JP5545570B2 - Optical path cross-connect device - Google Patents

Description

  The present invention relates to an optical path cross-connect device.

  The optical path cross-connect device can set a transfer destination node for each wavelength, and is configured to transfer data as it is without converting the data into an electrical signal. As a result, a high-speed and large-capacity optical path can be freely set according to the wavelength between the nodes in which the optical fibers are installed, so that it is possible to flexibly cope with the demand for communication capacity that increases in scale.

  FIG. 1 is a diagram conceptually showing an optical path cross-connect device between nodes. The optical path cross-connect device 10 is connected to a plurality of adjacent nodes by a plurality of optical fibers. Adjacent nodes # 1 to #D can be, for example, optical path cross-connect devices, IP routers, SDH devices, and the like. One of these adjacent nodes and the optical path cross-connect device 10 are usually connected by a pair of a plurality of input fibers and output fibers. Bidirectional wavelength division multiplexing (WDM) optical communication is realized between an adjacent node and the optical path cross-connect device 10 by a pair of an input-only (uplink) fiber and an output-only (downlink) fiber. Therefore, when the number of fibers between nodes is increased, the maximum communication capacity that can be set between the nodes can be increased.

  FIG. 2 is a diagram functionally illustrating the optical path cross-connect device. The optical path cross-connect device 20 is configured to realize an nD × nD optical switch function, assuming that n input / output fiber pairs are connected to each adjacent node. More specifically, the optical path cross-connect device 20 is configured such that a wavelength multiplexed optical signal from each input fiber can be switched to any of the nD output fibers according to the wavelength. Here, N (N = nD) obtained by multiplying the number D of nodes and the number n of fiber pairs between the nodes is called a degree of the optical path cross-connect device. As such an optical path cross-connect device, conventionally, a wavelength selective switch base configuration (see FIG. 18 of Non-Patent Document 1) and a matrix switch base configuration (see FIG. 17 of Non-Patent Document 1) are known. ing.

  FIG. 3 shows a configuration example of a wavelength selective switch-based optical path cross-connect device. The optical path cross-connect device 30 includes wavelength selective switches (WSS) 32-1 to 32-N connected to N input fibers, a wavelength selective switch 33 connected to an input fiber for Add signals, and N The wavelength selective switches 34-1 to 34-N are connected to the respective output fibers, and the wavelength selective switch 35 is connected to the drop signal output fiber. The function of the wavelength selective switch is to selectively guide a plurality of wavelength signals multiplexed on the input fiber to the output port in any combination. Each wavelength selective switch on the input side is connected to all the wavelength selective switches on the output side by an optical fiber at its output. However, the optical fiber between the wavelength selective switch 33 for the Add signal and the wavelength selective switch 34 for the Drop signal can be omitted. Here, the Add signal is a signal transmitted from the node of the optical path cross-connect device 30, and the Drop signal is a signal received by the node of the optical path cross-connect device 30.

  The wavelength selective switch on the input side can switch the wavelength multiplexed optical signal from the input fiber to the desired path according to the wavelength, and the wavelength selective switch on the output side can multiplex the optical signals from multiple paths Can do. With such a configuration, an N × N optical path cross-connect function can be realized between the input and output fibers.

  FIG. 4 shows a configuration example of a matrix switch-based optical path cross-connect device. The optical path cross-connect device 40 includes wavelength demultiplexers 42-1 to 42-N connected to N input fibers, and an optical matrix switch 44 for each wavelength, where M is the number of multiplexed wavelength multiplexed signal lights. -1 to 44-M, and wavelength multiplexers 46-1 to 46-N connected to N output fibers, respectively. Each optical matrix switch is connected to the wavelength demultiplexer for each wavelength on the input side, and is connected to the wavelength multiplexer for each wavelength on the output side. Each optical matrix switch is connected to an optical fiber for Add signal on the input side and connected to an optical fiber for Drop signal on the output side.

  Each optical matrix switch functions as an (N + 1) × (N + 1) optical switch for switching from N + 1 input paths including an Add signal path to N + 1 output paths including a Drop signal path. With such a configuration, an N × N optical path cross-connect function can be realized between the input and output fibers.

Ming C. Wu et al. “Optical MEMS for Lightwave Communication,” JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 24, NO. 12, DECEMBER 2006

  However, the wavelength selective switch-based configuration of FIG. 3 requires 1 × N (1 × (N + 1) including the Drop signal path) for each input fiber, and N × N for each output fiber. 1 (N + 1) × 1 output side WSS is required if the path for the Add signal is included. Since the normal WSS can exchange the input and the output, 2N 1 × N WSSs are required after all.

  First, WSS is an expensive device, and it is desirable to reduce the required number. Further, when N is large, it is difficult to realize, and N is about 9 at the level currently on the market. Therefore, the conventional wavelength selective switch-based configuration is not only economically expensive, but the number of adjacent nodes is D and the number of connected fibers is n, and N = nD, which is the degree of the optical path cross-connect device, is technically used. There is a problem that it is limited to.

  In the configuration of the matrix switch in FIG. 4, N × N (N + 1) × (N + 1)) matrix switches are required as many as the number M of wavelengths of the wavelength multiplexed signal light (including paths for Add signal and Drop signal). Become. For example, when M = 96, 96 N × N matrix switches are required, and when M is large, there is a problem that not only the cost increases but also the size increases.

  Therefore, the present invention provides an economical optical path cross-connect device. The present invention also provides a scalable optical path cross-connect device.

  In order to achieve such an object, the present invention provides an optical device for routing wavelength-multiplexed optical signals from a plurality of inputs to a plurality of nodes via a plurality of outputs according to wavelengths. A path cross-connect device, wherein wavelength-multiplexed optical signals from the plurality of inputs are selected by the wavelength selection function and the wavelength selection function capable of selecting any of the plurality of nodes according to the wavelength for each input. A switch function that can switch the optical signal of each node to any of the outputs corresponding to the node for each node, and an optical signal of the output corresponding to each node switched by the switch function for each output. And a multiplexing function.

  The invention according to claim 2 is the optical path cross-connect device according to claim 1, wherein the wavelength selection function can select a drop signal, and the multiplexing function combines an add signal. It is characterized by being capable of waves.

  According to a third aspect of the present invention, there is provided the optical path cross-connect device according to the first or second aspect, wherein the wavelength-multiplexed optical signal is routed according to a wavelength group.

  According to a fourth aspect of the invention, there is provided the optical path cross-connect device according to the third aspect, wherein the wavelength group is composed of continuous wavelengths.

  According to a fifth aspect of the present invention, in the optical path cross-connect device according to the third aspect, the wavelength group is composed of non-continuous wavelengths.

  The invention according to claim 6 is the optical path cross-connect device according to any one of claims 1 to 5, wherein the wavelength multiplexed optical signal has a different bit rate for each wavelength. .

  The invention according to claim 7 is the optical path cross-connect device according to any one of claims 1 to 5, characterized in that the wavelength division multiplexing optical signals are not evenly spaced.

  According to an eighth aspect of the present invention, in the optical path cross-connect device according to any one of the first to seventh aspects, an optical path cross-connect device in which an input and an output are switched is characterized.

It is the figure which showed notionally the optical path cross-connect apparatus between nodes. It is the figure which showed the optical path cross-connect device functionally. It is the figure which showed the structural example of the optical path cross-connect apparatus based on a wavelength selective switch. It is the figure which showed the structural example of the optical path cross-connect apparatus of a matrix switch base. It is the figure which showed the structural example of the optical path cross-connect apparatus by one Embodiment of this invention. It is the figure which showed the structural example of the mechanical wavelength selective switch which can be used for the optical path cross-connect apparatus by this invention. It is the figure which showed the structural example of the non-mechanical wavelength selective switch which can be used for the optical path cross-connect apparatus by this invention. It is the figure which showed an example of the wavelength group of the continuous arrangement type which can be used for the optical path cross-connect apparatus by this invention. It is the figure which showed an example of the wavelength group of a dispersion | distribution arrangement type which can be used for the optical path cross-connect apparatus by this invention. It is the figure which showed the structural example of the wavelength group selection switch which can be used for the optical path cross-connect apparatus by this invention. It is the figure which showed an example of the wavelength multiplexing / demultiplexing characteristic of the cyclic AWG which can be used as the multiplexer / demultiplexer of FIG.

  FIG. 5 shows a configuration example of an optical path cross-connect device according to an embodiment of the present invention. The optical path cross-connect device 50 has N 1 × D, where D is the number of connected nodes, n is the number of input and output fiber pairs between the nodes, that is, the degree of the optical path cross-connect device is N = nD. The wavelength selective switches 52-1 to 52-N, ND 1 × n optical switches 54-1 to 54-ND, and N N × 1 multiplexers 56-1 to 56-N are configured. Yes. Here, every n input fibers are coupled to nodes # 1 to #D, and every n output fibers are coupled to nodes # 1 to #D.

  Each wavelength selective switch is coupled to each input fiber on its input side and is coupled to the inputs of D 1 × n optical switches on its output side. On the other hand, N N × 1 multiplexers are coupled to each output fiber on the output side. Then, D 1 × n optical switches coupled to a certain 1 × D wavelength selective switch are coupled to the inputs of nD (that is, N) multiplexers on the output side. In the configuration example of FIG. 5, each wavelength selective switch has an additional output for the Drop signal, and each multiplexer has an additional input for the Add signal.

  In the configuration example of FIG. 5, D 1 × n optical switches coupled to one wavelength selective switch correspond to D nodes, respectively. Therefore, in the wavelength selective switch, the 1 × n optical switch corresponding to the destination node is selected according to the wavelength, and in the 1 × n optical switch, one of the multiplexers coupled to the destination node is selected. As a result, an nD × nD (ie, N × N) optical path cross-connect function is realized as a whole.

  Note that the number of input and output fiber pairs between nodes does not have to be n among all nodes, and the number of fiber pairs may be changed according to the nodes. In that case, the number of outputs of the optical switch, the number of multiplexers, and the number of inputs can be changed according to the number of fiber pairs. However, even in such a case, in consideration of the versatility of the optical path cross-connect device, the maximum number of input and output fiber pairs between nodes can be set to n, and the optical path cross-connect device can be configured as an nD × nD optical path cross-connect device. Good.

  Moreover, the input and output of the optical path cross-connect device according to the present invention can be interchanged. In this case, the wavelength selective switch has a D × 1 configuration, the optical switch has an n × 1 configuration, and the multiplexer is a duplexer.

  In the optical path cross-connect device according to the present invention, the wavelength selective switch may be, for example, a mechanical type or a non-mechanical type. 6 and 7 show configuration examples of a mechanical wavelength selective switch and a non-mechanical wavelength selective switch.

  The wavelength selective switch 60 in FIG. 6 can be realized by MEMS technology. As shown in FIG. 6, the wavelength multiplexed optical signal enters the grating 62 through the collimator 61 and is diffracted at different angles depending on the wavelength. The light wavelength-separated by the grating enters the micromirror 64 via the lens 63 and is reflected at a desired angle according to the wavelength. The light reflected by the micromirror enters the collimator lens 66 through the lens 63 and the grating 62. The wavelength selective switch 60 can output an optical signal having a specific wavelength to a specific port by adjusting the angle of the micromirror.

  The wavelength selective switch 70 shown in FIG. 7 includes a 1 × M demultiplexer 71, M 1 × N optical switches 72-1 to 72-M, and N number of wavelength multiplexed optical signals. N × 1 multiplexers 73-1 to 73-N. The wavelength-multiplexed optical signal is demultiplexed into individual wavelengths by the 1 × M demultiplexer 71, and the paths are selected by M 1 × N optical switches, respectively, and then multiplexed by the N × 1 multiplexer. . The wavelength selective switch 70 can output an optical signal having a specific wavelength to a specific port by selecting a path in the 1 × N optical switch.

  Further, in the optical path cross-connect device according to the present invention, the 1 × n optical switch can be realized by using n−1 1 × 2 optical switches. The multiplexer can be realized using a coupler. Alternatively, the multiplexer can be configured using a wavelength selective switch, or can be configured by combining a wavelength selective switch and a coupler. Using a wavelength selective switch increases the cost, but can reduce the loss.

  The optical path cross-connect device according to the present invention has the following advantages compared to the optical path cross-connect devices of FIGS. In the case of the optical path cross-connect device based on the wavelength selective switch of FIG. 3, although the wavelength selective switch on the output side can be replaced with a coupler, a wavelength selective switch is required for each input fiber. A wavelength selective switch is required (N = nD). On the other hand, the optical path cross-connect device according to the present invention can be composed of D wavelength selective switches as a whole. That is, the number of expensive wavelength selective switches can be greatly reduced to 1 / n.

  Further, the number of outputs of the wavelength selective switch is about 9 at the maximum in the current commercially available technology. Therefore, in the configuration of FIG. 3, only N of about 9 can be realized. On the other hand, with the configuration according to the present invention, it is possible to realize a D of about 9. In addition, the 1 × n optical switch can be easily formed up to about 32. Therefore, N can be expanded to about 288.

In the case of the matrix switch-based optical path cross-connect device of FIG. 4, if the N × N optical switch is configured using 2 × 2 optical switches, N ² 2 × 2 optical switches are required. Such N × N optical switches are required for the number of wavelengths M. On the other hand, in the optical path cross-connect device according to the present invention, when the 1 × n optical switch is configured using the 1 × 2 optical switch, only n−1 1 × 2 optical switches are required. Only ND of such 1 × n optical switches are required. That is, in the configuration of FIG. 4, 2 × 2 optical switches are required M × N ² , whereas in the configuration of the present invention, (n−1) × ND (ie, 1 × 2 optical switches) N ² -ND) are only required. In particular, in the configuration of FIG. 4, when the number M of wavelength multiplexing increases, the same number of N × N optical switches as the number of wavelength multiplexing is required, which is not practical.

  Next, regarding wavelength selection of wavelength multiplexed optical signals in the optical path cross-connect device according to the present invention, a configuration using a wavelength group selection switch that selects each wavelength group instead of the wavelength selection switch will be described. Here, the function of the wavelength group selection switch is to selectively guide a plurality of wavelength groups multiplexed on the input fiber to the output port in an arbitrary combination. Various methods can be used to configure the wavelength group, and in particular, a continuous arrangement type or a dispersion arrangement type can be used. FIG. 8 shows an example of a continuous arrangement type wavelength group, and FIG. 9 shows an example of a dispersion arrangement type wavelength group.

  The continuous arrangement type of FIG. 8 is configured to set a wavelength group of eight continuous waves in one path. On the other hand, the dispersion arrangement type of FIG. 9 is configured to set eight wavelengths obtained by interleaving consecutive wavelengths into one wavelength group. A wavelength selective switch that selects and switches for each wavelength group is called a wavelength group selective switch (WBSS). The WBSS can be realized with a simple configuration as compared with a normal WSS. Therefore, by employing WBSS in the present invention, an optical path cross-connect device can be realized with a simpler configuration. However, when WBSS is adopted instead of the wavelength selective switch, the wavelength selectivity is restricted, so that there are some restrictions on the wavelength path routing performance as an optical path cross-connect.

  FIG. 10 shows a configuration example of a wavelength group selection switch that can be used in the optical path cross-connect device according to the present invention. In this configuration example, the number of wavelengths of the wavelength multiplexed optical signal is 40, and the number of wavelength groups is 5 if the wavelength signal is an 8-wave signal. The wavelength group selection switch 100 includes a 1 × 5 wavelength group demultiplexer 101, five 1 × 8 optical switches 102-1 to 102-5, and eight 8 × 1 wavelength group multiplexers 103-1. 103-8. In this WBSS, the number of paths is reduced to 1/8 compared to the configuration of the wavelength selective switch of FIG.

  As shown in FIG. 11, cyclic AWG can be used as the wavelength group demultiplexer 101 and the wavelength group multiplexer 103 in FIG. Here, the cyclic AWG is an arrayed waveguide grating (AWG) in which the product of the number of output ports and the wavelength interval coincides with FSR (Free Spectral Range) and the output has a circular characteristic.

  Also, the optical path cross-connect device according to the present invention can be configured as an equally spaced wavelength arrangement as defined by the ITU, or by adjusting the wavelength characteristics of the WSS or WBSS to be used, It can also be configured as an arrangement. For example, wavelength allocation that is not equidistant can be used when high bit rate data is assigned to a specific wavelength and low bit rate data is assigned to a specific wavelength.

  While the present invention has been described with respect to several specific embodiments, the embodiments described herein are merely illustrative in view of the many possible embodiments to which the principles of the present invention can be applied. It is not intended to limit the scope of the invention. The configuration and details of the embodiment exemplified here can be changed without departing from the spirit of the present invention. Further, the illustrative components and procedures may be changed, supplemented, or changed in order without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 10 Optical path cross-connect apparatus 20 Optical path cross-connect apparatus 30 Optical path cross-connect apparatus 32-1 to 32-N Wavelength selection switch 33 Wavelength selection switch 34-1 to 34-N Wavelength selection switch 35 Wavelength selection switch 40 Optical path cross Connect device 42-1 to 42-N Wavelength demultiplexer 44-1 to 44-N Optical matrix switch 46-1 to 46-N Wavelength multiplexer 60 Wavelength selection switch 61 Collimator 62 Grating 63 Lens 64 Micromirror 66 Collimator lens Reference Signs List 70 wavelength selective switch 71 duplexer 72-1 to 72-M optical switch 73-1 to 73-N multiplexer 100 wavelength group selective switch 101 wavelength group duplexer 102-1 to 102-5 optical switch 103-1 To 103-5 Wavelength group multiplexer

Claims (8)

An optical path cross-connect device for routing wavelength multiplexed optical signals from a plurality of inputs to a plurality of nodes via a plurality of outputs according to wavelengths,
A wavelength selection function capable of selecting wavelength multiplexed optical signals from the plurality of inputs to any of the plurality of nodes according to the wavelength for each input;
A switch function capable of switching the optical signal of the node selected by the wavelength selection function to any of the outputs corresponding to the node for each node;
An optical path cross-connect device comprising: a multiplexing function for multiplexing output optical signals corresponding to each node switched by the switch function for each output.   2. The optical path cross-connect device according to claim 1, wherein the wavelength selection function is capable of selecting a Drop signal, and the multiplexing function is capable of multiplexing an Add signal. Cross-connect device.   3. The optical path cross-connect device according to claim 1, wherein the wavelength-multiplexed optical signal is routed according to a wavelength group.   4. The optical path cross-connect device according to claim 3, wherein the wavelength group is composed of continuous wavelengths.   4. The optical path cross-connect device according to claim 3, wherein the wavelength group is composed of non-continuous wavelengths.   6. The optical path cross-connect device according to claim 1, wherein the wavelength multiplexed optical signal has a different bit rate for each wavelength.   6. The optical path cross-connect device according to claim 1, wherein the wavelength-division multiplexed optical signals have wavelength intervals that are not uniform.   8. The optical path cross-connect device according to claim 1, wherein an input and an output are switched.

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