JP2000310756A - Optical frequency filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a smaller increase in the number of control electrodes even if the number of optical frequencies that can be selected is increased by connecting an optical gate switch for allowing the transmission of light or shutting off the light to output waveguides of a second array waveguide grating filter and connecting an optical joining circuit to the output waveguides of the optical gate switch. SOLUTION: Waveguides are arranged between the output waveguides or input waveguides adjacent to each other of the first and second array waveguide grating filters 1 and 3 in such a manner that the differences between the optical frequencies demultiplexed or multiplexed are equaled. The differences in the lengths between the array waveguides adjacent to each other of the first array waveguide grating filter 1 and the differences in the lengths between the array waveguides adjacent to each other of the second array waveguide grating filter 3 are so set as to attain the values different from each other. Further, the optical gate switch 4 for allowing the transmission of the demultiplexed light or shutting off the light is connected to at least >=2 output waveguides of the second array waveguide grating filter 3 and an optical joining circuit 5 is connected to the output waveguides of the optical gate switch 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical frequency filter. That is, the present invention relates to an integrated optical frequency filter used for optical communication, optical switching, optical information processing, optical measurement, and the like.

[0002]

2. Description of the Related Art In order to realize large-capacity communication, wavelength multiplexing optical communication for multiplexing and transmitting optical signals having a plurality of different optical frequencies (wavelengths) on a single optical fiber is being actively developed. Have been done. An optical frequency filter capable of selectively extracting only an optical signal of a specific optical frequency (wavelength) from a multiplexed optical signal composed of a plurality of optical frequencies is an optical add / drop device, an optical cross connect device. It is indispensable for realizing an optical switch.

An optical frequency filter in which a pair of arrayed waveguide grating filters and an optical gate switch are integrated can digitally and quickly select an optical frequency by turning on / off an electrical signal. Promising as a filter suitable for such applications. As a reported example of an optical frequency filter in which a pair of an arrayed waveguide grating filter and a semiconductor amplifier / gate switch are integrated on an InP semiconductor substrate, M. Zirngible et al. (IEEE Photonics.
Technology Letters, vol. 6, pp. 513-
515, 1994).

Further, there is known an optical filter device in which two filters having different resolutions are connected in series on a semiconductor wafer (JP-A-6-250132).
issue). In this optical filter device, electrical energy is supplied from a control circuit to a waveguide having a controllable transmittance that connects components of a filter defined on a wafer, whereby the entire filter includes a plurality of optical filters. Tune to a predetermined one of the frequencies. Such application of electrical energy creates a frequency selection path that can transmit one of the hundreds of selected optical frequencies across the region of the semiconductor medium.

Here, the operating characteristics of a conventional optical frequency filter will be described with reference to the drawings. FIG. 4 schematically illustrates a configuration when an optical frequency filter of eight channels is viewed from above. This filter includes three regions: an arrayed waveguide grating splitter 110, an arrayed waveguide grating multiplexer 111, and a semiconductor amplifier array 112. An optical waveguide is formed on the InP substrate 120,
It has a structure in which an InGaAsP core layer having a band gap wavelength of 1050 nm is sandwiched between InP clad layers.

Therefore, a wavelength of 1550 nm (optical frequency: to
193 THz) and is transparent to light near InP.
The light is confined in the InGaAsP layer having a higher refractive index than that of the above, and the light propagates along the waveguide pattern. Incident light 1
When 13 enters the input waveguide 121 of the first array grating splitter, the light is guided to the first slab waveguide 122. In the slab waveguide 122, light spreads out at a certain angle because there is no confinement effect due to the refractive index in the direction parallel to the substrate. This spread light is gradually coupled to a number of array waveguides 123 and guided to a second slab waveguide 124.

Light converges in the second slab waveguide 124 and couples into one of the plurality of output waveguides 125. Here, a certain difference in length is provided between adjacent waveguides of the arrayed waveguide 123. For this reason, the position where the light is converged in the plane between the second slab waveguide 124 and the output waveguide 125 changes depending on the frequency of the input light. For example, if light of a certain frequency f1 is coupled to the first output waveguide, light having a different frequency by Δf will be coupled to the adjacent second output waveguide.

That is, the first arrayed waveguide grating splitter is
It functions to distribute light having different optical frequencies to a plurality of output waveguides according to the frequency. On the other hand, the second arrayed waveguide grating combiner 111 includes an input waveguide 126, a first slab waveguide 127, an arrayed waveguide 128, a second slab waveguide 129, and an output waveguide 130. Has a symmetrical structure in which the arrangement of the input waveguide 121 and the output waveguide 125 of the arrayed waveguide grating duplexer 110 is interchanged.
Therefore, the operation of the second arrayed waveguide grating multiplexer 111 can be understood by considering how light travels in the opposite direction in the description of the operation of the first arrayed waveguide grating multiplexer. The second arrayed waveguide grating combiner 111 functions to combine the demultiplexed light into one waveguide.

Semiconductor amplifiers 112 are formed between the output waveguide 125 of the arrayed waveguide grating splitter 110 and the input waveguide 126 of the arrayed waveguide grating multiplexer / demultiplexer 111, respectively. The waveguide of the semiconductor amplifier 112 is made of InGaAsP having a band gap wavelength of 1550 to 1580 nm.
155 when no current is injected
Light near 0 nm is absorbed, and when current is injected, the light is amplified. That is, the semiconductor amplifier 112 outputs the current ON /
A gate that blocks or transmits light when turned off
Act as a switch. Therefore, by passing a current through a specific semiconductor amplifier 112 to allow light to pass through,
Only a specific wavelength from the light demultiplexed by the first arrayed waveguide grating demultiplexer 110 can be guided to the output waveguide 130.

The optical frequency filter having such a configuration has a feature that an optical frequency to be selected can be switched electrically at a high speed. The design of the arrayed waveguide grating filter will be described below. The frequency of light transmitted from a particular output waveguide of the arrayed waveguide grating filter is periodic. The period of this frequency is called a free spectral range (FSR) and is determined by the following equation. FSR = c / (n · ΔL) where c is the speed of light, n is the effective refractive index of the arrayed waveguide, Δ
L is the difference in length between adjacent arrayed waveguides.

That is, the FSR is determined by setting the length difference ΔL between the arrayed waveguides. Further, the difference in transmission frequency between adjacent output waveguides, that is, the channel frequency interval Δf can be determined by the interval between the output waveguides, the length of the slab waveguide, and the FSR. In the example shown in FIG. 4, the channel frequency interval Δf is 200 GHz, the number of channels (the number of output waveguides) is 8, and the FSR is 1.6 THz.
The FSR is set to be exactly the number of channels times the channel frequency interval. This filter operates as an optical frequency filter that selects only light of an arbitrary frequency from eight multiplexed optical signals arranged at intervals of 200 GHz.

[0012]

In the above prior art, as the number of selectable optical frequencies increases, an arrayed waveguide grating filter having a large number of output waveguides becomes necessary in proportion to the number. , The number of optical gates also increases. as a result,
The size of the element increases, and the number of electrodes increases. Increasing the element size causes a decrease in the number of elements that can be made from a unit wafer and a decrease in yield, and an increase in the number of electrodes leads to an increase in a wiring process for performing electric wiring and an increase in the scale of a control circuit. There was such a problem. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the conventional example and to provide an optical frequency filter which requires a small increase in the number of control electrodes even when the number of selectable optical frequencies increases.

[0013]

According to the first aspect of the present invention, there is provided an optical frequency filter for transmitting light incident on one input waveguide to at least two or more output waveguides. There is a split between a first arrayed waveguide grating filter having an action of splitting for each frequency and a second arrayed waveguide grating filter having an action of multiplexing the split light into one waveguide. In an optical frequency filter connected with an optical gate switch for transmitting or blocking the waved light, in the first and second arrayed waveguide grating filters, demultiplexing or splitting between adjacent output waveguides or input waveguides. The waveguides are arranged so that the difference between the multiplexed optical frequencies, that is, the so-called frequency channel interval, is equal in all the arrayed waveguide gratings, and the transmittance periodically generated in the first arrayed waveguide grating filter. Between the adjacent array waveguides of the first arrayed waveguide grating filter, such that the interval of the optical frequency and the interval of the transmitted light frequency periodically generated in the second arrayed waveguide grating filter are different by the frequency channel interval. The difference in length and the difference in length between adjacent array waveguides of the second arrayed waveguide grating filter are set to have different values, and at least two of the second arrayed waveguide grating filter are different. An optical gate switch for transmitting or blocking the split light is connected to the output waveguides described above, and an optical convergence circuit is connected to the output waveguide of the optical gate switch.

According to a second aspect of the present invention, there is provided an optical frequency filter for splitting light incident on one input waveguide into at least two or more output waveguides for different optical frequencies. The split light is transmitted between the first arrayed waveguide grating filter having the function and the second arrayed waveguide grating filter having the function of combining the split light into one waveguide. Or, in an optical frequency filter connected with an optical gate switch to be cut off, in the first and second arrayed waveguide grating filters, the optical frequency to be split or multiplexed between adjacent output waveguides or input waveguides. , The so-called frequency channel spacing is equal in all the arrayed waveguide gratings, and the interval between transmitted light frequencies periodically generated in the first arrayed waveguide grating filter. The difference in length between adjacent array waveguides of the first arrayed waveguide grating filter is set so that the interval between transmitted light frequencies periodically generated in the second arrayed waveguide grating filter differs by the frequency channel interval. And the difference in length between adjacent array waveguides of the second array waveguide grating filter is set to a different value, and an optical convergence distribution circuit is connected to the output waveguide of the optical gate switch. An optical gate switch for transmitting or blocking the demultiplexed light is connected to at least two or more output waveguides of the optical converging / distributing circuit, and the output waveguide of the optical gate switch is a second array. The waveguide grating filter is connected to different input waveguides.

According to a third aspect of the present invention, which achieves the above object, there is provided light for transmitting or blocking light split by the first arrayed waveguide grating filter between two arrayed waveguide grating filters. In the optical frequency filter to which the gate switch is connected, in the first arrayed waveguide grating filter, the difference between the optical frequencies split into adjacent output waveguides,
The waveguides are arranged so that the so-called frequency channel interval and the interval between transmitted light frequencies periodically generated in the second arrayed waveguide grating filter are equal to each other. The waveguide is arranged so that the difference between the optical frequencies demultiplexed into the waveguide, that is, the so-called frequency channel interval and the interval of the transmitted light frequency periodically generated in the first arrayed waveguide grating filter are equalized. An optical gate switch for transmitting or blocking the demultiplexed light is connected to at least two or more output waveguides of the arrayed waveguide grating filter, and an optical merging circuit is connected to the output waveguide of the optical gate switch. It is characterized by having been done.

According to a fourth aspect of the present invention, which achieves the above object, there is provided light for transmitting or blocking light demultiplexed by a first arrayed waveguide grating filter between two arrayed waveguide grating filters. In the optical frequency filter to which the gate switch is connected, in the first arrayed waveguide grating filter, the difference between the optical frequencies split into adjacent output waveguides,
The waveguides are arranged so that the so-called frequency channel interval and the interval between transmitted light frequencies periodically generated in the second arrayed waveguide grating filter are equal to each other. The waveguide is arranged so that the difference between the optical frequencies demultiplexed into the waveguide, the so-called frequency channel interval, and the interval between the transmitted light frequencies periodically generated in the first arrayed waveguide grating filter are equal. An optical convergence distribution circuit is connected to the output waveguide of the gate switch, and an optical gate switch for transmitting or blocking the distributed light is connected to at least two or more output waveguides of the optical convergence distribution circuit, The output waveguide of the optical gate switch is connected to different input waveguides of the second arrayed waveguide grating filter.

According to a fifth aspect of the present invention, which achieves the above object, there is provided light for transmitting or blocking light split by the first arrayed waveguide grating filter between two arrayed waveguide grating filters. In the optical frequency filter to which the gate switch is connected, in the output waveguide of the second arrayed waveguide grating filter, the transmitted optical frequency band is equal to or greater than the optical frequency band transmitted by the first arrayed waveguide grating filter, and It is set within a range equal to or less than the interval of the transmitted light frequency periodically generated by one arrayed waveguide grating filter, and, in the second arrayed waveguide grating filter, the optical frequency of the light split into adjacent output waveguides. The difference, the so-called frequency channel spacing, and the spacing of the transmitted light frequency periodically generated in the first arrayed waveguide grating filter are adjacent to each other in the first arrayed waveguide grating filter. The input waveguides of the second arrayed waveguide grating filter are arranged so as to be shifted by the difference of the optical frequency demultiplexed to the output waveguide, that is, the so-called frequency channel interval. An optical gate switch for transmitting or blocking the demultiplexed light is connected to one or more output waveguides, and an optical merging circuit is connected to the output waveguide of the optical gate switch.

[Operation] In the present invention, the first arrayed waveguide grating, the preceding stage optical gate switch array, the optical converging / distributing circuit, the latter stage optical gate switch array, and the second arrayed waveguide grating are used. And by appropriately designing the channel frequency interval between the preceding arrayed waveguide grating filter and the subsequent arrayed waveguide grating filter and the FSR between them, or by using the former arrayed waveguide grating filter and the latter arrayed waveguide grating filter. It is characterized in that the channel frequency intervals of the waveguide grating filter are equal, and the FSRs of the two have different values by the channel interval. The feature is that a large number of optical frequencies can be efficiently selected with less optical gate switches than the conventional method. In the optical frequency filter according to the present invention, the number of optical frequencies that can be selected with a small number of electrodes can be significantly increased by selecting a combination of the optical gate switch in the preceding stage and the optical gate switch in the subsequent stage.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows a first embodiment of the present invention. In this embodiment, an arrayed waveguide grating filter 1 having four channels and an FSR four times the channel interval is provided.
The present invention relates to a 20-channel optical frequency filter combining an arrayed waveguide grating filter 3 having 5 channels and an FSR of 5 times the channel interval.

In the figure, 1 is an arrayed waveguide grating filter having 4 channels and an FSR of 4 times the channel interval, 2 is an optical gate switch array having 4 channels, 3 is 5 channels,
An arrayed waveguide grating filter having an FSR of 5 times the channel interval, 4 is a 5-channel optical gate switch array, 5 is a 5-input / 1-output optical convergence circuit, and 6 is an optical gate control electrode. A large number of optical waveguides are formed on the InP semiconductor substrate, and the core layers of the waveguides of the arrayed waveguide grating filter portions 1 and 3 are made of InGaA having a band gap wavelength of 1050 nm.
It is formed of sP.

The composition of the waveguide layers of the semiconductor amplifier sections 2 and 4 used as optical gate switches is InGaAsP having a band gap wavelength of 1550 to 1580 nm, and the light having a wavelength of about 1550 nm (optical frequency: up to 193 THz). Has absorption or amplification action. Semiconductor amplifier 2,
By controlling the voltage between the optical gate control electrode 6 formed on the upper part of the substrate 4 and the electrode formed on the back surface of the substrate, and turning on / off the current flowing through the waveguide layer of the semiconductor amplifier, Is controlled. In the first arrayed waveguide grating filter 1, the frequency channel spacing 1
The array waveguide, the slab waveguide, and the input / output waveguide are arranged so as to have 00 GHz, 400 GHz FSR, and four channels.

In the second array waveguide grating filter 3,
Frequency channel spacing 100GHz, FSR500GH
An array waveguide, a slab waveguide, and an input / output waveguide are arranged so that z and the number of channels are five. Here, the operation of the optical frequency filter according to the present embodiment will be described.
The first arrayed waveguide grating filter 1 has four channels and F
Each array in the case where SR is 4 times the channel interval, the second arrayed waveguide grating filter 3 is an arrayed waveguide grating filter having 5 channels, FSR is 5 times the channel interval, and the channel intervals are equal. Tables 1 (a) and 1 (b) show the relationship between the input and output optical frequencies of the waveguide grating filters 1 and 3, respectively.

[0023]

[Table 1]

Table 1 (a) shows the relationship between the input and output optical frequencies of the arrayed waveguide grating filter 1, and Table 1 (b) shows the relationship between the input and output optical frequencies of the arrayed waveguide grating filter 3.
As shown in Table 1, when a signal is input from the same input port, the signal is output from a different output port according to the optical frequency of the signal light. It will be output to the port.

That is, the first arrayed waveguide grating filter 1
As shown in Table 1 (a), as shown in Table 1 (a), a signal incident on one input port is transmitted to four output ports according to optical frequencies f1 to f20.
As described in Table 1 (b), signals incident on four input ports are transmitted to five output ports according to the optical frequencies f1 to f20.

FIGS. 2A and 2B show the transmission characteristics of the arrayed waveguide grating filters 1 and 3, respectively. Optical gate
The optical gate switch element numbers of the switch arrays 2 and 4 are A1 to A4 and B1 to B5, respectively, and the optical gate switches A1 and B1 are operated in transmission, and the other optical gate switches are transmitted in the case of the cutoff operation. The characteristics of the first arrayed waveguide grating filter 1 are f1, f5, f9, f13, and f17 as shown by the solid line in FIG.
As shown by the solid line in (b), f1, f6, f11, f1
It becomes 6.

That is, in the first arrayed waveguide grating filter 1, as shown in FIG. 2A, a transmission frequency band is periodically generated at every third channel interval, and the optical frequency indicated by A1 to A4 in FIG. Are respectively output ports 1 to
It is split into four. Further, the signal light having the frequency indicated by the solid line in FIG. 1 is incident on the second arrayed waveguide grating filter 3 from the uppermost waveguide in FIG. . Since the optical gate switches A2 to A4 are turned off, no signal light enters from the other incident waveguides of the second arrayed waveguide grating filter 3.

The signal light transmitted through the optical gate switch A1 and output from the second arrayed waveguide grating filter 3 is periodically transmitted every four channel intervals as shown in FIG. 2B. Occurs, and the signal light having the optical frequencies indicated by B1 to B5 in the drawing is split into five output ports. By causing the optical gate switch B1 to perform the transmission operation, a periodic transmission frequency band is generated at every fourth channel interval as shown by the solid line. As a result, the optical gate
The output from the switch array 4 is obtained by multiplying both transmission characteristics.

That is, when a signal light having a frequency f1 as shown in FIG. 2C enters the optical convergence circuit 5 from the uppermost waveguide in FIG. 1, the optical gate switches B2 to B5
Is turned off, no signal light is incident from the other input waveguides of the optical convergence circuit 5. The output signal from the optical convergence circuit 5 becomes the transmission characteristic of this filter, and as shown in FIG. 2C, a transmission frequency band occurs every 20 channels (= 4 × 5). This optical frequency filter can be used as a filter that can select an arbitrary frequency from 20 channels.

Front and rear optical gate / switch arrays 2 and 4
It is easily understood from these figures and Table 1 that the arbitrary channel can be selected from the other 19 channels by changing the combination of the operation optical gates. Therefore, by using this filter, the frequency interval 10
Any one light can be extracted from light having 20 optical frequency components arranged at equal intervals at 0 GHz. Table 1 shows a correspondence table between the extracted optical frequency and the gate through which light is transmitted by passing a current.

In this embodiment, 191.0 THz is obtained by combining the operation gates of the two optical frequency selection filters.
The light of any channel can be extracted from the 20 frequency channels within the frequency range from to 192.9 THz. The number of electrodes to be controlled is nine. In the configuration of the conventional optical frequency filter, a filter capable of selecting an arbitrary frequency from among 20 channels has 20 filters.
It is found that the number of electrodes can be significantly reduced in the filter of this configuration by controlling 9 (= 5 + 4) optical gate switches.

It is clear that the greater the number of required frequency channels, the greater the effect of reducing the number of electrodes with the arrangement according to the invention. In this embodiment, the case where the optical amplifier is used as the optical gate switch has been described.However, the case where another device capable of changing the light transmittance, for example, an absorption type modulator, a grating reflector, or the like is used. Exactly the same effect can be expected. Further, the case of the 5-input / 1-output optical coupling circuit 5 has been described, but an N-input M-output circuit may be used. It is needless to say that a similar effect can be obtained even when the input side and the output side of the present embodiment are reversed.

[Embodiment 2] FIG. 3 shows a second embodiment of the present invention.
Shown in In this embodiment, 20 channels are used in the case of using an arrayed waveguide grating filter 7 having 4 channels and an FSR of 4 times the channel interval, and an arrayed waveguide grating filter 11 having 5 channels and an FSR of 5 times the channel interval. Optical frequency filter.

In the figure, reference numeral 7 denotes an arrayed waveguide grating filter having 4 channels and an FSR of 4 times the channel interval, 8 an optical gate switch array having 4 channels, 9 an optical multiplexing / distributing circuit having 4 inputs and 5 outputs, and 10 Is an optical gate switch array of 5 channels, 11 is an arrayed waveguide grating filter having 5 channels, FSR is 5 times the channel interval, and 12 is an optical gate control electrode.

A large number of optical waveguides are formed on an InP semiconductor substrate, and the core layers of the waveguides of the arrayed waveguide grating filter portions 7 and 11 have a bandgap wavelength of 1050 nm.
It is formed of nGaAsP. The composition of the waveguide layers of the semiconductor amplifier sections 8 and 10 used as optical gate switches is In with a band gap wavelength of 1550 to 1580 nm.
It is GaAsP and has a wavelength of 1550 nm (optical frequency: ~ 19
It absorbs or amplifies light near 3 THz).

The voltage is controlled between the optical gate control electrode 12 formed on the upper part of the semiconductor amplifier and the electrode formed on the back surface of the substrate, and the current flowing through the waveguide layer of the semiconductor amplifier is turned on / off. As a result, light transmission / blocking is controlled. In the first arrayed waveguide grating filter 7, the frequency channel interval is 100 GHz, and the FSR 400G
The array waveguide, the slab waveguide, and the input / output waveguide are arranged so that the frequency and the number of channels are 4 Hz.

The second arrayed waveguide grating filter 11 has a frequency channel interval of 100 GHz and an FSR of 500 G
The array waveguide, the slab waveguide, and the input / output waveguide are arranged so that the frequency is 5 Hz and the number of channels is 5. Here, the operation of the optical frequency filter according to the present embodiment will be described. In this embodiment, each arrayed waveguide grating filter 7,
Tables 2 (a) and (b) show the relationship between the input and output optical frequencies of No. 11 respectively.

[0038]

[Table 2]

Table 2 (a) shows the relationship between the input and output optical frequencies of the arrayed waveguide grating filter 7, and Table 2 (b) shows the relationship between the input and output optical frequencies of the arrayed waveguide grating filter 11. That is, as described in Table 2 (a), the optical frequency selection filter 7 transmits a signal incident on one input port to four output ports according to the optical frequencies f1 to f20,
In addition, as described in Table 1 (b), the arrayed waveguide grating filter 3 transmits signals incident on five incident ports to one output port.

Now, the optical gate switch arrays 8 and 1
The optical gate switch element numbers of 0 are A1 to A, respectively.
4, B1 to B5, and signal light is assumed to be incident on the first arrayed waveguide grating filter 7 from the uppermost waveguide. By allowing only the optical gate switch A1 to perform the transmission operation,
A signal light having a frequency indicated by a solid line in FIG. 2 is incident on the four-input / five-output optical merger / distributor 9 from the uppermost waveguide in the figure.

Since the optical gate switches A2 to A4 are turned off, no signal light enters from the other incident waveguides of the optical convergence / distribution circuit 9. The signal light that has passed through the optical gate switch A1 and entered the optical multiplexing / distributing circuit 9 is branched by the optical convergence / distributing circuit 9, and is incident on the 5-channel optical gate / switch array 10.

Now, by allowing only the optical gate switch B1 of the optical gate switch array 10 to perform the transmission operation, the signal enters the second arrayed waveguide grating filter 11 from only one input port, and the output signal is output. As shown by the solid line, a periodic transmission frequency band occurs at every fourth channel interval.

That is, the signal light transmitted through the optical gate switch array 10 and output from the second arrayed waveguide grating filter 11 has the frequencies f1 and f as shown in Table 2 (b).
2, f11, and f16, and a transmission frequency band is periodically generated at every four channel intervals as shown in FIG. 2B, and signal light having optical frequencies indicated by B1 to B5 in the figure is generated. An output is obtained from the output port when the light enters from each of the five input ports. As a result, the output from the second arrayed waveguide grating filter 11 is obtained by multiplying the two transmission characteristics. That is, the signal light having the frequency f1 as shown in FIG. 2C is output.

This output signal becomes the transmission characteristic of the filter shown in this embodiment, and as shown in FIG. 2C, a transmission frequency band occurs every 20 channels (= 4 × 5). This optical frequency filter can be used as a filter that can select an arbitrary frequency from 20 channels. By changing the combination of the operating optical gates of the front and rear optical gate switch arrays 8 and 10, selecting any channel from the other 19 channels can be easily understood from these figures and Table 1. .

Thus, by using this filter, it is possible to extract any one light from the light having 20 optical frequency components arranged at regular intervals at a frequency interval of 100 GHz. Table 1 shows a correspondence table between the extracted optical frequency and the gate through which light is transmitted by passing a current.
In this embodiment, the combination of the operation gates of the two optical frequency selection filters changes the frequency from 191.0 THz to 192.
Light of any channel can be extracted from 20 frequency channels within a frequency range up to 9 THz. The number of electrodes to be controlled is nine.

Further, in this embodiment, the case where the optical amplifier is used as the optical gate switch has been described. However, other devices capable of changing the light transmittance, for example,
Exactly the same effect can be expected when an absorption type modulator, a grating reflector or the like is used. Also, the case where the optical converging circuit has N inputs and M outputs has been described, but if the number of input ports and the number of output ports are N and M, respectively,
Similar effects can be expected. It is needless to say that a similar effect can be obtained even when the input side and the output side of the present embodiment are reversed.

The above-mentioned optical convergence circuit 5 and optical convergence distribution circuit 9
The most promising are the Y-branch type, star coupler type (used for AWG) and multi-mode interference type as shown in FIG. FIG. 5A shows a four-input one-output optical converging circuit configured by connecting Y-branch type optical converging circuits in multiple stages, and one of the light converging circuits propagates through a waveguide connected in a Y-shape. Guided to the output waveguide.

FIG. 5 (b) shows a star coupler type optical merging circuit, and FIG. 5 (c) shows a star coupler type optical merging / branching circuit. The beam propagates while spreading in the area of the beam and is coupled to the output waveguide, and is output to all output waveguides within the range of the beam spread. Therefore, N inputs and M outputs (N =
, M = 1, 2, 3,...) Can be easily formed.

FIG. 5D shows a multi-mode interference type optical multiplexing circuit, and FIG. 5E shows a multi-mode interference type optical multiplexing / branching circuit. While propagating in the region, a region with a high light intensity and a region with a low light intensity are generated due to the mode interference, and by arranging the output waveguide in the region with a high light intensity, N inputs and M outputs (N = 1, 2, 3, 3)
.., M = 1, 2, 3,. ..) Can be easily formed.

In the present invention, it is of course possible to use a commercially available fiber type coupler as the optical multiplexing / distributing circuit, and it is also possible to connect a multi-stage 3 dB coupler using, for example, a directional coupler. Absent. To put it in extreme terms, a plurality of input waveguides (or fibers) and an output waveguide (or fiber) of a compound text are simultaneously physically or optically (via a lens or the like) along the propagation direction of signal light. If they are connected to each other, they operate as an optical merging / branching circuit.

[Embodiment 3] FIG. 6 shows a third embodiment of the present invention.
Shown in In this embodiment, the input light is 20 at 100 GHz intervals.
The present invention relates to a frequency filter applied to a signal light in which a plurality of frequencies are multiplexed. In the figure, 31 is an arrayed waveguide grating filter having four channels and FSR is four times the channel interval, and 33 is an arrayed waveguide grating filter having five channels and the FSR is five times the channel interval. The channel spacing of the waveguide grating filter 31 is set to be equal to the FSR of the second arrayed waveguide element filter 33.

That is, the first arrayed waveguide grating filter 3
In Example 1, the array waveguide, the slab waveguide, and the frequency channel interval were set to 500 GHz, the transmission band per channel was 500 GHz, the FSR was 2000 GHz, and the number of channels was 4.
An input / output waveguide is arranged, and the second arrayed waveguide grating filter 33 has a frequency channel spacing of 100 GHz.
z, transmission band 100 GHz per channel, FSR500
An arrayed waveguide, a slab waveguide, and an input / output waveguide are arranged so as to have GHz and the number of channels is 5. 32 is 4
A channel optical gate switch array, 34 is a 5-channel optical gate switch array, 35 is a 5-input / 1-output optical merging circuit, and 36 is an electrode.

A large number of optical waveguides are formed on an InP semiconductor substrate, and the core layers of the waveguides of the arrayed waveguide grating filters 31 and 33 are made of In with a bandgap wavelength of 1050 nm.
It is formed of GaAsP. The composition of the waveguide layers of the semiconductor amplifier sections 32 and 34 used as the optical gate switch is In with a band gap wavelength of 1550 to 1580 nm.
It is GaAsP and has a wavelength of 1550 nm (optical frequency: ~ 19
It absorbs or amplifies light near 3 THz). The voltage is controlled between the electrode 36 formed on the upper part of the semiconductor amplifier and the electrode formed on the back surface of the substrate, and the current flowing through the waveguide layer of the semiconductor amplifier is turned on / off to transmit / transmit light. Shutdown control is performed.

Here, the operation of the device of this embodiment will be described. Input / output optical frequency of each arrayed waveguide grating filter when 20 frequency multiplexed signal lights are incident from an input port of the first arrayed waveguide grating filter 31 and each input port of the second arrayed waveguide grating filter 33 Are shown in Tables 3 (a) and 3 (b), respectively.

[0055]

[Table 3]

Table 3 (a) shows the arrayed waveguide grating filter 3.
For Table 1, Table 3 (b) shows the arrayed waveguide grating filter 3
Table 3 (c) shows the relationship between the input and output optical frequencies for the entire optical frequency filter of the third embodiment. The optical gate switch element numbers of the optical gate switch arrays 32 and 34 in FIG.
FIG. 7 shows the transmission characteristics when the optical gate switches A1 and B1 are operated in transmission, and the other optical gate switches are in the cutoff operation. In the first arrayed waveguide grating filter 31 of FIG. 6, as shown in FIG. 7A, five signal lights in which 20 frequency-multiplexed signal lights are continuous form a set, and output ports 1 to It is split into four.

By causing the optical gate switch A1 to perform a transmission operation, five frequency signal lights of f1 to f5 indicated by solid lines in the drawing are transmitted from the uppermost waveguide in FIG. The light enters the grating filter 33. Optical gate
Since the switches A2 to A4 are turned off, no signal light is incident from the other incident waveguides of the second arrayed waveguide grating filter 33. Next, the signal light that enters from the optical gate switch A1 and is output from the second arrayed waveguide grating filter 33 has transmission characteristics as shown in FIG. Every fifth periodic transmission frequency band occurs. By the way, the optical gate in the first stage
Since only f1 to f5 are selected in the switch array 32, only f1 is incident on B1 of the optical gate switch array 34 in the subsequent stage.

That is, the optical gate switch array 3 at the subsequent stage
The output from 4 is obtained by multiplying the transmission characteristics of the two, that is, as shown in FIG. 7C, a signal light having a frequency of f1 enters the optical converging circuit 35 from the uppermost waveguide in the figure. I do. Since the optical gate switches B2 to B5 are turned off, no signal light enters from the other incident waveguides of the optical convergence circuit 5. The output signal from the optical convergence circuit 5 becomes the transmission characteristic of this filter, and as shown in FIG. 7C, a transmission frequency band occurs every 20 waves (= 4 × 5).
This optical frequency filter can be used as a filter that can select an arbitrary frequency signal light from 20 frequency multiplexed signal lights. Front and rear optical gate / switch array 32
By changing the combination of the operating optical gates of (1) and (3), selecting any signal light from the other 19 frequency signal lights can be easily understood from these figures and Table 3.

Therefore, by using this filter, it is possible to extract any one light from the light having 20 optical frequency components arranged at equal intervals at a frequency interval of 100 GHz. Table 3 (c) shows the correspondence between the extracted optical frequency and the gate that transmits current and transmits light. In this embodiment, 191.0 THz is obtained by combining the operation gates of the two optical frequency filters.
Out of the 20 frequency-multiplexed signal lights within the frequency range from 12.9 to 192.9 THz. The number of electrodes to be controlled is nine. In the configuration of the conventional optical frequency filter, a filter capable of selecting an arbitrary frequency signal light from among the 20 frequency multiplexed signal lights requires control of 20 optical gate switches. 5+
It can be seen that it is sufficient to control the optical gate switch of 4), and the number of electrodes can be significantly reduced.

It is clear that the greater the number of required frequency channels, the greater the effect of reducing the number of electrodes with the arrangement according to the invention. In this embodiment, the case where the optical amplifier is used as the optical gate switch has been described.However, the case where another device capable of changing the light transmittance, for example, an absorption type modulator, a grating reflector, or the like is used. Exactly the same effect can be expected. Also, the case where the optical converging circuit has N inputs and one output has been described, but an N-input M-output circuit may be used. It is needless to say that a similar effect can be obtained even when the transmission characteristics of the first and second arrayed waveguide gratings of the present embodiment are reversed.

[Embodiment 4] FIG. 8 shows a fourth embodiment of the present invention.
Shown in In this embodiment, the input light is 20 at 100 GHz intervals.
The present invention relates to a frequency filter applied to a signal light in which a plurality of frequencies are multiplexed. In the figure, reference numeral 41 denotes an arrayed waveguide grating filter having 4 channels and an FSR of 4 times the channel interval, and 5 denotes an arrayed waveguide grating filter having 5 channels and an FSR of 5 times the channel interval. The channel spacing of the waveguide grating filter 41 is set to be equal to the FSR of the second arrayed waveguide grating filter 45.

That is, the first arrayed waveguide grating filter 4
In 1, the array waveguide, the slab waveguide, and the frequency channel spacing are 500 GHz, the transmission band between channels is 500 GHz, the FSR is 2000 GHz, and the number of channels is 4.
An input / output waveguide is disposed, and the second arrayed waveguide grating filter 45 has a frequency channel spacing of 100 GHz.
z, transmission band 100 GHz per channel, FSR500
An arrayed waveguide, a slab waveguide, and an input / output waveguide are arranged so as to have a frequency of 5 GHz and 5 channels. 42 is 4
Channel optical gate / switch array, 43 has 4 inputs and 5 inputs
The output optical converging / distributing circuit, 44 is a 5-channel optical gate
The switch array 46 is an electrode. A number of optical waveguides are formed on the InP semiconductor substrate, and the core layers of the waveguides of the arrayed waveguide grating filters 41 and 45 are formed of InGaAsP having a bandgap wavelength of 1050 nm.

The composition of the waveguide layers of the semiconductor amplifier sections 42 and 44 used as optical gate switches is InGaAsP having a band gap wavelength of 1550 to 1580 nm.
It absorbs or amplifies light near the wavelength of 1550 nm (light frequency: up to 193 THz). The voltage is controlled between the electrode 46 formed on the upper part of the semiconductor amplifier and the electrode formed on the back surface of the substrate, and the current flowing through the waveguide layer of the semiconductor amplifier is turned on / off to transmit / transmit light. Shutdown control is performed. Here, the operation of the device of the present invention will be described. Input / output optical frequency of each arrayed waveguide grating filter when 20 frequency multiplexed signal light is incident from an input port of the first arrayed waveguide grating filter 41 and each input port of the second arrayed waveguide grating filter 45 Are shown in Tables 4 (a) and (b), respectively.

[0064]

[Table 4]

Table 4 (a) shows the arrayed waveguide grating filter 4.
Table 1 (b) shows the arrayed waveguide grating filter 4
For Table 5, Table 4 (c) shows the relationship between the input and output optical frequencies for the entire optical frequency filter of the fourth embodiment. Now, the signal light is converted to the first arrayed waveguide grating filter 41.
It is assumed that light is incident from an entrance port having The optical gate switch element numbers of the optical gate switch arrays 42 and 44 in FIG. 8 are again denoted by A1 to A4 and B1 to B5, respectively.
The transmission characteristics when the other optical gate switches are in the cutoff operation are as shown in FIG.

By causing the optical gate switch A1 to perform the transmission operation, the signal light of the five frequencies f1 to f5 indicated by the solid lines in FIG. 7A is output from the uppermost waveguide in FIG. To the optical converging / distributing circuit 43. Optical gate
Since the switches A2 to A4 are turned off, other signal light does not enter from the other incident waveguides of the optical convergence / distribution circuit 43. The signal light that has entered the optical convergence distribution circuit 43 from the optical gate switch A1 is split by the optical convergence distribution circuit 43,
The light enters the 5-channel optical gate switch array 44. Now, in the second array waveguide grating filter 45, only one output port is used. Table 4 shows the output signal light.
7B, an output is obtained from the output port when the signal light having the optical frequency indicated by B1 to B5 in FIG. 7B enters from the input ports 1 to 5, respectively.

In the present embodiment, only the optical gate switch B1 of the optical gate switch array 44 is operated to be transmitted, and the optical gate switches B2 to B5 are turned off. And the signal light does not enter from other incident waveguides. In this case, in the transmission characteristics, a periodic transmission frequency band occurs every five channel intervals as shown by the solid line in FIG. 7B. By the way, since only f1 to f5 are selected in the former optical gate switch array 42, the light enters from B1 of the latter optical gate switch array 44,
Only f1 is output from the output port of the second arrayed waveguide grating 45. As a result, from the output port of the second arrayed waveguide grating 45, a signal light having a frequency of f1 is multiplied by the transmission characteristics of both, that is, as shown in FIG. Output from the output port of the waveguide grating 45.

This output signal becomes the transmission characteristic of the filter shown in this embodiment, and as shown in FIG. 7C, a transmission frequency band occurs every 20 waves (= 4 × 5).
This optical frequency filter can be used as a filter that can select an arbitrary frequency signal light from 20 frequency multiplexed signal lights. Front and back optical gate / switch array 42
By changing the combination of the operating optical gates of (44) and (44), selecting an arbitrary signal light from the other 19 frequency signal lights can be easily understood from these figures and Table 4. Therefore, by using this filter, any one light can be extracted from the light having 20 optical frequency components arranged at regular intervals at a frequency interval of 100 GHz. Table 4 (c) shows the correspondence between the extracted optical frequency and the gate that transmits current and allows light to pass therethrough.

In this embodiment, by combining the operation gates of the two optical frequency filters, it is possible to extract a signal light of an arbitrary frequency from 20 frequency-multiplexed signal lights within a frequency range from 191.0 THz to 192.9 THz. it can. The number of electrodes to be controlled is nine. In this embodiment, the case where the optical amplifier is used as the optical gate switch has been described.However, the case where another device capable of changing the light transmittance, for example, an absorption type modulator, a grating reflector, or the like is used. Exactly the same effect can be expected. Also, the case where the optical converging circuit has N inputs and M outputs has been described, but the same effect can be expected if the number of input ports and the number of output ports are N and M or more, respectively. It is needless to say that a similar effect can be obtained even when the transmission characteristics of the first and second arrayed waveguide gratings of the present embodiment are reversed.

[Embodiment 5] FIG. 9 shows a fifth embodiment of the present invention.
Shown in In this embodiment, the input light is 20 at 100 GHz intervals.
The present invention relates to a frequency filter applied to a signal light in which a plurality of frequencies are multiplexed. In the figure, reference numeral 51 denotes a channel number of 5, a channel interval of 100 GHz, and a transmission band of 100 GH for each channel.
z, FSR is five times the channel spacing, ie, 500 GHz
Is an arrayed waveguide grating filter. An array 53 has four channels, a channel interval of 500 GHz, and a transmission band for each channel is three times the channel interval of the first arrayed waveguide grating filter 51, ie, 300 GHz, and the FSR is four times the channel interval, ie, an array of 2000 GHz. It is a waveguide grating filter.

Note that the distance between the input waveguides at the junction of the second arrayed waveguide grating 53 with the slab waveguide is shown in FIG.
0, the channel spacing of the second arrayed waveguide grating filter 53 is 500 GHz and the signal light frequency spacing is 100 GHz.
They are shifted by the amount of z (600 GHz).
At this time, when multiplexed signal light enters from each input port of the second arrayed waveguide grating filter 53, each optical frequency signal is distributed to the focal position shown in FIG. 11 for each frequency. FIG. 11 shows the relationship between each of the optical frequency signals f1 to f20 and the focus position with respect to the incidence from each input port at this time (dotted line).

As can be seen from this figure, each of the 20 signals always passes through the center of the transmission band by appropriately selecting the input port of the second arrayed waveguide grating filter 53 (see the dotted frame in FIG. 11). (FIG. 12). Table 5 (a) is for the arrayed waveguide grating filter 51, Table 5 (b) is for the arrayed waveguide grating filter 58, and Table 5 (c) is for the entire optical frequency filter of the fifth embodiment. Shows the relationship. Therefore, Table 5 shows the transmission characteristics.
(B).

[0073]

[Table 5]

52 is a 5-channel optical gate switch array, 54 is a 4-channel optical gate switch array,
Reference numeral 55 denotes a four-input one-output optical merging circuit, and reference numeral 56 denotes an electrode.
A large number of optical waveguides are formed on an InP semiconductor substrate, and the core layers of the waveguides of the arrayed waveguide grating filters 51 and 53 are formed of InGaAsP having a bandgap wavelength of 1050 nm. The composition of the waveguide layers of the semiconductor amplifier sections 52 and 54 used as optical gate switches is InGaAsP having a band gap wavelength of 1550 to 1580 nm, and a wavelength of 1550 nm (optical frequency =: 193 THz).
It has an absorbing or amplifying effect on nearby light.

Electrode 56 formed above semiconductor amplifier
And a voltage between the electrode formed on the back surface of the substrate and
The ON / OFF operation of the current flowing through the waveguide layer of the semiconductor amplifier controls the transmission / blocking of light. Here, the operation of the device of the present invention will be described. FIG.
The optical gates of the optical gate switch arrays 52 and 54
It is assumed that the switch element numbers are A1 to A5 and B1 to B4, respectively, and that the optical gate switches A2 and B1 are operated in a transmissive manner, and the other optical gate switches are in a cutoff operation. The multiplexed light entering from the incident port of the first arrayed waveguide grating 52 is divided into an optical gate and
The switches are distributed to the switches A1 to A5 as shown in Table 5 (a). If A2 is turned on and A1 and A3 to A5 are turned off, f2, f7, f12, and f17 enter the input port 2 of the second arrayed waveguide grating 53, and signals enter other input ports. Absent.

The upper four signals input from the input port 2 of the second arrayed waveguide grating 53 are applied to the optical gate switches B1 to B4 according to the transmission characteristics shown in Table 5 (b).
7, f12, f17 and f2 are entered. Further, when the optical gate switch B1 is turned ON and the other optical gate switches B2 to B5 are turned OFF, only f7 enters the five-input one-output optical merging circuit 55, and finally this optical frequency filter The optical signal output from is f7. By changing the combination of the operating optical gates of the front and rear optical gate / switch arrays 42 and 44, it is easy to select an arbitrary signal light from the other 19 frequency signal lights from these figures and Table 5. Can be understood. Therefore, by using this filter, the frequency interval is 100 GHz.
It is possible to take out one arbitrary light from the light having 20 optical frequency components arranged at equal intervals. Table 5 (c) shows the correspondence between the extracted optical frequency and the gate that transmits current and transmits light.

In this embodiment, by combining the operation gates of the two optical frequency filters, it is possible to extract a signal light of an arbitrary frequency from 20 frequency multiplexed signal lights in a frequency range from 191.0 THz to 192.9 THz. it can. The number of electrodes to be controlled is nine. Conventionally, when an arrayed waveguide grating having a transmission characteristic of a Gaussian distribution is formed in a plurality of stages, the passing band tends to gradually narrow due to a design error or the like. An arrayed waveguide grating having the following structure is placed, and the signal to be selected can always pass through the center of the transmission band by devising the arrangement of the input waveguide of the subsequent arrayed waveguide grating at the connection point of the slab waveguide. Thereby, the effect of suppressing the band narrowing can be expected.

In this embodiment, the case where an optical amplifier is used as the optical gate switch has been described. However, other devices capable of changing the light transmittance, such as an absorption type modulator and a grating reflector, are used. The same effect can be expected in this case. Also, as an optical merging circuit, N
The case of input M output has been described, but the number of input ports,
Similar effects can be expected if the number of output ports is N or M or more, respectively.

[0079]

According to the present invention, as described above in detail based on the embodiments, it is possible to realize an optical frequency filter in which the number of optical frequencies (wavelengths) that can be selected by controlling a small number of electrodes is remarkably increased. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a first embodiment of the present invention.

FIG. 2A is an arrayed waveguide grating filter 1, 7;
2B is a graph showing the transmission spectrum of the arrayed waveguide grating filters 3 and 11, and FIG. 2C is a graph showing the transmission spectrum of the entire optical frequency filter.

FIG. 3 is a configuration diagram illustrating a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional example.

FIG. 5 is a configuration diagram illustrating a specific example of an optical convergence circuit and an optical convergence distribution circuit;

FIG. 6 is a configuration diagram illustrating a third embodiment of the present invention.

FIG. 7A shows an arrayed waveguide grating filter 31;
FIG. 7B is a graph showing transmission spectra for the array waveguide grating filters 33 and 45, and FIG. 7C is a graph showing transmission spectra for the entire optical frequency filter.

FIG. 8 is a configuration diagram illustrating a fourth embodiment of the present invention.

FIG. 9 is a configuration diagram illustrating a fifth embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a design of an input waveguide of an arrayed waveguide grating filter 53 according to a fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a relationship between input and output optical frequencies of an arrayed waveguide grating filter 53 according to a fifth embodiment of the present invention.

FIG. 12 is a graph showing transmission characteristics of an arrayed waveguide grating filter 53 according to a fifth embodiment of the present invention.

[Explanation of symbols]

1,3 Array waveguide grating filter 7,11 Array waveguide grating filter 2,4,8,10,11 Semiconductor amplifier / gate array 5 Optical converging circuit 6,12 Optical gate control electrode 9 Optical converging / distributing circuit 13, Reference Signs List 18 input optical waveguide 16, 21 output optical waveguide 14, 15, 19, 20 slab waveguide 17, 22 array waveguide 23 optical gate control electrode 24 InP substrate 31, 33 array waveguide grating filter 32, 34 semiconductor amplifier / gate Arrays 35, 55 Optical converging circuits 36, 46, 56 Electrode gate control electrodes 41, 45 Array waveguide grating filters 42, 44 Semiconductor amplifier gate array 43 Optical converging / distributing circuits 51, 53 Array waveguide grating filters 52, 54 Semiconductor Amplifier Gate Array 110 Arrayed Waveguide Lattice Demultiplexer 111 Arrayed Waveguide Sub-combiner 112 Semiconductor amplifier / gate array 120 InP substrate 121, 126 Input optical waveguide 125, 130 Output optical waveguide 122, 124, 127, 129 Slab waveguide 123, 128 Array waveguide

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yuzo Yoshikuni 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Japan Telegraph and Telephone Corporation (72) Inventor Hiroyuki Ishii 3- 192-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo No. Within Nippon Telegraph and Telephone Corporation (72) Inventor Masaki Shintoku 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo F-term within Nippon Telegraph and Telephone Corporation (reference) 2H079 AA05 AA13 BA01 CA07 DA16 EA05 EA07 EB15 HA07 5K002 BA02 BA05 BA06 BA07 DA02 FA01

Claims (5)

[Claims] 1. A first arrayed waveguide grating filter having a function of splitting light incident on one input waveguide into at least two or more output waveguides for each different optical frequency, An optical frequency filter comprising an optical gate switch for transmitting or blocking the demultiplexed light between a second arrayed waveguide grating filter having an operation of multiplexing the split light into one waveguide, In the first and second arrayed waveguide grating filters, the waveguides are arranged such that the difference between the optical frequencies to be demultiplexed or multiplexed between adjacent output waveguides or input waveguides is equal in all arrayed waveguide gratings. The interval between the transmitted light frequencies periodically arranged in the first arrayed waveguide grating filter and the interval between the transmitted light frequencies periodically generated in the second arrayed waveguide grating filter is the difference between the optical frequencies. Differently, the difference in length between adjacent array waveguides of the first array waveguide grating filter;
The difference in length between adjacent array waveguides of the second array waveguide grating filter is set to be a different value,
Further, an optical gate switch for transmitting or blocking the demultiplexed light is connected to at least two or more output waveguides of the second arrayed waveguide grating filter, and optically coupled to the output waveguide of the optical gate switch. An optical frequency filter to which a circuit is connected. 2. A first arrayed waveguide grating filter having the function of splitting light incident on one input waveguide into at least two or more output waveguides for each different optical frequency, An optical frequency filter comprising an optical gate switch for transmitting or blocking the demultiplexed light between a second arrayed waveguide grating filter having an operation of multiplexing the split light into one waveguide, In the first and second arrayed waveguide grating filters, the waveguides are arranged such that the difference between the optical frequencies to be demultiplexed or multiplexed between adjacent output waveguides or input waveguides is equal in all arrayed waveguide gratings. The interval between the transmitted light frequencies periodically arranged in the first arrayed waveguide grating filter and the interval between the transmitted light frequencies periodically generated in the second arrayed waveguide grating filter is the difference between the optical frequencies. Differently, the difference in length between adjacent array waveguides of the first array waveguide grating filter;
The difference in length between adjacent array waveguides of the second array waveguide grating filter is set to be a different value,
Further, an optical junction switch is connected to the output waveguide of the optical gate switch, and an optical gate switch for transmitting or blocking the split light is provided to at least two or more output waveguides of the optical junction switch. An optical frequency filter, wherein the output waveguides of the optical gate switch are connected to different input waveguides of a second arrayed waveguide grating filter. 3. An optical frequency filter in which an optical gate switch for transmitting or blocking light split by the first arrayed waveguide grating filter is connected between two arrayed waveguide grating filters. In the arrayed waveguide grating filter, the waveguides are arranged so that the difference between the optical frequencies demultiplexed to the adjacent output waveguides and the interval between the transmitted light frequencies periodically generated in the second arrayed waveguide grating filter are equal. Alternatively, in the second arrayed waveguide grating filter, the difference between the optical frequencies demultiplexed to adjacent output waveguides is equal to the interval of the transmitted light frequency periodically generated in the first arrayed waveguide grating filter. An optical gate switch for transmitting or blocking the demultiplexed light to at least two output waveguides of the second arrayed waveguide grating filter. And an optical converging circuit connected to an output waveguide of the optical gate switch. 4. An optical frequency filter in which an optical gate switch for transmitting or blocking light split by the first arrayed waveguide grating filter is connected between two arrayed waveguide grating filters. In the arrayed waveguide grating filter, the waveguides are arranged so that the difference between the optical frequencies demultiplexed to the adjacent output waveguides and the interval between the transmitted light frequencies periodically generated in the second arrayed waveguide grating filter are equal. Alternatively, in the second arrayed waveguide grating filter, the difference between the optical frequencies demultiplexed to adjacent output waveguides is equal to the interval between the transmitted light frequencies periodically generated in the first arrayed waveguide grating filter. A waveguide is arranged so that the optical gate switch is connected to an output waveguide of the optical gate switch, and at least two or more output waveguides of the optical merge / distribution circuit are connected to the output waveguide. An optical gate switch for transmitting or blocking the distributed light is connected, and an output waveguide of the optical gate switch is connected to different input waveguides of the second arrayed waveguide grating filter. An optical frequency filter. 5. An optical frequency filter in which an optical gate switch for transmitting or blocking light split by the first arrayed waveguide grating filter is connected between two arrayed waveguide grating filters. In the output waveguide of the arrayed waveguide grating filter, transmitted light whose optical frequency band transmitted is equal to or higher than the optical frequency band transmitted by the first arrayed waveguide grating filter and periodically generated by the first arrayed waveguide grating filter It is set within the range of the frequency interval or less, and in the second arrayed waveguide grating filter, the difference between the optical frequency demultiplexed to the adjacent output waveguide and the first arrayed waveguide grating filter periodically. The second arrayed waveguide grating is arranged such that the interval between the generated transmitted light frequencies is shifted by the difference between the optical frequencies split into adjacent output waveguides by the first arrayed waveguide grating filter. An optical gate switch for transmitting or blocking the demultiplexed light is connected to at least two output waveguides of the second arrayed waveguide grating filter, wherein the input waveguide of the filter is disposed; An optical frequency filter, wherein an optical converging circuit is connected to the output waveguide of the switch.