of the multi-mode interferometer. A port is connected, the front stage multi-mode interferometer and the multi-mode interferometer are connected and arranged, and the second light passing through the front stage multi-mode interferometer excites the refractive index change region. 3. The optical switch according to appendix 1 or 2, characterized in that

(Additional remark 4) The refractive index changing region has a waveguide structure, and the first light is guided in the refractive index changing region. Optical switch according to item.

(Supplementary note 5) The optical switch according to any one of supplementary notes 1 to 4, wherein the number of the optical input ports and the number of the optical output ports of the multimode interferometer are both two.

(Supplementary Note 6) The optical switch according to any one of Supplementary Notes 1 to 5, wherein the refractive index changing region is formed of a semiconductor optical amplifier.

(Supplementary Note 7) The optical switch according to Supplementary Note 6, wherein the first wavelength is a transparent wavelength at which the semiconductor optical amplifier has no gain.

(Supplementary Note 8) One or more optical input ports and 2
A multi-mode interferometer having one or more light output ports and one or more refractive index change regions in which a refractive index change is optically induced between the light input port and the light output port, An optical switch, wherein at least a part of light incident from an optical input port is passed through the refractive index changing region to change the light intensity, and light having different light intensities is emitted from each of the light output ports.

(Supplementary Note 9) The optical switch according to Supplementary Note 8, wherein the number of the optical input ports and the number of the optical output ports of the multimode interferometer are both two.

(Supplementary Note 10) An optical demultiplexer for splitting a signal light of a predetermined amount of information into a plurality of signals, wherein a signal light input waveguide having a signal light input section into which the signal light enters and control light enters. The optical switch includes a control light input waveguide having a control light input unit, and an optical switch having the same number as the desired number of divisions of the signal light, wherein the optical switch receives the signal light input port to which the signal light is incident and the control light is incident. A control light input port, a signal light output port through which the desired split signal lights are emitted, and an optical index change is induced between the light input port and the light output port. Equipped with a multi-mode interferometer having the above refractive index change region,
The control light is passed through the refractive index change region by each of the optical switches, the optical path distribution of the signal light is changed by the change of the refractive index, and the desired split of the signal light from each of the optical output ports. Is an optical demultiplexer.

(Supplementary Note 11) The optical demultiplexer according to Supplementary Note 10, wherein each of the optical switches has the input ports connected to the input waveguides and arranged in parallel.

(Supplementary Note 12) In each of the optical switches, the control light input port is connected to the control light input waveguide, and each of them is sequentially connected and arranged in series. The optical demultiplexer according to 1.

(Supplementary Note 13) The control light is a periodic pulse signal having a bit rate lower than that of the signal light, and the control light is synchronized with the signal light to periodically output the signal light output port of the signal light. 13. The optical demultiplexer according to any one of appendices 10 to 12, characterized in that the optical demultiplexer is switched over.

[0075]

According to the present invention, it is possible to simultaneously solve the problems of operating speed limitation due to light transit time, large optical circuit size, and polarization dependence, and to realize a more practical optical interference device function. However, an optical switch and an optical demultiplexer suitable for long-distance large-capacity optical communication and the like, which have a simple configuration and control and are stable in operation, are realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining the principle configuration of an optical switch of the present invention.

FIG. 2 is a schematic diagram showing a main configuration of the optical switch according to the first embodiment.

FIG. 3 is a characteristic diagram for explaining a push-pull operation in detail.

FIG. 4 is a schematic diagram showing a schematic configuration of an optical switch according to a second embodiment.

FIG. 5 is a characteristic diagram showing a change in refractive index in MMI.

FIG. 6 is a characteristic diagram showing a simulation by a beam propagation method in the first embodiment.

FIG. 7 is a schematic diagram showing a schematic configuration of an optical switch according to a third embodiment.

FIG. 8 is a schematic diagram showing a main configuration of an optical demultiplexer according to the first embodiment.

FIG. 9 is a schematic diagram showing a main configuration of an optical demultiplexer according to a second embodiment.

FIG. 10 is a schematic diagram showing a main configuration of a conventional optical switch.

FIG. 11 is a schematic diagram showing a method of electrically changing the refractive index inside the MMI, not optically.

[Explanation of symbols]

1,12,22,31-34,42,43 MMI 11A, 11B Optical input port 12A, 12B optical output port 13,25 Refractive index change area 21D, 21E Control light input port 22B, 22C, 24A signal light output port Waveguide 23, 24 41 optical switch

Claims (4)

[Claims] 1. One or more optical input ports and two or more optical output ports, and one or more refraction in which a refractive index change is optically induced between the optical input port and the optical output port. A multi-mode interferometer having a rate change region, the first having a first wavelength incident from the optical input port
Light is output from the light output port, second light having a second wavelength is passed through the refractive index change region, and the change in the refractive index causes the multi-beam of the first light to be transmitted. An optical switch, characterized in that an optical path distribution inside a mode interferometer is changed to emit the first lights having different light intensities from the respective light output ports. 2. A pre-stage multi-mode interferometer having one or more pre-stage optical input ports and two or more pre-stage optical output ports, wherein the pre-stage optical output port is provided at the optical input port of the multi-mode interferometer. Connected, the pre-stage multi-mode interferometer and the multi-mode interferometer are connected and arranged, and the second light passing through the pre-stage multi-mode interferometer is configured to excite the refractive index change region. The optical switch according to claim 1, wherein the optical switch is provided. 3. One or more optical input ports and two or more optical output ports, and one or more refraction in which a refractive index change is optically induced between the optical input port and the optical output port. A multi-mode interferometer having a refractive index change region, at least a part of the light incident from the optical input port is passed through the refractive index change region to change the light intensity, and the light intensity of each light output port is changed. An optical switch that emits different lights. 4. An optical demultiplexer for splitting a signal light of a predetermined amount of information into a plurality of signals, comprising: a signal light input waveguide having a signal light input section on which the signal light is incident; and control light on which the control light is incident. A control light input waveguide having an input section, and an optical switch having the same number as the desired division number of the signal light, wherein the optical switch is a signal light input port into which the signal light is incident and a control into which the control light is incident. An optical input port, a signal light output port from which each of the desired split signal lights is emitted, and one or more optical index changes are induced between the optical input port and the optical output port. It comprises a multi-mode interferometer having a refractive index change region, by each of the optical switch, the control light is passed through the refractive index change region, by changing the refractive index change the optical path distribution of the signal light. , The above Optical demultiplexer, characterized by emitting the desired split the signal lights from the optical output port.