Optical communication network system

Abstract

To provide an optical communication network system that can improve the efficiency of wavelength utilization. [Solution] The optical communication network system 10 comprises a wavelength selective switch (WSS) 11 that can select output ports 11O1 and 11O2 for each wavelength component of the signal input from input ports 11I1 and 11I2, a first multiplexing network 12-1 and a second multiplexing network 12-2 each including an optical transmission configuration in which a plurality of couplers 12A are connected in a tree-like manner and connected to the input ports of the WSS, and a first demultiplexing network 13-1 and a second demultiplexing network 13-2 each including an optical transmission configuration in which a plurality of couplers 13A are connected in a tree-like manner and connected to the output ports of the WSS.

Description

[Technical Field]

[0001] The present disclosure relates to an optical communication network system. [Background Art]

[0002] As an architecture for a reconfigurable optical add-drop multiplexer (ROADM), an architecture using Filtered Optical Network (FON) has been proposed (see, for example, Non-Patent Document 1). Non-Patent Document 1 proposes a FON in which each optical transmission configuration has two optical transmission structures in which a plurality of couplers are connected in a tree shape, and the two optical transmission structures are connected via the top couplers. Since this FON is mainly configured by passive optical devices such as optical couplers and splitters, a low power consumption and low cost network can be realized. [Prior Art Literature] [Non-Patent Literature]

[0003] [Non-Patent Literature 1] Omran Ayoub, Oleg Karandin, Memedhe Ibrahimi, Andrea Castoldi, Francesco Musumeci, and Massimo Tornatore, "Tutorial on filterless optical networks [Invited]," J. Opt. Commun. Netw. 14, 1-15 (2022). [Summary of Invention] [Problem to be Solved by Invention]

[0004] However, since optical signals are broadcast downstream in passive optical devices, wavelength reuse is limited in the ROADM architecture proposed in Non-Patent Document 1, leading to a decrease in optical path accommodation efficiency.

[0005] The purpose of this disclosure is to provide an optical communication network system that can improve the efficiency of wavelength utilization. It should be noted that this purpose is only one of several purposes that the various embodiments disclosed herein seek to achieve. Other purposes or problems and novel features will be revealed in the description herein or in the accompanying drawings. [Means for solving the problem]

[0006] The optical communication network system according to this disclosure includes a wavelength selective switch (WSS) having a first input port and a second input port, a first output port and a second output port, which can select an output port for each wavelength component of the signal input from the input port, and an optical transmission configuration having S1 (S1 is an integer of 2 or more) input ports and at least one output port, and in which a plurality of couplers are connected in a tree-like manner, and a first multiplexing network connected to the first input port of the WSS, and S2 (S2 is an integer of 2 or more) input ports and at least one output port, and in which a plurality of couplers are connected in a tree-like manner The system comprises: a second multiplexing network including an optical transmission configuration connected in a tree-like manner and connected to the second input port of the WSS; a first demultiplexing network including an optical transmission configuration having at least one input port and T1 (T1 is an integer of 2 or more) output ports and having a plurality of couplers connected in a tree-like manner and connected to the first output port of the WSS; and a second demultiplexing network including an optical transmission configuration having at least one input port and T2 (T2 is an integer of 2 or more) output ports and having a plurality of couplers connected in a tree-like manner and connected to the second output port of the WSS. [Effects of the Invention]

[0007] This disclosure makes it possible to provide an optical communication network system that can improve the efficiency of wavelength utilization. [Brief explanation of the drawing]

[0008] [Figure 1]This block diagram shows an example of an optical communication network system in this disclosure. [Figure 2A] This diagram illustrates communication using the optical communication network system disclosed herein. [Figure 2B] This diagram illustrates communication using the optical communication network system disclosed herein. [Figure 3] This block diagram shows another example of the optical communication network system disclosed herein. [Figure 4] This figure shows an example of wavelength assignment in this disclosure. [Figure 5] This block diagram shows another example of the optical communication network system disclosed herein. [Figure 6] This is a block diagram showing an example of an optical communication network system using a 4x4 wavelength selective switch. [Figure 7] This block diagram shows another example of the optical communication network system disclosed herein. [Modes for carrying out the invention]

[0009] Embodiments will be described below with reference to the drawings. In this disclosure, the drawings may be associated with one or more embodiments. Also, each element in the drawings may correspond to one or more embodiments. In embodiments, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. In this disclosure, “apparatus” may consist of one or more devices. Also, in this disclosure, “system” may consist of one or more devices. That is, in this disclosure, “apparatus” may be read as “system,” and “system” may be read as “apparatus.”

[0010] <First Embodiment> Figure 1 is a block diagram showing an example of an optical communication network system according to the present disclosure. In Figure 1, the optical communication network system 10 includes a Wavelength Selective Switch (WSS) 11, multiplexing networks 12-1 and 12-2, and demultiplexing networks 13-1 and 13-2. Hereinafter, when multiplexing networks 12-1 and 12-2 are not distinguished, each of them, or both multiplexing networks 12-1 and 12-2, may be simply referred to as multiplexing network 12. Similarly, when demultiplexing networks 13-1 and 13-2 are not distinguished, each of them, or both multiplexing networks 13-1 and 13-2, may be simply referred to as demultiplexing network 13.

[0011] Furthermore, this explanation assumes that the wavelength selector switch 11 has two input ports and two output ports, but the number of input ports and output ports of the wavelength selector switch 11 is not limited to these. The wavelength selector switch 11 may have three or more input ports and three or more output ports. In other words, the number of multiplexing networks 12 is not limited to two, but may be three or more. Similarly, the number of demultiplexing networks 13 is not limited to two, but may be three or more.

[0012] The multiplexer network 12 includes an optical transmission configuration in which multiple couplers 12A are connected in a tree-like structure. The multiplexer network 12-1 has S1 (S1 is an integer greater than or equal to 2) input ports 12I1 and output ports 12O11 connected to input ports 11I1 of WSS 11. Each coupler 12A has 2 inputs and 1 output. The couplers 12A are connected to each other by optical transmission lines. The input ports 12I1 are also connected to each coupler 12A by optical transmission lines. Furthermore, the couplers 12A are also connected to each output port 12O11 by optical transmission lines. In Figure 1, input port 12I11 represents one of the S1 input ports 12I1 of the multiplexer network 12-1. Also in Figure 1, output port 12O11 represents one of the output ports 12O1 of the multiplexer network 12-1.

[0013] Furthermore, the multiplexing network 12-2 has S2 (where S2 is an integer greater than or equal to 2) input ports 12I2 and an output port 12O21 connected to the input port 11I2 of the WSS 11. In Figure 1, input port 12I21 represents one of the S2 input ports 12I2 of the multiplexing network 12-2. Also, in Figure 1, output port 12O21 represents one of the output ports 12O1 of the multiplexing network 12-2.

[0014] The decoupler network 13 includes an optical transmission configuration in which multiple couplers 13A are connected in a tree-like structure. The decoupler network 13-1 has an input port 13I11 connected to the output port 11O1 of the WSS 11, and T1 (T1 is an integer greater than or equal to 2) output ports 13O1. The couplers 13A are connected to each other by optical transmission lines. The input port 13I1 is also connected to the coupler 13A by optical transmission lines. The coupler 13A is also connected to the output port 13O1 by optical transmission lines. In Figure 1, output port 13O11 represents one of the T1 output ports 13O1 of the decoupler network 13-1. Also in Figure 1, input port 13I11 represents one of the input ports 13I1 of the decoupler network 13-1.

[0015] Further, the demultiplexing network 13-2 includes an input port 13I21 connected to the output port 11O2 of the WSS 11, and T2 (where T2 is an integer of 2 or more) output ports 13O2. In FIG. 1, the output port 13O21 represents one output port among the T2 output ports 13O2 of the demultiplexing network 13-2. Further, in FIG. 1, the input port 13I21 represents one of the input ports 13I2 of the demultiplexing network 13-2.

[0016] Here, the output port 12O11 of the multiplexing network 12-1 may be connected to the top coupler 12A located at the top of the tree-shaped optical transmission configuration of the multiplexing network 12-1. Similarly, the output port 12O21 of the multiplexing network 12-2 may be connected to the top coupler 12A located at the top of the tree-shaped optical transmission configuration of the multiplexing network 12-2. Similarly, the input port 13I11 of the demultiplexing network 13-1 may be connected to the top coupler 13A located at the top of the tree-shaped optical transmission configuration of the demultiplexing network 13-1. Similarly, the input port 13I21 of the demultiplexing network 13-2 may be connected to the top coupler 13A located at the top of the tree-shaped optical transmission configuration of the demultiplexing network 13-2.

[0017] Alternatively, as in the embodiments described later, the output port 12O11 of the multiplexing network 12-1 may be connected to an intermediate coupler 12A (for example, a second-layer coupler) located in the middle of the tree-shaped optical transmission configuration of the multiplexing network 12-1. Similarly, the output port 12O21 of the multiplexing network 12-2 may be connected to an intermediate coupler 12A (for example, a second-layer coupler) located in the middle of the tree-shaped optical transmission configuration of the multiplexing network 12-2. Similarly, the input port 13I11 of the demultiplexing network 13-1 may be connected to an intermediate coupler 13A (for example, a second-layer coupler) located in the middle of the tree-shaped optical transmission configuration of the demultiplexing network 13-1. Similarly, the input port 13I21 of the demultiplexing network 13-2 may be connected to an intermediate coupler 13A (for example, a second-layer coupler) located in the middle of the tree-shaped optical transmission configuration of the demultiplexing network 13-2.

[0018] The wavelength selective switch 11 has a demultiplexing function, a switching function, and a multiplexing function. Further, the wavelength selective switch 11 includes input ports 11I1, 11I2 and output ports 11O1, 11O2.

[0019] For example, consider a case where multiple transmitting terminals 20, each connected to multiple input ports 12I of the multiplexing network 12-1, are assigned different transmission wavelengths. In this case, a multiplexed signal, obtained by multiplexing signals of different wavelengths transmitted from the multiple transmitting terminals 20, is input to the input port 11I1 of the wavelength selection switch 11. The wavelength selection switch 11 separates the multiplexed signal input to the input port 11I1 into components for each wavelength using its demultiplexing function. The wavelength selection switch 11 then uses its switching function to select the output destination of any wavelength component obtained by the demultiplexing function from output ports 11O1 and 11O2. The wavelength selection switch 11 then uses its multiplexing function to multiplex the wavelength components for each output port 11O and output a multiplexed signal. For example, the multiplexed signal output from output port 11O1 is input to the demultiplexing network 13-1 and broadcast to T1 (T1 is an integer greater than or equal to 2) output ports 13O1 of the demultiplexing network 13-1. The receiving terminal 30, connected to the output port 13O1, extracts the component corresponding to the wavelength assigned to it from the received multiplexed signal.

[0020] Figures 2A and 2B are diagrams used to illustrate communication using the optical communication network system of this disclosure.

[0021] First, let's assume that a first communication pair consists of a transmitting terminal 20-1 connected to the input port 12I11 of a multiplexing network 12-1 and a receiving terminal 30-2 connected to the output port 13O21 of a demultiplexing network 13-2, as shown in Figure 1. Also, let's assume that a second communication pair consists of a transmitting terminal 20-2 connected to the input port 12I21 of a multiplexing network 12-2 and a receiving terminal 30-1 connected to the output port 13O11 of a demultiplexing network 13-1, as shown in Figure 1. In this case, the multiplexing network 12-1 and demultiplexing network 13-2 corresponding to the first communication pair are completely different from the multiplexing network 12-2 and demultiplexing network 13-1 corresponding to the second communication pair. Therefore, as shown in Figure 2A, a common wavelength λ1 can be assigned to both the first and second communication pairs. This allows for the reuse of a single wavelength between communication pairs, thereby improving the efficiency of wavelength utilization.

[0022] For example, if receiving terminal 30-2 is connected to output port 13O1 of the decoupler network 13-1, just like receiving terminal 30-1, then, as shown in Figure 2B, it is not possible to assign a common wavelength λ1 to both the first and second communication pairs, and it is necessary to assign different wavelengths to the first and second communication pairs. Naturally, it is also not possible to assign a common wavelength to multiple transmitting terminals 20 connected to the same multiplexing network 12. Similarly, it is not possible to assign a common wavelength to multiple receiving terminals 30 connected to the same decoupler network 13.

[0023] The transmitting terminal 20 is configured to communicate using a wavelength selected from a plurality of wavelengths. For example, the transmitting terminal 20 may have a fixed-wavelength laser light source and a tunable-wavelength filter. Alternatively, the transmitting terminal 20 may have a tunable-wavelength laser light source.

[0024] As described above, according to the first embodiment, the wavelength selector switch 11 in the optical communication network system 10 has input ports 11I1 and 11I2 and output ports 11O1 and 11O2. The wavelength selector switch 11 is configured to select an output port for each wavelength component of the signal input from the input port. The multiplexing network 12 includes an optical transmission configuration in which a plurality of couplers 12A are connected in a tree-like structure. The multiplexing network 12-1 has S1 (S1 is an integer of 2 or more) input ports 12I1 and an output port 12O11 connected to the input port 11I1 of the WSS 11. The multiplexing network 12-2 has S2 (S2 is an integer of 2 or more) input ports 12I2 and an output port 12O21 connected to the input port 11I2 of the WSS 11. The decoupler network 13 includes an optical transmission configuration in which a plurality of couplers 13A are connected in a tree-like structure. The decoupler network 13-1 has an input port 13I11 connected to the output port 11O1 of the WSS11, and T1 (T1 is an integer greater than or equal to 2) output ports 13O1. The decoupler network 13-2 has an input port 13I21 connected to the output port 11O2 of the WSS11, and T2 (T2 is an integer greater than or equal to 2) output ports 13O2. In other words, the optical communication network system 10 is configured to be able to set up a number of optical paths equal to the value obtained by multiplying the sum of S1 and S2 by the sum of T1 and T2.

[0025] This configuration of the optical communication network system 10 improves the efficiency of wavelength utilization. Furthermore, this configuration of the optical communication network system 10 avoids the need to install a wavelength converter in the WSS 11, and also avoids the need to install a large-scale spatial switch in the WSS 11. As a result, lower power consumption and lower costs can be achieved.

[0026] As stated above, the number of input ports, output ports, multiplexing networks 12, and demultiplexing networks 13 of the wavelength selector switch 11 are not limited to two. The optical communication network system 10 can be rephrased as follows: The optical communication network system 10 has n (where n is an integer greater than or equal to 2) input ports and n output ports, and an n × n wavelength selector switch (WSS) capable of selecting an output port for each wavelength component of the signal input from the input ports, and n multiplexing networks connected to each of the n input ports of the WSS, wherein the i-th (where i is an integer greater than or equal to 1 or less than or equal to n) multiplexing network is S i n multiplexing networks, each having n input ports and an output port connected to any input port of the WSS, and n demultiplexing networks, each connected to the n output ports of the WSS, wherein the j-th (where j is an integer between 1 and n) demultiplexing network has an input port and T connected to any output port of the WSS. j The optical communication network system 10 comprises n demultiplexing networks, each having n output ports (where j is an integer between 1 and n). That is, the optical communication network system 10 has S for the n multiplexing networks. i The sum of the values ​​and the n demultiplexing networks are given by T j The system is configured to allow setting a number of optical paths equal to the sum of the values ​​multiplied by the value obtained by multiplying the sum of the values. For example, even when n is 3 or greater, the basic configuration of the optical communication network system 10 shown in Figure 1 is also included in the optical communication network system 10 when n is 3 or greater.

[0027] <Second Embodiment> The second embodiment relates to wavelength assignment.

[0028] Figure 3 is a block diagram showing another example of the optical communication network system of the present disclosure. In Figure 3, the optical communication network system 40 includes a wavelength allocation unit 41, a wavelength selection switch 11, multiplexing networks 12-1 and 12-2, and demultiplexing networks 13-1 and 13-2.

[0029] The wavelength assignment unit 41 assigns different wavelengths to transmitting terminals 20-1 and 20-2 if the communication partner terminal of transmitting terminal 20-1, which is connected to the multiplexing network 12-1 shown in Figure 1, and the communication partner terminal of transmitting terminal 20-2, which is connected to the multiplexing network 12-2, are connected to the same demultiplexing network 13. Furthermore, the wavelength assignment unit 41 assigns the same or different wavelengths to transmitting terminals 20-1 and 20-2 if the communication partner terminals of transmitting terminal 20-1 and 20-2 are connected to different demultiplexing networks 13.

[0030] Figure 4 shows an example of wavelength assignment according to this disclosure. Figure 4 shows, for example, that transmitting terminals 20-1 to 20-4 and transmitting terminals 20-9 to 20-12 share the same transmittable wavelengths λ1 to λ4 and belong to group #1. Transmitting terminals 20-5 to 20-8 and transmitting terminals 20-13 to 20-16 share the same transmittable wavelengths λ5 to λ8 and belong to group #2. Transmitting terminals 20-1 to 20-4 and transmitting terminals 20-5 to 20-8 are connected to the multiplexing network 12-1. Transmitting terminals 20-9 to 20-12 and transmitting terminals 20-13 to 20-16 are connected to the multiplexing network 12-2.

[0031] Even if two transmitting terminals 20 belong to the same group, if the multiplexing networks 12 to which the two transmitting terminals 20 are connected are different, and the two communication partner terminals of the two transmitting terminals 20 are connected to different demultiplexing networks 13, the wavelength allocation unit 41 can assign the same wavelength to the two transmitting terminals 20. On the other hand, if two transmitting terminals 20 belonging to the same group are connected to different multiplexing networks 12, and the two communication partner terminals of the two transmitting terminals 20 are connected to the same demultiplexing network 13, the wavelength allocation unit 41 needs to assign different wavelengths to the two transmitting terminals 20.

[0032] <Third Embodiment> The third embodiment relates to a configuration for increasing the number of wavelengths available in an optical communication network system.

[0033] Figure 5 is a block diagram showing another example of an optical communication network system according to the present disclosure. In Figure 5, the optical communication network system 50 includes a wavelength allocation unit 51, wavelength filters 52-1, 52-2, a wavelength selection switch 11, multiplexing networks 12-1, 12-2, and demultiplexing networks 13-1, 13-2.

[0034] In Figure 5, the multiplexing network 12-1 has output ports 12O11 and 12O12. Output port 12O11 is connected to an intermediate coupler 12A21 between the top coupler 12A1 and the bottom coupler 12A in the optical transmission configuration of the multiplexing network 12-1. The intermediate coupler 12A21 has two inputs and two outputs. Coupler 12A1 means that it is the first layer (i.e., top) coupler 12A. Intermediate coupler 12A21 means that it is one of the couplers 12A in the second layer. Output port 12O11 is also connected to the input port 11I1 of the wavelength selector switch 11. Output port 12O12 is also connected to the top coupler 12A1. Output port 12O12 is also connected to the input port 13I12 of the demultiplexing network 13-1 via a wavelength filter 52-1.

[0035] The multiplexing network 12-2 has output ports 12O21 and 12O22. Output port 12O21 is connected to an intermediate coupler 12A21 between the top coupler 12A1 and the bottom coupler 12A of the optical transmission configuration of the multiplexing network 12-2. Output port 12O21 is also connected to the input port 11I2 of the wavelength selector switch 11. Output port 12O22 is connected to the top coupler 12A1. Output port 12O22 is also connected to the input port 13I22 of the demultiplexing network 13-2 via a wavelength filter 52-2.

[0036] The decoupler network 13-1 has input ports 13I11 and 13I12. Input port 13I11 is connected to an intermediate coupler 13A21 between the top coupler 13A1 and the bottom coupler 13A of the optical transmission configuration of the decoupler network 13-1. The intermediate coupler 13A21 has two inputs and two outputs. Coupler 13A1 means that it is the first layer (i.e., top) coupler 13A. Intermediate coupler 13A21 means that it is one of the couplers 13A of the second layer. Input port 13I11 is also connected to the output port 11O1 of the wavelength selector switch 11. Input port 13I12 is also connected to the top coupler 13A1. Input port 13I12 is also connected to the output port 12O12 of the multiplexer network 12-1 via a wavelength filter 52-1.

[0037] The demultiplexing network 13-2 has input ports 13I21 and 13I22. Input port 13I21 is connected to the intermediate coupler 13A21 between the top coupler 13A1 and the bottom coupler 13A of the optical transmission configuration of the demultiplexing network 13-2. Input port 13I21 is also connected to the output port 11O2 of the wavelength selector switch 11. Input port 13I22 is connected to the top coupler 13A1. Input port 13I22 is also connected to the output port 12O22 of the multiplexing network 12-2 via the wavelength filter 52-2.

[0038] In the third embodiment, the wavelength selector switch 11 is configured to receive multiplexed signals of eight wavelengths at each of the input ports 11I1 and 11I2. The wavelength selector switch 11 is also configured to transmit multiplexed signals of eight wavelengths at each of the output ports 11O1 and 11O2. In this case, the wavelength assignment unit 51 assigns wavelengths from the "first wavelength group" to the transmitting terminal 20 connected to the input port 12I1 located below the intermediate coupler 12A21 of the multiplexing network 12-1. The wavelength assignment unit 51 also assigns wavelengths from the "second wavelength group" to the transmitting terminal 20 connected to the input ports 12I1 of the multiplexing network 12-1 other than the input port 12I1 located below the intermediate coupler 12A21. The wavelength assignment unit 51 also assigns wavelengths from the "first wavelength group" to the transmitting terminal 20 connected to the input port 12I2 located below the intermediate coupler 12A21 of the multiplexing network 12-2. Furthermore, the wavelength assignment unit 51 assigns wavelengths from the "third wavelength group" to the transmitting terminal 20 connected to input ports 12I2 of the multiplexing network 12-2, excluding input port 12I2 located below the intermediate coupler 12A21. The second wavelength group and the third wavelength group may have the same constituent wavelengths. The first wavelength group and the second wavelength group (third wavelength group) do not have overlapping constituent wavelengths. Here, the first wavelength group, the second wavelength group, and the third wavelength group are assumed to each contain eight wavelengths.

[0039] Wavelength filter 52-1 is, for example, a fixed filter. Wavelength filter 52-1 allows wavelengths of the second wavelength group to pass through and blocks all other wavelengths. Wavelength filter 52-2 is also, for example, a fixed filter. Wavelength filter 52-2 allows wavelengths of the third wavelength group to pass through and blocks all other wavelengths.

[0040] In this optical communication network system 50, a receiving terminal 30 connected to the output port 13O1 of the demultiplexing network 13-1 receives multiplexed signals of up to 16 wavelengths. Similarly, a receiving terminal 30 connected to the output port 13O2 of the demultiplexing network 13-2 receives multiplexed signals of up to 16 wavelengths. Thus, even though the demultiplexing network 13-1 is capable of handling multiplexed signals of 8 wavelengths, the optical communication network system 50 as a whole can handle multiplexed signals of 16 wavelengths.

[0041] Furthermore, the transmitting terminal 20 to which the second wavelength group is assigned can be a terminal group in which the communication partner is fixed to a receiving terminal 30 connected to the decoupled network 13-1. Similarly, the transmitting terminal 20 to which the third wavelength group is assigned can be a terminal group in which the communication partner is fixed to a receiving terminal 30 connected to the decoupled network 13-2. Furthermore, the transmitting terminal 20 to which the first wavelength group is assigned can be a terminal group in which either a receiving terminal 30 connected to the decoupled network 13-1 or a receiving terminal 30 connected to the decoupled network 13-2 can be selected as the communication partner.

[0042] <Fourth Embodiment> A fourth embodiment relates to an embodiment that enables a reduction in the scale of wavelength-selective switches used in the optical communication network system of the present disclosure.

[0043] Figure 6 is a block diagram showing an example of an optical communication network system using a 4x4 wavelength selective switch.

[0044] In Figure 6, the optical communication network system 10 includes a wavelength selection switch 11, multiplexing networks 12-1, 12-2, 12-3, 12-4, and demultiplexing networks 13-1, 13-2, 13-3, 13-4.

[0045] In Figure 6, the wavelength selector switch 11 is configured to receive multiplexed signals of four wavelengths at each input port. Furthermore, the wavelength selector switch 11 is configured to transmit multiplexed signals of four wavelengths at each output port.

[0046] Wavelength selective switches are known to cost in proportion to the square of the number of ports. Therefore, a configuration with fewer ports for wavelength selective switches is advantageous.

[0047] Figure 7 is a block diagram showing another example of the optical communication network system of the present disclosure. In Figure 7, the optical communication network system 60 includes a wavelength selection switch 11, multiplexing networks 12-1 and 12-2, and demultiplexing networks 61-1 and 61-2.

[0048] In Figure 7, the wavelength selector switch 11 is a 2x2 WSS. In Figure 7, the wavelength selector switch 11 is configured to receive 8-wavelength multiplexed signals at each of its input ports 11I1 and 11I2. The wavelength selector switch 11 is also configured to transmit 8-wavelength multiplexed signals at each of its output ports 11O1 and 11O2.

[0049] The decoupler network 61 includes an optical transmission configuration in which multiple couplers 61A are connected in a tree-like structure. The decoupler network 61-1 has an input port 61I11 connected to the output port 11O1 of the WSS11, and multiple output ports 61O. The decoupler network 61-1 also has a wavelength filter 61B1 between the top coupler 61A1 and the second layer coupler 61A21 of the optical transmission configuration of the decoupler network 61-1. The wavelength filter 61B1 is, for example, a fixed wavelength filter, a variable wavelength filter, or a bandpass filter. The decoupler network 61-1 also has a wavelength filter 61B2 between the top coupler 61A1 and the second layer coupler 61A22 of the optical transmission configuration of the decoupler network 61-1. The wavelength filter 61B2 is, for example, a fixed wavelength filter, a variable wavelength filter, or a bandpass filter. The wavelengths that the wavelength filter 61B1 allows to pass through are different from the wavelength filter 61B2 allowing to pass through. For example, as shown in Figure 7, wavelength filter 61B1 allows wavelengths λ1, λ2, λ3, and λ4 to pass through while blocking other wavelengths, while wavelength filter 61B2 allows wavelengths λ5, λ6, λ7, and λ8 to pass through while blocking other wavelengths.

[0050] Thus, the demultiplexing network 61-1 has a wavelength filter 61B1 between the top coupler 61A1 and the second layer coupler 61A21 of the optical transmission configuration of the demultiplexing network 61-1, and a wavelength filter 61B2 between the top coupler 61A1 and the second layer coupler 61A22. The wavelength groups that pass through the wavelength filter 61B1 and the wavelength groups that pass through the wavelength filter 61B2 do not overlap in terms of the wavelengths that make up the groups. With this configuration of the demultiplexing network 61-1, it is possible to construct a subnetwork of the output stage of the wavelength filter 61B1 and a subnetwork of the output stage of the wavelength filter 61B2. In Figure 7, the receiving terminal 30-1 connected to the subnetwork of the output stage of the wavelength filter 61B1 only needs to extract the wavelength assigned to the receiving terminal 30-1 from among wavelengths λ1, λ2, λ3, and λ4. Furthermore, in Figure 7, the receiving terminal 30-3 connected to the subnetwork of the output stage of the wavelength filter 61B2 only needs to extract the wavelength assigned to the receiving terminal 30-3 from among wavelengths λ5, λ6, λ7, and λ8.

[0051] Furthermore, the decoupler network 61-2 has an input port 61I21 connected to the output port 11O2 of WSS11, and a plurality of output ports 61O. The decoupler network 61-2 also has a wavelength filter 61B1 between the top coupler 61A1 and the second layer coupler 61A21 of the optical transmission configuration of the decoupler network 61-2. Additionally, the decoupler network 61-2 has a wavelength filter 61B2 between the top coupler 61A1 and the second layer coupler 61A22 of the optical transmission configuration of the decoupler network 61-2.

[0052] Although the present invention has been described above with reference to embodiments, the present invention is not limited thereto. Various modifications to the structure and details of the present invention can be made within the scope of the invention as can be understood by those skilled in the art. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0053] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments rather than with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create embodiments that are not explicitly illustrated or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps shown in any of the drawings may be changed as appropriate.

[0054] Some or all of the above embodiments may also be described as follows, but are not limited to the following: (Note 1) A wavelength selector switch (WSS) has a first input port and a second input port, and a first output port and a second output port, and allows the output port to be selected for each wavelength component of the signal input from the input port. A first multiplexing network having S1 (where S1 is an integer greater than or equal to 2) input ports and at least one output port, and including an optical transmission configuration in which a plurality of couplers are connected in a tree-like manner, and connected to the first input port of the WSS, A second multiplexing network having S2 (where S2 is an integer greater than or equal to 2) input ports and at least one output port, and including an optical transmission configuration in which a plurality of couplers are connected in a tree-like structure, and connected to the second input port of the WSS, A first demultiplexing network having at least one input port and T1 (T1 is an integer of 2 or more) output ports, and including an optical transmission configuration in which multiple couplers are connected in a tree-like structure, and connected to the first output port of the WSS, A second demultiplexing network having at least one input port and T2 (T2 is an integer greater than or equal to 2) output ports, and including an optical transmission configuration in which multiple couplers are connected in a tree-like structure, and connected to the second output port of the WSS, An optical communication network system equipped with the following features. (Note 2) It comprises an assignment means for assigning wavelengths to each of multiple transmitting terminals, The aforementioned allocation means is If the first receiving terminal, which is the communication partner of the first transmitting terminal, and the second receiving terminal, which is the communication partner of the second transmitting terminal, are connected to the same decoupled network, then different wavelengths are assigned to the first transmitting terminal and the second transmitting terminal. If the first receiving terminal, which is the communication partner of the first transmitting terminal, and the second receiving terminal, which is the communication partner of the second transmitting terminal, are connected to different decoupled networks, then the same or different wavelengths are assigned to the first transmitting terminal and the second transmitting terminal. The optical communication network system described in Appendix 1. (Note 3) The intermediate coupler located between the top and bottom layers of the optical transmission configuration of the first multiplexing network is connected to the intermediate coupler of the optical transmission configuration of the first demultiplexing network. The top coupler of the optical transmission configuration of the first multiplexing network is connected to the top coupler of the optical transmission configuration of the first demultiplexing network via a wavelength filter. The optical communication network system described in Appendix 1. (Note 4) It comprises an assignment means for assigning wavelengths to each of multiple transmitting terminals, The aforementioned allocation means is A wavelength is assigned from the first wavelength group to a transmitting terminal connected to an input port located below the intermediate coupler of the first multiplexing network. For both the input ports of the first multiplexing network other than the input ports under the intermediate coupler and the output ports of the first demultiplexing network other than the output ports under the intermediate coupler, a second wavelength group whose constituent wavelengths do not overlap with the first wavelength group is assigned. The optical communication network system described in Appendix 3. (Note 5) The first demultiplexing network has a wavelength filter between the top coupler and the second layer coupler of the optical transmission configuration of the first demultiplexing network. The optical communication network system described in Appendix 1. (Note 6) An n×n wavelength selector switch (WSS) has n (where n is an integer greater than or equal to 2) input ports and n output ports, and can select an output port for each wavelength component of the signal input from the input ports. n multiplexing networks connected to the n input ports of the WSS, wherein the i-th (where i is an integer between 1 and n) multiplexing network is S i The n multiplex networks each have an input port and an output port connected to any of the input ports of the WSS, n demultiplexing networks connected to each of the n output ports of the WSS, wherein the j-th (where j is an integer between 1 and n) demultiplexing network is connected to an input port and T j The n demultiplexer network has output ports (where j is an integer between 1 and n), An optical communication network system equipped with the following features. [Explanation of Symbols]

[0055] 10 Optical Communication Network Systems 11 Wavelength Selective Switch (WSS) 12 Multiplex Networks 12A Coupler 13-band splitter network 13A Coupler 20 Sending terminal 30 Receiving terminal 40 Optical Communication Network Systems 41 Wavelength allocation section 50 Communication Network Systems 51 Wavelength allocation section 52-wavelength filter 60 Optical Communication Network Systems 61 Splitter Network 61A Coupler 61B Wavelength Filter

Claims

1. A wavelength selector switch (WSS) has a first input port and a second input port, and a first output port and a second output port, and allows the output port to be selected for each wavelength component of the signal input from the input port. S １ (S １ A first multiplexing network having (2 or more integers) input ports and at least one output port, and including an optical transmission configuration in which a plurality of couplers are connected in a tree-like manner, and connected to the first input port of the WSS, S ２ (S ２ A second multiplexing network having (2 or more integers) input ports and at least one output port, and including an optical transmission configuration in which a plurality of couplers are connected in a tree-like manner, and connected to the second input port of the WSS, At least one input port and T １ (T １ The first demultiplexing network has output ports (where is an integer of 2 or more) and includes an optical transmission configuration in which a plurality of couplers are connected in a tree-like manner, and is connected to the first output port of the WSS, At least one input port and T ２ (T ２ The WSS has an optical transmission configuration in which multiple couplers are connected in a tree-like manner and has output ports (where is an integer of 2 or more), and a second demultiplexing network connected to the second output port of the WSS, An optical communication network system equipped with the following features.

2. It comprises an assignment means for assigning wavelengths to each of multiple transmitting terminals, The aforementioned allocation means is If the first receiving terminal, which is the communication partner of the first transmitting terminal, and the second receiving terminal, which is the communication partner of the second transmitting terminal, are connected to the same decoupled network, then different wavelengths are assigned to the first transmitting terminal and the second transmitting terminal. If the first receiving terminal, which is the communication partner of the first transmitting terminal, and the second receiving terminal, which is the communication partner of the second transmitting terminal, are connected to different decoupled networks, then the same or different wavelengths are assigned to the first transmitting terminal and the second transmitting terminal. The optical communication network system according to claim 1.

3. The intermediate coupler located between the top and bottom layers of the optical transmission configuration of the first multiplexing network is connected to the intermediate coupler of the optical transmission configuration of the first demultiplexing network. The top coupler of the optical transmission configuration of the first multiplexing network is connected to the top coupler of the optical transmission configuration of the first demultiplexing network via a wavelength filter. The optical communication network system according to claim 1.

4. It comprises an assignment means for assigning wavelengths to each of multiple transmitting terminals, The aforementioned allocation means is A wavelength is assigned from the first wavelength group to a transmitting terminal connected to an input port located below the intermediate coupler of the first multiplexing network. For both the input ports of the first multiplexing network other than the input ports under the intermediate coupler and the output ports of the first demultiplexing network other than the output ports under the intermediate coupler, a second wavelength group whose constituent wavelengths do not overlap with the first wavelength group is assigned. The optical communication network system according to claim 3.

5. The first demultiplexing network has a wavelength filter between the top coupler and the second layer coupler of the optical transmission configuration of the first demultiplexing network. The optical communication network system according to claim 1.

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