JP2008072374A - Optical switching device and optical switching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical switching device which improves flexibility of a node, with a simple wavelength conversion process, and with no conversion from optical signal to electric signal. <P>SOLUTION: The optical switching device is used for wavelength multiplex optical communication method in which a destination node or originator node is specified by wavelength. It comprises optical wavelength demultiplexing means 101-108 in which the wavelength multiplex signal that is received from input-side optical communication paths n1-n8 is wavelength-demultiplexed into the signal for a plurality of input side optical signal lines 1101-1132, an optical switch array 50 in which the demultiplexed signal is connected to output-side optical signal lines 1201-1232, outgoing to destination nodes, optical wavelength conversion means 1301-1332 in which the wavelength of the signal connected to the output-side optical signal lines 1201-1232 is converted into the wavelength that specifies a destination node, and optical wavelength multiplexing means 111-118 in which the signal that has been wavelength-converted is wavelength-multiplexed and is transmitted to output-side optical communication paths m1-m8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical switching device and an optical switching method. More particularly, the present invention relates to an optical switching apparatus and an optical switching method that are used in optical switching nodes that are connected to each other through optical communication paths that transmit wavelength multiplexed optical signals in an optical fiber network.

  A network in which a plurality of nodes are connected by optical fibers has become common. The node is provided with switching means for receiving a signal sent through an optical fiber cable and selecting the next node or drawing it into the own node according to the final destination of the signal. Such a node is called an optical switching node, and a system that performs switching using switching means provided in the optical switching node is called an optical switching system. In recent years, wavelength multiplexing has been adopted to increase the transmission capacity per optical fiber. A network using such a wavelength multiplexing method is widely adopted from a relatively small LAN (Local Area Network) to a WAN (Wide Area Network) targeting a relatively wide area. Even in a communication system using an optical wavelength division multiplexing system, a loop topology, a star topology, or a composite form thereof can be considered as in a general network, but a loop topology is generally used.

  As an example of an optical switching system adopting a loop topology, a wavelength-multiplexed signal on a looped optical fiber is wavelength-separated at an optical switching node, and a wavelength corresponding to its own node area is dropped, and conversely There is a form of add / drop max (OADM) in which a signal transmitted from the node area to another area is added and exchange processing is performed. In this form, the wavelength dropped in the own node is subjected to optical / electrical conversion (OE conversion). Return to the electrical signal, interpret the information contained in the electrical signal, and determine the route within the area. On the other hand, a signal traveling from its own area to another node is subjected to electrical / optical conversion (EO conversion), placed on a specific wavelength, added onto the fiber of the loop topology, and transmitted.

  FIG. 14 shows an example of an optical switching system employing a conventional loop topology. In FIG. 14, 1-1 to 1-6 are optical switching nodes, 2 is an optical fiber network connecting the optical switching nodes in a loop, 3-1, 3-2,... Are optical switching nodes 1-1. It is an optical fiber connected to the area. Although FIG. 14 shows a star topology having the optical switching node 1-1 as a node in the area of the optical switching node 1-1, a loop topology or other composite topologies may be used. An optical fiber network 2 connected in a loop is connected to the optical switching node 1-1, and signals with wavelengths λ1, λ2,. In addition, optical fibers 3-1, 3-2,... In the own node area are connected to the optical switching node 1-1. For example, signals from other optical switching nodes are connected to the optical fiber 3-1. A signal that is taken into the intra-node area at the wavelength λa and transmitted from the optical fiber 3-2 to the other optical switching node is input at the wavelength λb.

  FIG. 15 shows a configuration example of the optical switching node 1-1 used in FIG. The same parts as those in FIG. 14 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 15, 4 is an optical receiver, 5 is a specific wavelength separation module, 6-1 and 6-2 are OE conversion modules, 7-1 and 7-2 are reception signal buffers, transmission signal buffers, 8-1, 8-2 is an EO conversion module, 9 is a control device for the optical switching node 1-1, 9-1 and 9-2 are a reception signal control module, a transmission signal control module, and 10 is connected to the optical fiber 1-1. An optical transceiver module, 11 is a wavelength multiplexing module for combining specific wavelengths, and 12 is an optical transmitter.

  Next, the operation of the optical switching node 1-1 will be described. The optical signal of the loop optical fiber network 2 wavelength-multiplexed with wavelengths λ1, λ2,... Λn is received by the optical receiver 4 of the optical switching node 1-1, and is sent to the optical switching node 1-1 by the separation module 5. A signal having a specified specific wavelength λm is extracted. The signal of wavelength λm is converted into an electrical signal by the OE conversion module 6-1 and stored in the reception signal buffer 7-1, and EO conversion is performed by the control signal of the reception signal control module 9-1 based on an instruction from the control device 9. The module 8-1 converts the wavelength λa of the target route in the area in the node, and outputs it from the transmission / reception module 10 to the optical fiber 3-1 in the target route in the area, while the optical fiber from the node The signal λb on 3-2 is received by the optical transceiver module 10, converted into an electrical signal by the OE conversion module 6-2, and stored in the transmission signal buffer 7-2. Based on a control signal from the transmission signal control module 9-2 based on an instruction from the control device 9, the signal is converted into the wavelength λm by the EO conversion module 8-2, and the other wavelengths λ1, λ2,. 1, λm + 1,..., Λn are combined and transmitted from the optical transmitter 12 to the loop optical fiber network 2. Information for an instruction from the control signal 9 includes a method of separating and reading information embedded in the signal, or a method of reading from a signal received from another signal line.

  The same applies to the optical switching node when the optical switching system is configured in a star topology, and the wavelength-multiplexed wavelength signal of the optical fiber connected to the optical switching node is changed to the wavelength specified by the destination by the control signal. When performing exchange processing by changing the position, the optical signal on the optical fiber is generally converted into an electrical signal, and the necessary processing is performed. It was configured to be on the wavelength. This situation is the same in the case of a composite of loop topology and star topology.

  In other words, in the configuration of the conventional optical switching node, the optical signal to be exchanged is once converted into an electrical signal, and again converted into an optical signal having a wavelength corresponding to the target route and transmitted.

  In addition, as an optical switching apparatus that performs an exchange process without converting an optical signal into an electrical signal, one that is configured to allow broadcast communication (for example, see Patent Document 1), wavelength multiplexing using an arrayed waveguide grating There is one configured to connect a wave to an arbitrary port (see, for example, Patent Document 2).

JP-A-8-130756 (paragraphs 0022-0052, FIGS. 1-7, etc.) JP-A-10-51382 (paragraphs 0017 to 0040, FIGS. 1 to 8 etc.)

  However, an optical switching apparatus that converts an optical signal into an electrical signal and performs an exchange process requires an OE conversion module, an EO conversion module, a buffer, and the like, and the configuration is complicated. In addition, the conventional optical signal is converted into an electrical signal. Even in an optical switching apparatus that performs switching processing without converting to a wavelength, a switch function that converts a wavelength that represents a destination into a predetermined wavelength is configured to be semi-fixed or have time for conversion, and the wavelength used by the node is limited. Therefore, there is a limit to the scale expansion due to the flexibility of route selection at the node and the improvement of ease of use.

  An object of the present invention is to provide an optical switching apparatus and an optical switching method that do not convert an optical signal into an electrical signal, and that have a simple wavelength conversion process and a high path selection flexibility at a node.

  In order to solve the above problems, an optical switching device according to claim 1 is an optical switching device for a wavelength division multiplexing optical communication system in which a destination node or a source node is specified by a wavelength, as shown in FIG. In addition, optical wavelength separation means 101 to 108 for wavelength-separating wavelength multiplexed signals received from the input side optical communication paths n1 to n8 into signals to a plurality of incoming optical signal lines 1101 to 1132, and optical wavelength separation means 101 to The optical switch array 50 connects the signals separated into the input-side optical signal lines 1101 to 1132 by 108 to the output-side optical signal lines 1201 to 1232 toward the destination node, and the optical switch array 50 converts the signals to the output-side optical signal lines 1201 to 1232. Optical wavelength conversion means 13 that converts the wavelength of the connected signal into a wavelength that specifies a destination node or maintains a wavelength that specifies a destination node or a source node 1 to 1332 and optical wavelength multiplexing means 111 to 118 for wavelength multiplexing the signals wavelength-converted by the optical wavelength conversion means 1301 to 1332 or maintaining the wavelength and transmitting them to the output side optical communication paths m1 to m8. Prepare.

  Here, the exchange includes an add / drop concept in addition to the cross-connect. A destination node typically refers to a final destination node, and a source node typically refers to a source node, but includes a case where a via point is selected as a destination node or source node. This is because the number of wavelengths that can be handled by each node is finite, and if it is not possible to handle the wavelength that specifies the final destination node or source node, it is necessary to select a via point as the destination node or source node. is there. For example, if the Wakkanai station is the final destination, the Sapporo local station is used as a transit point. The reason why the source node is used in addition to the destination node is to perform wavelength multiplexing using different wavelengths for the same destination node. Further, the fact that the destination node or the source node is specified by the wavelength means that the source or destination of the signal is determined by the wavelength of the carrier wave of the signal. For example, a signal of wavelength λ2 is a signal having the Hachioji local station as a destination node or a source node, and a signal of wavelength λ5 is a signal having the Osaka local station as a destination node or a source node. Therefore, transmission from the Hachioji local station to the Osaka local station is achieved, for example, by switching and connecting the signal line having the wavelength λ2 to the signal line having the wavelength λ5 at the Tokyo central station. Typically, the caller side (add node) is specified by the caller node, and the callee side (drop node) is specified by the destination node. However, the destination node may be specified by the caller side. The source node may be specified on the side.

  Also, the outgoing optical signal line toward the destination node is typically an outgoing optical signal line (more precisely, output side optical communication) directly connected to the destination node (the last destination node or a transit point selected as the destination node). May be connected to the destination node indirectly via other waypoints. The wavelength for specifying the destination node is the wavelength of the carrier wave output from the outgoing optical signal line connected to the next node. When a via point is selected as a destination node, it is necessary to store the final destination in one of the switching tables (preferably in each switching table from the viewpoint of certainty). “Identify” is not limited to the wavelength that specifies the final destination node of the signal in this way, but also includes the wavelength that specifies the selected waypoint. “Incoming side” and “outgoing side” mean an input side and an output side with respect to the optical switch array. The optical wavelength conversion means can convert the wavelength, but as a result, the wavelength may not be converted. With this configuration, wavelength conversion processing can be realized with a single optical wavelength conversion means without converting optical signals into electrical signals, and the number of wavelengths applicable to each node is greatly increased. It is possible to provide an optical switching device with high flexibility in route selection at a node.

  According to a second aspect of the present invention, in the optical switching device according to the first aspect, a schedule for exchanging and connecting signals from the incoming optical signal lines 1101 to 1132 to the outgoing optical signal lines 1201 to 1232 is stored. The switching control means 60 which has a switching table and controls opening / closing of the optical switch elements 50101 to 53232 constituting the optical switch array 50 based on the switching table is provided. Here, the switching table is created for each optical switching node. The switching control means may be formed in the optical switching node, but a plurality of optical switching nodes are formed in another place, for example, a base station computer, and the optical switching element of each optical switching node can be remotely operated. May be controlled. In addition, an exchange connection means that, as in a so-called exchange, any input optical signal line is connected to only one output optical signal line and any output optical signal line is only one input optical signal at an arbitrary time. A connection in a mode connected to a signal line. If comprised in this way, opening and closing of an optical switch element can be controlled efficiently in a predetermined order based on a switching table.

  According to a third aspect of the present invention, in the optical switching device according to the second aspect, the switching table stores the opening / closing of the optical switch elements 50101 to 53232 as a function of time. If comprised in this way, since the switching control means can refer to a switching table uniformly and can control opening and closing of an optical switch element, the structure can be simplified.

  Further, in the optical switching device 100A according to the second aspect, the invention according to the fourth aspect is a carrier wavelength detection for detecting the carrier wavelength from the carrier wave of the incoming optical signal lines 1101 to 1132 as shown in FIG. Means 1401 to 1432 are provided, and the switching table includes incoming optical signal lines 1101 to 1132, carrier wavelengths of the incoming optical signal lines 1101 to 1132, and outgoing optical signal lines 1201 to which the incoming optical signal lines 1101 to 1132 should be connected. -1232 and the outgoing wavelength signal lines 1201 to 1232 are stored, and the switching control means 60 collates the carrier wavelengths detected by the carrier wavelength detection means 1401 to 1432 with the switching table, and switches the optical switch elements 50101 to 5012. Controls opening and closing of 53232. Here, the carrier wavelength detection means detects the wavelength of the carrier wave, and the switching control means 60 obtains the destination from the connection information of the switching table directly when the carrier wavelength specifies the destination, and when the source is specified, The switching of the optical switch elements 50101 to 53232 is controlled so as to switch to the destination. Further, the detection of the carrier wavelength may be detected before input to the input side optical signal line, or may be detected after input. With this configuration, since the carrier wavelength is detected from the carrier wave and the opening / closing of the optical switch element is controlled, the reliability of the replacement destination can be increased.

  Further, in the optical switching device 100B according to the first, second, or fourth aspect, the invention according to the fifth aspect is inserted in the middle of the incoming optical signal lines 1101 to 1116 as shown in FIG. 7, for example. And optical branching means 7001 to 7016 for branching the signals separated into the incoming optical signal lines 1101 to 1116 by the wavelength separating means 101 to 104 into the incoming optical signal lines 7101 to 7116. With this configuration, broadcast communication is possible.

  According to a sixth aspect of the present invention, in the optical switching device according to any one of the first to fifth aspects, the optical wavelength separation means 101-108 forms a grating element or a diffraction grating in the arrayed waveguide. It is a thing. If comprised in this way, an optical wavelength separation means can be integrated and highly accurate.

  According to a seventh aspect of the present invention, there is provided the optical switching device according to any one of the first to sixth aspects, wherein the optical switch elements 50101 to 53232 constituting the optical switch array 50 are MEMS (microelectronic machine). System) optical switch element. If comprised in this way, an optical switch array can be integrated and highly accurate.

  According to an eighth aspect of the present invention, in the optical switching device according to any one of the first to seventh aspects, the input-side optical signal lines 1101 to 1116 and the output-side optical signal lines 1201 to 1216 are optical. It is a waveguide. With this configuration, input / output signal lines can be integrated.

  The invention according to claim 9 is the wavelength conversion element in which the optical wavelength conversion means 1301 to 1332 use two-stage pumping light in the optical switching device according to any one of claims 1 to 8. . If comprised in this way, an optical wavelength conversion means can be integrated and highly accurate.

  In the optical switching device according to any one of claims 1 to 9, the optical wavelength multiplexing means 111-118 forms a grating element or a diffraction grating in the arrayed waveguide. It is a thing. If comprised in this way, an optical wavelength multiplexing means can be integrated and highly accurate.

  In order to solve the above problem, an optical switching method according to an eleventh aspect is an optical switching method of a wavelength division multiplexing optical communication system in which a destination node or a source node is specified by a wavelength as shown in FIG. Then, an optical wavelength separation step (S010) for wavelength-separating the wavelength multiplexed signals received from the input side optical communication paths n1 to n8 into signals to a plurality of incoming optical signal lines 1101 to 1116, and an optical wavelength separation step (S010) The optical switching step (S020) for connecting the signals separated by the incoming optical signal lines 1101 to 1132 to the outgoing optical signal lines 1201 to 1232 toward the destination node, and the outgoing optical signal line 1201 by the optical switching step (S020). Light that converts the wavelength of the signal connected to ˜1232 to a wavelength that identifies the destination node or maintains a wavelength that identifies the destination node or source node A wavelength conversion step (S040) of wavelength-multiplexing the signal subjected to wavelength conversion or the wavelength-maintained signal by the wavelength conversion step (S030) and transmitting the signals to the output side optical communication channels m1 to m8. ). With this configuration, it is possible to provide an optical switching method that does not convert an optical signal into an electrical signal, that is simple in wavelength conversion processing and that has high flexibility in route selection at a node. In addition, although wavelength conversion is possible in the optical wavelength conversion step, the wavelength may not be converted as a result.

  The invention described in claim 12 is the optical switching method according to claim 11, wherein the optical switching step (S020) sends signals from the input optical signal lines 1101-1132 to the output optical signal lines 1201-1232. The switching table for storing the exchange connection schedule is used to control the opening / closing of the optical switch elements 50101 to 53232 constituting the optical switch array 50 based on the switching table. If comprised in this way, opening and closing of an optical switch element can be controlled regularly and efficiently based on a switching table.

The optical communication method according to claim 13 is the optical switching node according to claim 12, wherein a plurality of optical switching nodes are network-connected by a wavelength division multiplexing optical communication system in which a destination node or a source node is specified by a wavelength. An optical communication method using the optical switching method of claim 1, wherein the optical switching method uses a carrier wave of an incoming optical signal line to an optical switching node based on a switching table or by means for detecting a wavelength of the carrier wave in an optical switching step. The destination wavelength is obtained by collating the carrier wavelength detected from the switching table with the switching table, and the destination node obtained for the input signal to the optical switching node is within the own node area. For the input signal from the local node area to the optical switching node Line by selecting and switching control so as to transmit the output side optical signal line selected the input signal.
Here, capturing into the own node area means dropping out to the own node area and carrying a signal toward a lower station in the area. With this configuration, the optical switching method according to the present invention is used for a network having an optical switching node, without converting an optical signal into an electrical signal, with a simple wavelength conversion process, and the flexibility of path selection at the node. An optical communication method with high performance can be provided.

The invention according to claim 14 is the optical communication method according to claim 13, wherein when each optical switching node constitutes a loop and the detected destination node is outside its own node area, Switching control is performed so that the signal passes through the next node of the loop.
With this configuration, it is possible to avoid unnecessary signal acquisition in a loop configuration network.

  According to the present invention, wavelength conversion processing can be realized with one optical wavelength conversion means without converting an optical signal into an electrical signal, and the wavelength applicable to each node is greatly increased. It is possible to provide an optical switching apparatus and an optical switching method with high flexibility in route selection at a node.

  Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 shows a configuration example of an optical switching apparatus 100 according to the first embodiment. Here, eight input side optical fibers n1 to n8 are used as input side optical communication paths, and eight output side optical fibers m1 to m8 are used as output side optical communication paths. An example will be described in which the wavelength division multiplexing number of the side optical fibers m1 to m8 is quadruple and the space division type optical switch 50 having a 32 row × 32 column array configuration is used as the optical switch array.

  The communication system of this embodiment is a wavelength division multiplexing optical communication system in which a destination node or a source node is specified by a wavelength. An optical switching node in which the optical switching device 100 is installed in an optical network may be configured with a loop topology or a star topology. The optical switching node receives signals from the adjacent optical switching nodes through the input optical communication paths n1 to n8, and transmits signals to the adjacent optical switching nodes through the output optical communication paths m1 to m8. Each of the input side optical communication paths n1 to n8 may be provided between different optical switching nodes, or may be provided overlapping with the same optical switching node. Further, each of the output side optical communication paths m1 to m8 may be provided between different optical switching nodes, or may be provided overlapping with the same optical switching node.

  In this embodiment, the input side optical fiber n1 is a signal of wavelengths λ1 to λ4, the input side optical fiber n2 is a signal of wavelengths λ5 to λ8,..., And the input side optical fiber n8 is a signal of wavelengths λ29 to λ32. Each is quadruple. Reference numerals 101 to 108 denote optical wavelength separation modules as optical wavelength separation means, and the optical wavelength separation module 101 wavelength-separates the signals of wavelengths λ1 to λ4 carried on the input side optical fiber n1 into λ1 to λ4, and signals of wavelength λ1. Are sent to the incoming optical waveguide 1101, the signal of wavelength λ2 is sent to the incoming optical waveguide 1102,..., And the signal of wavelength λ4 is sent to the incoming optical waveguide 1104. As the optical wavelength separation means, for example, an arrayed waveguide grating element or an arrayed waveguide diffraction grating can be used. These can be integrated in a plane using a planar lightwave circuit, and can be demultiplexed or multiplexed into, for example, 100 waves with one element (for example, “256 channel arrayed waveguide grating type wavelength multiplexing / demultiplexing module”, NTT Photonics Research) Introducing the research results 6-3, 2003), modularization is convenient.

In the space division type optical switch 50, the optical switch elements 50101 to 53232 are arranged in a planar space at the cross points of the input side optical waveguides 1101 to 1132 and the output side optical waveguides 1201 to 1232, and the input side optical waveguides 1101 to 1101 are arranged. 1132 and the outgoing optical waveguides 1201 to 1232 are switching-connected. Among these optical switch elements 50101 to 53232, for example, an optical switch element 50102 indicated by a circle indicates a switch-on state, that is, a state where the input side optical waveguide 1101 and the output side optical waveguide 1202 are connected. An optical switch element 50229 indicated by a circle indicates a switch-on state, that is, a state where the input side optical waveguide 1102 and the output side optical waveguide 1229 are connected. For example, an optical switch element not indicated by a circle Reference numeral 50101 denotes a switch-off state, that is, a state where the input-side optical waveguide 1101 and the output-side optical waveguide 1201 are not connected, and the same notation is used for other optical switch elements. As the optical switch elements 50101 to 53232 constituting the optical switching array 50, for example, MEMS (Micro Electro Mechanical Systems) optical switch elements can be used. The MEMS chip can downsize and highly integrate an optical switching array. For example, an adjacent switch interval is 500 μm, and 16 switches can be integrated in 1 cm × 2 cm (for example, “development of MEMS optical switch (MEMCROS ^™ )”, (See Makoto Katayama et al., SEI Technical Review No. 161, P32-36, September 2002). In addition, it is possible to manufacture a highly accurate switch element using microelectronic technology.

  Reference numeral 60 denotes switching control means for controlling opening / closing (ON / OFF) of the optical switch elements 50101 to 53232 arranged at 32 × 32 cross points in the space division type optical switch 50 as an optical switching array. The control signal is transmitted to each of the optical switch elements 50101 to 53232 through a control signal line (not shown) different from the input / output signal. The switching control means 60 has a switching table, and the switching table stores the opening and closing of each optical switch element 50101 to 53232 as a function of time. The switching control means 60 opens and closes each optical switching element 50101 to 53232 based on the switching table. To control.

  FIG. 2 shows an example of the switching table. At times t1 to t2, the input-side optical communication paths n1 to n8 and the wavelengths λ1 to λ32 of the input-side optical signal lines are used as rows, and the output-side optical communication paths m1 to m8 and the wavelengths λ1 to λ32 of the output-side optical signal lines are arranged. As shown, open / close of each optical switch element 50101 to 53232 located at the cross point is indicated by 0 (open: off) and 1 (closed: on). The contents of this opening and closing correspond to FIG. At this time, only one cross-point optical switch element is turned on for each of the input-side optical waveguides 1101 to 1132, and only one cross-point optical switch element is turned on for each of the output-side optical waveguides 1201 to 1232. To be controlled. That is, an input signal to any one input optical waveguide is connected to only one output optical waveguide and sent out. Therefore, in this embodiment, 32 or less optical switch elements are turned on at the same time, and more than 32 optical switch elements are never turned on.

  Returning to FIG. 1, reference numerals 1301 to 1332 denote optical wavelength conversion modules as optical wavelength conversion means, which are inserted on the output side of the optical switch array 50 in the middle of the output side optical waveguides 1201 to 1232, and are connected to the output side optical waveguides 1201 to 1232. A signal is input from the optical switch element side, the wavelength is converted, and the signal is output to the opposite side to the optical switch element of the same output optical waveguides 1201 to 1232. For example, the optical wavelength conversion module 1302 converts the signal of the wavelength λ1 on the optical switch element 50102 side in the outgoing optical waveguide 1202 into a signal of the wavelength λ2 that specifies the destination for the outgoing optical waveguide 1202, and is opposite to the optical switch element 50102. The optical wavelength conversion module 1329 converts the signal of wavelength λ 2 on the optical switch element 50229 side in the output optical waveguide 1229 into a signal of wavelength λ 29 that specifies the destination for the output optical waveguide 1229, and converts the signal to the optical switch element 50229. And output to the opposite side. Similarly for the other optical wavelength conversion modules, the signal on the optical switch element side in the output optical waveguide is converted into a signal having a wavelength for specifying the destination for the output optical waveguide and output to the opposite side of the optical switch element. The wavelength conversion here includes a case where the wavelength specifying the destination or the transmission source is maintained as it is, and as a result, the wavelength is not converted. For example, a multi-QPM-LN (quasi-phase matched LiNbO) wavelength conversion element can be used as the optical wavelength conversion element. For example, it is possible to convert to about 10 different wavelengths between 1515 and 1545 nm using a combination of excitation light wavelengths using two stages of excitation light (for example, “variable optical frequency shifter using multi-QPM-LN wavelength conversion element”) , Introduction of NTT Photonics Laboratories research results Optical signal processing technology-5, 2005, see). Further modularization is convenient for handling.

Reference numerals 111 to 118 denote optical wavelength multiplexing modules as optical wavelength multiplexing means, which multiplex signals on the output side optical waveguides 1201 to 1232 and send them to the output side optical fibers m1 to m8. The optical wavelength multiplexing module 111 multiplexes the signals from the four output optical waveguides 1201 to 1204 to the output side optical fiber m1, and the optical wavelength multiplexing module 112 receives the signals from the four output optical waveguides 1205 to 1208. The optical wavelength multiplexing module 118 multiplexes the signals from the four output optical waveguides 1229 to 1232 and sends them to the output optical fiber m8. As the optical wavelength multiplexing means, for example, an arrayed waveguide grating element or an arrayed waveguide diffraction grating can be used. These can be integrated in a plane using a planar lightwave circuit, and can be demultiplexed or combined into, for example, 100 waves with one element (for example, “development of MEMS optical switch (MEMCROS ^™ )”, Makoto Katayama et al., SEI Technical Review 161, P32-36, September 2002)), and modularization is convenient.

  In addition, when optical waveguides are used as optical input signal lines and optical output signal lines, they can be integrated on a plane using optical integrated circuit technology, and can be formed on MEMS chips, arrayed waveguide grating elements, or arrayed waveguide grating modules. Is preferred. In addition, if optical fibers are used as the input side optical communication path and the output side optical communication path, it is suitable for multiplex communication connection between remote optical switching nodes with low loss. In addition, in the network, a control unit that supervises the switching control unit of all the optical switching nodes is necessary, but it may be installed in any one of the base stations or any one of the optical switching nodes. Alternatively, distributed control may be performed by installing in a plurality of base stations or a plurality of optical switching nodes. A common signal line is provided between the overall control means and each switching control means to exchange information with each other.

  FIG. 3 shows an example of a processing flow of the optical switching method in the present embodiment. For example, a signal having a wavelength λ1 conveyed through an input-side optical fiber n1 serving as an input-side optical communication path is mechanically wavelength-separated by an optical wavelength separation module 101 serving as an optical wavelength separation unit, and is used as an optical input signal line. The light is sent to the input side optical waveguide 1101 (optical wavelength separation step: step S010). Next, in the space division type optical switch 50 as an optical switch array, for example, the optical switch element 50102 is turned on at time t1 to t2 under the control of the switching control means 60, and the signal of the wavelength λ1 on the input side optical waveguide 1101 is It is sent out to the output side optical waveguide 1202 as an optical output signal line (optical switching process: step S020). The switching control means 60 has a switching table, and the switching is recorded as a function of time for each of the optical switch elements 50101 to 53232, and the switching control means 60 is based on the information recorded in this switching table. The optical switch elements 50101 to 53232 are controlled through control signal lines (not shown). Next, in the optical wavelength conversion module 1302 as the optical wavelength conversion means, the signal of the wavelength λ1 in the output optical waveguide 1202 is converted into the signal of the wavelength λ2 that specifies the destination node for the output optical waveguide 1202 (optical wavelength conversion). Step: S030). Next, the optical wavelength multiplexing module 111 as the optical wavelength multiplexing means multiplexes the signals from the four output side optical waveguides 1201 to 1204 and sends them to the output side optical fiber m1 (optical wavelength multiplexing step: S040).

  Further, for example, the signal of wavelength λ2 carried through the input-side optical fiber n1 is mechanically wavelength-separated by the optical wavelength separation module 101 and sent to the input-side optical waveguide 1102 (step S010). Next, in the space division type optical switch 50, for example, the optical switch element 50229 is turned on at time t1 to t2 by the control of the switching control means 60, and the signal of wavelength λ2 on the input side optical waveguide 1102 is sent to the output side optical waveguide 1229. It is sent out (step S020). Next, the optical wavelength conversion module 1329 converts the signal of wavelength λ2 on the output optical waveguide 1229 into a signal of wavelength λ29 corresponding to the destination node for the output optical waveguide 1229 (S030). Next, the optical wavelength multiplexing module 118 multiplexes signals from the four output optical waveguides 1229 to 1232 and sends them to the output optical fiber m8 (S040). Similarly, input signals of other arbitrary wavelengths are wavelength-separated, switching-connected, wavelength-converted, and wavelength-multiplexed, and transmitted as output signals of a predetermined wavelength to any output-side optical communication path. As a result, the original wavelength may be maintained in the optical wavelength conversion step.

  Assuming that the optical switching node in FIG. 1 is the Tokyo central office, FIG. 4 shows the relationship between the wavelengths specifying the optical fiber, signal line, source node or destination, the central office, and the local office. The transmission source is a transmission source corresponding to the input side optical fibers n1 to n8 (Tokyo central office, Osaka central office,..., Sapporo central office) and a transmission source corresponding to the input side optical signal lines 1101 to 1132 (Tokyo region). Station, Hachioji Regional Station, ..., Obihiro Regional Station), destinations corresponding to the output side optical fibers m1 to m8 (Tokyo Central Office, Osaka Central Office, ..., Sapporo Central Office) ) And destinations corresponding to the outgoing optical signal lines 1201 to 1232 (Tokyo local station, Hachioji local station,..., Obihiro local station). Signals of wavelengths λ1 to λ4 are multiplexed and input from the four local stations in the Tokyo central office area by the input side optical fiber n1, and signals of wavelengths λ1 to λ4 are input to the Tokyo central office area by the output side optical fiber m1. Are multiplexed and output. In addition, signals with wavelengths λ5 to λ8 are multiplexed with the Osaka central office, input through the input side optical fiber n2, and output through the output side optical fiber m2,... With the Sapporo central office, wavelengths λ29 to λ32 Are multiplexed, input through the input side optical fiber n8, and output through the output side optical fiber m8. In FIG. 1 and FIG. 4, the wavelengths of signals traveling between the stations are specified. However, these wavelengths can be arbitrarily changed and transported. According to the switching table of FIG. 2, among the signals from the Tokyo central office area, the signal of wavelength λ2 from the Hachioji local station is added from the node and the wavelength λ29 to the Sapporo local station from time t1 to t2. The wavelength is converted to the next wavelength and transported to the next node, the Sapporo Central Office. Also, the signal of wavelength λ5 from the Osaka local station is converted into a signal of wavelength λ4 to the Saitama local station at the node and dropped into the Tokyo central office area. A signal of wavelength λ1 from the Tokyo local station in the Tokyo central station area is converted into a signal of wavelength λ2 to the Hachioji local station. Signals from other local stations inside and outside the Tokyo central office area are also switched based on the switching information stored in the switching table, wavelength-converted, and conveyed to the next node.

  The final destination node of each signal is grasped by a control unit (not shown) that controls the switching control unit, analyzes the traffic of the entire network, determines the path of each signal and the switching control data in each optical switching node, The switching control data is transmitted to the switching control means of each node via the common signal line, and stored as a function of time in the switching table of each node. Thereafter, the switching control means arranged at each optical switching node controls the optical switch elements of the switching array 50 while referring to its own switching table.

  As described above, according to the present embodiment, the wavelength conversion process can be realized by one optical wavelength conversion means without converting the optical signal into an electric signal, and the wavelength applicable to each node is simple. Therefore, it is possible to provide an optical switching apparatus and an optical switching method with high flexibility in route selection at a node.

[Second Embodiment]
In the first embodiment, an example in which the switching table stores the opening / closing of each optical switch element as a function of time has been described. However, in the second embodiment, the carrier wave of the signal input to the optical switch array is subtracted from the carrier wave. A description will be given of an example in which carrier wavelength detection means for detecting the length is provided, and the switching control means controls the opening / closing of the optical switch element by comparing the carrier wavelength detected by the carrier wavelength detection means with the switching table.

  FIG. 5 shows a configuration example of an optical switching apparatus 100A according to the second embodiment. In addition, the same code | symbol is attached | subjected about the site | part same as FIG. 1, and the overlapping description is abbreviate | omitted. The carrier wavelength detectors 1401 to 1432 are inserted into the input side of the optical switch array 50 in the middle of the input optical waveguides 1101 to 1132 as input optical signal lines, and are transmitted from the carrier wave input to the input optical waveguides 1101 to 1132. Is detected and notified to the switching control means 60. The switching table includes incoming optical signal lines 1101 to 1132, carrier wavelengths of the incoming optical signal lines 1101 to 1132, outgoing optical signal lines 1201 to 1232 and outgoing optical signals to which the incoming optical signal lines 1101 to 1132 are connected. The relationship between the carrier wavelengths of the lines 1201 to 1232 is stored, and the switching control means 60 controls the opening and closing of the optical switch elements 50101 to 53232 by comparing the wavelength of the carrier wave detected by the carrier wavelength detection means 1401 to 1432 with the switching table.

  Assuming that the optical switching node in FIG. 5 is the Tokyo central office, input side optical fibers n1 to n8, output side optical fibers m1 to m8, input side optical signal lines 1101 to 1132, output side optical signal lines 1201 to 1232, transmission source It is assumed that the relationship between the wavelengths λ1 to λ32 specifying the node or the destination and the central station and the local station is as shown in FIG. From the Tokyo central office area, signals of wavelengths λ1 to λ4 are multiplexed and inputted by the input side optical fiber n1, and signals of wavelengths λ1 to λ4 are multiplexed by the output side optical fiber m1 to the Tokyo central office area. Is output. In addition, signals with wavelengths λ5 to λ8 are multiplexed with the Osaka central office, input through the input side optical fiber n2, and output through the output side optical fiber m2,... With the Sapporo central office, wavelengths λ29 to λ32 Are multiplexed, input through the input side optical fiber n8, and output through the output side optical fiber m8. As a result, the up, drop, and cross connect in this case are the same as those in the first embodiment.

  FIG. 6 shows an example of the switching table. A row is a table indicating an input side, and a column is a table indicating an output side. In addition to the time described in the table, on the input side, the input side optical communication paths n1 to n8, the transmission source, the input side optical signal lines 1101 to 1132, the carrier wavelength, and the specific type (the one specified by the carrier wavelength is the transmission source Or the destination). Among these, time, carrier wavelength, and specific type are variable. The transmission sources are the transmission sources (Tokyo central office, Osaka central office,..., Sapporo central office) corresponding to the input side optical communication channels n1 to n8, and the corresponding transmission sources (Tokyo, Tokyo). (Local station, Hachioji local station, ..., Obihiro local station). The specific type is 0 when specifying the source, and 1 when specifying the destination. The carrier wavelengths λ1 to λ4 are the wavelengths of the carrier waves from the four local stations in the Tokyo central office area to the Tokyo central office, and the carrier wavelengths λ5 to λ32 are the carrier wavelengths to the central offices to the Tokyo central office. When the specific type is 0, the carrier wavelength represents the source. When the carrier wavelength is different from the source wavelength, for example, the incoming optical signal line 1108 that is normally used for communication from the Nara local station is a communication whose source is the Fukuoka local station (specified wavelength λ13) having a specific type of 0. The incoming optical signal line 1109, which is normally used for communications from the Nagoya local station, is used for communications with the specific type 1 and the destination being the Kanazawa local station (specified wavelength λ21). Means.

  On the output side, output side optical communication paths m1 to m8, destination, output side optical signal lines 1201 to 1232, carrier wavelength, specific type, and final destination are shown. Among these, the carrier wavelength, the specific type, and the final destination are variable. The destination corresponds to the output side optical communication paths m1 to m8 (Tokyo central station, Osaka central station,..., Sapporo central station) and the destination corresponding to the output side optical signal lines 1201 to 1232 (Tokyo local station, Hachioji Regional Station, ..., Obihiro Regional Station). The specific type is 0 when specifying the source, and 1 when specifying the destination. The carrier wavelengths λ1 to λ4 are the wavelengths of the carrier waves from the Tokyo central office to the four local stations in the Tokyo central office area, and the carrier wavelengths λ5 to λ32 are the carrier wavelengths from the Tokyo central office to each central station. When the specific type is 1, the carrier wavelength represents the destination. When the carrier wavelength is different from the destination wavelength, for example, the outgoing optical signal line 1208 that is normally used for communication to the Nara local station is used for communication in which the specific type is 0 and the source is the Sendai local station (specified wavelength λ25). The outgoing optical signal line 1225 that is normally used for communication to the Sendai local station is specified as 1 and is used for communication with the Sapporo local station (specified wavelength λ29) as the destination. means. If the destination specified by the carrier wavelength is different from the final destination, the network uses the control means that supervises the switching control means of all optical switching nodes or the switching table through which the signal passes to determine the final destination. It is necessary to keep. In the present embodiment, when the destination is different from the final destination in each switching table, the final destination is also displayed. For example, Fukuoka, Sapporo, and Wakkanai are displayed as final destinations in the columns of destinations Nara, Sendai, and Asahikawa. In the switching table of FIG. 6, the input side optical communication paths n1 to n8 and the wavelengths λ1 to λ32 of the input side optical signal lines are arranged in rows, and the wavelengths λ1 to λ32 of the output side optical communication paths m1 to m8 and the output side optical signal lines are set. As columns, open / close of each of the optical switch elements 50101 to 53232 positioned at the cross point is indicated by 0 (open: off) and 1 (closed: on). The contents of this opening and closing substantially correspond to FIG.

  The carrier wavelength detection means 1401 to 1432 can use a spectroscopic wavelength meter or the like, and detects the wavelength of the carrier wavelength. In this case, when the carrier wave wavelength specifies the destination by collating with a specific type of the switching table, the destination is obtained directly from the carrier wavelength, and when the source is identified, the switching table is collated and the crosspoint is determined. The destination and the wavelength of the carrier wave are obtained from (display is 1). In this case, the wavelength of the carrier wave is changed from the wavelength specifying the transmission source to the wavelength specifying the destination, and the wavelength conversion is performed by the optical wavelength conversion modules 1301 to 1332. However, there are cases where the wavelength of the transmission source is maintained as it is and wavelength conversion is not performed. Further, the detection of the carrier wavelength may be detected before input to the incoming optical signal line (that is, the carrier wavelength detection means is inserted before the optical wavelength separation means), or may be detected after input. In this way, the carrier wavelength of each input signal is detected, the destination node is obtained by collating with the switching table, and each of the input side optical waveguides 1101 to 1132 can be connected to the output side optical waveguides 1201 to 1232. it can. In addition, since the destination is determined from the carrier wavelength of each input signal and the opening and closing of the optical switch element is controlled, the reliability of the replacement destination can be increased.

  For example, when the carrier wavelength λ2 of the incoming optical signal line 1102 is detected by the carrier wavelength detection unit 1401, the specific type is 0 from the switching table and the transmission source is indicated. It can be seen that this is the power output optical signal line 1229. Since the specific type of the outgoing optical signal line 1229 is 1 and the wavelength λ29 specifies the Sapporo local station as the destination node, the incoming optical signal line 1102 should be switched to the outgoing optical signal line 1229 toward the Sapporo local station. It can be seen that the wavelength should be converted from λ2 to λ29. That is, the switching control means 60 refers to the switching table, turns on the optical switch element 50229 so as to connect the input-side optical signal line 1102 to the output-side optical signal line 1229, and enters the input-side optical signal line 1102 and the output-side light. All other optical switch elements connected to the signal line 1229 are turned off. According to the present embodiment, the carrier wavelength detected by the carrier wavelength detection means in this manner can be checked against the switching table, and switching control can be performed reliably.

  The configuration of the optical switching apparatus 100A in the present embodiment is the same as that of the first embodiment except for the addition of the destination detection means 1401 to 1432 and the difference in the switching table, and the optical signal is transmitted in the same manner as in the first embodiment. It is possible to provide an optical switching apparatus and an optical switching method that do not convert into an electric signal, that are easy to perform wavelength conversion processing, and that have high flexibility in route selection at a node.

[Third Embodiment]
In the first embodiment, there are eight input-side optical communication paths. In the third embodiment, there are four input-side optical communication paths, and two optical signals having the same wavelength are split after passing through the optical wavelength separation means. An example is shown. That is, in this embodiment, broadcast communication to different destinations is possible.

  FIG. 7 shows a configuration example of an optical switching device 100B in the third embodiment. In addition, the same code | symbol is attached | subjected about the site | part same as FIG. 1, and the overlapping description is abbreviate | omitted. In the present embodiment, four input side optical fibers n1 to n4 are used as input side optical communication paths, and eight output side optical fibers m1 to m8 are used as output side optical communication paths. n4, the wavelength division multiplexing number of each of the output side optical fibers m1 to m8 is quadruple, and a space division type optical switch 50 having a 32 row × 32 column array configuration is used as the optical switch array. The signals from the input side optical fibers n1 to n4 are branched into two by optical splitters 7001 to 7016 as optical branching means after passing through the optical wavelength separation modules 101 to 104, respectively.

  Optical splitters 7001 to 7016 are inserted on the input side of the optical switch array in the middle of the input optical waveguides 1101 to 1116 as optical input signal lines, and the signals of wavelengths λ1 to λ4 separated by the optical wavelength separation modules 101 to 104 are In addition to outputting to the optical switch array side of the input-side optical waveguides 1101 to 1116, it outputs to the input-side branch optical waveguides 7101 to 7116 as input-side branch optical signal lines. For example, the optical splitter 7001 branches the signal of wavelength λ 1 in the input optical waveguide 1101 to the input branch optical waveguide 7101, and the optical splitter 7002 transfers the signal of wavelength λ 2 in the input optical waveguide 1102 to the input branch optical waveguide 7102. The optical splitter 7016 branches the signal having the wavelength λ16 in the incoming optical waveguide 1116 to the incoming optical waveguide 7116. Similarly to the input-side optical waveguides 1101 to 1116, the optical switch elements 70101 to 71632 of the optical switch array are also arranged in the branched input-side branch optical waveguides 7101 to 7116. Other configurations are the same as those of the first embodiment.

  FIG. 8 shows a processing flow example of the optical switching method in the third embodiment. The signal of wavelength λ1 carried through the input side optical fiber n1 as the input side optical communication path is wavelength-separated by the optical wavelength separation module 101 as the optical wavelength separation means, and the input side optical waveguide 1101 as the optical input signal line. (Optical wavelength separation step: step S110). Next, the optical splitter 7001 as an optical branching unit branches the signal having the wavelength λ1 on the incoming optical waveguide 1101 to the incoming optical waveguide 7101 (optical branching step: step S115).

  Next, in the space division type optical switch 50 as an optical switch array, for example, the optical switch element 50102 is turned on at time t1 to t2 under the control of the switching control means 60, and the signal of the wavelength λ1 on the input side optical waveguide 1101 is output. At the same time, the optical switch element 70105 is turned on, and the signal of the wavelength λ1 on the input side branch optical waveguide 7101 is transmitted to the output side optical waveguide 1205 as an optical output signal line (optical switching step). : Step S120). The switching control means 60 has a switching table. For each optical switch element 50101 to 51632, 70101 to 71632, for example, as shown in FIG. 2, opening and closing is recorded as a function of time, and the switching control means 60 records in this switching table. Based on the obtained information, each optical switch element 50101 to 51632, 70101 to 71632 is controlled by a control signal line (not shown).

  Next, in the optical wavelength conversion module 1302 as the optical wavelength conversion means, for example, the signal of the wavelength λ1 in the output side optical waveguide 1202 is converted into the signal of the wavelength λ2 that specifies the destination for the output side optical waveguide 1202 as the optical output signal line. At the same time, the optical wavelength conversion module 1305 converts the signal of wavelength λ1 in the output optical waveguide 1204 into a signal of wavelength λ5 that specifies the destination for the output optical waveguide 1205 as an optical output signal line (optical wavelength conversion step). : S130). Next, in the optical wavelength multiplexing module 111 as an optical wavelength multiplexing means, the signals from the four output side optical waveguides 1201 to 1204 are multiplexed and sent to the output side optical fiber m1, and at the same time in the optical wavelength multiplexing module 112, The signals from the four output side optical waveguides 1205 to 1208 are multiplexed and sent to the output side optical fiber m2 (optical wavelength multiplexing step: S140). Input signals other than the wavelength λ1 are also bifurcated by the optical splitter, respectively, are subjected to switching control, converted into a signal having a wavelength specified at the destination, and sent to the output side optical fiber. As a result, the original wavelength may be maintained in the optical wavelength conversion step.

  When the optical switching node of FIG. 8 is compared with FIG. 1, the output side is the same as FIG. 1, but the input side optical fibers n1 to n4 are halved, and the central station on the input side is, for example, Tokyo Central Office, Osaka Central Half of the number of stations, Nagoya Central Office, Fukuoka Central Office, and local stations are also limited to these areas. In addition, broadcast communication from the optical switching node to the two central office areas becomes possible. For example, a signal of wavelength λ14 from the Kumamoto regional station is dropped at a node of the Tokyo central office, converted into a signal of wavelength λ4 to the Saitama regional station, and transported to the Tokyo central office area at the same time as the Hakodate regional station. It is converted into a signal of wavelength λ30 and is transported within the Sapporo Central Office area. Thus, it can be transported outside the four central office areas.

  The other configuration of the optical switching apparatus 100B in the present embodiment is the same as that of the first embodiment, the optical signal is not converted into an electrical signal, the wavelength conversion process is simple, and the node It is possible to provide an optical switching device and an optical switching method with high flexibility in route selection.

[Fourth Embodiment]
In the third embodiment, an example in which the switching table stores the opening / closing of each optical switch element as a function of time has been described. However, in the fourth embodiment, the carrier wave of the signal input to the optical switch array is subtracted from the carrier wave. A description will be given of an example in which carrier wavelength detection means for detecting the length is provided, and the switching control means controls the opening / closing of the optical switch element by comparing the carrier wavelength detected by the carrier wavelength detection means with the switching table.

  FIG. 9 shows a configuration example of an optical switching apparatus 100C according to the fourth embodiment. In addition, about the same site | part as FIG. 7, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted. The carrier wavelength detectors 1401 to 1432 are inserted in front of the optical branching units 7001 to 7016 in the middle of the incoming optical waveguides 1101 to 1132 as incoming optical signal lines, and are generated from the carrier waves input to the incoming optical waveguides 1101 to 1132. The wavelength of the carrier wave is detected and notified to the switching control means 60. The switching table includes incoming optical signal lines 1101 to 1132, carrier wavelengths of the incoming optical signal lines 1101 to 1132, outgoing optical signal lines 1201 to 1232 and outgoing optical signals to which the incoming optical signal lines 1101 to 1132 are connected. The relationship between the carrier wavelengths of the lines 1201 to 1232 is stored, and the switching control means 60 controls the opening and closing of the optical switch elements 50101 to 53232 by comparing the wavelength of the carrier wave detected by the carrier wavelength detection means 1401 to 1432 with the switching table.

  The carrier wavelength detecting means 1401 to 1416 can use a spectroscopic wavelength meter or the like, and detect the wavelength of the carrier wave. In this case, when the carrier wave wavelength specifies the destination by collating with a specific type of the switching table, the destination is obtained directly from the carrier wavelength, and when the source is identified, the switching table is collated and the crosspoint is determined. The destination and the wavelength of the carrier wave are obtained from (display is 1). In this case, the wavelength of the carrier wave is changed from the wavelength specifying the transmission source to the wavelength specifying the destination, and the wavelength conversion is performed by the optical wavelength conversion modules 1301 to 1332. However, there are cases where the wavelength of the transmission source is maintained as it is and wavelength conversion is not performed. By the way, since the wavelength of a carrier wave can specify only one destination, for example, the destination of a branched signal needs to be stored in advance in a switching table. Further, the detection of the carrier wavelength may be detected before input to the input side optical signal line, or may be detected after input. In this way, the carrier wavelength of each input signal is detected, the destination node is obtained by collating with the switching table, and each of the input side optical waveguides 1101 to 1132 can be connected to the output side optical waveguides 1201 to 1232. it can. In addition, since the destination is determined from the carrier wavelength of each input signal and the opening and closing of the optical switch element is controlled, the reliability of the replacement destination can be increased.

  The configuration of the optical switching apparatus 100C in the present embodiment is the same as that of the third embodiment except for the addition of the carrier wavelength detection means 1401 to 1416 and the difference of the switching table, and the optical signal is the same as that of the third embodiment. The optical switching device and the optical switching method can be provided without converting the signal into an electrical signal, with a simple wavelength conversion process, and with high flexibility in route selection at the node.

[Fifth Embodiment]
Further, the present invention can be realized as an optical communication method using the optical switching device or the optical switching method described in the above embodiment. That is, in a mode in which a plurality of optical switching nodes are network-connected in a wavelength division multiplexing optical communication system in which a destination node or a transmission source node is specified by a wavelength, light using the optical switching device or the optical switching method in each optical switching node Communication method is established.
In the fifth embodiment, for example, the optical switching device (see FIG. 5) according to the second embodiment is arranged in each station as an optical switching node, and a star configuration that enables direct communication between the central offices. There will be described an example in which the network is applied in a star configuration from the central station to the lower stations.

  FIG. 10 shows a configuration of an optical switching network according to the fifth embodiment. A communication station having the optical switching device according to the second embodiment is arranged at each optical switching node. FIG. 10 (a) shows a star network configuration, and FIG. 10 (b) shows a configuration around a branch station in a configuration in which a branch station is inserted between the central station and the local station. In FIG. 10A, eight central stations X1 to X8 are connected so as to be able to communicate with each other directly (in order to simplify the expression, only communication lines connecting only the central station X1 to other central stations are shown. , Communication lines connecting the other central stations are omitted), each local station has four local stations (X11 to X14, etc.), each local station has four lower stations (X111 to X144, etc.), each lower station Subordinate stations (such as X1111 to X1444) are connected to the stations in a star shape. The central offices X1 to X8 have eight input side optical communication paths (quadruple) and eight output side optical communication paths (quadruple), of which seven pairs are one pair to other central stations. Is further separated into 4 pairs (single) and connected to 4 local stations in the area. The local station has five input side optical communication paths (quadruplex) and five output side optical communication paths (quadruple), and is connected to one central station and four lower stations. The subordinate station has five input side optical communication paths (quadruplex) and five output side optical communication paths (quadruple), and is connected to four lower stations with one local station. .

  FIG. 11 shows an example of a processing flow of a communication method using the optical switching method in the fifth embodiment. First, in each optical switching node, for example, after the optical wavelength separation step (S110), the carrier wavelength detectors 1401 to 1432 detect the wavelength of the carrier wave from the carrier wave input to the incoming optical waveguides 1101 to 1132 (carrier wavelength). Detection step: S112). Next, the switching control means 60 collates the wavelength of the carrier wave detected by the carrier wavelength detection means 1401 to 1432 with the switching table, and controls the opening and closing of the optical switch elements 50101 to 53232 (optical switching process: S120). The switching table includes incoming optical signal lines 1101 to 1132, carrier wavelengths of the incoming optical signal lines 1101 to 1132, outgoing optical signal lines 1201 to 1232 and outgoing optical signals to which the incoming optical signal lines 1101 to 1132 are connected. The relationship between the carrier wavelengths of the lines 1201 to 1232 is stored, and when the detected carrier wave wavelength specifies the destination, the destination is directly determined from the carrier wavelength, and when the source is specified, the switching table is checked. The destination and the wavelength of the carrier wave are obtained from the cross point (indicated by 1). Next, in the optical wavelength conversion step (S130), the wavelength of the signal connected to each outgoing optical signal line is converted to a wavelength for specifying the destination. However, there are cases where the wavelength of the transmission source is maintained as it is and wavelength conversion is not performed. Next, in the optical wavelength multiplexing step (S140), the wavelength-converted signal is wavelength multiplexed and transmitted to the output side optical communication path.

  The optical switching step (S120) and the optical wavelength conversion step (S130) will be described with reference to FIG. The optical switching node is assumed to be a Tokyo central office. First, as described above, when the detected carrier wavelength specifies the destination, the destination is obtained directly from the carrier wavelength, and when the source is specified, the switching table is collated and the destination is determined from the crosspoint. And the wavelength of the carrier wave. Thereafter, the processing is divided at the requested destination node. In principle, the destination and wavelength are changed at the add node and the drop node. First, in the case of an add node, that is, for a signal from its own node area, if the wavelength specifying the obtained destination node is an applicable wavelength at the node, the outgoing optical signal line toward the destination node To maintain or change the wavelength of the carrier wave to a wavelength that identifies the destination node. In the add node, the wavelength of the carrier wave often specifies the transmission source (specific type is 0). In this case, the destination node is changed and the wavelength is changed. For example, since the signal of wavelength λ2 from the Hachioji local station indicates the source, the Tokyo central station separately obtains the final destination node from the switching table. For example, when the Sapporo local station (wavelength λ29 corresponding to the destination node) is obtained, the signal of wavelength λ2 from the Hachioji local station is switched to the outgoing optical signal line toward the Sapporo local station as the final destination node. The wavelength is converted into a signal of wavelength λ29 that identifies the station as the destination node, and is transported to the Sapporo Central Office. In addition, when the wavelength specifying the obtained destination node is a wavelength that cannot be adapted by the node, the destination node that can be adapted by the local node is selected as a waypoint, that is, a new destination node, and is directed to the new destination node. Switch to the outgoing optical signal line, and change the wavelength of the carrier wave to a wavelength that specifies a new destination node. For example, if the final destination node cannot be selected from the Tokyo Central Office, such as Wakkanai Station and Naha Station, and cannot be adapted, select Asahikawa Regional Station (λ31) and Kagoshima Local Station (λ16) as the waypoints. The final destination node can be reached by transmitting the signal to these optical switching nodes which are via points, and selecting the Wakkanai station and Naha station as the destination nodes when the signal reaches the via point. If the destination and the wavelength are converted at either the add node or the drop node, either one may be performed.

  In the case of a drop node, that is, for a signal from other than the own node area, if the determined destination node is in the own node area, the signal is taken into the own node area and Control is performed so as to switch to the outgoing optical signal line toward the destination node in the area. In the drop node, the wavelength of the carrier wave often specifies the destination, but the source may also be specified. For example, since the signal of wavelength λ5 from the Osaka local station indicates the transmission source, the Tokyo central station separately obtains the final destination node. For example, when the Saitama local station (wavelength λ4 specifying the destination node) is obtained, The station determines that it is a node within its own node area (when λ1 to λ4), captures it into its own node area, switches to the outgoing optical signal line toward the local station, which is the destination node, and sets the wavelength of the carrier wave to the destination The wavelength is changed to a wavelength λ4 that specifies the node. In addition, when the determined destination node is the local node selected as the via point, the destination node is changed to the final destination node in the local node area or another via point, and the destination node directed to the new destination node is changed. Switch to the side optical signal line, and change the wavelength of the carrier wave to a wavelength that specifies the final destination node or another waypoint. For example, when a Takao station (wavelength λ201 specifying the destination node) is detected as the final destination node, the Hachioji local station (wavelength λ2 specifying the destination node) is selected as a transit point and conveyed to the Hachioji local station.

  Also, if the node is neither an add node nor a drop node but a relay node (but not in a pure star configuration), that is, if the detected destination node is outside its own node area, the signal is continued as it is. Pass to node and do not change wavelength. It is possible to perform amplification and waveform shaping.

  As a result, using the optical switching method according to the present invention, the optical signal is not converted into an electrical signal, and the wavelength conversion processing can be realized by one optical wavelength conversion means, and can be easily applied to each node. Therefore, the optical communication method that increases the flexibility of the node can be provided.

  One of the effects of the present invention is that the flexibility of route selection is high. If the wavelength can be changed to 32 ways, the destination is not limited to 4 even if there is only one pair of n2 and m2 (4 channels from λ5 to λ9) between Tokyo and Osaka. If the time is divided and the wavelength is changed, it is possible to adapt to 32 destinations (λ1 to λ32).

  If this is used, for example, Hachioji local station-λ2 → Tokyo central station-λ7 → Osaka central station-λ7 → Kobe local station Hachioji local station-λ7 → Tokyo central station-λ7 → Osaka central station-λ7 → Kobe It is possible to pass the local station and the Kobe local station that is the final destination from the beginning with the wavelength λ7. Even if subordinate stations are included, Takao station-λ201 → Hachioji local station-λ2 → Tokyo central station-λ7 → Osaka central station-λ7 → Kobe local station-λ701 → Rokko station Takao station-λ7 → Hachioji local station-λ7 → Tokyo Central Office-λ7 → Osaka Central Office-λ7 → Kobe Regional Station-λ701 → Rokko Station. This can be said to be a substantially relayable configuration. It is also possible to perform destination and wavelength conversion at both the add node and the drop node. Specifically, from Takao Station (λ201), when Rokko Station (λ701) is the final destination and Hachioji Regional Station (λ2) is added to Hachioji Regional Station, λ7) is selected as a transit point, and the Rokko station (λ701) is selected as the final destination at the Kobe local station of the drop node. The route is as follows: Takao station-λ2 → Hachioji local station-λ7 → Tokyo central station-λ7 → Osaka central station-λ7 → Kobe local station-λ701 → Rokko station.

  In the optical switching node configuration of the local station, 32 local stations (λ1 to λ32) are selected and added to the central station, and the local station is dropped from the central station as a destination node (including a waypoint). There is a pair of channels, add and drop, with the central office. In the case of an add, this one channel is used by dividing the time and switching the wavelength. In addition, 16 pairs of channels are used for 4 subordinate stations in the local station area and 16 subordinate stations. Thus, a 5 × 5 communication path and a 20 × 20 switch element array can be configured. Using this configuration, for example, in the Hachioji local station (λ2), it is possible to select the destination of 32 local stations (λ1 to λ32) using one add channel by switching the wavelength by dividing the time, There are 16 channels to the 4 subordinate stations (λ201 to λ204) and the 16 subordinate stations (λ205 to λ220) in the Hachioji local station area. It is possible to select by switching the wavelength and separating the wavelengths. In this case, in addition to 32 local stations (λ1 to λ32), the total number of wavelengths used is 52 for 4 subordinate stations (λ201 to λ204) and 16 subordinate stations (λ205 to λ220) in the Hachioji local station area. , 52 wavelengths can be converted.

  FIG. 10B shows a configuration around the branch station when a branch station is inserted between the central station and the local station as a modification of the star configuration of FIG. 10A. Between the central station and the local station, there are 4 pairs of channels (λ1 to λ4) each between the central station and 4 pairs of channels each between the 4 local stations. If a branch station having (λ1 to λ4) is provided, the central station and the local stations are quadrupled, and the local stations are also quadrupled. Other configurations are the same as the star configuration of FIG.

  In the subordinate stations, there are four pairs of add and drop channels to the local station, and 32 local stations (λ1 to λ32) used by switching the wavelength by dividing time are selected and added to the central station. In addition, there are 16 channels for the lower four stations (for example, λ205 to λ209) and the further lower 16 stations (for example, λ221 to λ236). Can be selected. In this case, the total number of wavelengths used is 32 for the 32 local stations (λ1 to λ32), the lower 4 stations in the lower station area, and the 16 lower stations in the lower station area, and wavelength conversion to 52 wavelengths is possible. Configured. Further, the configuration of the lower stations is almost the same.

  In the case of such a network, if the Takao station (λ201) in the Hachioji regional station area is the source and the final destination is the Yokosuka station (λ301) in the Tokyo central office area, λ3) is selected as a waypoint, and Yokosuka Station (λ301) is selected as the final destination at the Yokohama Regional Station. If the final destination is the Tachikawa station (λ202) in the same Hachioji regional station area, the Hachioji regional station can select the Tachikawa station as the final destination, but the Takao station (λ201) directly selects the Tachikawa station (λ202). ) Can also be selected.

[Sixth Embodiment]
In the fifth embodiment, the example in which the optical switching device in the second embodiment is applied to a star configuration network has been described. In this embodiment, the optical switching device in the fourth embodiment is the first An example applied to a network having the same star configuration as in the fifth embodiment will be described.

  The processing flow of the communication method using the optical switching method in the sixth embodiment is the optical branching step (S115) after the carrier wavelength detection step (S112) with respect to the processing flow of the fifth embodiment shown in FIG. Are inserted into the incoming optical signal lines 1101 to 1116 and the incoming optical signal lines 7101 to 7116 in the optical switching step (S120), and then output to the outgoing optical signal lines 1201 to 1232 for specifying the destination node. Connecting. The other processing flow is the same as that of the fifth embodiment, and has the same effect.

  In FIG. 9, the optical switching node is assumed to be a Tokyo central office. A difference from the fifth embodiment is that signals are switched from the incoming optical signal lines 1101 to 1116 to the outgoing optical signal lines 1201 to 1232 at the same time from the incoming optical signal lines 7101 to 7116, and broadcast communication is performed. Is the point where is performed. For example, a signal of wavelength λ14 from the Kumamoto regional station in the Fukuoka central office area is dropped on the node of the Tokyo central office, converted into a signal of wavelength λ4 to the Saitama regional station, and then transported into the Tokyo central office area. The signal is converted into a signal of wavelength λ30 to the Hakodate regional station and conveyed to the Sapporo Central Station area.

  Other configurations are the same as those of the fifth embodiment, and the wavelength conversion process is simple without using the optical switching device or the optical switching method according to the present invention without converting the optical signal into an electrical signal. In addition, it is possible to provide an optical communication method that increases the flexibility of the node.

[Seventh Embodiment]
In the fifth embodiment, the optical switching node has the configuration shown in FIG. 5 and is a star configuration in which information can be directly communicated with each other between the central stations. Although an example has been described, in the present embodiment, the optical switching node has the configuration of FIG. 9, a network in which eight central stations are connected to one uppermost station in a star configuration, and a central configuration is connected to lower stations in a star configuration. An example will be described.

  FIG. 12 shows a configuration of an optical switching network according to the seventh embodiment. The central stations X1 to X8 are connected below the uppermost station X0, the lower stations X11 to X84 are connected below it, and the lower stations are connected below it in a star shape. If the configuration of FIG. 5 is applied to the top station, the input side optical fibers n1 to n8 and the output side optical fibers m1 to m9 are all connected to the central station. When applied to the central station, the input side optical fiber n1 and the output side optical fiber m1 are connected to the top station, and the input side optical fibers n2 to n8 and the output side optical fibers m2 to m8 are connected to the local station. When applied to a local station, the input side optical fiber n1 and the output side optical fiber m1 are connected to the central station, and the input side optical fibers n2 to n8 and the output side optical fibers m2 to m8 are connected to the lower stations.

  In FIG. 5, the optical switching node is assumed to be a Tokyo central office. In order to avoid confusion, the optical fiber and wavelength codes are distinguished by adding a '. The input side optical fiber n2 'and the output side optical fiber m2' are connected to the Tokyo local station, and the input side optical fiber n8 'and the output side optical fiber m8' are connected to the Utsunomiya local station. First, if it is an add node, for the signal from its own node area, if the wavelength that specifies the determined destination node is adaptable at the node, switch to the outgoing optical signal line toward the destination node, Maintain or change the wavelength of the carrier wave to a wavelength that identifies the destination node. For example, a signal of wavelength λ5 'from the Tokyo local station is input to the Tokyo central station, converted to a signal of wavelength λ4' for the top station, and then carried to the top station. Further, for example, a signal of wavelength λ31 'from the Utsunomiya local station is converted into a signal of wavelength λ6' to the Tokyo local station and is carried in the Tokyo local station area. In addition, when the wavelength for specifying the determined destination node is a wavelength that cannot be adapted by the node, a via point that can be adapted by the own node is selected as a new destination node, and the outgoing side light toward the new destination node is selected. Switch to the signal line and change the wavelength of the carrier wave to a wavelength that specifies the new destination node. For example, when the final destination node is not applicable to the node, such as the Osaka local station or the Sapporo local station, the top station is selected as a waypoint, and the signal is transmitted to the top station that is a waypoint. When the route point is reached, the final destination node can be reached by selecting the Osaka local station and the Sapporo local station as destination nodes.

  In the case of a drop node, for signals from other than the local node area (signal from the top station), if the determined destination node is within the local node area, the signal is transferred to the local node area. Capture and switch to the outgoing optical signal line toward the destination node, and change the wavelength of the carrier wave to a wavelength that identifies the destination node. For example, a signal of wavelength λ2 'from the top station is converted into a signal of wavelength λ29' to the Utsunomiya local station and conveyed into the Utsunomiya local station area. Further, when the determined destination node is the local node selected as the via point, the destination node is changed to the final destination node or another via point, and switched to the outgoing optical signal line toward the new destination node. Then, the wavelength of the carrier wave is changed to a wavelength that specifies a new destination node.

  Other configurations are the same as those of the fifth embodiment, and the wavelength conversion process is simple without using the optical switching device or the optical switching method according to the present invention without converting the optical signal into an electrical signal. In addition, it is possible to provide an optical communication method that increases the flexibility of the node.

[Eighth Embodiment]
In the fifth embodiment, the optical switching node has the configuration shown in FIG. 5 and is a star configuration in which information can be directly communicated with each other between the central stations. Although an example has been described, the present embodiment describes an example in which the optical switching node has the configuration of FIG. 5 and is a network in which eight central stations are connected in a loop configuration, and the central station and lower stations are connected in a star configuration. To do.

  FIG. 13 shows the configuration of an optical switching network according to the eighth embodiment. Central stations X1 to X8 are connected in a loop, local stations X1 to X8 are below it, lower stations X11 to X84 are below it, and lower stations are connected below it in a star shape. The loop is configured so that signals are transmitted in the order of, for example, Tokyo Central Office-Nagoya Central Office-Osaka Central Office-Hiroshima Central Station-Fukuoka Central Station-Kanazawa Central Station-Sapporo Central Station-Sendai Central Station-Tokyo Central Station. Shall be. If the configuration of FIG. 5 is applied to the central station, the input side optical fiber n1 and the output side optical fiber m1 are connected to local stations in the central station area, and the input side optical fibers n2 to n8 and the output side optical fibers m2 to m8 are It continues to other central stations through the loop. That is, the signals of wavelengths λ1 to λ32 are configured to circulate in the loop except for the wavelength related to the own node area. When applied to a local station, the input side optical fiber n1 and the output side optical fiber m1 are connected to the central station, and the input side optical fibers n2 to n8 and the output side optical fibers m2 to m8 are connected to the lower stations. When applied to a lower station, the input side optical fiber n1 and the output side optical fiber m1 are connected to a local station, and the input side optical fibers n2 to n8 and the output side optical fibers m2 to m8 are connected to lower stations. Further, the same configuration is applied to lower stations.

  In FIG. 5, the optical switching node is assumed to be a Tokyo central office. First, if it is an add node, for the signal from its own node area, if the wavelength that specifies the determined destination node is adaptable at the node, switch to the outgoing optical signal line toward the destination node, The wavelength of the carrier wave is changed to a wavelength that identifies the destination node. For example, a signal of wavelength λ2 from the Hachioji local station is added from a node of the Tokyo central station, converted into a signal of wavelength λ29 to the Sapporo local station, and carried in the Sapporo central station area. In addition, when the wavelength for specifying the determined destination node is a wavelength that cannot be adapted by the node, a via point that can be adapted by the own node is selected as a new destination node, and the outgoing side light toward the new destination node is selected. Switch to the signal line and change the wavelength of the carrier wave to a wavelength that specifies the new destination node. For example, if the final destination node is not applicable to the node, such as the Wakkanai Regional Station or Naha Regional Station, select the Sapporo Central Station and the Fukuoka Central Station as the waypoints, and renew these optical switching nodes as the waypoints. When the signal is transmitted as a destination node and the signal reaches the waypoint, the final destination node can be reached by selecting the Wakkanai local station and the Naha local station as destination nodes.

  In the case of a drop node, for signals from other than the local node area, if the determined destination node is within the local node area, the signal is taken into the local node area and output to the destination node. Switch to the side optical signal line and change the wavelength of the carrier wave to a wavelength that identifies the destination node. For example, a signal of wavelength λ5 from the Osaka local station is dropped at a node of the Tokyo central station, converted into a signal of wavelength λ4 to the Saitama local station, and carried in the Tokyo central station area. Further, when the determined destination node is the local node selected as the via point, the destination node is changed to the final destination node or another via point, and switched to the outgoing optical signal line toward the new destination node. Then, the wavelength of the carrier wave is changed to a wavelength that specifies a new destination node. If the requested destination node is outside the own node area, the optical switching node is passed through without changing the destination node or performing wavelength conversion. That is, the optical switch element at the diagonal position of the switching array 50 in FIG. 5 is controlled to turn on.

  Up to now, the connection between the central station and the local station, between the local station and the subordinate station, and below the subordinate station has been considered in a star configuration, but a loop configuration is also possible. In the case of a local station, one add / drop node to the central station and five nodes of the four local stations are configured in a loop, and each local station adds and drops to four lower stations. Then, each node in the local station functions similarly to each node in the central station. In the case of a subordinate station, a loop configuration is made of one add / drop node to a local station and five nodes of four subordinate stations, and each subordinate station adds and drops to four subordinate stations. To do. Then, each node in the subordinate station functions similarly to each node in the central station.

  The present invention can also be realized as a program for causing a computer to execute the optical switching method described in the above embodiment. The program may be stored and used in a built-in memory of the switching control means, stored in a storage device inside or outside the optical switching device, or downloaded from the Internet and used. Moreover, it is realizable also as a recording medium which recorded the said program.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and it is obvious that various modifications can be made to the embodiment without departing from the spirit of the present invention. It is.

  For example, in the above embodiment, the network configuration including the optical switching node is not particularly limited, but may be a loop topology or a star topology. In the above embodiment, an example in which the lower network has a star configuration has been described. However, a loop configuration may be used. In this case, for example, if one node constituting the loop is configured to be connected to the upper station and the other nodes are connected to the lower station, it functions in substantially the same manner as the loop described in the seventh embodiment. In the configuration of the fifth embodiment, a loop that circulates signals between the central offices can be configured. In this case, if each node does not correspond to a destination node or a waypoint node, the signal is used as it is. Functions as a relay node that passes to the next node. In addition, although the switching control means has been described in each optical switching node and in the base station, it may be in another optical switching node. In addition, each of the input side optical communication paths n1 to n8 and each of the output side optical communication paths m1 to m8 may be provided between different optical switching nodes, and are provided overlapping with the same optical switching node. May be. In the first embodiment, the wavelengths of the signals carried on the input side optical communication paths are all different from each other. For example, λ5 = λ1, λ6 = λ2, λ7 = λ3, λ8 = λ4, λ9 = As in λ1, λ10 = λ2,..., wavelengths may overlap in a plurality of input side optical communication paths.

  In the first and third embodiments, the description has been made based on the so-called pre-assignment method in which time is specified in the switching table provided in each optical switching node. However, the present invention is not limited to this. There is also an embodiment in which the contents of the switching table are rewritten as needed in accordance with instructions from the network control means that controls the switching control means of each node. Thereby, the connection by what is called demand assignment is realizable. In addition, the switching table stores the opening / closing of the switch element as a function of time, the incoming optical signal line, the carrier wavelength of the incoming optical signal line, the outgoing optical signal to which the incoming optical signal is connected, and the outgoing optical signal. Although the example of storing the relationship of the carrier wavelength of the side optical signal has been described, when the destination is a waypoint, it is preferable to store the final destination together, and other information such as the source may be stored. Further, in the description of FIG. 11, the destination node is changed to the final destination node at the via point, but it may be changed to a new via point again. In addition, although the wavelength for specifying the destinations below the local station has been described as being different from each other, it is also possible to use the same wavelength on the assumption that the upper local station is different. However, the wavelength expression is used separately. In the above embodiment, the wavelength specifying the central station as the destination or the transmission source is not specified. However, such a wavelength is specified, for example, the central station is used as a via point, and a new destination is selected here. It is also possible to make it. It is also possible to increase or decrease the number of central stations, local stations, and subordinate stations. The number of input-side optical communication paths, the number of output-side optical communication paths and the number of multiplexed wavelengths, the number of rows and columns of optical switch arrays, the number of input-side optical The number of branches from the signal line can be arbitrarily changed. Further, an example using an arrayed waveguide grating element or an arrayed waveguide grating as the optical wavelength separation means and the optical wavelength multiplexing means, a MEMS optical switch element as the optical switch element, and a multi-QPM-LN wavelength conversion element as the optical wavelength conversion means. However, other optical wavelength separation means or the like may be used.

  The present invention is used for optical switching aimed at all-optical processing in an optical fiber network.

It is a figure which shows the structural example of the optical switching apparatus in 1st Embodiment. It is a figure which shows the example of the switching table in 1st Embodiment. It is a figure which shows the example of a processing flow of the optical switching method in 1st Embodiment. It is a figure which shows the relationship between the wavelength which specifies an optical fiber, a signal wire | line, a transmission origin node, or a destination, a central station, and a local station. It is a figure which shows the structural example of the optical switching apparatus in 2nd Embodiment. It is a figure which shows the example of the switching table in 2nd Embodiment. It is a figure which shows the structural example of the optical switching apparatus in 3rd Embodiment. It is a figure which shows the example of a processing flow of the optical switching method in 3rd Embodiment. It is a figure which shows the structural example of the optical switching apparatus in 4th Embodiment. It is a figure which shows the example of the optical switching network structure in 5th Embodiment. It is a figure which shows the example of a processing flow of the optical communication method in 5th Embodiment. It is a figure which shows the example of the optical switching network structure in 7th Embodiment. It is a figure which shows the example of the optical switching network structure in 8th Embodiment. It is a figure which shows an example of the optical switching system which employ | adopted the conventional loop topology. It is a figure which shows the structural example of the conventional optical switching node 1-1.

Explanation of symbols

1-1 to 1-6 Optical switching node 2 Optical fiber network 3-1 to 3-3 Optical fiber 4 Optical receiver 5 Separation module 6-1 and 6-2 OE conversion module 7-1 Reception signal buffer 7-2 Transmission signal Buffers 8-1 and 8-2 EO conversion module 9 Optical switching node control device 9-1 Reception signal control module 9-2 Transmission signal control module 10 Optical transmission / reception module 11 Wavelength multiplexing module 12 Optical transmitter 50 Optical switch array (space division) Type optical switch)
60 Switching control means 100, 100A to 100C Optical switching devices 101 to 108 Optical wavelength separation means (optical wavelength separation module)
111-118 Optical wavelength multiplexing means (optical wavelength multiplexing module)
1101 to 1132 Optical input signal line (incoming optical waveguide)
1201-1232 Optical output signal line (outside optical waveguide)
1301 to 1332 Optical wavelength conversion means (optical wavelength conversion module)
1401 to 1432 Carrier wavelength detection means 7001 to 7016 Optical branching means (optical splitter)
50101 to 53232 Optical switch elements m1 to m8 Output side optical communication path (output side optical fiber)
n1 to n8 Input side optical communication path (input side optical fiber)
λ1 to λ32, λa, λb Signal wavelengths X1 to X8, X11 to X84 Communication stations

Claims (14)

An optical switching device for a wavelength division multiplexing optical communication system in which a destination node or a source node is specified by a wavelength;
Optical wavelength separation means for wavelength-separating wavelength multiplexed signals received from the input side optical communication path into signals to a plurality of input side optical signal lines;
An optical switch array for connecting the signal separated by the optical wavelength separation means to the incoming optical signal line to an outgoing optical signal line toward the destination node;
Optical wavelength conversion means for converting a wavelength of a signal connected to the outgoing optical signal line by the optical switch array into a wavelength for specifying the destination node or maintaining a wavelength for specifying the destination node or the source node; ;
An optical wavelength multiplexing unit that wavelength-multiplexes the signal wavelength-converted by the optical wavelength conversion unit or the wavelength-maintained signal and transmits the multiplexed signal to the output-side optical communication path;
Optical switching device. A switching table for storing a schedule for exchanging and connecting a signal from the input-side optical signal line to the output-side optical signal line, and controlling opening and closing of the optical switch elements constituting the optical switch array based on the switching table Switching control means for
The optical switching device according to claim 1. The switching table stores the opening and closing of each optical switch element as a function of time;
The optical switching device according to claim 2. A carrier wavelength detecting means for detecting a carrier wavelength from a carrier wave of the incoming optical signal line;
The switching table has a relationship between the incoming optical signal line, the carrier wavelength of the incoming optical signal line, the outgoing optical signal line to which the incoming optical signal line is connected, and the carrier wavelength of the outgoing optical signal line. Remember;
The switching control means controls the opening and closing of the optical switch element by comparing the carrier wavelength detected by the carrier wavelength detecting means with the switching table;
The optical switching device according to claim 2. Optical branching means for branching the signal inserted into the incoming optical signal line and separated into the incoming optical signal line by the wavelength separation means into the incoming branched optical signal line;
The optical switching device according to claim 1, claim 2, or claim 4. The optical wavelength separating means is a grating element or a diffraction grating formed on an arrayed waveguide;
The optical switching device according to claim 1. The optical switch element constituting the optical switch array is a MEMS (micro electro mechanical system) optical switch element;
The optical switching device according to any one of claims 1 to 6. The input-side optical signal line and the output-side optical signal line are optical waveguides.
The optical switching device according to any one of claims 1 to 7. The light wavelength conversion means is a wavelength conversion element using two-stage excitation light;
The optical switching device according to any one of claims 1 to 7. The optical wavelength multiplexing means is formed by forming a grating element or a diffraction grating in an arrayed waveguide;
The optical switching device according to any one of claims 1 to 9. A wavelength division multiplexing optical communication method in which a destination node or a source node is specified by a wavelength;
An optical wavelength separation step of wavelength-separating the wavelength multiplexed signal received from the input side optical communication path into signals to a plurality of input side optical signal lines;
An optical switching step of connecting the signal separated into the incoming optical signal line by the optical wavelength separation step to an outgoing optical signal line directed to the destination node;
An optical wavelength converting step of converting a wavelength of a signal connected to the outgoing optical signal line by the optical switching step into a wavelength specifying the destination node or maintaining a wavelength specifying the destination node or the source node; ;
An optical wavelength multiplexing step of wavelength multiplexing the signal wavelength-converted by the optical wavelength conversion step or the wavelength-maintained signal and transmitting the wavelength-multiplexed signal to the output side optical communication path;
Light exchange method. The optical switching step uses a switching table that stores a schedule for exchanging and connecting a signal from the input-side optical signal line to the output-side optical signal line, and configures the optical switch array based on the switching table Control the opening and closing of
The optical exchange method according to claim 11. 13. An optical communication method using an optical switching method according to claim 12, wherein a plurality of optical switching nodes are network-connected by a wavelength division multiplexing optical communication system in which a destination node or a source node is specified by a wavelength. And
In the optical switching method, in the optical switching step, the destination node is collated with a carrier wavelength detected from a carrier wave of the incoming optical signal line to the optical switching node based on the switching table and the switching table. If the destination node obtained for the input signal to the optical switching node is within the own node area, the input signal is taken into the own node area, and the input signal from the own node area to the optical switching node is obtained. Switching control is performed so that the outgoing optical signal line directed to the determined destination node is selected and the input signal is transmitted to the selected outgoing optical signal line;
Optical communication method. When each of the optical switching nodes constitutes a loop, if the determined destination node is outside its own node area, switching control is performed so that the input signal is passed to the next node of the loop;
The optical communication method according to claim 13.

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