Patent Publication Number: US-2023136142-A1

Title: Optical and Electronic Integrated Switch

Description:
TECHNICAL FIELD 
     The present invention relates to a high-performance optical and electronic integrated switch belonging to network switches. 
     BACKGROUND ART 
     In conventional techniques, electronic-circuit-based packet switches are often used for network switches used for the Internet. An example of an electronic circuit that controls this packet switch is a network processor, the capacity of which tends to increase year by year. The capacity of this network processor is determined by the value obtained by multiplying the signal speed by the number of ports. However, the increase in the capacity of the network processor increases the number of signals inputted to and outputted from the network processor, requiring an increase of the number of wiring lines (which may be called electrical wiring) through which electrical signals used for the input and output pass or an increase of the signal speed. 
     The higher the signal speed of the signals propagating through electrical wiring, the shorter the propagable distance of the signals, while the density of electrical wiring cannot be increased beyond the physical upper limit. For this reason, a further increase in the capacity of the network processor makes it difficult even to propagate electrical signals to the distance within the board or so. Under these circumstances, it is being studied to convert electrical signals into optical signals within the propagable distance and use optical wiring which is capable of long-distance transmission compared to electrical signals. Note that techniques related to the above description are disclosed in non-patent literature 1 and non-patent literature 2. 
     Techniques embodying the above study points are also being proposed. For example, non-patent literature 1 discloses an optical transceiver used for such applications that electronic circuits such as a network processor and optical transceivers having photoelectric conversion functions are provided side by side on a substrate and that these electronic circuits and optical transceivers are connected to one another with metal wiring or the like formed of an electrical conductor. 
       FIG.  1    is a top view diagram illustrating a schematic configuration for the case in which a technique disclosed in non-patent literature 1 is applied to a network switch  10 . With reference to  FIG.  1   , this network switch  10  includes, on the upper surface of a substrate  1 , a network processor  2  and a optical transceiver  3  having a photoelectric conversion function, and these devices are connected to one another with metal wiring  4 . The network processor  2  is an electronic circuit that provides core functions of the packet switch, and is typically configured as an application specific integrated circuit (ASIC) in many cases. The optical transceiver  3  is a small component including an optical receiver (RX)  3   a  configured inside as a module, a laser (LASER)  3   b , an electrical-processing function unit  3   c , and an optical transmitter (TX)  3   d , and also includes a connector  3   e , optical fibers  3   f , and the like. This optical transceiver  3  enables a plurality of optical transceivers  3  to be arranged side by side on the substrate  1  and thereby achieve high-density packaging like tiles. 
     As for the optical transceiver  3 , the optical receiver  3   a , in the case of coherent detection, plays roles of selectively enhancing the optical signals having wavelengths close to that of the laser  3   b  out of the optical signals inputted from the connected optical fiber  3   f  and converting the enhanced optical signals into electrical signals by optical-electrical conversion. The electrical-processing function unit  3   c  plays roles of performing electrical-signal digital signal processing at the time when signals are sent to or received from the network processor  2  and amplifying electrical signals at the time of transmission and reception of optical signals. The optical transmitter  3   d  plays roles of performing electrical-optical conversion by modulating the light inputted from the laser  3   b  using electrical signals inputted from the electrical-processing function unit  3   c , and outputting the resultant signals to the connected optical fiber  3   f . The connector  3   e  is provided for the connection with the network processor  2 . 
     In general, the packet switching function provided by the network processor  2  is a highly functional one that can specify a destination for each packet but consumes a large amount of electric power per processing capacity. Meanwhile, the optical switch generally requires time for switching paths, and thus the applications of the optical switch are limited to the ones in which paths are fixed or the ones for switching in units of flows that continue for a long time. However, as for the optical switch, the power consumption required for switching is smaller than that of the packet switch, and it is not dependent on the signal speed and has an approximately constant value. 
     Nowadays, in order to reduce the electric power consumed by the network switch, techniques are being studied for reducing the switching capacity required for the packet switch by disposing the optical switch in parallel with the packet switch and transmitting long flows to the optical switch. Specifically, in these techniques, flows in which switching does not often occur are dealt with the optical switch, and thereby the switching capacity required for the packet switch is reduced. Related techniques are disclosed in Non-Patent Literature 3. 
     An example of such a optical switch is a waveguide optical switch fabricated using planar lightwave circuit (PLC) techniques. 
     However, a network switch having such a configuration will have a problem in communication if it is assumed that the communication counterpart is a signal source that is a node far from the network switch to the same degree as the transmission distance (for example, approximately 2 km) allowed by the optical transmission-reception function of the optical transceiver. Specifically, the packet switch in the network switch and a signal source can communicate with each other, but in the case in which signals are sent from a signal source to a signal source of another node via the optical switch, communication is impossible because it exceeds the upper limit of the transmission distance. 
     To avoid such a problem, the distances between the signal sources of all nodes and the packet switch need to be restricted such that they be shorter than approximately half the transmission distance allowed by the optical transmission-reception function of the optical transceiver, for example, within 1 km. This means that the transmission distance is restricted. Note that even if the distance between a signal source and the packet switch is longer than half the transmission distance allowed by the optical transmission-reception function, if it is only one node, communication is possible by restricting the distances between the signal sources of all the other nodes and the packet switch such that they be shorter than half the transmission distance allowed by the optical transmission-reception function. 
     CITATION LIST 
     Non-Patent Literature 
     
         
         Non-Patent Literature 1: “Consortium For On-Board Optics The Use of On-Board Optic Compliant Modules in Coherent Applications”, COBO Release 1.0 Whitepaper (http://onboardoptics.org/wp-content/uploads/2019/05/COBO-CohOBO-AppNote-March-2018.pdf) 
         Non-Patent Literature 2: “Optical Connectivity Optaions for 400 Gbps and Higher On-Board Optics”, COBO Connectivity Whitepaper, Revision 1.0 (http://onboardoptics.org/wp-content/uploads/2019/03/COBO-Optical-Connectivity-Whitepaper-March-2019.pdf) 
         Non-Patent Literature 3: “Helios: A Hybrid Electrical/Optical Switch Architecture for Modular Data Centers”, Nathan Farrington, George Porter, Sivasankar Radhakrishnan, Hamid Hajabdolali Bazzaz, Vikram Subramanya, Yeshaiahu Fainman, George Papen, and Amin Vahdat [In: Proceedings of the ACM SIGCOMM 2010 Conference on SIG-COMM (SIGCOMM &#39;10), pp. 339-350 (2010): University of California, San Diego] 
       
    
     SUMMARY OF THE INVENTION 
     The present invention has been made to solve the foregoing problem. An object of the embodiments according to the present invention is to provide a high-performance optical and electronic integrated switch in which a packet switch and a optical switch are integrated so that the transmission distance can be extended effectively. 
     An aspect of the present invention to achieve the above object is a optical and electronic integrated switch including a packet switch and a optical switch, in which the packet switch includes an electronic circuit and a plurality of optical transceivers provided near the electronic circuit and having a photoelectric conversion function, paths connecting between the electronic circuit and the plurality of optical transceivers are formed of wiring through which an electrical signal passes, a plurality of optical waveguides are connected to an input side and an output side of the optical switch, part of the plurality of optical transceivers have a regeneration relay function that, using the photoelectric conversion function, converts an inputted optical signal into an electrical signal by optical-electrical conversion, turns back the electrical signal and converts the electrical signal into a optical signal by electrical-optical conversion, and outputs the optical signal, and the part of the plurality of optical transceivers have routing optical waveguides that are routed such that at least part of the input sides of the part of the plurality of optical transceivers are connected to part of the plurality of optical waveguides on the output side of the optical switch, and that at least part of the output sides of the part of the plurality of optical transceivers are connected to part of the plurality of optical waveguides on the input side of the optical switch, and optical waveguides are used for paths for connecting, to input-output ports of the optical and electronic integrated switch, the input and output of the optical transceivers not having the regeneration relay function, the input and output of the optical transceivers having the regeneration relay function but not connected to the routing optical waveguides, and the plurality of optical waveguides for the optical switch, not connected to the routing optical waveguides. 
     In the optical and electronic integrated switch with the above configuration, part of the optical transceivers near the electronic circuit have a regeneration relay function that, using the photoelectric conversion function, converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signal and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. The optical transceivers having the regeneration relay function are connected to routing optical waveguides that are connected to the optical waveguides connected to the optical switch and route optical signals in cooperation with the optical waveguides of the optical switch. This makes it possible for the optical transceivers having the regeneration relay function to perform optical communication with external signal sources via the routing optical waveguides and the optical switch. As a result, it is possible to integrate the packet switch and the optical switch to extend the transmission distance effectively, making it possible to widen the operational range of the optical network that uses the optical and electronic integrated switch as a network switch. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a top view diagram illustrating a schematic configuration of a network switch disclosed in Non-Patent Literature 1. 
         FIG.  2    is a diagram illustrating a schematic configuration of a optical and electronic integrated switch according to a preferred embodiment of the present invention. Part (A) is a plan view from the upper surface direction. Part (B) is a side cross-sectional view from the arrow IIB direction of a portion of part (A) in a state in which the portion is implemented on an interposer with optical waveguides. 
         FIG.  3    is a top view diagram illustrating a schematic configuration of a optical and electronic integrated switch according to Embodiment 1 of the present invention. 
         FIG.  4    is a top view diagram illustrating a schematic configuration of a optical and electronic integrated switch according to Embodiment 2 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, optical and electronic integrated switch according to several embodiments of the present invention will be described in detail with reference to the drawings. 
     First, a technical overview of the optical and electronic integrated switch according to a preferred embodiment of the present invention will be briefly described with reference to  FIG.  2   .  FIG.  2    is a diagram illustrating a schematic configuration of a optical and electronic integrated switch  100  according to the preferred embodiment of the present invention.  FIG.  2 (A)  is a plan view of the optical and electronic integrated switch  100  from the upper surface direction.  FIG.  2 (B)  is a side cross-sectional view from the arrow IIB direction of a portion of  FIG.  2 (A)  in a state in which the optical and electronic integrated switch  100  is implemented on a substrate  11 . 
     With reference to  FIGS.  2 (A) and  2 (B) , the optical and electronic integrated switch  100  includes a network processor  20  and a plurality of optical transceivers  30  having photoelectric conversion functions, the network processor  20  and the plurality of optical transceivers  30  composing a packet switch, and the optical and electronic integrated switch  100  also includes an optical relay switch  60 . Of these, the network processor  20  is an electronic circuit that controls the functions of the packet switch and is capable of receiving and outputting a large number of high-speed signals. Each optical transceiver  30  is provided near the network processor  20  and has a configuration the same as or similar to the optical transceiver  3  described with reference to  FIG.  1   , but to simplify it, only its outer shape is illustrated. The optical relay switch  60  is an example of an optical switch and should preferably be a waveguide optical switch made by using PLC techniques. 
     In this optical and electronic integrated switch  100 , metal wiring  40  through which electrical signals pass is used for the paths connecting between the network processor  20  and each optical transceiver  30 . A plurality of optical waveguides  50  are connected to the input and output sides of the optical relay switch  60 . For the paths connecting between the optical transceivers  30  and the optical relay switch  60 , not only can the optical waveguides  50  be used, but also optical transmission members such as optical fibers can be used. Note that routing of the traces of the optical waveguides  50  is actually complicated. Thus, in  FIG.  2 (A) , only the portions of optical waveguides  50   IN  on the input side and optical waveguides  50   OUT  on the output side related to the optical relay switch  60  are illustrated, and most of them are omitted. Part of the optical transceivers  30  have a regeneration relay function that, using the photoelectric conversion function, converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. 
     At least part of the input sides of the optical transceivers  30  having the regeneration relay function are connected to part of the optical waveguides  50   OUT  on the output side of the optical waveguides  50  of the optical relay switch  60 . Then, at least part of the output sides of the optical transceivers  30  having the regeneration relay function are connected to part of the optical waveguides  50   IN  on the input side of the optical waveguides  50  for the optical relay switch  60 . The optical transceivers  30  have routing optical waveguides configured (routed) as above. Optical waveguides can be used for the paths for connecting between the input-output ports of the optical and electronic integrated switch  100  and the input and output of the optical transceivers  30  not having the regeneration relay function, the input and output of the optical transceivers  30  having the regeneration relay function but not connected to the routing optical waveguides, and the optical waveguides  50   IN  and  50   OUT  of the optical relay switch  60 , not connected to the routing optical waveguides. For example, optical fibers F or the like can be used for them. 
     In the optical and electronic integrated switch  100  described above, the network processor  20 , the optical transceivers  30 , the optical relay switch  60 , the metal wiring  40 , and the optical waveguides (or optical fibers F)  50  are implemented on the upper surface of one and the same substrate  11 . The metal wiring  40  and the optical waveguides  50  compose an interposer with optical waveguides. In this implemented state, the network processor  20 , the optical transceivers  30 , and the optical relay switch  60  should preferably be arranged in one and the same plane of the upper surface of the interposer with optical waveguides. Note that the optical relay switch may be integrated as part of the optical waveguides  50  in the interposer with optical waveguides. In addition, in the area of the optical waveguides  50  of each optical switch, optical function devices are provided as necessary. Examples of the optical function devices include, in addition to optical switches for various applications, optical splitters and arrayed waveguide gratings (AWG). 
     Regarding the optical and electronic integrated switch  100  having the configuration outlined as above, a description will be given of embodiments for integrating the packet switch and the optical switch to extend the transmission distance effectively. 
     Embodiment 1 
       FIG.  3    is a top view diagram illustrating a schematic configuration of a optical and electronic integrated switch  100 A according to Embodiment 1 of the present invention. 
     With reference to  FIG.  3   , the optical and electronic integrated switch  100 A includes a network processor  20 A which is an electronic circuit configured to control the functions of the packet switch, a plurality of optical transceivers  30 A and  30 A 1  having a photoelectric conversion function, and an optical relay switch  60 A. The network processor  20 A and the optical transceivers  30 A and  30 A 1  compose the packet switch. Wiring through which electrical signals pass, such as metal wiring, is used for the paths connecting between the network processor  20 A and the optical transceivers  30 A. Defining the plurality as N (where N is a natural number of two or more), the optical relay switch  60 A, which is an optical switch, is of an N×N type (N inputs and N outputs). The N×N type means that it has N inputs and N outputs, and the same is true of the following description. The optical relay switch  60 A has an input side to which a plurality of optical waveguides  50 A IN  are connected and an output side to which a plurality of optical waveguides  50 A OUT  are connected. Each of optical transceivers  30 A and  30 A 1  is provided near the network processor  20 A, and each optical transceivers  30 A 1  has a regeneration relay function that, using the photoelectric conversion function, converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. 
     The optical transceivers  30 A 1  are an extended part to the optical transceivers  30 A, and the input sides of the optical transceivers  30 A 1  are connected to routing optical waveguides  50   a   1  which are part of the optical waveguides  50 A OUT  on the output side of the optical relay switch  60 A. The output sides of the optical transceivers  30 A 1  are connected to routing optical waveguides  50   a   2  which are part of the optical waveguides  50 A IN  on the input side of the optical relay switch  60 A. 
     In the optical and electronic integrated switch  100 A described above, optical fibers F can be used for the paths for connecting to the optical waveguides  50 A IN  and  50 A OUT  connected to the optical relay switch  60 A, except the routing optical waveguides  50   a   1  and  50   a   2 . 
     In this optical and electronic integrated switch  100 A, four optical transceivers  30 A 1  having the regeneration relay function are an extended part to the optical transceivers  30 A not having the regeneration relay function. Then, the paths connecting between the output sides of the optical transceivers  30 A 1  and part of the optical waveguides  50 A IN  (for four extension ports) on the input side of the optical relay switch  60 A are the routing optical waveguides  50   a   2 . The paths connecting between the input sides of the optical transceivers  30 A 1  and part of the optical waveguides  50 A OUT  (for four extension ports) on the output side of the optical relay switch  60 A are the routing optical waveguides  50   a   1 . Note that the optical transceivers  30 A 1  described here have the regeneration relay function that, using the photoelectric conversion function, converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. 
     The following description is based on the assumption that the optical and electronic integrated switch  100 A having the configuration described above is used to perform optical communication between a signal source  71  which is a long-distance communication-counterpart node and a signal source  72  which is a short-distance communication-counterpart node. In this case, optical fibers F are connected between the long-distance signal source  71  and an optical transceiver  30 A. Optical fibers F are also connected between the long-distance signal source  71  and optical waveguides  50 A IN  and  50 A OUT  of the optical relay switch  60 A at locations not being the routing optical waveguides  50   a   1  and  50   a   2 . Further, in this system configuration, optical fibers F are connected between the short-distance signal source  72  and optical waveguides  50 A IN  and  50 A OUT  of the optical relay switch  60 A at locations not being the routing optical waveguides  50   a   1  and  50   a   2 . 
     Specifically, optical fibers F for transmitting and receiving optical signals are connected between the signal source  71  and an optical transceiver  30 A. Optical fibers F are also connected between the signal source  71  and one of the optical waveguides  50 A IN  on the input side and one of the optical waveguides  50 A OUT  on the output side of the optical relay switch  60 A, the ones at specified locations not connected to the routing optical waveguides  50   a   1  and  50   a   2 . In addition, optical fibers F are connected between the signal source  72  and one of the optical waveguides  50 A IN  on the input side and one of the optical waveguides  50 A OUT  on the output side of the optical relay switch  60 A, the ones at different specified locations not connected to the routing optical waveguides  50   a   1  and  50   a   2 . 
     In the above system configuration, optical signals are transmitted from the signal source  71  to the optical transceiver  30 A through an optical fiber F. The optical transceiver  30 A converts the transmitted optical signals into electrical signals by optical-electrical conversion and transmits the electrical signals to the network processor  20 A through wiring that electrical signals pass through. The electrical signals outputted from the network processor  20 A are inputted to the optical transceiver  30 A through wiring that electrical signals pass through. The optical transceiver  30 A converts the electrical signals into optical signals by electrical-optical conversion and transmits the optical signals to the long-distance signal source  71  through an optical fiber F. 
     In addition, in the above system configuration, optical signals are inputted from the signal source  71  to the optical relay switch  60 A through the optical fiber F connected to one of the optical waveguides  50 A IN  on the input side, the one at a specified location (for example, the fifth location from the left end) not connected to a routing optical waveguide  50   a   2 . At the optical relay switch  60 A, the optical signals inputted from the signal source  71  pass through one of the optical waveguides  50 A OUT  on the output side, the one at a specified location (for example, the location at the left end) connected to a routing optical waveguide  50   a   1 , then through the routing optical waveguide  50   a   1 , and transmitted to an optical transceiver  30 A 1 . The optical transceiver  30 A 1  converts the inputted optical signals into electrical signals by optical-electrical conversion, then turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and transmits the optical signals via a routing optical waveguide  50   a   2  to one of the optical waveguides  50 A IN  on the input side of the optical relay switch  60 A, the one at a specified location (for example, the location at the left end) connected to the routing optical waveguide  50   a   1 . At the optical relay switch  60 A, the optical signals turned back from the optical transceiver  30 A 1  pass through the optical fiber F connected to one of the optical waveguides  50 A OUT  on the output side, the one at a different specified location (for example, the second location from the right end) not connected to a routing optical waveguide  50   a   1 , and transmitted to the signal source  72 . 
     Note that the signal source  71  uses optical fibers F for connecting to the optical transceiver  30 A. The signal source  71  also uses optical fibers F for connecting to the optical waveguides  50 A IN  and  50 A OUT  of the optical relay switch  60 A on the input and output sides, not connected to routing optical waveguides  50   a   1  and  50   a   2 . Here, the number of paths to the network processor  20 A via the optical transceivers  30 A does not have to be the same as the number of paths to the optical relay switch  60 A. Optical fibers F are used to connect the paths described above. 
     Further, in the above system configuration, optical signals are inputted from the signal source  72  to the optical relay switch  60 A through the optical fiber F connected to one of the optical waveguides  50 A IN  on the input side, the one at a different specified location (for example, the second location from the right end) not connected to a routing optical waveguides  50   a   2 . At the optical relay switch  60 A, the optical signals inputted from the signal source  72  pass through one of the optical waveguides  50 A OUT  on the output side, the one at a different specified location (for example, the second location from the left end) connected to a routing optical waveguide  50   a   1 , then through the routing optical waveguide  50   a   1 , and is transmitted to an optical transceiver  30 A 1  having the regeneration relay function at a different specified location (for example, the second location from the right end). The optical transceiver  30 A 1  converts the inputted optical signals into electrical signals by optical-electrical conversion, then turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and transmits the optical signals to the optical relay switch  60 A via a routing optical waveguide  50   a   2  and one of the optical waveguides  50 A IN  on the input side of the optical relay switch  60 A, the one at a different specified location (for example, the second location from the left end) connected to the routing optical waveguide  50   a   2 . At the optical relay switch  60 A, the optical signals are transmitted to the signal source  71  through the optical fiber F connected to one of the optical waveguides  50 A OUT  on the output side, the one at a specified location (for example, the fifth location from the left end) not connected to a routing optical waveguide  50   a   1 . 
     In other words, in the above system configuration, the optical signals that the signal source  71  transmits and receives are regenerated and relayed by the optical transceiver  30 A 1 . As has been described with reference to  FIG.  3   , the optical communication by the transmission and reception of the signal source  71  requires two optical transceivers  30 A 1  having the regeneration relay function for one node. 
     In the optical and electronic integrated switch  100 A of Embodiment 1, of the optical transceivers  30 A and  30 A 1  provided near the network processor  20 A, the optical transceivers  30 A 1  have the regeneration relay function that converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. In addition, the paths connecting to the optical transceivers  30 A 1  are formed of the routing optical waveguides  50   a   1  and  50   a   2 . Further, in the optical and electronic integrated switch  100 A, part of the optical waveguides  50 A IN  on the input side and part of the optical waveguides  50 A OUT  on the output side of the optical relay switch  60 A, the parts not connected to the routing optical waveguides  50   a   1  and  50   a   2 , are selected, and those parts can be connected to external communication counterparts. 
     With the system configuration as described above, an optical transceiver  30 A 1  receives optical signals from an external signal source  71  or  72  and transmits the optical signals to the other external signal source, so that optical communication can be performed between the two external signal sources  71  and  72 . Thus, the system configuration makes it possible to integrate the packet switch and the optical switch to extend the transmission distance effectively, making it possible to widen the operational range of the optical network that uses the optical and electronic integrated switch  100 A as a network switch. Note that the communication counterpart of the signal source  71  may be another long-distance signal source. 
     Embodiment 2 
       FIG.  4    is a top view diagram illustrating a schematic configuration of a optical and electronic integrated switch  100 B according to Embodiment 2 of the present invention. 
     With reference to  FIG.  4   , the optical and electronic integrated switch  100 B includes a network processor  20 B which is an electronic circuit configured to control the functions of the packet switch, a plurality of optical transceivers  30 B and  30 B 1  having a photoelectric conversion function, and an optical relay switch  60 B. The network processor  20 B and the optical transceivers  30 B and  30 B 1  compose the packet switch. Wiring through which electrical signals pass, such as metal wiring, is used for the paths connecting between the network processor  20 B and the optical transceivers  30 B. The optical relay switch  60 B, which is an optical switch, is also of an N×N type, and the optical relay switch  60 B has an input side to which a plurality of optical waveguides  50 B IN  are connected and an output side to which a plurality of optical waveguides  50 B OUT  are connected. The optical transceivers  30 B and  30 B 1  are provided near the network processor  20 B, and each optical transceiver  30 B 1  has a regeneration relay function that converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. 
     The optical transceivers  30 B 1  are an extended part to the optical transceivers  30 B, and the input sides of the optical transceivers  30 B 1  at specified locations and the output sides of the optical transceivers  30 B 1  at different specified locations are provided with outgoing optical waveguides  50   b   2  for connecting to input-output ports of the optical and electronic integrated switch  100 B, separately from the optical waveguides  50 B IN  and  50 B OUT  on the input and output sides of the optical relay switch  60 B. Here, also for the optical waveguides  50 B IN  and  50 B OUT , routing optical waveguides  50   b   1  are used for the connection between the output sides of the optical transceivers  30 B 1  at specified locations and part of the optical waveguides  50 B IN  on the input side of the optical relay switch  60 B. The routing optical waveguides  50   b   1  are also used for the connection between part of the optical waveguides  50 B OUT  on the output side of the optical relay switch  60 B and the input sides of the optical transceivers  30 B 1  at different specified locations. In other words, as for the optical transceivers  30 B 1 , the input sides at specified locations different from the locations connected to the routing optical waveguides  50   b   1  and the output sides at specified locations different from the locations connected to the routing optical waveguides  50   b   1  are provided with the outgoing optical waveguides  50   b   2  for connecting to the input-output ports of the optical and electronic integrated switch  100 B. 
     In other words, in the optical and electronic integrated switch  100 B, the outgoing optical waveguides  50   b   2  on the input sides of the optical transceivers  30 B at specified locations are used for direct input connection with long-distance communication counterparts. In addition, the outgoing optical waveguides  50   b   2  on the output sides of the optical transceivers  30 B at the different specified locations are used for direct output connection with the long-distance communication counterparts. These outgoing optical waveguides  50   b   2  for input connection are indicated by P×2 in  FIG.  4   , which means input for two ports. 
     Also in this optical and electronic integrated switch  100 B, four optical transceivers  30 B 1  having the regeneration relay function are an extended part to the optical transceivers  30 B not having the regeneration relay function. Note that the optical transceivers  30 B 1  here also have the regeneration relay function that, using the photoelectric conversion function, regenerates inputted optical signals by converting the inputted optical signals into electrical signals by optical-electrical conversion, and converting the electrical signal into optical signals by electrical-optical conversion. Then, part of the optical waveguides  50 B IN  on the input side (the two ports from the left end) of the optical relay switch  60 B are connected through the routing optical waveguides  50   b   1  to the output sides of the optical transceivers  30 B 1  at specified locations (the two pieces on the left side in  FIG.  4   ). In addition, part of the optical waveguides  50 B OUT  on the output side (the two ports from the left end) of the optical relay switch  60 B are connected through the routing optical waveguides  50   b   1  to the input sides of the optical transceivers  30 B 1  at different specified locations (the two pieces on the right side in  FIG.  4   ). 
     The following description is based on the assumption that the optical and electronic integrated switch  100 B having the configuration described above is used to perform optical communication between a signal source  71  which is a long-distance communication-counterpart node and a signal source  72  which is a short-distance communication-counterpart node. In this case, optical fibers F are connected between the signal source  71  and an optical transceiver  30 B. Optical fibers F are also connected between the signal source  71  and the outgoing optical waveguide  50   b   2  on the input side of the optical transceiver  30 B 1  at a specified location and between the signal source  71  and the outgoing optical waveguide  50   b   2  on the output side of the optical transceiver  30 B 1  at a different specified location. Further, in this system configuration, optical fibers F are connected between the signal source  72  and optical waveguides  50 A IN  and  50 A OUT  of the optical relay switch  60 B at locations not connected to the routing optical waveguides  50   a   1  and  50   a   2 . 
     Specifically, optical fibers F for transmitting and receiving optical signals are connected from the signal source  71  to an optical transceiver  30 B. In addition, the signal source  71  is connected to the outgoing optical waveguide  50   b   2  on the input side of the optical transceiver  30 B 1  at a specified location, by using an optical fiber F. Then, the signal source  71  is connected to the outgoing optical waveguide  50   b   2  on the output side of the optical transceiver  30 B 1  at a different specified location by using an optical fiber F. Further, optical fibers F are connected between the signal source  72  and the optical waveguides  50 B IN  and  50 B OUT  of the optical relay switch  60 B at locations not connected to the routing optical waveguides  50   b   1  and  50   b   2 . 
     In the above system configuration, optical signals are transmitted from the signal source  71  to the optical transceiver  30 B through an optical fiber F. The optical transceiver  30 B converts transmitted optical signals into electrical signals by optical-electrical conversion and transmits the electrical signals to the network processor  20 B through electrical wiring. The electrical signals outputted from the network processor  20 B are inputted to the optical transceiver  30 B through wiring that electrical signals pass through. The optical transceiver  30 B converts the electrical signals into optical signals by electrical-optical conversion and sends out the optical signals to the long-distance signal source  71  through an optical fiber F. 
     In addition, in the above system configuration, optical signals are transmitted from the signal source  71  through the optical fiber F connected to the outgoing optical waveguide  50   b   2  (indicated by a thick line) on the input side of the optical transceiver  30 B 1  at a specified location (for example, the location at the left end). The optical transceiver  30 B 1  converts the inputted optical signals into electrical signals by optical-electrical conversion, then turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and transmits the optical signals via a routing optical waveguide  50   b   1  to one of the optical waveguides  50 B IN  on the input side of the optical relay switch  60 B, the one at a specified location (for example, the location at the left end) connected to the routing optical waveguide  50   b   1 . At the optical relay switch  60 B, the optical signals turned back from the optical transceiver  30 B 1  pass through the optical fiber F connected to one of the optical waveguides  50 B OUT  on the output side, the one at a different specified location not connected to a routing optical waveguide  50   b   1 , and are transmitted to the signal source  72 . Note that the different specified location is, for example, the second location from the right end. 
     Also in this optical and electronic integrated switch  100 B, the number of paths to the network processor  20 B via the optical transceivers  30 B does not have to be the same as the number of the paths to the optical relay switch  60 B. 
     Further, in the above system configuration, optical signals are inputted from the signal source  72  through the optical fiber F connected to one of the optical waveguides  50 B IN  on the input side of the optical relay switch  60 B, the one at a different specified location not connected to a routing optical waveguide  50   b   1 . Note that the different specified location is, for example, the second location from the right end. At the optical relay switch  60 B, the inputted optical signals pass through one of the optical waveguides  50 B OUT  on the output side, the one at a specified location (for example, the location at the left end) for a routing optical waveguide  50   b   1 , and through the routing optical waveguide  50   b   1 , and are transmitted to the optical transceiver  30 B at a different specified location. Note that the different specified location is, for example, the second location from the right end. The optical transceiver  30 B converts the inputted optical signals into electrical signals by optical-electrical conversion, then turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and transmits the optical signals to the signal source  71  through the optical fiber F connected to an outgoing optical waveguide  50   b   2  on the output side. 
     In other words, in the above system configuration, the optical signals that the signal source  71  transmits and receives are regenerated and relayed by the optical transceiver  30 B 1 . As has been described with reference to  FIG.  4   , also here, the optical communication by transmission and reception of the signal source  71  requires two optical transceivers  30 B 1  having the regeneration relay function for one node. 
     In the optical and electronic integrated switch  100 B of Embodiment 2, of the optical transceivers  30 B and  30 B 1  provided near the network processor  20 B, the optical transceivers  30 B 1  have the regeneration relay function that converts inputted optical signals into electrical signals by optical-electrical conversion, turns back the electrical signals and converts them into optical signals by electrical-optical conversion, and outputs the optical signals. The paths connecting between the optical transceivers  30 B 1  and the optical relay switch  60 B are formed of the routing optical waveguides  50   b   1 . Further, external communication counterparts can be connected to the outgoing optical waveguides  50   b   2  led from the input sides of the optical transceivers  30 B 1  at specified locations and the output sides of the optical transceivers  30 B 1  at different specified locations and can be connected to the input and output sides of the optical relay switch  60 B not connected to the routing optical waveguides  50   b   1 . 
     Also with the system configuration as described above, an optical transceiver  30 B 1  receives optical signals from an external signal source  71  or  72  and transmits the optical signals to the other external signal source, so that optical communication can be performed between the two external signal sources  71  and  72 . Thus, as in the case of Embodiment 1, it is possible to integrate the packet switch and the optical switch to extend the transmission distance effectively, making it possible to widen the operational range of the optical network that uses the optical and electronic integrated switch  100 B as a network switch.