JP2002072157A - Wavelength-changeable filter and spatial-optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength-changeable filter which takes out a prescribed wavelength signal from luminous signals having multiplexed wavelength at a high speed, and to provide a spatial optical switch. SOLUTION: An input waveguide 11 which a luminous signal is inputted to, a slab waveguide 13 for distributing the luminous signal to an array waveguide 12, the array waveguide 12 equipped with a triangle electrode 14 for injecting current or impressing voltage to change a refractive index, a slab waveguide 16 for coupling light outputted from the array waveguide 12 with an output waveguide 15 and the output waveguide 15 outputting the luminous signal are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength tunable filter and a spatial light switch for extracting a desired wavelength signal from a plurality of wavelength-multiplexed optical signals at a high speed.

[0002]

2. Description of the Related Art Data traffic typified by the Internet has exploded, and large-capacity optical packet processing is required. For this reason, a wavelength multiplexing system for multiplexing optical signals of a plurality of wavelengths and transmitting the multiplexed optical signal through one optical fiber is rapidly developing. In such a wavelength division multiplexing transmission system, a wavelength tunable optical filter technology for extracting an optical signal of a desired wavelength from a plurality of multiplexed optical signals at high speed is indispensable.

Conventionally, an arrayed waveguide grating type wavelength multiplexer / demultiplexer (AWG) employs an arrayed waveguide grating (having a function of spatially distributing an input wavelength-division multiplexed signal to different output ports for each wavelength). Separate the signals, insert optical gates (electro-absorption optical modulators, semiconductor laser amplifiers, etc.) into each port, open only the optical gates through which optical signals of the desired wavelengths pass by the control signal, and process the reverse of the above. The function of the wavelength tunable filter is realized by integrating into one output port by the arrayed waveguide grating.

However, in this case, as the number of wavelength multiplexes increases, the number of optical gates increases, resulting in a rather large and complicated device as a whole.

[0005] Therefore, it is desired to realize the same function with one element. Conventionally, an etalon-type element utilizing the multiple interference effect is used. In this case, by changing the refractive index of the semiconductor material sandwiched between the highly reflective films at high speed by current injection or electric field application, the resonance wavelength of the etalon is changed and the function of the wavelength filter is realized.

However, the wavelength range Δλ that changes due to this is
Is represented by λ ₀ Δn / n (λ ₀ : resonance wavelength when there is no change in refractive index, Δn: amount of change in refractive index, n: refractive index of semiconductor), and Δn / n = 0.3%, λ ₀ = If it is 1.55 μm, Δλ = 4.65 nm, and it is impossible to realize a value of several tens nm required in an actual system.
If a material such as liquid crystal having a large change in the refractive index is used, Δλ can be increased, but the operating speed becomes extremely low.

As described above, in an element in which an arrayed waveguide grating is combined with a plurality of semiconductor optical gates, it is possible to take out only a desired wavelength signal at a high speed, but the device becomes considerably large. Further, an etalon-type element can be simply configured with one element, but it is impossible to achieve both high speed and a wide wavelength variable range.

Further, data traffic represented by the Internet is explosively increasing, and large-capacity optical packet processing is required, and high-speed switching of optical signals from a plurality of input ports to a plurality of output ports is arbitrarily performed. A spatial light switch is indispensable. Conventionally, as shown in FIG. 17, an optical signal from one input port 01 is branched into the number of output ports by a demultiplexer 02 such as a star coupler, and a semiconductor laser amplifier (SOA) and an electro-absorption optical modulator are respectively provided. (E
AM) or the like, and a method of multiplexing the same output ports 04 with the multiplexer 05 again has been proposed.

As shown in FIG. 18, optical switches are arranged in a crossbar (FIG. 18A) or in a tree shape (FIG. 1).
8 (B)) is proposed.

In the above-described method of FIG. 17, as the number of output ports increases, the loss due to branching increases, and the number of optical gates increases in proportion. It is extremely difficult to control these many optical gates. Becomes

Although the number of optical switches required in the method shown in FIG. 18 differs depending on the configuration, a considerably large number of optical switches are required in any configuration, and the overall control becomes considerably complicated. Further, since the optical signal passes through a plurality of optical switches, the loss is also considerable.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a small wavelength tunable filter that achieves both high speed and wide wavelength tunability, and a spatial light switch that can be controlled more easily.

[0013]

To solve the above-mentioned problems, the refractive index of each waveguide of the arrayed waveguide of the arrayed waveguide grating type wavelength multiplexing / demultiplexing device (AWG) of the present invention [Claim 1] is determined. It is characterized in that it has a means for changing the total amount of change in the refractive index so as to change at a fixed rate between the respective waveguides.

According to a second aspect of the present invention, the refractive index of each waveguide of the arrayed waveguide of the arrayed waveguide grating type wavelength multiplexing / demultiplexing device (AWG) is determined by the total amount of change in the refractive index between the respective waveguides. And two sets of means for changing the refractive index of the respective waveguides so as to change at a fixed rate, and the total amount of change in the refractive index of each waveguide between the respective waveguides by one means and the respective waveguides by the other means. Is characterized in that the amount of change in the refractive index between the respective waveguides is reversed.

According to a third aspect of the present invention, in the first or second aspect, the refractive index of each waveguide of the arrayed waveguide is changed at a constant rate between the total changes in the refractive index. The changing means is a triangular electrode.

According to a fourth aspect of the present invention, in the first or second aspect, the refractive index of each waveguide of the arrayed waveguide is changed at a fixed rate between the total changes in the refractive index. The changing means is a set of a saw-shaped electrode and a step-shaped electrode.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the optical signal is distributed to p input waveguides for inputting an optical signal and p array waveguide groups. P slab waveguides, p array waveguide groups each independently equipped with triangular electrodes for current injection or voltage application to change the refractive index, and p It comprises one slab waveguide for coupling output light from the arrayed waveguide group to the output waveguide, and q output waveguides for extracting optical signals, and is characterized by being developed in parallel.

According to a sixth aspect of the present invention, in any one of the first to fourth aspects, a multistage connection is provided.

According to a seventh aspect of the present invention, in any one of the first to fifth aspects, the invention is characterized in that it is of a reflection type.

The invention of claim 8 is the invention according to claim 5, wherein the arrayed waveguides are divided into a plurality of groups, and the lowermost waveguide lengths of each group are all equal, and the distance between adjacent waveguides of each group is equal. The optical path length differences are all equal, and only saw-shaped electrodes are provided.

The invention of a space optical switch according to claim 9 is as follows.
A plurality of output waveguides are provided in the wavelength tunable filter according to any one of the first to eighth aspects.

[0022]

In the wavelength tunable filter of the present invention, the wavefront at the output end of the arrayed waveguide is controlled by changing the refractive index of the semiconductor waveguide at high speed, and the wavelength coupled to the output port is changed. Thereby, high-speed and wide-range wavelength tunable becomes possible. Switching to a large number of output ports is possible by serial connection. Further, since the direction of change of the wavefront can be reversed, the number of output ports can be doubled, and the electrode area can be significantly reduced, thereby realizing higher-speed operation.

In the spatial light switch of the present invention, the wavefront at the output end of the arrayed waveguide is controlled by changing the refractive index of the semiconductor waveguide at high speed, and the output port to be coupled can be switched.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[First Embodiment] FIG. 1 shows an embodiment of a wavelength tunable filter according to the first embodiment. The wavelength tunable filter of the present embodiment includes an input waveguide 11 for inputting an optical signal, a slab waveguide 13 for distributing the optical signal to the arrayed waveguide 12, and a current injection or voltage for changing the refractive index. Triangular electrode 1 for applying voltage
And an array waveguide 12 equipped with
A slab waveguide 16 for coupling the output light from the optical waveguide to the output waveguide 15, and an output waveguide 15 for outputting an optical signal.

In the above configuration, the optical signal input from the input waveguide 11 spreads through the slab waveguide and couples to each of the array waveguides 12. Here, FIG.
As shown in the explanatory diagram of (b), the distance between adjacent waveguides is m.
An optical path length corresponding to λ ₀ (m is an integer) is given.
Therefore, the light of wavelength λ ₀ has a uniform wavefront (a surface connecting the peaks of the optical electric field) at the output end of the arrayed waveguide. Then, the respective lights emitted from the array waveguide 12 to the output side slab waveguide 16 interfere with each other on the opposite end surface (focal plane) of the slab waveguide 16,
It is collected at a certain point. If the output waveguide 15 is set at the focal point, the light having the wavelength λ ₀ input from the input waveguide 11 is output from the output waveguide 15.

Here, a triangular electrode 14 is formed on the array waveguide 12 such that the overlap length with the array waveguide 12 increases by ΔL. The array waveguide 12 is a semiconductor material
It has a pin structure, and changes the refractive index of the waveguide immediately below the electrode due to the plasma effect caused by current injection from the electrode 12 or the Franz-Keldysh effect (quantum confined Stark effect in the case of a quantum well structure) caused by voltage application. Can be done. In the present embodiment, the triangular electrode 14 adjusts the refractive index of each waveguide in the arrayed waveguide.
The function of a means for changing the total amount of change in the refractive index between the waveguides so as to be changed at a constant rate is provided.

As shown in FIG. 2B, the wavefront of the light having the wavelength λi is rotated in accordance with the change in the refractive index, and the wavefront is aligned at the output end of the arrayed waveguide 12. It is possible to extract light having a wavelength of λi from the light. Assuming that the refractive index of the waveguide changes by Δn, the change Δλ in the wavelength extracted from the output waveguide is ΔnΔL / m
It is represented by

Now, Δn / n = 0.3%, n = 3.2, Δ
Assuming that L = 100 μm and m = 30, Δλ = 32n
m, so that a variable wavelength range about 7 times that of the etalon type is obtained.

As the shape of the electrode 14, besides the triangular shape, for example, as shown in FIG. 3, the capacitance is further reduced by adopting a comb-shaped electrode 21 from which a portion which is not on the waveguide is removed. Becomes possible.

[Second Embodiment] FIG. 4 shows an embodiment of a wavelength tunable filter according to the second embodiment. In the present embodiment, in the wavelength tunable filter of the first embodiment, two vertically symmetric triangular electrodes 14A and 14A are provided.
B is equipped. Note that reference numeral 1 in FIG.
7 is an inverter, 18 is a control signal generator, and 19 is a diode.

In the case of the conventional etalon type element, the change in the refractive index can be changed only in one direction, positive or negative, according to the physical phenomenon used. Therefore, the change in the wavelength also changes in one direction with an increase in the control signal. Only change can be obtained. In the present embodiment, as shown in FIG.
4B, the control signal having the same sign is applied to both the electrodes when the control signal is positive and the control signal is negative through the inverter, so that the wavefront of the light can be clockwise or counterclockwise. Can also be rotated. As a result,
As a result, a variable wavelength range that is twice as large as the control signal having the same absolute value is obtained.

[Third Embodiment] FIG. 5 shows an embodiment of a wavelength tunable filter according to the third embodiment. In the present embodiment, in the wavelength tunable filter of the first or second embodiment, a saw-shaped electrode 22 and a step-shaped electrode 23 are provided instead of the triangular electrode.

In the above-described method, since it is necessary to largely rotate the entire wavefront around a certain point, a larger change is required for a waveguide farther from the center of rotation, that is, the electrode length needs to be proportionally longer. Becomes Therefore, in the current injection, the entire current value increases, and the operation speed decreases due to the capacitance that increases in proportion to the electrode area. Here, in order to realize the same performance, it is only required that the wavefronts (peaks of the optical electric field) at the output end in the arrayed waveguide be uniform, and it is not necessary to cause a phase change portion of an integral multiple of 2π.

Then, as shown in FIG. 5 showing the wavelength tunable filter of the present embodiment, it is considered to attach two electrodes, ie, a saw-shaped electrode 22 and a step-shaped electrode 23.
In this case, the sawtooth-shaped electrode 22 finely rotates the wavefront in each cycle, and furthermore, the stepwise electrode 23 corrects the shift of the wavefront between the respective wavefront groups, so that the wavefront at the output end of the arrayed waveguide is corrected. The entire wavefront will be aligned. As a result, the area of the triangular electrode decreases in inverse proportion to the number of saw cycles. For phase correction between adjacent wavefront groups, an electrode of about 200 μm may be added.

In this embodiment, as shown in FIG. 4, it is needless to say that the variable wavelength range can be doubled by using a vertically symmetric electrode.

[Fourth Embodiment] FIG. 6 shows a tunable filter according to a fourth embodiment of the present invention. In the present embodiment, in the wavelength tunable filters of the first to third embodiments, the reflection film 31 is provided at the center of the arrayed waveguide 12.
And an input / output slab waveguide 32 in which the signal light is reflected and the slab current path on the input side is used together with the slab waveguide for output.
The output waveguide 15 is arranged in parallel with the input waveguide 11.

As described above, the array waveguide 12 is cleaved at the center thereof, a reflecting mirror 31 is formed on the end face thereof, and the light is folded back to equivalently double the interaction length due to a change in the refractive index. It becomes possible. Conversely, the electrode area for obtaining the same variable wavelength range as described above can be halved, and the speed can be further increased.

[Fifth Embodiment] FIG. 7 shows a tunable filter according to a fifth embodiment. In the present embodiment, in the wavelength tunable filters of the first to fourth embodiments, the array waveguide 12 is divided into a plurality of groups 12A,
12B and 12C, the lowermost waveguide length of each group is equal, the optical path length difference between adjacent waveguides of each group is all equal, and only the saw-shaped electrode 22 is provided.

In the wavelength tunable filter shown in FIG. 5, the step-like electrode 23 for correcting the phase between the wavefront groups was required. In the wavelength tunable filter according to the present embodiment, as shown in FIG. 7, K array waveguides 12 (four in this embodiment) 12A, 12B, 1
2C, the lengths of the lowermost waveguides in each group are all unified, and an arrayed waveguide structure in which an optical path length difference of mλ ₀ is added upward as described above.

Further, the end faces of the respective waveguides are cut vertically by etching, and a high reflection film 3 is formed on the end faces of the waveguides.
By applying 1, a reflection type is formed as in FIG. In this case, jK + 1th from the bottom (j = 0, 1,
Since the waveguide lengths of 2,... Are all the same, the wavefronts are always aligned at the ends regardless of the wavelength. However, since a phase shift of 2πmΔλ / λ occurs between adjacent waveguides, the wavefront is inclined in each waveguide group, and a sawtooth wavefront is formed as a whole at the emission end.

If the saw-shaped electrode 22 is formed at the same period as the arrayed waveguide and the inclination of the wavefront is corrected,
As described above, since the phases of the wavefront groups are completely aligned, the entire wavefront is aligned at the emission end. That is, it is not necessary to use the above-mentioned step-like electrode completely.

In this case, it becomes impossible to provide a plurality of output waveguides on the output side and extract light of a plurality of wavelengths at the same time as in a conventional arrayed waveguide grating. The output light can be extracted from the output waveguide 15 installed in parallel, and the light returning to the input waveguide 11 can be extracted by an optical circulator.

[Sixth Embodiment] FIG. 8 shows an optical packet switch according to a sixth embodiment. In the present embodiment, in the wavelength tunable filters of the first to fourth embodiments, a plurality of output waveguides 15 for spatially distributing an input optical signal of one wavelength by a control signal applied to the electrode 14 are arranged in parallel. It is arranged in. In the above-described embodiment, a method of extracting optical signals having different wavelengths from one output port has been discussed. Here, it is considered that a signal having one wavelength is coupled to a different output waveguide.

As shown in FIG. 8, a plurality of output waveguides 15
Is installed, and a control signal is applied to the electrode 14, the wavefront at the output end changes according to the same principle as described above, and it becomes possible to switch the output waveguide to be coupled.

Although the present embodiment has been described based on FIG. 1, it goes without saying that the rate can be increased by the same method as shown in FIGS.

Further, all the discussions so far are based on the semiconductor array waveguide, but the wavelength tunable filter is similarly formed on the polymer waveguide on the silicon substrate by changing the refractive index by the thermo-optic effect. Needless to say, it is possible.

[Seventh Embodiment] FIG. 9 shows an embodiment of a spatial light switch according to the seventh embodiment. As shown in FIG. 9, the spatial optical switch according to the present embodiment includes an input waveguide 11 for inputting an optical signal, a slab waveguide 13 for distributing the optical signal to an arrayed waveguide 12, and a refractive index. An arrayed waveguide 12 equipped with triangular electrodes 14 for performing current injection or voltage application for changing;
A slab waveguide 16 for coupling the output light from the arrayed waveguide 12 to the output waveguide 15;
The output waveguides 15 are provided.

As shown in FIG. 9, an optical signal input from the input waveguide 11 spreads in the slab waveguide 13 and is coupled to each of the array waveguides 12. An optical path length corresponding to mλ ₀ (m is an integer) may be provided between adjacent waveguides, similarly to the conventional arrayed waveguide grating, or m = 0. FIG. 9 showing this embodiment shows a case where m = 0, that is, the lengths of all the waveguides are equal.
At this time, as shown in FIG. 10A, the wavefronts (surfaces connecting the peaks of the optical electric field) of the lights of all the wavelengths are aligned at the emission end of the arrayed waveguide. The respective lights emitted from the array waveguide 12 to the slab waveguide 16 interfere with each other on the opposite end surface (between the focal points) of the slab waveguide 16 and are condensed at a certain point. When the output waveguide 15 is set at the focal point, the optical signal input from the input waveguide 11 is output from the output waveguide 15.

Here, similarly to the first embodiment, a triangular electrode 14 is formed on the array waveguide such that the overlap length with the array waveguide increases by ΔL. The array waveguide is composed of a semiconductor material pin structure, and the waveguide directly under the electrode is formed by the plasma effect by current injection from the electrode, the Franz-Keldysh effect by voltage application (the quantum confined Stark effect in the case of the quantum well structure), etc. Can be changed at a high speed. Therefore Figure 1
As shown in FIG. 0 (b), the incident light has a phase difference of 2πΔnΔL / λ between adjacent waveguides in accordance with the change Δn in the refractive index. Will change.

That is, the output waveguide 15 can be switched by changing the control signal to the electrode.

In FIG. 9, there is one input port.
As shown in FIG. 1, it is needless to say that by arranging a plurality of input waveguides 11, it is possible to switch from an arbitrary input port to an arbitrary output port.

Although it is possible to switch the input light between a plurality of output waveguides by the above-described method, in order to increase the number of output ports, Δn and ΔL are increased, that is, the control signal is increased and the electrode area is increased. Needs to be increased. An increase in the control signal causes an increase in power consumption, and an increase in the electrode area causes a decrease in response speed. Therefore, a method for increasing the number of output ports by connecting the spatial light switches in multiple stages will be considered.

[Eighth Embodiment] FIG. 12 shows an embodiment of a spatial light switch according to the eighth embodiment. The spatial optical switch according to the present embodiment is configured such that the output of the previous stage is used as the input of the next stage and the optical switch of the seventh embodiment is connected in k stages in series, thereby switching to n-th k output ports. Is made possible.

As shown in FIG. 12, the first optical switch 4
The output waveguide from 1 is connected to the slab waveguide 13 as the input waveguide of the second optical switch 42. Assuming that three ports are switched in the first optical switch 41, the input waveguide interval of the second optical switch 42 is expanded to three times the output waveguide interval of the first optical switch 41.
At this time, the optical signal from the first input waveguide is switched to any one of the lower three of the nine output waveguides and output by the control signal of the second optical switch.

Instead of the triangular electrode 14 described above,
As shown in FIG. 3, it is needless to say that the capacitance can be further reduced by adopting a comb shape in which a portion not existing on the waveguide is removed.

[Ninth Embodiment] FIG. 13 shows a spatial light switch according to a ninth embodiment of the present invention. As shown in FIG. 13, the spatial light switch according to the present embodiment is provided with two vertically symmetric triangular electrodes 14A and 14B in the seventh and eighth spatial light switches.

Since the change in the refractive index can be changed only in one positive or negative direction according to the physical phenomenon to be used, the inclination direction of the wavefront can only be changed in one direction with an increase in the control signal.

In the case of the switch of the present embodiment, vertically symmetric electrodes 14A and 14B are provided as shown in FIG. 13, and when the control signal is positive and when the control signal is negative, the electrodes are distributed and the same sign is applied via an inverter. If the control signal is applied, the wavefront of the light can be rotated clockwise or counterclockwise, so that the number of output ports is twice as large as the control signal having the same absolute value. Become.

[Tenth Embodiment] FIG. 14 shows an embodiment of a spatial optical switch according to the tenth embodiment. FIG.
As shown in FIG. 4, the spatial light switch according to the present embodiment is provided with a saw-shaped electrode 22 and a step-shaped electrode 23 in place of the triangular electrodes in the seventh to ninth spatial optical switches. .

As shown in FIG. 14, in the above method, it is necessary to largely rotate the entire wavefront around a certain point, so that a waveguide farther from the center of rotation requires a larger change, that is, the electrode length is proportional to it. You need a long one. Therefore, in the current injection, the entire current value increases, and the operation speed decreases due to the capacitance that increases in proportion to the electrode area. In order to achieve the same performance, it is only required that the wavefronts (peaks of the optical electric field) in the arrayed waveguide be uniform, and it is not necessary to cause a phase change portion that is an integral multiple of 2π. Therefore, as shown in FIG. 14, the attachment of two electrodes, ie, a saw-shaped electrode 22 and a step-shaped electrode 23, is considered. In this case, the sawtooth-shaped electrode 22 finely rotates the wavefront in each cycle, and the stepwise electrode 23 corrects the shift of the wavefront between the respective wavefront groups, so that the entire wavefront in the arrayed waveguide is aligned. It will be.

As a result, the area of the triangular electrode decreases in inverse proportion to the number of saw cycles. For phase correction between adjacent wavefront groups, an electrode of about 200 μm may be added.

Also in this case, as shown in FIG. 13, it is needless to say that the number of output ports can be doubled by using the vertically symmetrical electrodes together.

[Eleventh Embodiment] FIG. 15 shows an embodiment of the spatial optical switch according to the eleventh embodiment. FIG.
As shown in FIG. 5, in the spatial optical switch according to the present embodiment, in the seventh to tenth spatial optical switches, a reflective film 31 is provided at the center of the arrayed waveguide 12, the signal light is reflected, and the input side slab is formed. The waveguide is an input / output slab waveguide 32 used in combination with an output slab waveguide, and the output waveguide 15 is arranged in parallel with the input waveguide 1.

As shown in FIG. 15, a reflecting mirror 31 is formed on the end face of the arrayed waveguide 12, and the light is turned back.
The interaction length can be equivalently doubled by the change in the refractive index. Conversely, it is possible to halve the electrode area for obtaining the same number of output ports as above,
Further, higher speed can be realized.

[Twelfth Embodiment] FIG. 16 shows an embodiment of the spatial optical switch according to the twelfth embodiment. FIG.
As shown in FIG. 6, the spatial optical switch according to the present embodiment includes p (three in the present embodiment) input waveguides 51A, 51B, and 51C for inputting an optical signal, and p (this embodiment). (3 in this embodiment) for distributing optical signals to the array waveguide groups 52A, 52B, 52C (three in this embodiment).
Slab waveguides 53A, 53B, 53C and triangular electrodes 54A, 54B, 54C for performing current injection or voltage application for changing the refractive index are each independently provided with p array waveguide groups. 52A, 52B, 52C
And one slab waveguide 56 for coupling the output light from the p array waveguide groups to the output waveguide 55.
And q (three in this embodiment) output waveguides 55A, 55B, and 55C for extracting optical signals.

As shown in FIG. 16, a plurality of input waveguides 5
Optical signals from 1A, 51B, 51C are coupled to respective array waveguides 52A, 52B, 52C by respective slab waveguides 53A, 53B, 53C. The plurality of groups of arrayed waveguides 52A, 52B, and 52C are uniformly arranged on the input surface of one output-side slab waveguide 56, so that the respective arrayed waveguides 52A, 52B, and 5C are arranged.
The focal positions formed by the optical signals from 2C on the focal plane of the slab waveguide 56 are all equal. Further, each array waveguide 5
2A, 52B and 52C have independent electrodes 54A and 54
B, 54C, and can independently rotate the wavefront of the optical signal, so that the optical signal from each of the input waveguides 51A, 51B, 51C can be independently converted into an arbitrary output waveguide 55A, 55B. , 55C.

FIG. 11 in the seventh embodiment described above.
In the method described above, it is not possible to independently switch the output ports of the optical signals incident from different incident ports at the same time, but according to the present embodiment, this is possible.

Although the above discussions are all based on semiconductor optical waveguides, the spatial optical switch is similarly formed on a polymer waveguide on a silicon substrate by changing the refractive index by the thermo-optic effect. Needless to say, it is possible.

[0070]

As described above, according to the tunable filter of the present invention, by changing the refractive index of the semiconductor array waveguide and controlling the wavefront of the propagating light, the light coupled to the output waveguide can be controlled. Can be changed at high speed over a wide range.

According to the spatial light switch of the present invention,
By controlling the wavefront of propagating light by changing the refractive index of the semiconductor array waveguide, it is possible to switch a plurality of output waveguides at high speed over a wide range.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a filter according to a first embodiment.

FIG. 2 is an explanatory diagram of a filter according to the first embodiment.

FIG. 3 is a schematic view of another electrode shape.

FIG. 4 is a schematic diagram of a filter according to a second embodiment.

FIG. 5 is a schematic view of a filter according to a third embodiment.

FIG. 6 is a schematic diagram of a filter according to a fourth embodiment.

FIG. 7 is a schematic view of a filter according to a fifth embodiment.

FIG. 8 is a schematic diagram of a switch according to a sixth embodiment.

FIG. 9 is a schematic diagram of a switch according to a seventh embodiment.

FIG. 10 is an explanatory diagram of a switch according to a seventh embodiment.

FIG. 11 is a schematic diagram of another switch according to the seventh embodiment;

FIG. 12 is a schematic view of a switch according to an eighth embodiment.

FIG. 13 is a schematic view of a switch according to a ninth embodiment.

FIG. 14 is a schematic view of a switch according to a tenth embodiment.

FIG. 15 is a schematic diagram of a switch according to an eleventh embodiment.

FIG. 16 is a schematic view of a switch according to a twelfth embodiment.

FIG. 17 is a schematic view of a conventional optical switch.

FIG. 18 is a schematic view of another conventional optical switch.

[Explanation of symbols]

 11, 51 Input waveguide 12, 52 Array waveguide 13, 53 Slab waveguide 14, 54 Triangular electrode 15, 55 Output waveguide 16, 56 Slab waveguide 17 Inverter 18 Control signal generator 19 Diode 21 Comb shape Electrode 22 saw-shaped electrode 23 step-shaped electrode 31 reflective film 32 input / output slab waveguide 41 first optical switch 42 second optical switch

Continued on the front page (72) Inventor Hirokazu Takenouchi 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 2H047 KA03 KA12 LA19 MA05 RA08 TA12 2H079 AA02 AA05 AA12 BA04 CA05 CA07 DA16 EA07 EB12 HA15 KA08 2K002 AB04 AB40 BA06 DA11 EA07 EB05 GA10 HA01 HA17

Claims (9)

[Claims] An array waveguide grating type wavelength multiplexer / demultiplexer (AW)
A wavelength tunable filter comprising means for changing the refractive index of each waveguide of the arrayed waveguide G) such that the total amount of change in the refractive index is changed at a constant rate between the respective waveguides. 2. An array waveguide grating type wavelength multiplexer / demultiplexer (AW).
G) has two sets of means for changing the refractive index of each waveguide of the arrayed waveguide so that the total amount of change in the refractive index is changed at a constant rate between the respective waveguides. The amount of change in the refractive index of the waveguide between the waveguides and the amount of change in the refractive index of the waveguide by the other means between the waveguides are reversed. Variable wavelength filter. 3. The device according to claim 1, wherein the means for changing the refractive index of each waveguide of the arrayed waveguide so that the total amount of change in the refractive index is changed at a constant rate between the waveguides. A tunable filter characterized by being an electrode having a shape. 4. The means according to claim 1, wherein the means for changing the refractive index of each waveguide of the arrayed waveguide is such that the total amount of change in the refractive index is changed at a constant rate between the respective waveguides. A tunable filter comprising a pair of a shape-shaped electrode and a step-shaped electrode. 5. The optical system according to claim 1, wherein p input waveguides for inputting an optical signal and p slab waveguides for distributing the optical signal to a group of p array waveguides are provided. Each of the p-channels is independently equipped with a waveguide and a triangular-shaped electrode for performing current injection or voltage application for changing the refractive index.
A plurality of arrayed waveguide groups, one slab waveguide for coupling output light from the p arrayed waveguide groups to the output waveguides, and q output waveguides for extracting optical signals, A tunable filter characterized by being developed in parallel. 6. The tunable filter according to claim 1, wherein the tunable filter is a multistage connection. 7. The tunable filter according to claim 1, wherein the tunable filter is of a reflection type. 8. The array waveguide according to claim 5, wherein the arrayed waveguides are divided into a plurality of groups, and the lowest waveguide lengths of each group are all equal, and the optical path length differences between adjacent waveguides of each group are all equal. And a wavelength tunable filter comprising only saw-shaped electrodes. 9. A spatial light switch, wherein a plurality of output waveguides are installed in the tunable filter according to claim 1. Description: