JPS61184997A - Light time switch - Google Patents

Abstract

PURPOSE:To decrease the necessary number of an optical delaying means by forming the optical signal of plural wavelengths by the means to separate for every time slot and output from the mutually different output terminals, plural light delaying means and the light coupler and using multiply the light delaying means by plural wavelengths. CONSTITUTION:An optical signal on an input light highway 101, for which the time base and wavelength base are multiplexed, is branched to the time base optical signal of three wavelengths lambda1, lambda2 and lambda3 a light branching filter 102, and inputted into optical switches 103, 104 and 105 of 1X3 respectively. The optical switches 103, 104 and 105 are respectively inputted for respective time slots for the time base signal of respective wavelengths prior to light branching filters 106, 107 and 108 to either of the first, second and third light delaying lines 109, 110 and 111 in which the mutual difference of propagating delay times is an integer-fold of the time of one time slot. The optical signal of wavelengths lambda1, lambda2 and lambda3 to which prescribed delay is given by respective light delay lines 109, 110 and 111, is linked by a light coupler 112 and sent to an output light highway 113.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical time switch that time-divisionally exchanges time-division multiplexed and wavelength-division multiplexed optical signals as they are.

(Prior art) Optical communication using optical fibers as transmission paths has advantages such as being able to transmit a large amount of information because the optical fiber has a wide band, and that the optical fiber is not subject to induced noise. Therefore, it is expected that it will be widely used in the future. Optical switching equipment used in this optical communication is preferably an optical switching equipment that can exchange optical signals in the optical domain without converting optical signals into electricity and exchanging them in electrical circuits. Application 58-033069 ``Optical switching equipment'' performs both time-division exchange, which swaps time slots between time-division and wavelength-division multiplexed input optical signals and output optical signals, and wavelength division exchange, which swaps wavelengths. An optical switch has been proposed.

FIG. 5 is a diagram showing the configuration of the optical switch described in the above-mentioned Japanese Patent Application No. 58-033069. Optical signals on the input optical highway 510 that have been subjected to 0 time division multiplexing and n wavelength division multiplexing are passed through the optical time switch 511. Time division exchange consultation for each wavelength,
Subsequently, the optical wavelength switch 512 performs wavelength division switching for each time slot, and finally, the optical time switch 513 performs time division switching for each wavelength again, and then sends out to the output optical highway 514.

FIG. 6 is a time chart for explaining the operation of the optical exchange shown in FIG.

In FIG. 6, 6001, 6004, 6007,
6010 represents a time slot sequence of a time division multiplexed optical signal of wavelength ^1; similarly, 6002, 6005, 600
8, 6011 is the wavelength λ.

Time slot sequences 6001 and 6002 representing the time slot sequence of the time division multiplexed optical signal correspond to the optical signal on the input optical highway 510 in FIG. 5, and time slot sequences 6004 and 6005 represent the optical time in FIG. The time slot arrays 6007 and 6008 correspond to the optical signals between the switch 511 and the optical wavelength switch 512, and the time slot arrays 6007 and 6008 correspond to the optical wavelength switch 512 and the optical time switch 513 in FIG.
A time slot sequence 6010 corresponds to an optical signal between.

6011 corresponds to the optical signal on the output optical highway 514 in FIG. When the optical time switch 511 moves the input optical signal between time slots with the same wavelength, the signal corresponding to the time slot 6003 moves to 6006 in the output optical signal of the optical time switch 511. In the optical wavelength switch 512, when the optical signals output from the optical time switch 511 are shifted between wavelengths in the same time slot, the optical wavelength switch 512
In the output optical signal of , the signal corresponding to time slot 6006 moves to 6009. In the optical time switch 513c, as a result of moving the optical signal output from the optical wavelength switch 512 between time slots of different times with the same wavelength, the optical signal on the output optical highway 514 corresponds to the time slot 6009. The signal moves to 6012. In this way, the optical time switch 511 and the optical wavelength switch 5
12. By adopting a three-stage configuration of the optical time switch 513, a communication channel is established between a signal of an arbitrary wavelength and an arbitrary time slot of the input optical signal and a signal of an arbitrary wavelength and an arbitrary time slot of the output optical signal. can be formed.

FIG. 7 is a diagram showing a specific example of the optical time switch 511 shown in FIG. According to FIG. 7, the optical time switch 51
1 is an optical demultiplexer 7112 connected to an input terminal of an input optical highway 7111 subjected to time division multiplexing and wavelength division multiplexing.
and n single wavelength optical time switches 7113 whose input terminals are respectively connected to the n output terminals of this optical demultiplexer 7112.
and an optical multiplexer 7114 having n input terminals connected to the output terminals of the n single-wavelength optical time switches 7113 and an output terminal connected to an output optical highway 7115 subjected to time division multiplexing and wavelength division multiplexing. , the input optical signals are converted into λ1 . Each time-division multiplexed optical signal is time-division-switched by n single-wavelength optical time switches 7113, and the single-wavelength optical time switches 7113 The outputs are multiplexed by an optical multiplexer 7114. In this way, time-division exchange for each wavelength is performed between the input optical highway 7111 and the output optical highway 7115.

FIG. 8 shows the single wavelength optical time switch 711 shown in FIG.
FIG. 3 is a diagram showing a specific example of No. 3;

According to FIG. 8, the single wavelength optical time switch includes a 1×3 optical switch 8102 whose input terminal is connected to an input optical highway 8101, and a first, second, and third output terminal of this optical switch 8102. first, second, and third optical delay lines 8103 whose input terminals are connected to each other and whose propagation delay times have a difference in integer multiple of one time slot;
8104 and 8105, and this optical delay wA8103,
Connect the input terminal to the output terminal of 8104 and 8105 (7), and connect the output terminal to the output optical highway 8107.
The input-stage optical switch 8102, which includes the optical coupler 8106 and the optical coupler 8106, can be configured using, for example, an optical directional coupler. (For details on optical switches using optical directional couplers, see Kondo et al., ``Car-Mode Optical Fiber Array 1''
．． 37＠LiNbO54 8102, first, second and third optical delay lines 8103, 8104 and 81 for each time slot.
05 and is delayed by a predetermined tom slot. The optical signals of each time slot given a predetermined delay from each optical delay line 8103, 8104, and 8105 are combined by an optical coupler 8106 and sent to an output optical highway 8107 as an output time division multiplexed optical signal. By doing so, the time slots of the optical signals at the input wavelengths are switched, and the device operates as an optical time switch.

(Problems to be Solved by the Invention) As described above, in the conventional optical time switch shown in FIG. 7, which performs time division switching for each wavelength, the single wavelength optical time switch 71
13 is required for the number of wavelengths multiplexed (n). Since the single wavelength optical time switch 7113 requires a plurality of optical delay lines 8103, 8104, and 8105 as shown in No. 8rXJ, the conventional optical time switch that performs time division switching for each wavelength requires an extremely large number of optical delay lines, etc. requires optical delay means of
This caused an increase in the number of parts in the optical switch.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical time switch that can receive time-division and wavelength-division multiplexed optical signals and perform time-division switching for each wavelength, and that requires only a small number of optical delay means such as optical delay lines. .

(Means for Solving the Problems) In order to solve the above-mentioned problems, the optical time switch provided by the first invention of the present application uses input light that transmits time-division multiplexed and wavelength-division multiplexed optical signals. means for separating optical signals of a plurality of wavelengths into time slots and outputting them from different output terminals, each having an input terminal connected to a highway; It is characterized by comprising a plurality of optical delay means whose time is an integral multiple of the time of a slot, and an optical coupler which combines the output lights of the plurality of optical delay means and outputs it to an output optical highway.

In order to solve the above-mentioned problems, the optical time switch provided by the second invention of the present application is provided with an input optical signal that is time-division multiplexed and wavelength-division multiplexed to an input terminal, and for each time slot, the input optical signal is n optical demultiplexers that split the signal into two groups of optical signals in terms of wavelength and output them to a first output terminal and a second output terminal, respectively; The propagation delay time inserted between the first output terminal of the demultiplexer and the i+1th input terminal of the optical demultiplexer is 1.
n-1 optical delay means equal to the time of a time slot, the second output terminals of the first to n-1th branching filters, and the first output of the nth branching filter; an optical coupler each having a plurality of input terminals connected to its terminals, the input terminal of the first branching filter being connected to the input optical highway, and the output terminal of the optical coupler being connected to the output optical highway. It is characterized by

(Function) The present invention reduces the required number of optical delay means by using multiple optical delay means at multiple wavelengths.

(Embodiment) FIG. 1 is a block diagram showing a first embodiment of the first invention of the present application.An optical signal on an input optical highway 101 that has been subjected to time division and wavelength division multiplexing is sent to an optical demultiplexer 102. by λ
1. Enter 1. input, and are demultiplexed into time-division optical signals of three wavelengths, each of which is connected to a 1×3 optical switch 103 , 104 , 105 .
is input to. Optical switches 103, 104, and 105 pass the time-division optical signals of each wavelength through optical multiplexers 106, 107, and 108 for each time slot, so that the difference in propagation delay time is equal to the time of one time slot. First, second and third optical delay lines 109, 110 which are integral multiples
, 111 respectively. For example, from the optical switches 103, 104, 105 to the optical delay line 10
The optical signals inputted to λ8.9 have different wavelengths, and have wavelengths of λ8. λ1. λ. And each optical delay line 109
, 110, 111, the wavelength λ3. Enter 8. The input optical signals are combined by an optical coupler 112 and sent to an output optical highway 113.

FIG. 2 is a diagram showing a second embodiment of the first invention of the present application. In FIG. 2, for example, a variable demultiplexer 202 diffracts an arbitrary plurality of wavelength optical signals among inputted time-division and wavelength-division multiplexed optical signals for each time slot, and outputs the optical signals from a first output terminal 209. It has a function of outputting an optical signal of another wavelength from the second output terminal 210. Further, the propagation delay times of optical delays *204°205 and 206 are respectively 1, 2 and 3 times the same time as one time slot. Further, 217, 218, 219 are the wavelengths λ1 . λ2. λ
, and 220 , 221 , 222 represent the optical signal strings of wavelengths λ1 . λ8. ^, represents an optical signal train.

As an example, time slot T! on input optical highway 201! The optical signal 213 with the wavelength λ1 is moved to the time slot T on the output optical highway 208 and the optical signal 21
The case where it is set to 4 will be explained. In the time slot TI, the variable demultiplexer 202 is controlled so as to output the optical signal at the input wavelength from the output terminal 210 without diffracting it. In the time slot T+, the variable demultiplexer 203
It is controlled to diffract an optical signal of wavelength λ1 and output it from output terminal 211.

As a result, the optical signal 213 is input to the optical delay line 205 and given a delay of two time slots, and then passes through the optical coupler 207 and becomes the optical signal 214 in the time slot T on the output optical highway 208. . At this time, in time slot T1, the variable demultiplexer 202 does not diffract not only the optical signal of wavelength λ1 but also the optical signal of wavelength λ8, and in the time slot TI, the variable demultiplexer 203 diffracts the optical signal of wavelength λ8. If controlled, the optical signal 215 of wavelength λ8 on the input optical highway 201 will also be transmitted to the output optical highway 2.
Time slot T on 08.

The optical signal 216 can be moved to the optical signal 216 .

In this way, the second embodiment of the present invention shown in FIG. 2 uses optical delay lines 204, 205, and 206 for wavelength multiplexing to
A predetermined delay can be given to the time-division optical signal of 11 people, λ.

FIG. 3 is a plan view showing a specific example of the variable duplexer 202 in FIG. 2. The variable demultiplexer 202 includes a transducer 302 that performs electro-sonic wave conversion and is configured on a crystal 301 (eg, niobium oxide) having an acousto-optic effect.

By applying the output of a high-frequency power supply 303 (this power supply is represented by a symbol in the figure) at a frequency fl, the transducer 302 also generates a sound wave, and the input light 304 with a wavelength λ, ~, applied to the crystal 301. A specific wavelength λ
Only the optical signal of 1 is diffracted by the acousto-optic effect and becomes diffracted light 3
05, and the optical signals other than input and input go straight and are output as undiffracted light 306.

In this variable demultiplexer, by changing the output frequency of the high frequency power source 303, it is possible to diffract only an optical signal of an arbitrary wavelength. Furthermore, if the high frequency power source 303 has a plurality of output frequencies, it is possible to simultaneously diffract optical signals of a plurality of wavelengths corresponding to each frequency. Regarding such a variable demultiplexer, see the literature IEE, Journal of Quantum Electronics, CIEEE, Journal of Qu.
antum Electronics) Volume 13, 1
It is described in detail in the February 977 issue, pages 43-46.

FIG. 4 is a diagram showing an embodiment of the second invention of the present application.

In FIG. 4, for example, a variable demultiplexer 402 diffracts optical signals of arbitrary plural wavelengths among inputted time-division and wavelength-division multiplexed optical signals for each time slot.
The second output terminal 411 outputs an optical signal having a wavelength that cannot be diffracted. Further, the propagation delay time of the optical delay lines 403, 405 and 407 is equal to the time of one time slot. 416, 417, 41
8 is the wavelength λ1.8 on the input optical highway 401. λ8. λ,
419° 420, 421 are the optical signal trains of λ1° input 2. on the output optical highway 409. The optical signal train of λ,
424 , 428 , 429 are the wavelengths λ1 . λ8. input, optical signal strings 426, 43
0, 431 is the wavelength λ1 input to the variable demultiplexer 406
．． λ1. λ, respectively represent optical signal trains.

As an example, an optical signal 422 of wavelength λ at time slot T+ on input optical highway 401 is moved to time slot T on output optical highway 409, and optical signal 422 is moved to time slot T on output optical highway 409.
23 will be explained. Time slot T1
The variable demultiplexer 402 is controlled to diffract the optical signal of wavelength λ1 and output it from the output terminal 410. As a result, the optical signal 422 is input to the optical delay line 403 and given a delay of one time slot, and becomes an optical signal 425 that is input to the variable demultiplexer 404 at time slot T. In time slot T, the variable demultiplexer 424 is controlled to diffract an optical signal with a wavelength input □ and output it from the output terminal 412. As a result, the optical signal 425 is input to the optical delay line 405 and further delayed by one time slot.
6 becomes an optical signal 427 inputted to 6. time slot T
In , the variable demultiplexer 406 is controlled so as to output the optical signal of wavelength λ□ from the output terminals 4 and 5 without diffracting it.

As a result, the optical signal 427 passes through the optical coupler 408 and becomes the optical signal 423 on the output optical highway 409.

At this time, the variable demultiplexer 402
, 404 and 406 are controlled to diffract not only the optical signal of wavelength λ1 but also the optical signal of wavelength λ, the optical signal 432 of wavelength λ of time slot T on the input optical highway 401 will be output in the same way. The optical signal 433 of time slot T on the optical highway 409 can be moved to the optical signal 433 .

In this manner, the third embodiment of the present invention shown in FIG.
1. λ8. A predetermined delay can be given to the time-division optical signal of λ.

(Effects of the Invention) According to the present invention, as explained above, it is possible to receive time-division and wavelength-division multiplexed optical signals and perform time-division exchange for each wavelength, and a small number of optical delay means such as optical delay lines are required. We can provide an optical time switch that is sufficient for

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram showing a first embodiment of the first invention of the present application, and FIG. 2 is a block diagram showing a second embodiment of the first invention of the present application. 3 is a plan view showing a specific example of the variable demultiplexer 203 in the embodiment shown in FIG. 2, FIG. 4 is a block diagram showing an embodiment of the second invention of the present application, and FIG. A block diagram showing the configuration, FIG. 6 is a time chart for explaining the operation of the conventional optical switch shown in FIG. 5, and FIG. 7 is an optical time switch 511 in the conventional optical switch shown in FIG.
FIG. 8 is a block diagram showing a specific example of the single wavelength optical time switch 7113 in the optical time switch of FIG. 102, 7112... optical demultiplexer, 103, 104
, 105 , 8102... optical switch, 106 ,
107, 108, 7114... optical multiplexer, 109
, 110 , 111 , 204 , 205 , 206
, 403 , 405 . 407, 8103, 8104, 8105... optical delay line, 112, 207. 408, 8106... optical coupler, 202, 20
3, 402, 404, 406... variable demultiplexer,
301... Acousto-optic crystal, 302... Transducer, 303... High frequency power supply. Representative Patent Attorney Shinsuke Honjo Figure 3 Figure 7 Figure 8

Claims (2)

[Claims] (1) means whose input terminal is connected to an input optical highway through which time-division multiplexed and wavelength-division multiplexed optical signals are transmitted, and which separates optical signals of a plurality of wavelengths for each time slot and outputs them from different output terminals; A plurality of optical delay means each having an input terminal connected to the output terminal and each having a difference in propagation delay time that is an integral multiple of the time of one time slot, and output light by combining the output lights of the plurality of optical delay means. An optical time switch characterized by comprising an optical coupler that outputs to a highway. (2) An input optical signal that has been time-division multiplexed and wavelength-division multiplexed is applied to the input terminal, and the input optical signal is demultiplexed into two groups of optical signals in terms of wavelength for each time slot. n optical demultiplexers each outputting to an output terminal, the first output terminal of the i-th (1≦i≦n-1) optical demultiplexer and the i+1-th optical demultiplexer; n-1 optical delay means inserted between the input terminals and whose propagation delay time is equal to the time of one time slot;
an optical coupler having a plurality of input terminals connected to the second output terminal of the first demultiplexer and the first output terminal of the n-th demultiplexer, respectively; An optical time switch characterized in that an input terminal of a demultiplexer is connected to an input optical highway, and an output terminal of the optical coupler is connected to an output optical highway.