JPH09186693A - Optical atm switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a switch which has high speed and large capacity and is easy in the reduction of optical power loss and the synchronization of an optical signal as compared with a conventional optical ATM switch. SOLUTION: Bufferings are performed for the electric ATM cells of plural input lines in input buffer circuits 2-1 to 2-N. The optical short pulse strings of plural wavelengths are generated at the repeating period corresponding to the signal speed of the electric ATM cells and the pulse strings are inputted in the time division multiplex circuits 4-1 to 4-m corresponding to each wavelength In the time division multiplex circuits 4-1 to 4-m corresponding to each wavelength, intensity modulations are performed for the optical short pulse strings by the electric ATM cells of the plural channels, the pulse strings are converted into optical ATM cells, a bit multiplex is performed for the optical ATM cell of each channel and the cell is outputted. A wavelength multiplex is performed for the optical ATM cell for which the bit multiplex is performed for each wavelength, by an optical star coupler 6. On the output side of the optical star coupler 6, the optical pulse of a prescribed time slot is selected from the optical ATM cell for which the bit multiplex is performed for each wavelength, further the optical ATM cell of a prescribed wavelength is selected from the optical pulse of the prescribed time slot and the cell is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed and large capacity optical ATM switch capable of not only one-to-one communication but also multicasting.

[0002]

2. Description of the Related Art FIG. 18 shows the structure of a conventional time division type optical ATM switch. In the figure, a cell signal string in which the number of bits of one cell is L and the time length of one cell is T is input from input signal lines 91-1 to 91-n having a signal speed V (bit / s). . Cell coder 92-1 corresponding to each input signal line
92-n are optical short pulse trains with a repetition period 1 / V (s) supplied from the short pulse light source 93 through the optical coupler 94, which are modulated by the electric cells of the respective input signal lines to be converted into optical signals.
Further, it is converted into a high-speed optical cell and output. These high-speed optical cells are time-division multiplexed by the optical star coupler 95 to generate high-speed optical highways and distribute them to each outgoing line.

For each outgoing line, the cell selectors 96-1 to 96-n for selecting a desired optical cell, the cell buffers 97-1 to 97-n for controlling outgoing line conflict avoidance, and the high-speed optical cell are used as original sources. Cell decoders 98-1 to 98- for converting to low-speed electric cells
n are connected in order. The address information is the cell coder 92.
From the cell selector 9
Address determination is performed at 6 to control the cell selector 96 and the cell buffer 97. The cell buffer 97 is 1 × m
It consists of an optical tree type switch, an optical fiber delay line and an optical coupler.

[0004]

The conventional optical ATM switch shown in FIG. 18 is called an output buffer type optical ATM switch and has a simple structure and a small number of internal blocks. The advantage is that the effects of disability are less likely to occur. However, (1) optical power loss is high when generating high-speed optical cells, (2) it is difficult to realize an optical cell memory in a cell buffer, (3) it is difficult to synchronize when detecting optical cells, etc. There was a problem.

According to the present invention, the capacity can be increased by utilizing time division and wavelength division, and it is easy to adopt a configuration according to traffic and switch throughput.
It is an object of the present invention to provide an optical ATM switch that can reduce optical power loss and can easily synchronize optical signals as compared with a TM switch.

[0006]

The optical ATM switch of the present invention is an electric ATM switch which is input from a plurality of input lines.
Buffer cells in the input buffer circuit. on the other hand,
An optical short pulse train of a plurality of wavelengths is generated at a repetition period corresponding to the signal speed of an electric ATM cell, and is input to a time division multiplexing circuit corresponding to each wavelength. In the time division multiplexing circuit corresponding to each wavelength, the optical short pulse train is intensity-modulated by a plurality of channels of electrical ATM cells to be converted into optical ATM cells, and the optical ATM cells of each channel are bit-multiplexed and output. The optical ATM cell bit-multiplexed for each wavelength is input to the optical star coupler and wavelength-multiplexed. On the output side of the optical star coupler, a predetermined time slot is selected from the optical ATM cells bit-multiplexed for each wavelength, and further an optical ATM cell having a predetermined wavelength is selected from the optical ATM cells of the predetermined time slot and output. To do.

Further, when a plurality of cells are allowed to arrive at each output in the same cell cycle, a plurality of time slots are selected, and an optical ATM cell of a predetermined wavelength is selected from the optical ATM cells of the respective time slots. Then, the data is output in parallel, and the output buffer circuit controls and outputs the contention. in this way,
In the optical ATM switch of the present invention, functions such as optical cell generation, bit multiplexing, optical cell selection, and synchronization are realized by optical signal processing technology using optical short pulse and wavelength multiplexing technology, and buffering processing is performed by electrical technology. To be realized. Thus, for example, if the electrical processing time is sub-nanosecond, the width of the optical short pulse is several picoseconds, and the wavelength multiplexing number is about 4 to 8, Tbi
A capacity of the order of t / s can be obtained, and AT can be obtained by conventional electrical signals.
The signal speed of the M switch can be increased and the switch capacity can be increased. Further, the optical power loss is reduced as compared with the conventional optical ATM switch, and the optical signal is easily synchronized. Further, the input / output buffer circuit can be configured according to the traffic and the switch throughput.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The optical ATM switch of the present invention is divided into a case where competition control of the same cell cycle is performed and a case where competition control is not performed. The optical ATM switch according to a first aspect of the present invention is configured to perform contention avoidance control on the input side so that a plurality of cells do not arrive at each output in the same cell cycle.

The optical ATM switch according to the second and third aspects has a configuration in which contention avoidance control is performed on the input side, and control is performed to allow each cell to arrive at a plurality of cells within the same cell period with a predetermined number as an upper limit. is there. The optical ATM switch according to a fourth aspect of the present invention has a configuration in which contention avoidance control is not performed on the input side, and the number of cells arriving at each output in the same cell cycle is unlimited.

(First Embodiment) The first embodiment is a configuration in which conflict avoidance control is performed on the input side, and settings are made so that a plurality of cells do not arrive at each output in the same cell cycle. FIG. 1 shows a first embodiment of the optical ATM switch of the present invention. In the figure, 1-1 to 1-N are electric ATM cell input lines, 2-1 to 2-N are input buffer circuits, 3 is a multi-wavelength short pulse light source, and 4-1 to 4-m are n inputs respectively. Time division multiplexing circuit connected to the buffer circuit, 5-1 to 5-1
5-m is an input optical waveguide having an equal optical path length, 6 is an optical star coupler, 7-1 to 7-N are output optical waveguides, and 8-1 to
8-N is an optical cell selection circuit, 10-1 to 10-N are optical ATs.
M cell output line, 100 is input buffer circuits 2-1 to 2-
It is a control circuit for controlling N and the optical cell selection circuits 8-1 to 8-N. The optical cell selection circuits 8-1 to 8-N include a time slot selection circuit 20 and a wavelength selection circuit 50, respectively.
It consists of.

An electric ATM cell having a signal speed V (bit / s) is
Electric ATM cell input lines 1-1 to 1-N are input to the corresponding input buffer circuits 2-1 to 2-N. Each input buffer circuit sends the destination address of the cell at the head of the cell memory to the control circuit 100. Control circuit 10
0 controls transmission of cells from the input buffer circuit based on each address so that contention of cells does not occur on the output side.
A well-known control algorithm (reference: Arturo Cisneros, et al., "A largeATM switc
h based on memory switches and optical star cou
pler ", IEEE, J.Selected areas in communications, V
ol.9, No.8, pp.1348-1360, 1991).

An optical short pulse train of wavelengths λ _{1 to} λ _m with a repetition period 1 / V (s) output from the multi-wavelength short pulse light source 3 is
These are respectively input to the time division multiplexing circuits 4-1 to 4-m.
The time division multiplexing circuit 4-1 is an electric AT that outputs the optical short pulse train of wavelength λ ₁ from the input buffer circuits 2-1 to 2-n.
It is modulated by M cells, converted into an optical signal, bit-multiplexed and output. The same applies to the time division multiplexing circuits 4-2 to 4-m to which the optical short pulse trains with wavelengths λ _{2 to} λ _m are input.

The outputs of the time division multiplexing circuits 4-1 to 4-m are input to the optical star coupler 6 via the input optical waveguides 5-1 to 5-m, and the time positions of the leading bits are aligned. The wavelengths are multiplexed from λ ₁ to λ _m . Time-division multiplexed and wavelength-multiplexed optical ATM cells are output to the output optical waveguides 7-1 to 7-m of the optical star coupler 6. The time slot selection circuit 20 of the optical cell selection circuits 8-1 to 8-N selects a time slot corresponding to a desired one channel from the bit-multiplexed optical ATM cells. Wavelength selection circuit 50
Selects a desired wavelength of one channel from the wavelengths λ _{1 to} λ _m . The control of the time slot selection circuit 20 and the wavelength selection circuit 50 is performed based on the routing information received by the control circuit 100 from each input buffer circuit.

(Second Embodiment) The second embodiment has a configuration in which contention avoidance control is performed on the input side and a plurality of cells are allowed to arrive at each output within the same cell period with a predetermined number as an upper limit. is there. FIG. 2 shows a second embodiment of the optical ATM switch of the present invention. The difference from the first embodiment is that each of the optical cell selection circuits 8'-1 to 8'-N has a plurality of optical ATMs.
The cells are selected in parallel, and the output buffer circuits 9-1 to 9-N are selected.
In this case, the competition of a plurality of optical ATM cells is controlled and output to the optical ATM cell output lines 10-1 to 10-N. The optical cell selection circuits 8'-1 to 8'-N have k sets of time slot selection circuits 20 'and wavelength selection circuits 50', respectively, and the time slot selection circuits 20'-1 to 20-k are cascaded. It is a connected configuration. Other configurations are the same as those of the first embodiment.

The optical cell selection circuits 8'-1 to 8'-N include
Input of a plurality of optical ATM cells time-division multiplexed and wavelength-multiplexed in the same cell cycle is allowed. The time slot selection circuits 20'-1 to 20'-k sequentially select time slots of desired channels and send them to the corresponding wavelength selection circuits 50'-1 to 50'-k. The wavelength selection circuits 50'-1 to 50'-k select wavelengths multiplexed in each time slot and output buffer circuits 9-1 to 9-1.
9-N in parallel. Note that the number of sets of the time slot selection circuit 20 'and the wavelength selection circuit 50' is determined by the required switch throughput, and the output buffer circuit 9 is required to have the ability to process as many inputs as the number of outputs.

(Third Embodiment) The third embodiment is a configuration in which the contention avoidance control is not performed on the input side and no upper limit is set for the number of cells arriving at each output in the same cell cycle. FIG. 3 shows a third embodiment of the optical ATM switch of the present invention. The difference from the second embodiment is that the input buffer circuits 2'-1 to 2'-N set the destination address of the cell to the control circuit 1.
00, and the cell transmission control is not performed. Therefore, as in the second embodiment,
The optical cell selection circuits 8'-1 to 8'-N and the output buffer circuits 9-1 to 9-N process a plurality of optical ATM cells time-division multiplexed and wavelength-multiplexed in the same cell cycle. In addition, the time slot selection circuit 20 'and the wavelength selection circuit 5
The number of 0's is determined by the required switch throughput, and the output buffer circuit 9 is required to have the ability to process the number of outputs.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A configuration example of each constituent element in each embodiment of the optical ATM switch of the present invention will be described below. (Configuration Example of Each Component in First Embodiment) FIG.
Shows a configuration example of the multi-wavelength short pulse light source 3.

The multi-wavelength pulse light source 3 shown in (a), optical short pulse laser 11-1 to 11-m of the oscillation wavelength lambda ₁ to [lambda] _m
It consists of. Each short light pulse laser is synchronized with a control electric signal for generating a short light pulse. The multi-wavelength short pulse light source 3 shown in (b) has a predetermined wavelength band (for example, 1.55).
High power short pulse laser 12 having an oscillation wavelength of (μm band) 12
, A dispersion shift fiber 13 having a minimum dispersion value in the wavelength band, and a 1 × m demultiplexer 14 demultiplexing into wavelengths λ _{1 to} λ _m.
It consists of. When a short optical pulse of high peak intensity output from the high output short pulse laser 12 is input to the dispersion shift fiber 13, several types of optical nonlinear effects occur, and a short optical pulse train having an ultra-wide band (several 10 nm) spectrum is generated. Generated (reference: T. Morioka, et al., "Multiple
output, 100Gbit / s all-optical demultiplexer based
on multichannel four-wave mixing pumped by a li
nearly-chirped square pulse ", Electron. Lett., Vol.
30, No. 23, pp.1956-1961, 1994). By demultiplexing the short optical pulse train by the 1 × m demultiplexer 14, wavelengths λ _{1 to} λ
A short optical pulse train of _m is obtained.

FIG. 5 shows a configuration example of the time division multiplexing circuit 4-1. In the figure, the time division multiplexing circuit 4-1 includes a 1 × n branching device 15, intensity modulators 16-1 to 16-n, and optical waveguides 17-1 to 17-for giving a relative time delay between optical path lengths.
It is composed of n and n × 1 combiners 18. The optical short pulse train of wavelength λ ₁ output from the multi-wavelength short pulse light source 3 is 1
Intensity modulators 16-1 to 16-1 are branched into n by the × n splitter 15.
6-n is input. Intensity modulator 16-1 to 16-n
Is an input buffer circuit 2-1 for the optical short pulse train of wavelength λ _1.
It is modulated by the electric ATM cells outputted from ~ 2-n and converted into an optical signal. The n-channel optical ATM cell has an optical waveguide 17- having a relative time delay Δt between adjacent channels.
Since it is input to the n × 1 combiner 18 via 1 to 17-n, it is bit-multiplexed for each Δt and output from the n × 1 combiner 18. The same applies to the time division multiplexing circuits 4-2 to 4-m to which the optical short pulse trains with wavelengths λ _{2 to} λ _m are input.

Here, the time division multiplexing circuit 4 when n = 3
FIG. 6 shows an operation example of -1 to 4-m. (1) is an electric ATM cell input to the time division multiplexing circuits 4-1 to 4-m, (2)
Is an intensity modulator 16-1 of the time division multiplexing circuits 4-1 to 4-m.
Is converted by the intensity modulator 16-2 of the time division multiplexing circuits 4-1 to 4-m and converted into the optical waveguide 17-2. The output channel 2 optical ATM cell, (4) is the channel 3 optical ATM cell which is converted by the intensity modulator 16-3 of the time division multiplexing circuits 4-1 to 4-m and output to the optical waveguide 17-3. ,
(5) is an optical ATM cell bit-multiplexed with the wavelength λ ₁ output from the time-division multiplexing circuit 4-1 and (6) is bit-multiplexed with the wavelength λ ₂ output from the time-division multiplexing circuit 4-2. Light A
TM cell (7) is an optical ATM cell bit-multiplexed at the wavelength λ _m output from the time division multiplexing circuit 4-m.

FIG. 7 shows a configuration example of the time slot selection circuit 20 in the first embodiment. In the figure, the time slot selection circuit 20 includes an optical branching device 21, an optical synchronization circuit 22, an optical switch 23, and an optical switch drive circuit 24. The time slot selection circuit is an extremely difficult band to handle electrically when selecting a desired optical cell from a high-speed optical signal train exceeding 100 Gbit / s, so optical / optical processing is effective Is. Specifically, optical / optical switching using an optical nonlinear effect, an optical PLL circuit, or the like is used.

FIG. 8 shows a configuration example of the optical switch 23 and the optical switch drive circuit 24 in the first embodiment.
In the figure, the optical switch drive circuit 24 is composed of an optical switch control light source 31 and a cell selection timing setting circuit 32. The optical switch 23 includes a multiplexer 33, an optical fiber 34, a demultiplexer 35, and an analyzer 36.

Here, in the time slot selection circuit 20 of the optical cell selection circuit 8-1 to which the bit-multiplexed optical ATM cell is input, the optical switch 2 using the optical nonlinear effect is provided.
An example of operation No. 3 will be described with reference to FIG. Wavelength λ ₁
Signal light of λ _m and control light pulse of wavelength λ ₀ are combined by the multiplexer 33.
Are multiplexed and input to the optical fiber 34. By giving an appropriate power to the control light pulse, a third-order optical nonlinear effect (optical Kerr effect) occurs in the optical fiber 34, and the refractive index changes. As a result, in the signal light whose timing coincides with that of the control light pulse, a phase difference occurs between the orthogonal polarizations, and when the phase difference deviates by just π, the direction of the linear polarization rotates 90 degrees. Therefore, the signal light corresponding to the control light pulse can be selected by adjusting the analyzer 36 on the output side to the polarization direction of the switching pulse. The control light pulse is separated from the signal light by the demultiplexer 35.

The optical fiber 34 may be an ordinary one, or an optical waveguide (such as a chalcogenide optical fiber) doped with a substance having a large nonlinear constant may be used (reference: M. Asobe, et al., "Laser"). -diode-driven ultrafast
all-optical switching byusing highly nonlinear c
halcogenide glass fiber ", OSA, Optical Letters, Vo
l.18, No.13, pp.1056-1058, 1993). As another configuration of the optical switch 23 using the optical nonlinear effect, for example, one using four-wave mixing or one using a nonlinear Sagnac interferometer can be used.

In the optical ATM switch of the present invention, it is necessary to switch the selected bit string for each cell cycle. Therefore, the optical switch drive circuit 24 causes the optical switch control light source 31 to output an optical pulse of a predetermined cycle according to the output of the optical synchronization circuit 22, and the cell selection timing setting circuit 32 provides control information provided from the control circuit 100. The phase of the optical pulse is controlled in accordance with the above, and is given to the optical switch 23 as a control optical pulse.

The optical synchronizing circuit 22 for bit-synchronizing the control light pulse and the signal light detects the correlation between the signal light pulse and the clock pulse by modulating the gain of the traveling wave type semiconductor laser amplifier with a clock, and detects the detected phase. This can be realized by an optical phase-locked loop that feeds back the error output to the clock and synchronizes the frequency of the clock pulse with the repetition frequency of the signal light pulse (Kawanishi, et al. "Ultrafast optical pulse synchronization technology using all-optical correlation detection") , NTT R & D, vol.42, No.5,
pp.679-688, 1993).

FIG. 10 shows a cell selection timing setting circuit 3
2 shows a configuration example. In the figure, the cell selection timing setting circuit 32 alternately connects the 2 × 2 optical switches 41-1 to 41-M and the optical delay line pairs 42-1 to 42-M, and finally connects the 2 × 1 optical coupler 43. It is a connected configuration. The optical delay line pair 42-1 in the first stage has a relative time difference of Δt, the optical delay line pair 42-2 in the second stage has a relative time difference of 2Δt, ... ^M-1 Δt. The control signal of the 2 × 2 optical switch 41 is the control circuit 10
Given from 0. Note that the relationship between the number M of 2 × 2 optical switches and the number n of multiplexed channels is Log ₂ n ≦ M.

Here, an operation example in the case of 4-channel multiplexing will be described with reference to FIG. In this case, the two 2 × 2 optical switches 41-1 and 41-2 are controlled. It is assumed that the 2 × 2 optical switches 41-1 and 41-2 are in the through state when 0 is given as a control signal and in the cross state when 1 is given. The control signals of the 2 × 2 optical switches 41-1 and 41-2 are 2 bits,
A control signal (1, 0) that sets a delay of 0 when channel 1 is selected, a control signal (0, 1) that sets a delay of 1 when channel 2 is selected, and a control signal (0, 1) that sets delay 1 when channel 2 is selected. Control signal (1, 1) for setting delay 2 and control signal (0, 0 for setting delay 3 when channel 4 is selected
0) is used.

FIG. 12 shows a configuration example of the wavelength selection circuit 50 in the first embodiment. In the figure, the wavelength selection circuit 50 includes a 1 × m demultiplexer 51 and optical gate circuits 52-1 to 52-5.
It is composed of a 2-m, m × 1 multiplexer 53. Wavelength-multiplexed light of the selected channel time slot selection circuit 20 is inputted is demultiplexed on the wavelength lambda ₁ to [lambda] _m at 1 × m demultiplexer 51 to the optical gate circuits 52-1 to 52-m. An optical ATM cell having a desired wavelength is selected by the corresponding optical gate circuit and output to the optical ATM cell output line 10 via the m × 1 multiplexer 53.

(Structural example of each constituent element in the second embodiment) Multi-wavelength short pulse light source 3 and time division multiplexing circuit 4
Is similar to that of the first embodiment. FIG. 13 shows a configuration example of the time slot selection circuit 20 'in the second embodiment. In the figure, a time slot selection circuit 2
0'is an optical branching device 21, an optical synchronizing circuit 22, an optical switch 2
3 ', composed of an optical switch drive circuit 24.

FIG. 14 shows a configuration example of the optical switch 23 'and the optical switch drive circuit 24 in the second embodiment. In the figure, an optical switch drive circuit 24 is shown as an optical switch control light source 31 and a cell selection timing setting circuit 3.
2. The optical switch 23 'includes the multiplexer 3
3, an optical fiber 34, a demultiplexer 35, and a polarization beam splitter 37.

Here, an operation example of the optical switch 23 'using the optical nonlinear effect in the time slot selection circuit 20' of the optical cell selection circuit 8'-1 to which the bit-multiplexed optical ATM cell is input is shown in FIG. Will be described with reference to.
The functions of the multiplexer 33, the optical fiber 34 and the demultiplexer 35 are similar to those of the first embodiment. At one output of the demultiplexer 35, the polarization of the signal light whose timing coincides with that of the control light pulse is rotated by 90 degrees and extracted. The polarization beam splitter 37 has an optical ATM cell of a predetermined channel corresponding to a control light pulse to be sent to the wavelength selection circuit 50 ', and a time slot selection circuit 2 of the next stage, according to the polarization state of the signal light.
The optical ATM cells of the remaining channels to be sent to 0'are separated. The optical switch drive circuit 24 is similar to that of the first embodiment.

FIG. 12 shows an example of the structure of the wavelength selection circuit 50 'in the second embodiment. In the figure, a wavelength selection circuit 50 'includes a 1 × m demultiplexer 51 and an optical gate circuit 52.
-1 to 52-m. The wavelength-multiplexed light of the channel selected by the time slot selection circuit 20 'is 1 ×
The wavelengths of λ _{1 to} λ _m are demultiplexed by the _m demultiplexer 51 and input to the optical gate circuits 52-1 to 52-m. Light of desired wavelength A
The TM cell is selected by the corresponding optical gate circuit and output to the output buffer circuit 9.

(Another Configuration Example of Optical Cell Selection Circuit 8'in the Second Embodiment ... Claim 3) FIG. 13 shows another configuration example of the optical cell selection circuit 8'in the second embodiment. In the figure, an optical cell selection circuit 8'displays the wavelength-division multiplexed light input from the output optical waveguide 7 of the optical star coupler 6 at wavelengths λ ₁ ~
1 × m demultiplexer 51 that demultiplexes to λ _m , and a plurality of time slot selection circuits 20′-1 to 20′-j on each demultiplexing output line.
Are arranged. Time slot selection circuit 20 '
-1 to 20'-j have the same configurations as those shown in FIGS. 13 and 14, and the time slot of the desired channel is sequentially selected for each wavelength to output buffer circuits 9-1 to 9-.
Send to N in parallel. In the present configuration, the wavelength selection circuit 50 is unnecessary as compared with the configuration shown in FIG. 2, but the number of time slot selection circuits 20 is increased.

[0035]

As described above, the optical ATM of the present invention
Since the switch uses the optical short pulse train with a small pulse width for high-speed processing and uses the wavelength multiplexing technique,
It is possible to generate high speed optical highway of bit / s level.
This makes it possible to realize a large-capacity optical ATM switch capable of multicasting.

Further, in the structure using the output buffer circuit, the traffic characteristic can be improved. Also,
It is superior to the conventional optical ATM switch in terms of reduction of optical power loss and ease of synchronization, and can also increase switch throughput.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of an optical ATM switch of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the optical ATM switch of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the optical ATM switch of the present invention.

FIG. 4 is a block diagram showing a configuration example of a multi-wavelength short pulse light source 3.

FIG. 5 is a block diagram showing a configuration example of a time division multiplexing circuit 4-1.

FIG. 6 is a time division multiplexing circuit 4-1 to 4-m when n = 3.
3 is a timing chart showing an operation example of FIG.

FIG. 7 is a block diagram showing a configuration example of a time slot selection circuit 20 according to the first embodiment.

FIG. 8 is a block diagram showing a configuration example of an optical switch 23 and an optical switch drive circuit 24 according to the first embodiment.

FIG. 9 is a diagram for explaining the operation of the optical switch 23.

FIG. 10 is a block diagram showing a configuration example of a cell selection timing setting circuit 32.

FIG. 11 is a diagram showing an operation example of the time slot selection circuit 20.

FIG. 12 is a block diagram showing a configuration example of a wavelength selection circuit 50 according to the first embodiment.

FIG. 13 is a block diagram showing a configuration example of a time slot selection circuit 20 ′ according to the second embodiment.

FIG. 14 is a block diagram showing a configuration example of an optical switch 23 ′ and an optical switch drive circuit 24 according to a second embodiment.

FIG. 15 is a view for explaining the operation of the optical switch 23 ′.

FIG. 16 is a wavelength selection circuit 50 ′ according to the second embodiment.
FIG. 3 is a block diagram showing a configuration example of FIG.

FIG. 17 is an optical cell selection circuit 8 ′ according to the second embodiment.
The block diagram which shows the other structural example.

FIG. 18 is a block diagram showing a configuration of a conventional time division type optical ATM switch.

[Explanation of symbols]

 1 Electric ATM Cell Input Line 2 Input Buffer Circuit 3 Multi-wavelength Short Pulse Light Source 4 Time Division Multiplexing Circuit 5 Input Optical Waveguide 6 Optical Star Coupler 7 Output Optical Waveguide 8 Optical Cell Selection Circuit 9 Output Buffer Circuit 10 Optical ATM Cell Output Line 11 Short Optical pulse laser 12 High-power short pulse laser 13 Dispersion shift fiber 14 1 × m demultiplexer 15 1 × n splitter 16 Intensity modulator 17 Optical waveguide 18 n × 1 combiner 20 Time slot selection circuit 21 Optical splitter 22 Optical Synchronous circuit 23 Optical switch 24 Optical switch drive circuit 31 Optical switch control light source 32 Cell selection timing setting circuit 33 Multiplexer 34 Optical fiber 35 Splitter 36 Analyzer 37 Polarizing beam splitter 41 2 × 2 optical switch 42 Optical delay line Pair 43 2 × 1 optical coupler 50 Wavelength selection circuit 51 1 × m demultiplexer 52 Optical gate Circuit 53 m × 1 multiplexer 100 controller

Claims (6)

[Claims] 1. A plurality of input buffer circuits for buffering electric ATM cells respectively inputted from a plurality of input lines, and optical short pulse trains of a plurality of wavelengths at a repetition period corresponding to a signal speed of the electric ATM cells. Multi-wavelength short pulse light source, and a plurality of electric short pulse trains for each wavelength
A plurality of time division multiplexing circuits for intensity-modulating cells to convert into optical ATM cells, and bit-multiplexing for each wavelength, and outputting the wavelength-multiplexed optical ATM cells for bit-multiplexing for each wavelength. An optical star coupler, a time slot selection circuit for selecting a predetermined time slot from the optical ATM cells bit-multiplexed for each wavelength, and an optical ATM cell of a predetermined wavelength from the optical ATM cells of the predetermined time slot. A plurality of optical cell selection circuits having a wavelength selection circuit, and each electric ATM notified from the input buffer control circuit
An optical ATM switch comprising: a conflict avoidance control of the input buffer circuit based on a destination address of a cell; and a control circuit for controlling selection of a time slot and a wavelength of each of the optical cell selection circuits. 2. A plurality of input buffer circuits for buffering electric ATM cells respectively inputted from a plurality of input lines, and generating optical short pulse trains of a plurality of wavelengths at a repetition period corresponding to a signal speed of the electric ATM cells. Multi-wavelength short pulse light source, and a plurality of electric short pulse trains for each wavelength
A plurality of time division multiplexing circuits for intensity-modulating cells to convert into optical ATM cells, and bit-multiplexing for each wavelength, and outputting the wavelength-multiplexed optical ATM cells for bit-multiplexing for each wavelength. An optical star coupler, a plurality of time slot selection circuits for selecting a predetermined time slot from optical ATM cells bit-multiplexed for each wavelength, and an optical ATM cell having a predetermined wavelength from the optical ATM cells of each selected time slot. A plurality of optical cell selection circuits each having a plurality of wavelength selection circuits for selecting cells and outputting the cells in parallel, and a plurality of optical ATM cells respectively output in parallel from the plurality of optical cell selection circuits are controlled to control competition. A plurality of output buffer circuits for outputting, and each electric ATM notified from the input buffer control circuit
An optical ATM switch comprising: a conflict avoidance control of the input buffer circuit based on a destination address of a cell; and a control circuit for controlling selection of a time slot and a wavelength of each of the optical cell selection circuits. 3. An optical demultiplexer for demultiplexing, for each wavelength, an optical ATM cell bit-multiplexed for each wavelength, in place of the plurality of optical cell selection circuits of the optical ATM switch according to claim 2. An optical ATM switch comprising a plurality of optical cell selection circuits having a plurality of time slot selection circuits for selecting optical ATM cells of a predetermined time slot from each demultiplexed output and outputting them in parallel. 4. The time slot of each optical cell selection circuit based on the destination address of each electric ATM cell notified from the input buffer control circuit instead of the control circuit of the optical ATM switch according to claim 2. An optical ATM switch having a control circuit for controlling wavelength selection. 5. The optical AT according to claim 1 or 2.
In the M switch, the time division multiplexing circuit includes a 1 × n branching device for branching an optical short pulse train into n and an electric ATM corresponding to each optical short pulse train.
N intensity modulators that perform intensity modulation in cells, n optical waveguides that give a relative time delay to the optical ATM cells of each channel output from each intensity modulator, and optical ATM cells that have passed through each optical waveguide. An optical ATM switch, comprising: an n × 1 combiner that outputs by bit multiplexing. 6. The optical AT according to claim 1 or 2.
In the M switch, the time slot selection circuit of the optical cell selection circuit includes an optical branching device that branches an optical ATM cell that is bit-multiplexed and is input, and a bit of a control optical pulse that is input from one of the branched optical ATM cells. An optical synchronizing circuit for synchronizing, an optical switch driving circuit for controlling the phase of a control optical pulse which is bit-synchronized according to a selected channel, and the other branched optical ATM
An optical ATM switch, comprising: an optical switch for inputting cells to select an optical ATM cell of a channel according to the control optical pulse.