JP3746093B2 - Frequency multiplexing optical switch - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a frequency multiplex optical switch that is connected to a frequency multiplex transmission line using light such as an optical fiber and outputs an arbitrary frequency channel of an incoming path to an arbitrary outgoing path.
[0002]
[Prior art]
The literature on the conventional device of the frequency multiplexing optical switch includes “Introduction to optical switching technology” written by Kenichi Yukimatsu, which describes three methods. One of them is to input the frequency multiplexed optical signal of the incoming path to the frequency channel selection element and separate it by frequency, and input each separated frequency light to the optical matrix switch and output it to the desired outgoing path. This is a circuit switching method. The second is a system in which the optical signal of the incoming route is branched by the number of outgoing routes and input to the multi-frequency selection filter, and only light of a desired frequency is output to the outgoing route. The third method is a method in which a circuit-switching switch capable of setting a circuit for each frequency of an input multi-frequency optical signal is constituted by, for example, a 2 × 2 switch of an acousto-optic (AO) element.
[0003]
[Problems to be solved by the invention]
Among these conventional methods, the first method is advantageous in that power loss is small and switching of a large number of routes can be easily realized. A conventional switch N (M, N is a natural number) that handles M multiple lines of frequency multiplicity N is connected to a frequency channel selection element for each multiple line, and is separated into N frequency-specific outputs. Each frequency is configured to be connected to the matrix switch. Therefore, even if only the input stage is considered, the NxM connecting lines cross three-dimensionally, so that there is a disadvantage that the space factor is bad and the manufacturing is troublesome.
[0004]
It is an object of the present invention to provide a frequency division multiplexing optical switch having a simple configuration that eliminates the drawbacks of the prior art.
[0005]
[Means for Solving the Problems]
According to the present invention, input / output ends are connected to M optical transmission lines that transmit frequency-multiplexed optical signals that are frequency-multiplexed to a multiplicity N (M and N are natural numbers, respectively), and the frequency between the input / output ends is In a frequency multiplexing optical switch that switches multiplexed optical signals, the optical switch has M input terminals to which frequency multiplexed optical signals are input and is connected to M optical transmission lines and demultiplexes the frequency multiplexed optical signals. A demultiplexing element for outputting N optical signals having different frequencies to M sets and NxM output terminals, and NxM input terminals for receiving N sets of N optical signals having different frequencies from each other. A multiplexing element that multiplexes M sets of N optical signals into frequency multiplexed optical signals of N multiplicity and outputs them from M output terminals, and M input terminals to which optical signals of the same frequency are input. The input optical signal is input to the desired output terminals of the M output terminals. N matrix switches that output to N and Mx optical signals of the same frequency among optical signals obtained from the NxM output terminals of the demultiplexing element are input to the same switch of the N matrix switches. First connection means connected to the ends and M output ends of the same switch among the N matrix switches are respectively connected to M input ends of the same frequency among the input ends of the multiplexing elements. Second connection means.
[0006]
According to the present invention, M first ports for transmitting frequency multiplexed optical signals each having N multiplicity and NxM second ports for transmitting N sets of N optical signals having different frequencies from each other. When the frequency multiplexed optical signals arrive at the M first ports, they are demultiplexed and output to the NxM second ports, and the NxM second ports have different frequencies. When N optical signals arrive, an optical frequency router is provided that multiplexes them and outputs them to the M first ports.
[0007]
Thus, M input / output terminals connected to the frequency multiplexing transmission line, M output terminals of the demultiplexing element connected to each of the M input / output terminals of the N matrix switches, and multiplexing The M input ends of the element are adjacent to each other. Therefore, the optical fiber connecting the input / output ends of the switch or the connection means of the optical connection path on the optical wiring board is arranged in parallel, and the multiplicity N is separated and multiplexed inside the frequency router of the input / output stage. Therefore, the number of connection wirings is reduced as compared with the conventional method.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a frequency multiplexing optical switch according to the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a functional block diagram showing an embodiment of a frequency multiplexing optical switch according to the present invention. The frequency multiplexing optical switch 10 of the embodiment has two frequency routers 11 and 12, and the frequency router 11 on one side, that is, the incoming side, accommodates the frequency multiplexing optical transmission line of the optical fiber cable of the incoming path 13. The other side, that is, the outgoing side frequency router 12 accommodates a frequency multiplexed optical transmission line of the optical fiber cable of the outgoing route 14, and outputs an arbitrary frequency channel of the incoming route 13 to the arbitrary outgoing route 14. It is a circuit switching device.
[0009]
The frequency routers 11 and 12 may have the same configuration. In this embodiment, the frequency routers 11 and 12 are 9 × 9 type optical routing elements having a maximum frequency multiplexing number of 9 that can be handled by 9 ports. As shown in FIG. 3, the logical configuration includes nine ports a of # 1 to # 9 and nine ports b of # 1 to # 9, and the optical signal of the input port a that is frequency-multiplexed. Is routed to output port b. Each of the ports a1 to a9 and b1 to b9 has frequency selection characteristics as shown in FIG. More specifically, when optical signals having different frequencies f0 to f8 are input to the ports a1 to a9, the optical signals having the frequencies shown in the respective columns in the matrix 15 are output to the ports b1 to b9. Similarly, when optical signals having frequencies f0 to f8 are input to the ports b1 to b9, optical signals having the frequencies shown in the respective rows in the matrix 15 are output to the ports a1 to a9. When such an optical routing element is applied to the ingress frequency router 11, only the input ports a1, a2 and a3 are used, and when applied to the egress frequency router 12, the output ports a1, a2 and a3 Use only. In this example, the frequencies used are f2, f5 and f8.
[0010]
FIG. 4 is a functional diagram showing the relationship between the ports used by the frequency routers 11 and 12 of FIG. 1 and their frequencies. In FIG. 3, when applied to the incoming frequency router 11, for example, when optical signals of multiple frequencies f 2, f 5, and f 8 are input to adjacent ports a 1, a 2, and a 3, As indicated by blocks 16, 17 and 18, an optical signal of frequency f2 is transmitted to adjacent ports b1, b2 and b3, similarly frequency f5 is transmitted to ports b4, b5 and b6, and frequency f8 is transmitted to ports b7, b8 and Each is output to b9. That is, the same frequency is collected and output to adjacent ports. Conversely, when applied to the outgoing frequency router 12, as shown by the dotted blocks 16, 19, and 20 in the matrix 15, the ports b1 to b3, b4 to b6, and b7 to b9 are adjacent to each other, respectively. When optical signals having frequencies f2, f5, and f8 are input, optical signals having multiple frequencies f2, f5, and f8 are output to adjacent ports 1a to 3a. In this way, by appropriately selecting the frequencies f0 to f8 of the frequency router 11 or 12, separation of multiple frequencies and frequency multiplexing are realized using adjacent ports.
[0011]
If the number of input / output ports a and b of the frequency router 11 or 12 shown in FIG. 3 is a natural number n (same for both input and output), NxM = n because the number of ports with frequency multiplicity N is M. Since the number of input / output ports n is considered to be 144, a frequency router with M = 12 and N = 12 is realized. As the frequency interval, light of M times the wavelength of the closest state, that is, light having a frequency f (M0 + Mi) is used. However, i = 1, 2, 3,..., And M0 is a constant.
[0012]
FIG. 2 conceptually shows an example of the mechanism of the optical frequency router 11 or 12 shown in FIG. In this embodiment, the optical frequency routers 11 and 12 are each formed in a planar shape on the optical wiring board 30. Planar waveguides 21 and 23 are formed on the optical wiring board 30, and both are connected to each other through a waveguide array 25. One planar waveguide 21 has ports a1, a2 and a3, to which a waveguide array 22 is connected. The other planar waveguide 23 has ports b1 to b9, to which another waveguide array 24 is connected. The interconnected waveguide array 25 is configured by arranging a plurality of NW individual waveguides 25a having different lengths to be connected to the planar waveguides 21 and 23 at a pitch d and arranged in a plane. The waveguide array 22 includes three individual waveguides arranged at an angle of Δθ between adjacent ones corresponding to the ports a1, a2 and a3. Corresponds to road 14. In the present embodiment, adjacent waveguides in the waveguide array 24 are also arranged with a guide angle Δθ. If the refractive index of the planar waveguides 21 and 23 is ns, the optical path length difference between adjacent waveguides 25a in the waveguide array 25 is ΔL, and the average wavelength used is λ0, then the wavelengths λi and λi + 1 Is a wavelength interval ΔλW between ΔλW = 2nsdΔθ / m, where m = 2nc ΔL / λ0, where nc is the equivalent refractive index in the waveguide array 25. Further, the half wavelength width ΔλFW of the demultiplexing wavelength is ΔλFW = λ0 / (NWm).
[0013]
As described above, since the wavelength interval may be M times the close-packed state, that is, MΔλ _W = Δλ _FW , the angle Δθ between adjacent waveguides of the waveguide array 22 is Δθ = λ _0. It can also be / 2n _s dMN _W.
[0014]
Returning to FIG. 1, an optical matrix switch 43 is disposed between the outgoing ports b1 to b3 of the frequency router 11 and the incoming ports b1 to b3 of the frequency router 12 as shown in the figure. Similarly, an optical matrix switch 44 is connected between the output ports b4 to b6 of the frequency router 11 and the input ports b4 to b6 of the frequency router 12, and the output ports b7 to b9 of the frequency router 11 and the frequency router 12 are input. Between the ports b7 to b9, optical matrix switches 45 are respectively arranged as shown in the figure. In this embodiment, the optical matrix switches 43, 44, and 45 are disposed on the optical wiring board 30, and an input signal having a single frequency is converted into an external control signal at each of the input ports 31, 32, and 33. It is an input / output 3x3 switch that responds and switches to any output port 34, 35 and 36 for output. As a result, the frequency multiplexing optical switch 10 as a whole has a function equivalent to that described as the first method in relation to the prior art on the optical wiring board 30 in a planar shape, that is, complicated three-dimensional wiring or crossing. This can be realized without providing wiring.
[0015]
The frequency router 11 at the input stage provided on the optical wiring board 30 is adjacently arranged when multiplexed optical signals of frequencies f2, f5 and f8 are input from the incoming path 13 connected to the ports a1, a2 and a3. The optical signals of frequencies f2, f5, and f8 are distributed and output to the ports b1 to b3, b4 to b6, and b7 to b9, respectively. The frequency router 11 is an optical connection path formed on the optical wiring board 30, or an input port 31 of an optical matrix switch 43, 44 and 45 corresponding to each frequency f2, f5 and f8 via an optical fiber link 41. Connected with ~ 33. The outgoing ports 34-36 of each switch 43, 44 and 45 are connected to the incoming ports b1-b3, b4-b6 and b7-b9 of the frequencies f2, f5 and f8 of the frequency router 12 via a link 42 similar to the link 41. It is connected. One link 41 is a path between the corresponding frequency router 11 and the adjacent three ports 31 to 33 in each of the switches 43, 44 and 45, and the other link 42 is connected to the corresponding frequency router 12 and each An optical signal path is formed between the adjacent three ports 34 to 36 in the switches 43, 44 and 45, and they are arranged in order. Therefore, there is no cross intersection of path wiring between optical switches as in the prior art.
[0016]
Similarly, the output stage frequency router 12 provided on the optical wiring board 30 multiplexes the optical signals of the frequencies f2, f5 and f8 input from the input ports b1 to b3, b4 to b6 and b7 to b9, respectively. And output as a multiplexed signal to the outgoing route 14.
[0017]
In the operating state, for example, when the optical signal of the channel f5 of the port a1 of the frequency router 11 is connected to the port a3 of the frequency router 12, the transfer is performed by the following route in response to the control signal from the outside. That is, (port a1 of the frequency router 11) − (ports b4 to b6) − (link 41) − (ports 31 to 33 of the optical matrix switch 20) − (ports 34 to 36) − (link 42) − (Ports b4 to b6 of the frequency router 12)-(same port a3). Thus, according to the present invention, complete circuit switching between a plurality of ports and between frequency channels can be realized without providing complicated three-dimensional wiring or cross wiring.
[0018]
【The invention's effect】
As described above, according to the present invention, the frequency demultiplexing element that separates the frequency multiplexing channels at the input stage and the frequency multiplexing optical element that performs frequency multiplexing at the output stage use frequency routers of the same configuration, and A plurality of terminals having the same frequency connected from the output stage to the optical matrix switch are arranged adjacent to each other. Therefore, the optical connection paths on the optical fiber or the optical wiring board are neatly arranged in parallel and the number of them is small, so there is no three-dimensional wiring or cross wiring in the conventional technology, the space factor is good, and the number of manufacturing steps is reduced. Multiple optical switches can be provided.
[Brief description of the drawings]
FIG. 1 is a functional block diagram showing an embodiment of a frequency multiplexing optical switch according to the present invention.
2 is a configuration diagram conceptually showing an example of a mechanism on an optical wiring board of the frequency router of the embodiment shown in FIG. 1;
FIG. 3 is a diagram illustrating an example of a matrix of frequency characteristics of the ports of the frequency router in the embodiment.
4 is a functional diagram illustrating the relationship between ports and frequencies of the frequency router shown in FIG. 3;
[Explanation of symbols]
10 Frequency multiplexing optical switch
11, 12 frequency router
13 Entry way
14 Outbound
15 Matrix
43, 44, 45 Optical matrix switch

Claims (4)

Input / output terminals are connected to M optical transmission lines that transmit frequency-multiplexed optical signals that are frequency-multiplexed to multiplicity N (M and N are natural numbers, respectively), and the frequency-multiplexed optical signal is transmitted between the input / output terminals. In a frequency multiplexing optical switch that switches, the optical switch comprises:
The M optical transmission lines are connected to the M optical transmission lines and have M input terminals to which the frequency-multiplexed optical signals are input. The optical signals are multiplexed into N sets of N optical signals having different frequencies. , A demultiplexer that outputs to NxM output terminals,
There are M sets of N optical signals having different frequencies, and NxM input terminals to which the optical signals are input. The M optical signals are multiplexed into a frequency multiplexed optical signal having a multiplicity of N, and M optical signals are multiplexed. A multiplexing element that outputs from the output end of
N matrix switches having M input terminals to which optical signals of the same frequency are input, and outputting the input optical signals to desired ports of the M output terminals;
First connection means for connecting M optical signals having the same frequency among optical signals obtained from NxM output terminals of the demultiplexing element to input terminals of the same switch among the N matrix switches; ,
Second connection means for connecting M output terminals of the same switch of the N matrix switches to M input terminals of the same frequency among the input terminals of the multiplexing element, respectively .
The demultiplexing element and the multiplexing element each include an optical frequency router that distributes an optical signal arriving at an input end to an output end according to a frequency,
Further, the optical frequency router uses a wavelength obtained by adding a wavelength that is M × i ( i is a natural number) times as a wavelength interval of the optical signal at the wavelength in the most dense state, and has a characteristic corresponding to the wavelength. first and second planar waveguide means respectively, are arranged in accordance with the supply of the frequency multiplexed optical signals and the frequency of the multiplicity N different N optical signals,
A frequency division multiplexing optical switch comprising: arrayed waveguide means for connecting the first and second planar waveguide means to each other . In the frequency-multiplexed optical switch according to claim 1, wherein the frequency router and port M present at the output terminal of the same frequency of the NxM this output end is Ru arranged adjacent to each other of the demultiplexing device, wherein to have a port for the M inputs of the same frequency of the input terminals of the multiplexing elements are arranged adjacent to each other, wherein the operating frequency is selected, the frequency characteristic of operating at said selected operating frequency A frequency multiplexing optical switch characterized by being arranged. A wavelength obtained by adding M × i (where i is a natural number) times the wavelength interval of the optical signal as the wavelength interval of the optical signal at the wavelength in the most dense state is used as the operating frequency condition . A first port, and N sets of NxM second ports for transmitting N sets of N optical signals having different frequencies, and the frequency multiplexed optical signal arrives at the M first ports. , Demultiplexes the signals and outputs them to the NxM second ports. When N optical signals having different frequencies arrive at the NxM second ports, they are multiplexed and the M number of optical signals are multiplexed. An optical frequency router that outputs to a first port. The optical frequency router according to claim 3 , wherein the optical frequency router comprises:
An optical wiring board;
A first planar waveguide disposed on the optical wiring substrate and connected to the M first ports;
A second planar waveguide disposed on the optical wiring substrate and connected to the NxM second ports;
A plurality of planar waveguides disposed on the optical wiring board and having different optical path lengths, and a planar waveguide array for connecting the first and second planar waveguides to each other; Optical frequency router.

Images