JPH0634534B2 - Wavelength / time division optical switch - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch for exchanging a signal as an optical signal between an input optical signal and an output optical signal which are wavelength division multiplexed and time division multiplexed.

(Prior Art) Optical communication using an optical fiber in a transmission line has an advantage that a large amount of information can be transmitted because the optical fiber has a wide band and the optical fiber does not receive induced noise. Therefore, it is expected to be widely used in the future. The switch used in this optical communication is preferably an optical switch capable of switching optical signals in the optical range. Such an optical switch includes, for example, Japanese Patent Application No. 58-033069, "Optical Switch," which is a wavelength-division-changing input and output optical signal that is wavelength-swapped and wavelength-switched. An optical switch has been proposed which performs both of the split switching.

FIG. 2 is a diagram showing such a conventional optical switch, which is an input optical highway 20 that is time division multiplexed and n wavelength division multiplexed.
A means T211 for performing time division exchange for each wavelength connected to the input terminal 1, and a means for performing wavelength division exchange for each time slot connected to this input terminal at the output terminal λ21
2 and means for performing time-division exchange for each wavelength connected to the output terminal of the output optical highway 210 which is time-division multiplexed and n wavelength-division multiplexed with the output terminal as the input terminal.

FIG. 3 is a time chart diagram for explaining the operation of FIG.

In FIG. 3, 4001, 4004, 4007 and 4010 represent time slot sequences of the time division optical signal of wavelength λ ₁ . Similarly 4002, 400
5, 4008 and 4011 represent time slot sequences of the time division optical signal of wavelength λn. The time slot trains 4001 and 4002 correspond to the optical signal on the input optical highway in FIG. 2, the time slot trains 4004 and 4005 correspond to the optical signal between T211 and λ212 in FIG. 2, and the time slot train 4007, 4008 corresponds to the optical signal between λ212 and T213 in FIG. 2, and the time slot trains 4010 and 4011 are the output optical highway 10 in FIG.
Corresponds to the optical signal above. At T211, the time slot is moved at the same wavelength of the input optical signal, and as a result, the signal corresponding to the time slot 4003 is moved to 4006 in the output optical signal of T211. At λ212, as a result of moving the time slots aligned with the same time of the optical signal output from T211, the signal corresponding to the time slot 4006 in the output optical signal of λ212 moves to 4009. At T213, the time slot is moved between the signals of the same wavelength of the optical signal output from λ12, and as a result, the optical signal on the output optical highway 10 moves the signal corresponding to the time slot 4009 to 4012. By thus adopting the three-stage configuration of T211, λ212, and T213, a call can be made between a signal of an arbitrary time slot having an arbitrary wavelength of an input signal and a signal of an arbitrary time slot having an arbitrary wavelength of an output optical signal. Channels can be formed.

FIG. 4 is a diagram showing a concrete example of the means T211 for performing time division exchange for each wavelength shown in FIG. According to Fig. 4, T211
Is an optical demultiplexer 112 having an input terminal connected to an input optical highway 111 which is time division multiplexed and n wavelength division multiplexed, and input terminals are respectively connected to n output terminals of the optical demultiplexer 112. n optical time switches 113, and n input terminals were connected to the output terminals of the n optical time switches 113, and time-division multiplexed and n wavelength division multiplexed output optical highways 115 were connected to the output terminals. An optical multiplexer 114 is included. The input optical signal is demultiplexed by the optical demultiplexer 112 into time division optical signals of wavelengths λ ₁ , λ _{2 to} λn, and each time division optical signal is time division exchanged by n optical time switches. The optical time switch output of each wavelength is multiplexed by the optical multiplexer 114. In this way, time-division exchange for each wavelength is performed between the input optical highway 111 and the output optical highway 115. Light time switch 11
For example, the optical phase conversion switch described in JP-A-53-2012 can be used as the switch 3. JP-A-53-2012 discloses 2
An optical delay line memory in which an optical switch with two inputs and two outputs and a delay circuit with an optical fiber are connected in a ring and an optical time switch for circulating and memorizing light and performing a predetermined delay and then reading the light to form a time slot are configured. ing.

To enter. The wavelength conversion element 124 receives λ ₁ , λ _2, ... Whichever of the n wavelengths of λ ₁ , λ _{2 ,} .
The optical signal of any one of the n wavelengths of λn is output. The outputs of the n wavelength conversion elements 124 having different wavelengths are output to the output optical highway 126 that is multiplexed by the optical multiplexer 125.

The tunable wavelength selection element 123 is, for example, a tunable wavelength selection element using an EO grating control optical directional coupler which can be configured by an EO grating control optical directional coupler in which an EO grating is provided on an optical directional coupler on a LinbO ₃ substrate. For details, see, for example, Miki et al. "LiNbO ₃ Waveguide Wavelength Tunable Filter" Proceedings of the Autumn Meeting of the Applied Physics Society of Japan in 1981.
See 9P-M-9P246.

FIG. 6 is a diagram showing a specific example of the wavelength conversion element 124 shown in FIG. According to FIG. 6, the wavelength conversion element 124 shown in FIG. 5 includes a 1 × 2 optical switch 1242 whose input terminal is connected to an input optical highway 1241, and this optical switch 1242.
Output of this harmonic wave generating element 1243, the output of this harmonic wave generating element 1243, and the second output of the optical switch 1242, and the output of this optical wave combiner 1244. Is included as an input, and the output optical highway 1246 includes an injection type semiconductor laser 1245 connected to the output. Input optical highway 12
The optical signal having the wavelength of λi transmitted from 41 is converted to a wavelength in which λi is shorter than the output wavelength λi peculiar to the injection type semiconductor laser. Input directly to the device 1244.
On the other hand, in the case of wavelength conversion in which λi has a wavelength longer than λj, it is input to the optical switch 1242, converted into an optical signal having a wavelength shorter than λj, and input to the optical multiplexer 1244. Optical switch over
The switching of 1242 is performed by the communication path control unit that stores the wavelengths of λi and λj as data. This allows the optical multiplexer
Each of the outputs of 1244 is an optical signal having a wavelength shorter than λj, and by injecting it into the injection type semiconductor laser 1245,
The injection type semiconductor laser 1245 oscillates at λj, and an optical signal wavelength-converted from λi to λj is sent to the output optical highway 1246. The high frequency generating element 1243 can be realized by a non-linear optical crystal such as LiNbO ₃ crystal. Injection type semiconductor laser 1245
Can be realized, for example, by a semiconductor laser having a planar stripe type double hetero structure. For more information on injection type semiconductor lasers, refer to Kawaguchi “Bistable Oscillations of Semiconductor Lasers” IEICE Technical Report ED81-10, PP7-13.

(Problems to be Solved by the Invention) In such a conventional exchange that handles wavelength-division-multiplexed and time-division-multiplexed optical signals, means T211 and T212 for performing time-division switching for each wavelength and each time slot are provided. Since a total of three means λ212 for performing wavelength division switching are required for
There is a drawback that the hardware becomes large when the number of optical components required is large and the number of lines is large.

An object of the present invention is to provide an optical switch which handles time division multiplexed and wavelength multiplexed signals with a small amount of hardware even if the number of optical components required is small and the number of lines is large.

(Means for Solving the Problems) A wavelength / time division optical switch provided by the present invention is a wavelength division multiplexing in which a plurality of time division multiplexed optical signals having a plurality of time slots and different wavelengths are wavelength division multiplexed. A time-division-multiplexed optical signal is incident from an input optical highway, and the wavelength-division-multiplexed and time-division-multiplexed optical signal from the input optical highway is branched into a plurality of wavelength-division-multiplexed and time-division-multiplexed optical signals. An optical branching device, a plurality of wavelength selecting elements for selecting an optical signal of a specific wavelength from a plurality of wavelength division multiplexed and time division multiplexed optical signals from the optical branching element, and outputs of the plurality of wavelength selecting elements A plurality of variable wavelength conversion circuits, each of which receives an optical signal and converts the optical signal into an optical signal of an arbitrary wavelength for each time slot, and each of the optical signals from the plurality of variable wavelength conversion circuits, is input. A matrix optical switch that emits light to an arbitrary output end; a plurality of optical delay elements that receive an optical signal from the matrix optical switch and have a difference in delay amount that is an integer multiple of the time per one time slot; An optical combiner that combines the optical signals from the optical delay element and outputs the combined optical signal to the output optical highway, and the matrix optical switch is configured to replace a plurality of input optical signals with each of the time slots. It is characterized in that each of the plurality of optical delay elements connected to the output end is switched.

The wavelength / time-division optical switch provided by the present invention further includes a plurality of optical switches in which the matrix optical switch has a plurality of output ends and outputs an input optical signal to any of the plurality of output ends. , And a plurality of optical combiners that combine and output the optical signals from the plurality of optical switches.

(Operation) In the present invention, by adopting such a configuration, a specific wavelength is selected from the wavelength-division-multiplexed and time-division-multiplexed optical signals, and the optical signal of the selected wavelength is wavelength-switched for each time slot. Since it can be performed and the time slots can be exchanged, an optical signal of an arbitrary wavelength and an arbitrary time slot can be connected to an arbitrary outgoing line, and since it has a one-stage configuration, the number of optical components can be reduced as compared with the conventional one.

(Embodiment) FIG. 1 is a diagram showing a wavelength / time division optical switch according to a first embodiment of the present invention, which is an example of a wavelength division multiplexing degree of 2 and a time division multiplexing degree of 3.

The time-division optical signals of wavelengths λ ₁ and λ ₂ on the input optical highway 1 are input to the wavelength selection elements 3 and 4 via the optical branching device 2. The wavelength selection elements 3 and 4 select optical signals of wavelengths λ ₁ and λ ₂ from the wavelength multiplexed optical signals and send them to the variable wavelength conversion circuits 5 and 6. The variable wavelength converters 5 and 6 convert the wavelengths into wavelengths λ ₁ and λ ₂ for each output time slot of the wavelength selection elements 3 and 4, and send them to the optical switches 7 and 8, respectively. Optical switch 7, 8 and optical combiner, 9, 10 and 11 are 2 × 3
It constitutes a matrix optical switch. Optical switch 7,
Reference numeral 8 sends the outputs of the variable wavelength conversion circuits 5 and 6 to any one of the optical multiplexers 9, 10 and 11 for each time slot. The optical multiplexers 9, 10, and 11 are fiber delay lines having delay amounts of T2T and 3T (T is a time per one time slot) of the outputs of the optical switches 7 and 8 with respect to the input optical signal, respectively. Send to 12, 13, and 14. Fiber delay line 12, 13,
The output from 14 is sent to the output highway 16 via the optical combiner 8.

FIG. 7 is a time chart for explaining the operation of FIG. As an example, the signal of the first time slot T ₁ of the optical signal of the wavelength λ ₁ of the input highway 1 is output to the highway.
A case where the 16 optical signals of wavelength λ ₂ are output to the third time slot T ₃ will be described. The wavelength selection element 3 of FIG.
Since the optical signals of the wavelengths λ ₁ and λ ₂ are selected from the input highway 1 signals of the four wavelengths λ ₁ and λ _2, the variable wavelength conversion circuits 5 and 6 input the input highway 1 signal 700 of the wavelength λ ₁ , respectively.
The input highway signal 701 of wavelength λ ₂ is input. As shown in the input signal 702 of the optical switch 7, the wavelength of the optical signal in the first time slot T ₁ is converted from the wavelength λ ₁ to λ ₂ by the variable wavelength conversion circuit 5. The optical switch 7 sends the optical signal of wavelength λ _{2 to} the fiber delay line 13 via the optical multiplexer 10 in the input first time slot T ₁ . Then, if a delay amount of two time slots is given to the optical signal by the fiber delay line 13, the output of the fiber delay line 13 progresses.
As shown at 705, the signal of wavelength λ _{2 in} the first time slot T ₁ of the fiber delay line input signal 704 moves to the third time slot T ₃ . Therefore output highway 16 signal 70
As shown in the output highway 16 signal of wavelength λ ₂ out of 6, 707, the first optical signal of wavelength λ ₁ of input highway 1
The optical signal of the time slot T ₁ can be output to the third time slot T ₃ of the light traveling of the wavelength λ ₂ of the output highway 16. As described above, with the configuration shown in FIG. 1, it becomes possible to move the input optical signal of an arbitrary time slot of an arbitrary wavelength to an arbitrary time slot of an arbitrary wavelength. Further, since it has a one-stage structure, it is possible to reduce the number of optical components as compared with the conventional one.

FIG. 8 is a diagram showing a specific example of the variable wavelength conversion circuits 5 and 6 in FIG. The input optical signal 81 is converted into an electric signal by the photoelectric converter 82 and sent to the modulator 88. To the modulator 88, the DC light of the wavelength selected by the variable wavelength selection 87 is input from the wavelength multiplexed light obtained by combining the outputs of the light sources 83 and 85 of the wavelengths λ ₁ and λ ₂ by the optical combiner, and An output optical signal 89 is emitted according to the output of the electric converter 82. FIG. 8 shows an example in which the wavelength λ ₁ of the input signal 81 and the selection wavelength of the variable wavelength selection element 87 are λ ₂ , and the wavelength conversion from λ ₁ to λ ₂ is performed. The output wavelength can also be changed for each time slot by switching the selected wavelength of the variable wavelength selection element 87 for each time slot. A wavelength conversion circuit using a non-linear optical element described in Japanese Patent Application No. 61-209008 is used as an optical / electrical converter 82.
If used instead of the modulator 88, the same effect can be obtained without converting an optical signal into electricity. Further, a configuration in which the variable wavelength light source is modulated by the output of the optical / electrical converter 82 is also possible.

(Effects of the Invention) As described above, according to the wavelength / time-division optical switch of the present invention, an optical signal of an arbitrary wavelength and an arbitrary time slot can be connected to an arbitrary outgoing line, and since it has a single-stage configuration, it has a conventional three-stage structure. The number of optical components can be reduced compared to the configuration, and the hardware can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram showing a conventional optical switch, FIG. 3 is a time chart diagram for explaining the operation of FIG. 2, and FIG. FIG. 2 is a diagram showing a concrete example of means T ₁₁ for performing time division switching for each wavelength, and FIG. 5 is a diagram showing a concrete example of means λ 12 for performing wavelength division switching for each time slot of FIG. FIG. 6 is a diagram showing a concrete example of the wavelength conversion element 124 of FIG. 5, FIG. 7 is a time chart diagram for explaining the operation of FIG. 1, and FIG. 8 is a concrete example of the variable wavelength conversion circuit of FIG. It is a figure which shows an example. In the figure, 1 is an input optical highway, 2 is an optical branching device, 3 and 4 are wavelength selection elements, 5 and 6 are variable wavelength conversion circuits, 7 and 8 are optical switches, and 9, 10, 11, 15 Is an optical coupler, 12, 13, and 14 are fiber delay lines, and 16 is an output optical highway.

Claims (2)

[Claims] 1. A wavelength-division-multiplexed and time-division-multiplexed optical signal in which a plurality of time-division multiplexed optical signals having a plurality of time slots and different wavelengths are wavelength-division-multiplexed is input from an input optical highway. An optical branching device for branching the wavelength division multiplexed and time division multiplexed optical signal from the highway into a plurality of wavelength division multiplexed and time division multiplexed optical signals; and a plurality of wavelength division multiplexed and time division optical signals from the optical branching device. A plurality of wavelength selection elements for selecting an optical signal of a specific wavelength from the division-multiplexed optical signals, and output optical signals of the plurality of wavelength selection elements are respectively input and converted into optical signals of arbitrary wavelengths for each time slot. A plurality of variable wavelength conversion circuits; a matrix optical switch that receives each of the optical signals from the plurality of variable wavelength conversion circuits and outputs it to an arbitrary output end; A plurality of optical delay elements whose optical signals are input from the switch and the difference in delay amount is an integer multiple of the time per time slot, and the optical signals from the plurality of optical delay elements are combined to output optical signals. An optical combiner for outputting to a highway, and the matrix optical switch is provided to each of a plurality of optical delay elements connected to the output end for replacing a plurality of input optical signals with each of the time slots. Wavelength / time division optical switch characterized by switching. 2. The matrix optical switch has a plurality of output terminals and outputs an input optical signal to an arbitrary output terminal of the plurality of output terminals; and a plurality of optical switches from the plurality of optical switches. The wavelength / time division optical switch according to claim 1, comprising a plurality of optical combiners that combine and output optical signals.