Optical Gateway Equipment

Abstract

A first multiplexer / demultiplexer splits an optical signal input from a first port and outputs the results from a plurality of second ports, and multiplexes optical signals input from the plurality of second ports and outputs the result from the first port. A second multiplexer / demultiplexer splits an optical signal input from a third port and outputs the results from a plurality of fourth ports, and multiplexes optical signals input from the plurality of fourth ports and outputs the result from the third port. A direction of travel of a wavelength component having a first wavelength, of an optical signal that passes through the first port of the first multiplexer / demultiplexer, and a direction of travel of a wavelength component having the first wavelength, of an optical signal that passes through the third port of the second multiplexer / demultiplexer, are mutually opposite directions. An optical switch is provided with a plurality of fifth ports and a plurality of sixth ports. The second ports of the first multiplexer / demultiplexer and the fourth ports of the second multiplexer / demultiplexer are connected to the plurality of fifth ports of the optical switch.

Description

[Technical field]

[0001] The present invention relates to an optical gateway device. [Background technology]

[0002] Non-Patent Document 1 describes an optical gateway that constitutes an all-photonics network. The optical gateway is provided between a core network and multiple service devices. An example of the service device is CPE (Customer Premises Equipment). As shown in Non-Patent Document 1, the optical gateway sets the wavelength of the optical signal transmitted by the service device and the route between the core network and the service device. The optical gateway includes an optical switch, a multiplexer / demultiplexer, etc. The optical switch connects the service device and the core network. The multiplexer / demultiplexer wavelength division multiplexes multiple optical signals with different wavelengths. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Tomoaki Yoshida, Photonic Gateway and Optical Access Technology Supporting APN, "Monthly Business Communication", Business Communication Co., Ltd., 2020, vol. 57, no. 10, pp. 16-17 Summary of the Invention [Problem to be solved by the invention]

[0004] A service device such as a CPE is connected downstream of the optical gateway device. If upstream and downstream communications are performed via the same transmission path, bidirectionally on a single core, using signals of the same wavelength, reflection of the own transmission signal will cause degradation in reception of the signal from the opposing device. Therefore, when upstream and downstream communications are performed via the same transmission path in a single-core bidirectional manner in a service device or core network, it is preferable to perform the upstream and downstream communications with optical signals of different wavelengths. Therefore, when transmission is performed in a single core bidirectional manner in at least a part of the communication path, the optical gateway device assigns different wavelengths to the service device as the wavelengths of the upstream and downstream optical signals.

[0005] On the other hand, in order to efficiently use the wavelength resources of optical signals, it is desirable to use all available wavelengths in each transmission line. When transmitting upstream and downstream communications of different wavelengths in both directions over a single fiber through the same transmission line, it is assumed that the available wavelengths are assigned fixedly to the upstream and downstream wavelengths, for example, in a one-to-one ratio, such that some wavelengths are dedicated to the upstream and some are dedicated to the downstream. In that case, when the upstream and downstream are separated in both directions over a single fiber, and only the upstream and downstream are multiplexed, and transmitted in one direction over two fibers as the transmitting side and the receiving side, respectively, only half of the available wavelengths are used in each transmission line. Therefore, it is preferable to assign the wavelength assigned to the upstream in one service device to the downstream in another service device and use it in both directions. For example, by assigning a first wavelength to the upstream signal of a first service device and a second wavelength to the downstream signal, and assigning the second wavelength to the upstream signal of a second service device and the first wavelength to the downstream signal, and multiplexing these upstream and downstream signals, it is possible to effectively utilize wavelengths even in a transmission path that transmits optical signals by multiplexing and demultiplexing a signal transmitted in both directions over a single core into two cores in one direction.

[0006] Incidentally, the multiplexers and demultiplexers that make up the optical gateway usually use AWGs (Arrayed Waveguide Gratings), which have a fixed combination of input and output wavelengths and ports on the split side. Therefore, in an optical gateway device, it is difficult to connect a transmission line that transmits both upstream and downstream signals in a single-core bidirectional manner using different wavelengths to the split side port of the AWG and make it conductive. An object of the present invention is to provide an optical gateway device which can assign different wavelengths for upstream and downstream signals to a service device and can use the same wavelength for the upstream and downstream signals in a core network. [Means for solving the problem]

[0007] One aspect of the present invention includes a first multiplexer / demultiplexer, a second multiplexer / demultiplexer, and an optical switch. The first multiplexer / demultiplexer includes a first port and a plurality of second ports, and separates an optical signal input from the first port and outputs it from the plurality of second ports, and multiplexes the optical signals input from the plurality of second ports and outputs it from the first port. The second multiplexer / demultiplexer includes a third port and a plurality of fourth ports, and separates an optical signal input from the third port and outputs it from the plurality of fourth ports, and multiplexes the optical signals input from the plurality of fourth ports and outputs it from the third port. The optical switch includes a plurality of fifth ports and a plurality of sixth ports, and the second port and the fourth port are connected to the plurality of fifth ports, and switches optical signals between the plurality of fifth ports and the plurality of sixth ports. The direction in which a wavelength component of a first wavelength of the optical signal passing through the first port advances is opposite to the direction in which a wavelength component of the first wavelength of the optical signal passing through the third port advances. Effect of the Invention

[0008] According to the above aspect, different wavelengths can be assigned to the service device for the upstream signal and the downstream signal, and the same wavelength can be used for the upstream signal and the downstream signal in the core network. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a configuration of an optical network according to a first embodiment. [Diagram 2] 1 is a schematic block diagram showing a configuration of an optical gateway device according to a first embodiment. [Diagram 3] FIG. 2 is a diagram illustrating a signal flow in the optical gateway device according to the first embodiment. [Figure 4] FIG. 2 is a diagram illustrating a configuration of an optical gateway device according to a first modified example of the first embodiment. [Diagram 5] FIG. 11 is a diagram illustrating a configuration of an optical gateway device according to a second modified example of the first embodiment. [Figure 6] FIG. 11 is a diagram illustrating a configuration for connecting to a core network of single-core unidirectional transmission by an optical gateway device according to a second modification of the first embodiment. [Figure 7] FIG. 13 is a diagram illustrating a configuration of an optical gateway device according to a third modified example of the first embodiment. [Figure 8] FIG. 11 is a schematic block diagram showing a configuration of an optical gateway device according to a second embodiment. [Figure 9] FIG. 13 is a diagram illustrating a configuration of an optical gateway device according to a first modified example of the second embodiment. [Figure 10] FIG. 13 is a diagram illustrating a configuration of an optical gateway device according to a second modification of the second embodiment. [Figure 11] FIG. 13 is a diagram illustrating a configuration of an optical gateway device according to a third modified example of the second embodiment. [Figure 12] FIG. 13 is a diagram illustrating a configuration of an optical gateway device according to a fourth modified example of the second embodiment. [Figure 13] FIG. 13 is a diagram illustrating a relationship between a multiplexer / demultiplexer and wavelengths according to a fourth modified example of the second embodiment. [Figure 14] FIG. 13 is a diagram illustrating a relationship between a wavelength and a multiplexer / demultiplexer according to a fifth modified example of the second embodiment. [Figure 15] FIG. 13 is a diagram illustrating a configuration of an optical gateway device according to a sixth modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First Embodiment Optical network configuration Hereinafter, the embodiments will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of an optical network 1 according to the first embodiment. The optical network 1 includes a plurality of optical gateway devices 30 connected to a core network 10. The core network 10 is a ring network. For the sake of simplicity, the core network 10 is a ring network consisting of one transmission path that transmits signals in a counterclockwise direction. In other embodiments, the core network 10 may be a network having a counterclockwise transmission path and a clockwise transmission path, or may be a multi-ring network in which a plurality of ring networks are coupled. In other embodiments, the core network 10 may be a full mesh network instead of a ring network. In the optical network 1, optical signals of N wavelengths are used. A signal in which optical signals of a plurality of wavelengths are multiplexed is called a multiplexed signal. The core network 10 performs single-core unidirectional transmission. In this specification, "single-core unidirectional" refers to a method in which only optical signals traveling in the same direction can be transmitted through one transmission path. The transmission path may be a single-core fiber or a multi-core fiber. When the transmission path is a multicore fiber, a transmission method in which only optical signals traveling in the same direction (one-way) are transmitted within one core in the core, and the optical signals travel in different directions between cores, is also called single-core one-way transmission. In other words, "single core" is not limited to one core of a single-core fiber, but also includes one core in a multicore fiber.

[0011] The optical gateway device 30 is provided between the core network 10 and the service device 50, and relays communication between the service devices 50. Hereinafter, the side of the optical gateway device 30 connected to the core network 10 is referred to as the "upstream side", and the side connected to the service device 50 is referred to as the "downstream side". The optical gateway device 30 according to another embodiment may be connected to another optical gateway device 30 without going through the core network 10. In this case, the side connected to the other optical gateway device 30 is referred to as the "upstream side". The service device 50 and the optical gateway device 30 according to the first embodiment are connected through a third fiber 51. The third fiber 51 passes an optical signal going in the upstream direction and an optical signal going in the downstream direction. That is, the third fiber 51 performs single-core bidirectional transmission. In this specification, "single-core bidirectional" refers to a method that enables transmission of optical signals traveling in directions facing each other on one transmission path. When the transmission line is a multi-core fiber, a transmission method in which optical signals traveling in opposite directions within one core of the fiber are transmitted is called single-core bidirectional transmission. Note that the wavelengths of the optical signals in the upstream direction and the downstream direction are different from each other.

[0012] Configuration of the Optical Gateway Device 30 2 is a schematic block diagram showing a configuration of an optical gateway device 30 according to the first embodiment. The optical gateway device 30 according to the first embodiment includes a first multiplexer / demultiplexer 31, a second multiplexer / demultiplexer 32, an optical switch 33, and L up / down separators 34. One service device 50 can be connected to one up / down separator 34. In other words, a maximum of L service devices 50 are connected to the optical gateway device 30.

[0013] The first multiplexer / demultiplexer 31 has one upstream port 31U and N downstream ports 31D. The upstream port 31U is connected to a first fiber 11 extending from an upstream optical gateway device 30 (the adjacent optical gateway device 30 on the left) in the core network 10. The N downstream ports 31D are connected to corresponding upstream ports 33U of the optical switch 33. The first multiplexer / demultiplexer 31 separates a multiplexed signal input to the upstream port 31U into N optical signals with different wavelengths, and outputs them from downstream ports 31D corresponding to each wavelength. An AWG, for example, can be used as the first multiplexer / demultiplexer 31.

[0014] The second multiplexer / demultiplexer 32 has one upstream port 32U and N downstream ports 32D. The upstream port 32U is connected to a second fiber 12 extending from a downstream optical gateway device 30 (the optical gateway device 30 on the right) in the core network 10. The N downstream ports 32D are connected to corresponding upstream ports 33U of the optical switch 33. The second multiplexer / demultiplexer 32 multiplexes optical signals input to the N downstream ports 32D, and outputs the multiplexed signal from the upstream port 32U. As the first multiplexer / demultiplexer 31, for example, an AWG can be used.

[0015] The optical switch 33 includes 2N upstream ports 33U, 2L downstream ports 33D, and a control device 33C. The optical switch 33 transmits an optical signal input to the upstream port 33U to a downstream port 33D assigned by the control device 33C among the 2L downstream ports 33D. The optical switch 33 also transmits an optical signal input to the downstream port 33D to an upstream port 33U assigned by the control device 33C among the 2N upstream ports 33U. That is, the optical switch 33 switches an optical signal between the upstream port 33U and the downstream port 33D. The connection relationship between the upstream port 33U and the downstream port 33D in the optical switch 33 is determined according to a control signal from the control device 33C. The optical switch 33 may be, for example, an FXC (Fiber Cross Connect) or other many-to-many optical switch.

[0016] The control device 33C may use a processor. The control device 33C may be a computer that includes a processor, a memory, an auxiliary storage device, and the like connected by a bus, and executes a program to execute a predetermined process. Examples of the processor include a central processing unit (CPU), a graphic processing unit (GPU), and a microprocessor. Examples of the processor include custom large-scale integrated circuits (LSIs) such as application specific integrated circuits (ASICs) and programmable logic devices (PLDs). Examples of PLDs include programmable array logic (PALs), generic array logic (GALs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs).

[0017] The control device 33C sets the wavelength and the route so as to satisfy all of the following three conditions. The first condition is that different wavelengths are assigned to the upstream signal and the downstream signal of one service device 50. The second condition is that the wavelength of the upstream signal passing through the same transmission path in the core network 10 is different for each service device 50. The third condition is that the wavelength of the downstream signal passing through the same transmission path in the core network 10 is different for each service device 50. In the optical gateway device 30 according to the present embodiment, the control device 33C of the optical switch 33 assigns the wavelength, but this is not limited to this in other embodiments. For example, the optical gateway device 30 according to other embodiments may include a higher-level control device separately from the control device 33C of the optical switch 33, and the higher-level control device may assign the wavelength. In this case, the higher-level control device outputs a switching instruction of the route or the connection to the control device 33C based on the result of the wavelength assignment. In other embodiments, a device that controls the entire network may assign the wavelength.

[0018] The up / down separator 34 includes an upstream input port 34UI, an upstream output port 34UO, and a downstream port 34D. The upstream input port 34UI and the upstream output port 34UO are connected to the downstream port 33D of the optical switch 33. The downstream port 34D is connected to the third fiber 51. The up / down separator 34 outputs an optical signal input to the upstream input port 34UI from the downstream port 34D. The up / down separator 34 outputs an optical signal input to the downstream port 34D from the upstream output port 34UO. The up / down separator 34 may be formed of, for example, an optical circulator. The up / down separator 34 may also be formed of, for example, an AWG or other multiplexing / demultiplexing module.

[0019] Actions and Effects 3 is a diagram showing a signal flow in the optical gateway device 30 according to the first embodiment. As described above, in the optical gateway device 30 according to the first embodiment, the first multiplexer / demultiplexer 31 processes downstream optical signals related to N wavelengths, and the second multiplexer / demultiplexer 32 processes upstream optical signals related to N wavelengths. That is, in the optical gateway device 30, the direction in which the wavelength component of the first wavelength of the optical signal passing through the upstream port 31U of the first multiplexer / demultiplexer 31 advances is opposite to the direction in which the wavelength component of the first wavelength of the optical signal passing through the upstream port 32U of the second multiplexer / demultiplexer 32 advances. As a result, the optical gateway device 30 can prevent interference caused by reflection between the upstream signal and the downstream signal by making the wavelengths of the optical signals transmitted in both directions through a single core in the service device 50 different in the upstream direction and the downstream direction. Furthermore, the optical gateway unit 30 can improve wavelength utilization efficiency by using the same wavelength for both the upstream signal and the downstream signal, rather than dedicating the same wavelength exclusively for the upstream signal or the downstream signal, in each transmission path of the core network 10 that transmits optical signals in one direction over a single core. In other words, the optical gateway unit 30 sets the same wavelength for the upstream signal of a certain service device 50 and the downstream signal of another service device 50.

[0020] 3, when the first wavelength is assigned to the upstream signal of the service device 50A and the second wavelength is assigned to the downstream signal, the optical gateway device 30 can assign the second wavelength to the upstream signal of the service device 50B and the first wavelength to the downstream signal. Similarly, the optical gateway device 30 can assign the third wavelength to the upstream signal of the service device 50C and the fourth wavelength to the downstream signal of the service device 50C, and the fourth wavelength to the upstream signal of the service device 50D and the third wavelength to the downstream signal of the service device 50D.

[0021] The optical gateway unit 30 does not have to set two wavelengths as a pair so that the wavelengths of the pair are reversed between the upstream signal and the downstream signal of the two service devices 50. That is, the optical gateway unit 30 does not have to set one of the pair of wavelengths to the upstream signal of one of the two service devices 50 and the other of the pair of wavelengths to the downstream signal, set one of the pair of wavelengths to the downstream signal of the other of the two service devices 50, and set the other of the pair of wavelengths to the upstream signal. For example, among optical signals obtained by separating a direction-multiplexed signal into each direction, optical signals in the same direction may be multiplexed and transmitted on the same transmission path, and the wavelengths of the upstream signals may be shifted and assigned as downstream signals. For example, when the optical gateway device 30 assigns a first wavelength to the upstream signal of the service device A, a second wavelength to the upstream signal of the service device B, a third wavelength to the upstream signal of the service device C, and a fourth wavelength to the upstream signal of the service device D, the optical gateway device 30 may assign the second wavelength to the upstream signal of the service device A, the third wavelength to the upstream signal of the service device B, the fourth wavelength to the upstream signal of the service device C, and the first wavelength to the upstream signal of the service device D. The optical network 1 according to the first embodiment increases the wavelengths available to the service device 50, thereby improving the fault tolerance of the service device 50.

[0022] The upper and lower separators 34 may be configured according to the wavelength settings. For example, of the N wavelength signals, the optical signals relating to the first to [N / 2]th wavelengths (first wavelength group, i.e., the short wavelength side) head in the downstream direction, and the optical signals relating to the [N / 2+1]th to second [N / 2]th wavelengths (second wavelength group, i.e., the long wavelength side) head in the upstream direction. Note that [·] is a Gaussian symbol, and represents the maximum integer value that does not exceed the inner value. In other words, if N is an even number, 2[N / 2] is N, and if N is an odd number, 2[N / 2] is (N-1). If N is an odd number, the optical signal relating to the Nth wavelength does not need to be used.

[0023] In this case, each of the upper and lower separators 34 can be configured by a wavelength filter that separates an optical signal into a component of the first wavelength group and a component of the second wavelength group. In this case, the control device 33C controls each of the upper and lower separators 34 so that it is connected to only one of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32.

[0024] The control device 33C controls the optical switch 33 so as to connect the downstream port 33D of the optical switch 33 connected to the upstream input port 34UI of the up / down separator 34 with the upstream port 33U connected to the downstream port on the first wavelength group side of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32. The control device 33C also controls the optical switch 33 so as to connect the downstream port 33D of the optical switch 33 connected to the upstream output port 34UO of the up / down separator 34 with the upstream port 33U connected to the downstream port on the second wavelength group side of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream input port 34UI of the up / down separator 34 via the optical switch 33 to a downstream signal of the service device 50 connected to the up / down separator 34. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO of the upstream / downstream separator 34 via the optical switch 33 to the upstream signal of the service device 50 connected to the upstream / downstream separator 34.

[0025] The first to [N / 2]th wavelengths may be on the long wavelength side, and the [N / 2+1]th to [N / 2]th wavelengths may be on the short wavelength side. In this case, the control device 33C assigns the wavelengths of the upstream signal and the downstream signal to the opposing service devices 50 so that they are reversed.

[0026] A periodic filter such as an MZ (Mach-Zehnder) filter may be used as the up-down separator 34. When a 2×2 port MZ filter is used, one of the two downstream ports is non-reflectively terminated. In this case, the control device 33C assigns wavelengths corresponding to the passing wavelengths of the two upstream ports of the up-down separator 34 connected to the service device 50 as the wavelengths of the up-down signal and the down-down signal of each service device 50. Then, the control device 33C controls to connect the downstream port 33D of the optical switch 33 connected to the upstream input port 34UI of the up-down separator 34 and the upstream port 33U of the optical switch 33 connected to the downstream port 31D of the first multiplexer / demultiplexer 31 that corresponds to the wavelength assigned to the down-down signal of the service device 50 connected to the up-down separator 34. In addition, the control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the upstream output port 34UO of the upstream / downstream separator 34 to the upstream port 33U of the optical switch 33 connected to the downstream port 32D of the second multiplexer / demultiplexer 32 that corresponds to the wavelength assigned to the upstream signal of the service device 50 connected to the upstream / downstream separator 34.

[0027] A circulator may be used as the up-down separator 34. In this case, the control device 33C may assign any wavelengths different from each other as the wavelengths of the up-down signal and the down-down signal of each service device 50. The control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the upstream input port 34UI of the up-down separator 34 to the upstream port 33U of the optical switch 33 connected to the downstream port 31D of the first multiplexer / demultiplexer 31 corresponding to the wavelength assigned to the down-down signal of the service device 50 connected to the up-down separator 34. The control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the upstream output port 34UO of the up-down separator 34 to the upstream port 33U of the optical switch 33 connected to the downstream port 32D of the second multiplexer / demultiplexer 32 corresponding to the wavelength assigned to the up-down signal of the service device 50 connected to the up-down separator 34. This also applies to the modified examples and embodiments described below.

[0028] First Modified Example In the optical gateway device 30 according to the first embodiment, the up / down separator 34 is provided downstream of the optical switch 33, but this is not limited to this. For example, in the optical gateway device 30 according to other embodiments, the up / down separator 34 may be provided upstream of the optical switch 33. Fig. 4 is a diagram showing a configuration of the optical gateway device 30 according to a first modified example of the first embodiment.

[0029] The upstream input port 34UI of the up / down separator 34 of the optical gateway device 30 according to the first modification is connected to the downstream port 31D of the first multiplexer / demultiplexer 31. In addition, the upstream output port 34UO of the up / down separator 34 is connected to the downstream port 32D of the second multiplexer / demultiplexer 32. The downstream port 34D of the up / down separator 34 is connected to the upstream port 33U of the optical switch 33. The downstream port 33D of the optical switch 33 is directly connected to the third fiber 51. Since the number of up / down separators 34 is L, it is sufficient that the optical switch 33 according to the first modification has L upstream ports 33U and L downstream ports 33D.

[0030] In this case, the control device 33C sets the wavelength and the route so as to satisfy all of the following five conditions. The first condition is that different wavelengths are assigned to the upstream signal and the downstream signal of one service device 50. The second condition is that the wavelengths of the upstream signals passing through the same transmission path in the core network 10 are different for each service device 50. The third condition is that the wavelengths of the downstream signals passing through the same transmission path in the core network 10 are different for each service device 50. The fourth condition is that the upstream signal of the service device 50 is assigned a wavelength corresponding to the port of the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO of the up / down separator 34 connected to the service device 50. The fifth condition is that the downstream signal of the service device 50 is assigned a wavelength corresponding to the port of the first multiplexer / demultiplexer 31 connected to the upstream input port 34UI of the up / down separator 34 connected to the service device 50.

[0031] As the upstream / downstream separator 34, a wavelength filter may be used with the same connections and wavelengths as those of the optical gateway device 30 according to the first embodiment shown in Fig. 2. For example, among N wavelength signals, optical signals relating to the first to [N / 2]th wavelengths (first wavelength group, i.e., short wavelength side) head in the downstream direction, and optical signals relating to the [N / 2+1]th to second [N / 2]th wavelengths (second wavelength group, i.e., long wavelength side) head in the upstream direction.

[0032] In this case, each of the upstream and downstream separators 34 can be configured by a wavelength filter that separates an optical signal into a component of the first wavelength group and a component of the second wavelength group. The control device 33C controls the optical switch 33 so as to connect the upstream port 33U of the optical switch 33 connected to the downstream port 34D of the upstream and downstream separator 34 with the downstream port 33D of the optical switch 33. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream input port 34UI of the upstream and downstream separator 34 to a downstream signal of the service device 50 connected to the upstream and downstream separator 34. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO of the upstream and downstream separator 34 to an upstream signal of the service device 50 connected to the upstream and downstream separator 34.

[0033] The first to [N / 2]th wavelengths may be on the long wavelength side, and the [N / 2+1]th to [N / 2]th wavelengths may be on the short wavelength side. In this case, the control device 33C assigns the wavelengths of the upstream signal and the downstream signal to the opposing service devices 50 so that they are reversed.

[0034] A periodic filter such as an MZ filter may be used. The upstream input port 34UI of the up-down separator 34 is connected to the downstream port 31D of the first multiplexer / demultiplexer 31, which has a wavelength corresponding to the passing wavelength of the upstream input port 34UI. The upstream output port 34UO of the up-down separator 34 is connected to the downstream port 32D of the second multiplexer / demultiplexer 32, which has a wavelength corresponding to the passing wavelength of the upstream output port 34UO. In this case, the control device 33C assigns, as the wavelengths of the upstream signal and the downstream signal of each service device 50, a wavelength corresponding to the downstream port 31D of the first multiplexer / demultiplexer 31 connected to the upstream input port 34UI of one up-down separator 34, and a wavelength corresponding to the downstream port 32D of the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO. The control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the service device 50 to the upstream port 33U of the optical switch connected to the up-down separator 34, which corresponds to the wavelength assigned to the service device 50.

[0035] A circulator may be used as the up / down separator 34. In this case, the upstream input port 34UI of the up / down separator 34 is connected to the downstream port 31D of the first multiplexer / demultiplexer 31. The upstream output port 34UO of the up / down separator 34 is connected to the downstream port 32D of the second multiplexer / demultiplexer 32, which corresponds to a wavelength different from the wavelength input to the upstream input port 34UI. In this case, the control device 33C assigns, as the wavelengths of the upstream signal and the downstream signal of each service device 50, a wavelength corresponding to the downstream port 31D of the first multiplexer / demultiplexer 31 connected to the upstream input port 34UI of one up / down separator 34 and a wavelength corresponding to the downstream port 32D of the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO. The control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the service device 50 to the upstream port 33U of the optical switch connected to the up / down separator 34 corresponding to the wavelength assigned to the service device 50.

[0036] According to the first modification of the first embodiment, bidirectional signals are input to the upstream port 33U and the downstream port 33D of the optical switch 33, and bidirectional signals are output. As in the first embodiment, the optical gateway device 30 according to the first modification can prevent interference due to reflection between the upstream signal and the downstream signal by making the wavelengths of the optical signals transmitted in one-core bidirectional manner in the service device 50 different in the upstream direction and the downstream direction. Moreover, the optical gateway device 30 according to the first modification can improve wavelength utilization efficiency by using the same wavelength component for both the upstream signal and the downstream signal, rather than dedicating it exclusively for the upstream signal or the downstream signal, in each transmission path of the core network 10 that transmits optical signals in one direction over a single core. That is, the optical gateway device 30 sets the same wavelength for the upstream signal of a certain service device 50 and the downstream signal of another service device 50.

[0037] Second Modified Example In the optical gateway device 30 according to the first embodiment, the optical fiber connected to the upstream side performs single-core unidirectional transmission, but is not limited to this. For example, the optical fiber connected to the upstream side of the optical gateway device 30 according to another embodiment may perform single-core bidirectional transmission. Fig. 5 is a diagram showing the configuration of the optical gateway device 30 according to a second modification of the first embodiment.

[0038] The first fiber 11 and the second fiber 12 according to the second modification perform single-core bidirectional transmission. For example, among the N wavelength signals passing through the first fiber 11, the optical signals related to the first to [N / 2]th wavelengths (first wavelength group, i.e., short wavelength side) travel downstream, and the optical signals related to the [N / 2+1]th to second [N / 2]th wavelengths (second wavelength group, i.e., long wavelength side) travel upstream.

[0039] That is, in the first multiplexer / demultiplexer 31 according to the second modification, the optical signal related to the first wavelength group is directed downstream, and the optical signal related to the second wavelength group is directed upstream. On the other hand, among the N wavelength signals passing through the second fiber 12, the optical signals related to the first to [N / 2]th wavelengths are directed upstream, and the optical signals related to the [N / 2+1]th to [N / 2]th wavelengths are directed downstream. That is, in the second multiplexer / demultiplexer 32 according to the second modification, the optical signal related to the first wavelength group is directed upstream, and the optical signal related to the second wavelength group is directed downstream. In this case, each of the up-down separators 34 can be configured by a wavelength filter that separates the optical signal into the components of the first wavelength group and the components of the second wavelength group. In this case, the control device 33C controls each of the up-down separators 34 so that it is connected to only one of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32.

[0040] The control device 33C controls the optical switch 33 so as to connect the downstream port 33D of the optical switch 33 connected to the upstream input port 34UI of the up / down separator 34 with the upstream port 33U connected to the downstream port on the first wavelength group side of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32. The control device 33C also controls the optical switch 33 so as to connect the downstream port 33D of the optical switch 33 connected to the upstream output port 34UO of the up / down separator 34 with the upstream port 33U connected to the downstream port on the second wavelength group side of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream input port 34UI of the up / down separator 34 via the optical switch 33 to a downstream signal of the service device 50 connected to the up / down separator 34. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO of the upstream / downstream separator 34 via the optical switch 33 to the upstream signal of the service device 50 connected to the upstream / downstream separator 34.

[0041] In another modification, the first to [N / 2]th wavelengths may be on the long wavelength side, and the [N / 2+1]th to [N / 2]th wavelengths may be on the short wavelength side. In this case, the control device 33C assigns the wavelengths of the upstream signal and the downstream signal to the opposing service devices 50 so that they are reversed.

[0042] In another modification, a periodic filter such as an MZ filter may be used as the up / down separator 34. When a 2×2 port MZ filter is used, one of the two downstream ports is non-reflectively terminated. In this case, the control device 33C assigns wavelengths to each service device 50 so that the upstream wavelength and the downstream wavelength correspond to each period of the passing wavelength in the MZ filter. Then, the control device 33C controls to connect the downstream port 33D of the optical switch 33 connected to the upstream input port 34UI of the up / down separator 34 to the upstream port 33U of the optical switch 33 connected to the downstream port of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 corresponding to the wavelength assigned to the downstream signal of the service device 50 connected to the up / down separator 34. The control device 33C also controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the upstream output port 34UO of the up / down separator 34 to the upstream port 33U of the optical switch 33 connected to the downstream port 32D of the second multiplexer / demultiplexer 32 that corresponds to the wavelength assigned to the upstream signal of the service device 50 connected to the up / down separator 34 among the downstream ports 32D. In other words, the control device 33C sets the wavelength of the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32, which flows from the upstream input port 34UI of the up / down separator 34 to the downstream port 34D and is connected to the upstream input port 34UI via the optical switch 33, to the wavelength of the downstream signal of the service device 50. In addition, the control device 33C sets the wavelength of the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32, which flows from the downstream port 34D of the upstream separator 34 to the upstream output port 34UO and is connected to the upstream output port 34UO via the optical switch 33, to the wavelength of the upstream signal of the service device 50.

[0043] In another modified example, when a circulator is used as the up-down separator 34, the wavelengths in the upstream direction and the wavelengths in the downstream direction may be determined without being divided into long wavelength side and short wavelength side. That is, the wavelengths corresponding to any half of the ports of the first multiplexer / demultiplexer 31 may be selected as the upstream wavelengths, and the wavelengths corresponding to the remaining half of the ports may be selected as the downstream wavelengths. In this case, the upstream and downstream optical signals may be multiplexed / demultiplexed by the same multiplexer / demultiplexer, or may be multiplexed / demultiplexed by different multiplexer / demultiplexers. In this case, the control device 33C also assigns the wavelengths of the upstream signal and the downstream signal to be reversed between the opposing service devices 50. The control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the upstream input port 34UI of the up-down separator 34 to the upstream port 33U of the optical switch 33 connected to the downstream port of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 corresponding to the wavelength assigned to the downstream signal of the service device 50 connected to the up-down separator 34. The control device 33C controls the connection between the upstream output port 34UO of the upstream / downstream separator 34 and a downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 corresponding to the wavelength assigned to the upstream signal of the service device 50 connected to the upstream / downstream separator 34 via 33U and 33D.

[0044] As in the first embodiment, the optical gateway device 30 according to the second modification can prevent interference caused by reflection between upstream and downstream signals by making the wavelengths of optical signals transmitted in both directions over a single core in the service device 50 different in the upstream and downstream directions. Moreover, the optical gateway device 30 according to the second modification can improve wavelength utilization efficiency by using the same wavelength components in each transmission path of the core network 10.

[0045] In this case, the control device 33C sets the wavelengths and routes so as to satisfy all of the following four conditions. The first condition is that different wavelengths are assigned to the upstream signal and downstream signal of one service device 50. The second condition is that the wavelengths of the upstream signal passing through the same transmission path in the core network 10 are different for each service device 50. The third condition is that the wavelengths of the downstream signal passing through the same transmission path in the core network 10 are different for each service device 50. The fourth condition is that the wavelengths of the first wavelength group are assigned to one of the upstream signal and downstream signal of one service device 50, and the wavelengths of the second wavelength group are assigned to the other.

[0046] As another modification, the wavelengths used for the upstream and downstream in the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 may be the same. For example, the optical gateway device 30 may be configured as follows. In both the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32, an upstream signal is input to half of the ports on the short wavelength side of the separation side ports, and a downstream signal is output from half of the ports on the long wavelength side. In both the up and down separators 34, the upstream port on the short wavelength side is the upstream output port 34UO, and the upstream port on the long wavelength side is the upstream input port 34UI. In this case, each up and down separator 34 may be connected to the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32. In this case, the control device 33C controls the route so that one of the two service devices 50 to which the same wavelength is assigned is connected to the first multiplexer / demultiplexer 31 and the other is connected to the second multiplexer / demultiplexer 32. When the first fiber 11 and the second fiber 12 are used for single-core bidirectional transmission as in this modification, the transmission path between the optical gateway devices 30 is not a unidirectional transmission path. Therefore, the configuration of this modification is suitable for communication in which the optical gateway devices 30 face each other on the same transmission path.

[0047] In the second modification, when the output of the optical gateway device 30 is single-core bidirectional transmission and the core network 10 performs single-core unidirectional transmission, two circulators 71 and 72, a splitter 73, and a coupler 74 are provided at the upstream end of the optical gateway device 30, so that the optical gateway device 30 can be connected to the core network 10 performing single-core unidirectional transmission. FIG. 6 is a diagram showing a configuration for connecting the optical gateway device 30 of the second modification according to the first embodiment to the core network 10 performing single-core unidirectional transmission. Specifically, it is as follows. The circulator 71 connected to the upstream port 31U of the first multiplexer / demultiplexer 31 separates the signal passing through the upstream port 31U into an uplink signal and a downlink signal. The circulator 72 connected to the upstream port 32U of the second multiplexer / demultiplexer 32 separates the signal passing through the upstream port 32U into an uplink signal and a downlink signal. A splitter 73 connected to the first fiber 11 separates the downstream signal transmitted from the first fiber into two wavelength groups and distributes them to the circulators 71 and 72. A coupler 74 connected to the second fiber 12 combines the upstream signals of each service device 50 transmitted from the circulators 71 and 72, and transmits the combined signals to the second fiber 12.

[0048] The circulators 71 and 72, the splitter 73, and the coupler 74 may be included in the optical gateway device 30. From the viewpoint of loss, a low-loss filter that divides the first wavelength group and the second wavelength group into two may be used as the coupler, instead of an AWG or an MZ filter. Also, instead of the circulators 71 and 72, an MZ filter with a ring resonator that has a steeper change in transmission and blocking characteristics, or a WDM (Wavelength Division Multiplexing) filter that divides the wavelengths to be used into two may be used. For example, when the first wavelength group and the second wavelength group are divided into two at the [N / 2]th wavelength in the optical gateway device 30, a WDM filter that switches between transmission and reflection between the [N / 2]th wavelength and [N / 2+1] may be used instead of the circulators 71 and 72. Furthermore, for example, when the first wavelength group and the second wavelength group are switched every predetermined number of wavelengths in the optical gateway device 30, MZ filters can be used instead of the circulators 71 and 72.

[0049] According to the second embodiment, it is possible to add an AWG on demand, and it is possible to achieve the effect of unifying the AWG type. When adding an AWG on demand, the control device 33C of the optical gateway device 30 allows the use of multiple routes in the same direction for one service device 50, and the use of the same wavelength for each route. For example, the control device 33C may assign the first and second wavelengths to the upstream signal of one service device 50, and the third and fourth wavelengths to the downstream signal. In addition, the control device 33C allows signals of the same wavelength to be assigned to different service devices 50 when an AWG is added. This allows the optical gateway device 30 to realize the addition of an AWG on demand. Specifically, a multiplexer / demultiplexer of the same type as the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 is added according to an increase in the service devices 50 to be connected. Then, the upstream port of the added multiplexer / demultiplexer is combined with the upstream port of first multiplexer / demultiplexer 31 or second multiplexer / demultiplexer 32 to connect the added multiplexer / demultiplexer to core network 10 .

[0050] In the configuration of the second modification, the positions of the up-down separators 34 may be different as in the first modification. That is, the optical gateway device 30 may have the following configuration. Half of the multiple up-down separators 34 have their upstream input ports 34UI connected to the downstream ports 31D of the first multiplexer / demultiplexer 31 corresponding to the first wavelength group, and their upstream output ports 34UO connected to the downstream ports 31D of the first multiplexer / demultiplexer 31 corresponding to the second wavelength group. The remaining half of the multiple up-down separators 34 have their upstream input ports 34UI connected to the downstream ports 32D of the second multiplexer / demultiplexer 32 corresponding to the second wavelength group, and their upstream output ports 34UO connected to the downstream ports 32D of the second multiplexer / demultiplexer 32 corresponding to the first wavelength group.

[0051] A wavelength filter according to the wavelength setting may be used as the upstream / downstream separator 34. For example, among signals of N wavelengths, optical signals related to the first to [N / 2]th wavelengths (first wavelength group, i.e., short wavelength side) are directed downstream, and optical signals related to the [N / 2+1]th to second [N / 2]th wavelengths (second wavelength group, i.e., long wavelength side) are directed upstream.

[0052] In this case, each of the upstream and downstream separators 34 can be configured by a wavelength filter that separates an optical signal into a component of the first wavelength group and a component of the second wavelength group. The control device 33C controls the optical switch 33 so as to connect the upstream port 33U of the optical switch 33 connected to the downstream port 34D of the upstream and downstream separator 34 with the downstream port 33D of the optical switch 33. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream input port 34UI of the upstream and downstream separator 34 to a downstream signal of the service device 50 connected to the upstream and downstream separator 34. The control device 33C assigns a wavelength corresponding to the downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32 connected to the upstream output port 34UO of the upstream and downstream separator 34 to an upstream signal of the service device 50 connected to the upstream and downstream separator 34.

[0053] The first to [N / 2]th wavelengths may be on the long wavelength side, and the [N / 2+1]th to [N / 2]th wavelengths may be on the short wavelength side. In this case, the control device 33C assigns the wavelengths of the upstream signal and the downstream signal to the opposing service devices 50 so that they are reversed.

[0054] Moreover, a periodic filter such as an MZ filter may be used as the up / down separator 34. The upstream input port 34UI of the up / down separator 34 is connected to a downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32, which has a wavelength corresponding to the passing wavelength of the upstream input port 34UI. The upstream output port 34UO of the up / down separator 34 is connected to a downstream port of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32, which has a wavelength corresponding to the passing wavelength of the upstream output port 34UO. In this case, the control device 33C assigns, as the wavelengths of the upstream signal and the downstream signal of each service device 50, a wavelength corresponding to the downstream port of the multiplexer / demultiplexer connected to the upstream input port 34UI of one up / down separator 34 and a wavelength corresponding to the downstream port of the multiplexer / demultiplexer connected to the upstream output port 34UO. Then, the control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the service device 50 to the upstream port 33U of the optical switch connected to the upstream and downstream separator 34 corresponding to the wavelength assigned to the service device 50.

[0055] Alternatively, a circulator may be used as the up-down separator 34. In this case, the upstream input port 34UI and the upstream output port 34UO of the up-down separator 34 are connected to different downstream ports 32D of the first multiplexer / demultiplexer 31 or the second multiplexer / demultiplexer 32. In this case, the control device 33C assigns, as the wavelengths of the upstream signal and the downstream signal of each service device 50, a wavelength corresponding to the downstream port of the multiplexer / demultiplexer connected to the upstream input port 34UI of one up-down separator 34 and a wavelength corresponding to the downstream port of the multiplexer / demultiplexer connected to the upstream output port 34UO. The control device 33C controls the optical switch 33 to connect the downstream port 33D of the optical switch 33 connected to the service device 50 and the upstream port 33U of the optical switch connected to the up-down separator 34 corresponding to the wavelength assigned to the service device 50.

[0056] In this case, the control device 33C sets the wavelength and the route so as to satisfy all of the following six conditions. The first condition is that different wavelengths are assigned to the upstream signal and the downstream signal of one service device 50. The second condition is that the wavelengths of the upstream signal passing through the same transmission path in the core network 10 are different for each service device 50. The third condition is that the wavelengths of the downstream signal passing through the same transmission path in the core network 10 are different for each service device 50. The fourth condition is that a combination of the wavelengths of the optical signals passing through one multiplexer / demultiplexer 31, 32 is assigned to the upstream signal and the downstream signal of one service device 50. The fifth condition is that a wavelength corresponding to the port of the multiplexer / demultiplexer 31, 32 connected to the upstream output port 34UO of the up / down separator 34 connected to the service device 50 is assigned to the upstream signal of the service device 50. The sixth condition is that the downstream signal of the service device 50 is assigned a wavelength corresponding to the ports of the multiplexers / demultiplexers 31 and 32 connected to the upstream input port 34UI of the upstream / downstream separator 34 connected to the service device 50.

[0057] In the second modification, the optical gateway device 30 in which the position of the up / down separator 34 is the same as that in the first modification can also be connected to the core network 10 performing single-core unidirectional transmission by providing two circulators 71 and 72, a splitter 73, and a coupler 74 as shown in Fig. 6. The circulator 71 is connected to the upstream port 31U of the first multiplexer / demultiplexer 31. The circulator 72 is connected to the upstream port 32U of the second multiplexer / demultiplexer 32. The splitter 73 is provided between the first fiber 11 and the two circulators 71 and 72. The coupler 74 is provided between the second fiber 12 and the two circulators 71 and 72.

[0058] Third Modification In the optical gateway device 30 according to the first embodiment, the optical fiber connected to the downstream side performs single-core bidirectional transmission, but is not limited to this. For example, the optical gateway device 30 according to another embodiment may perform single-core unidirectional transmission using an optical fiber for an upstream signal and an optical fiber for a downstream signal with the service device 50. Fig. 7 is a diagram showing the configuration of the optical gateway device 30 according to the third modification of the first embodiment.

[0059] When the optical fiber connected to the downstream side performs single-core unidirectional transmission, the optical gateway device 30 according to the third modification of the first embodiment does not need to include the up / down separator 34. As in the first embodiment, the optical gateway device 30 according to the third modification can allocate all N wavelengths to upstream and downstream signals while preventing interference between upstream and downstream signals of the same wavelength caused by wavelength reflection.

[0060] The control device 33C sets the wavelengths and routes so as to satisfy all of the following three conditions. The first condition is that different wavelengths are assigned to the upstream signal and the downstream signal of one service device 50. The second condition is that the wavelengths of the upstream signals passing through the same transmission path in the core network 10 are different for each service device 50. The third condition is that the wavelengths of the downstream signals passing through the same transmission path in the core network 10 are different for each service device 50.

[0061] Second embodiment The first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 according to the first embodiment are composed of AWGs. Some AWGs have wavelength cyclicity. The optical gateway device 30 according to the second embodiment realizes transmission of multiplexing and demultiplexing signals transmitted in one fiber in both directions at different wavelengths with a simpler configuration than that of the first embodiment by using AWGs having wavelength cyclicity as the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32. Note that, instead of the AWGs having wavelength cyclicity, the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 may be a combination of an optical multiplexer / demultiplexer or the like and an MZ filter with a ring resonator or a WDM filter having a sufficiently wide transmission band and a sharp change in transmission and blocking characteristics. For example, the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 may include a plurality of MZ filters whose phases are shifted so that the connection of the upstream wavelength and the downstream wavelength is inverted, and an optical multiplexer / demultiplexer connected to the upstream port of each MZ filter. Furthermore, for example, the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 may each include a plurality of WDM filters having different reflection wavelength ranges, and an optical multiplexer / demultiplexer connected to the upstream port of each WDM filter.

[0062] 8 is a schematic block diagram showing the configuration of an optical gateway device 30 according to the second embodiment. The optical gateway device 30 according to the second embodiment includes a first multiplexer / demultiplexer 31, a second multiplexer / demultiplexer 32, an optical switch 33, a first coupler 35, a second coupler 36, a first circulator 37, and a second circulator 38. The first coupler 35 and the second coupler 36 are formed of an AWG or a WDM filter, and perform wavelength-selective multiplexing / demultiplexing.

[0063] The first coupler 35 has one first port and two second ports. The first port is connected to the first fiber 11, and the second port is connected to the first circulator 37 and the second circulator 38. The first coupler 35 separates the multiplexed signal input from the first fiber 11 into signals of the first wavelength group and signals of the second wavelength group. The first coupler 35 outputs the signals of the first wavelength group to the first circulator 37, and outputs the signals of the second wavelength group to the second circulator 38.

[0064] The second coupler 36 has one first port and two second ports. The first port is connected to the second fiber 12, and the second port is connected to the first circulator 37 and the second circulator 38. The second coupler 36 multiplexes the signal of the second wavelength group input from the first circulator 37 and the signal of the first wavelength group input from the second circulator 38. The second coupler 36 outputs the multiplexed signal to the second fiber 12.

[0065] The first circulator 37 is connected to the upstream port 31U of the first multiplexer / demultiplexer 31, the first coupler 35, and the second coupler 36. The first circulator 37 outputs the signal input from the first coupler 35 to the upstream port 31U of the first multiplexer / demultiplexer 31. The first circulator 37 outputs the signal input from the upstream port 31U of the first multiplexer / demultiplexer 31 to the second coupler 36.

[0066] The second circulator 38 is connected to the upstream port 32U of the second multiplexer / demultiplexer 32, the first coupler 35, and the second coupler 36. The second circulator 38 outputs the signal input from the first coupler 35 to the upstream port 32U of the second multiplexer / demultiplexer 32. The second circulator 38 outputs the signal input from the upstream port 32U of the second multiplexer / demultiplexer 32 to the second coupler 36.

[0067] The first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 according to the second embodiment are configured with AWGs having wavelength cyclicity with a periodicity of M. The periodicity M that can realize bidirectional transmission using the same wavelength is 2 or more and [N / 2] or less. The periodicity M of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 according to the second embodiment is 2. In this case, the number of wavelengths per period is [N / 2].

[0068] The first multiplexer / demultiplexer 31 has one upstream port 31U and M downstream ports 31D. The upstream port 31U is connected to the first circulator 37. The M downstream ports 31D are connected to corresponding upstream ports 33U of the optical switch 33. The first multiplexer / demultiplexer 31 separates the multiplexed signal input to the upstream port 31U into M optical signal groups, and outputs the M optical signal groups from the corresponding downstream ports 31D.

[0069] The second multiplexer / demultiplexer 32 has one upstream port 32U and [N / M] downstream ports 32D. The upstream port 32U is connected to a second circulator 38. The M downstream ports 32D are connected to corresponding upstream ports 33U of the optical switch 33. The second multiplexer / demultiplexer 32 multiplexes the optical signals input to the [N / M] downstream ports 32D, and outputs the multiplexed signal from the upstream port 32U.

[0070] Here, if the wavelength group consisting of the 1st to [N / 2]th wavelengths from the shortest wavelength side among the N wavelengths is defined as the first wavelength group, and the wavelength group consisting of [N / 2+1]th to 2[N / 2]th wavelengths is defined as the second wavelength group, then in each downstream port 31D of the first multiplexer / demultiplexer 31 and each downstream port 32D of the second multiplexer / demultiplexer 32, the multiple wavelengths in a circular relationship include wavelengths belonging to the first wavelength group and wavelengths belonging to the second wavelength group.

[0071] The optical switch 33 includes at least 2[N / M] upstream ports 33U, a plurality of downstream ports 33D, and a control device 33C. The downstream port 33D is connected to the third fiber 51. The optical switch 33 transmits an optical signal input to the upstream port 33U to one of the plurality of downstream ports 33D. The optical switch 33 also transmits an optical signal input to the downstream port 33D to the upstream port 33U corresponding to the wavelength. The correspondence between the upstream port 33U and the downstream port 33D in the optical switch 33 is determined according to a control signal by the control device 33C. The control device 33C assigns the wavelengths of the first wavelength group and the wavelengths of the second wavelength group, which are in a circular relationship, to the upstream signal and the downstream signal of the third fiber 51. As a result, the downstream signal of the first wavelength, which is a wavelength of the first wavelength group, and the upstream signal of the second wavelength, which is in a circular relationship with the first wavelength, pass through one downstream port 31D of the first multiplexer / demultiplexer 31. Similarly, an upstream signal with a first wavelength and a downstream signal with a second wavelength pass through one downstream port 32D of the second multiplexer / demultiplexer 32.

[0072] The control device 33C sets the wavelengths and routes so as to satisfy all of the following four conditions. The first condition is that different wavelengths in a circular relationship are assigned to the upstream signal and downstream signal of one service device 50. The second condition is that the wavelength of one of the upstream signal and the downstream signal belongs to a first wavelength group, and the other wavelength belongs to a second wavelength group. The third condition is that the wavelengths of the upstream signal passing through the same transmission path in the core network 10 are different for each service device 50. The fourth condition is that the wavelengths of the downstream signal passing through the same transmission path in the core network 10 are different for each service device 50.

[0073] Actions and Effects In this way, in the optical gateway device 30 according to the second embodiment, the first multiplexer / demultiplexer 31 processes the downstream signal of the first wavelength group and the upstream signal of the second wavelength group, and the second multiplexer / demultiplexer 32 processes the downstream signal of the second wavelength group and the upstream signal of the first wavelength group. That is, in the optical gateway device 30, the direction in which the wavelength component of the first wavelength of the optical signal passing through the upstream port 31U of the first multiplexer / demultiplexer 31 advances is opposite to the direction in which the wavelength component of the first wavelength of the optical signal passing through the upstream port 32U of the second multiplexer / demultiplexer 32 advances. Also, the first wavelength group and the second wavelength group are in a circulating relationship with each other in the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32. As a result, the optical gateway device 30 can prevent interference due to reflection between the upstream signal and the downstream signal by making the wavelengths of the optical signal transmitted in both directions of a single core in the service device 50 different in the upstream direction and the downstream direction. Furthermore, the optical gateway device 30 can improve wavelength utilization efficiency by using the same wavelength components in each transmission path of the core network 10. Furthermore, the optical gateway device 30 according to the second embodiment can reduce the number of ports of the first multiplexer / demultiplexer 31, the second multiplexer / demultiplexer 32, and the optical switch 33.

[0074] In the second embodiment, an example has been described in which the periodic number M of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 is 2. However, in other embodiments, the periodic number M does not have to be 2 as long as it is greater than or equal to 2 and less than or equal to [N / 2]. For example, by setting the number of periods M to 4 or more, that is, by setting one port to 4 or more, the degree of freedom and the expandability of the optical gateway device 30 can be improved. For example, if the number of wavelengths N is 80 and the number of periods M is 4, when 40 wavelengths are used at the introduction stage of the optical gateway device 30 and the remaining 40 wavelengths are added at the time of expansion to use 80 wavelengths, the same as the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 can be used as the multiplexer / demultiplexer to be expanded. When expanding, the first coupler 35 and the second coupler 36 are replaced with AWGs or filters that divide the wavelength into four. Also, optical couplers may be installed between the first coupler 35 and the second coupler 36 and each circulator, and the upstream and downstream may be split and each may be connected to a circulator. Also, a component that splits and splits may be installed between the circulator and the multiplexer / demultiplexer. Furthermore, the control device 33C can realize on-demand AWG expansion by allowing the use of multiple routes in the same direction to one service device 50, the use of the same wavelength on each route, and assignment of signals of the same wavelength to different service devices 50.

[0075] Another advantage is that the AWG type can be unified. When an AWG is added on demand, the control device 33C of the optical gateway device 30 allows the use of multiple routes in the same direction for one service device 50, and the use of the same wavelength for each route. For example, the control device 33C may assign the first and second wavelengths to the upstream signal of one service device 50, and the third and fourth wavelengths to the downstream signal. Furthermore, when an AWG is added, the control device 33C allows signals of the same wavelength to be assigned to different service devices 50. This allows the optical gateway device 30 to realize the addition of an AWG on demand. Specifically, a multiplexer / demultiplexer of the same type as the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 is added according to an increase in the service devices 50 to be connected. The added multiplexer / demultiplexer is connected to core network 10 by combining / branching the upstream port of the added multiplexer / demultiplexer with the upstream port of first multiplexer / demultiplexer 31 or second multiplexer / demultiplexer 32. Addition in this manner is possible up to the number of AWGs [N / (2m)].

[0076] First Modified Example In the optical gateway device 30 according to the second embodiment, the optical fiber connected to the upstream side performs single-core unidirectional transmission, but is not limited to this. For example, the optical fiber connected to the upstream side of the optical gateway device 30 according to another embodiment may perform single-core bidirectional transmission. FIG. 9 is a diagram showing the configuration of the optical gateway device 30 according to a first modification of the second embodiment. In the first fiber 11 of the core network 10 according to the first modification of the second embodiment, the optical signal related to the first wavelength group travels downstream, and the optical signal related to the second wavelength group travels upstream. In addition, in the second fiber 12 of the core network 10 according to the first modification of the second embodiment, the optical signal related to the first wavelength group travels upstream, and the optical signal related to the second wavelength group travels downstream. In this case, the optical gateway device 30 does not need to include the first coupler 35, the second coupler 36, the first circulator 37, and the second circulator 38. In other words, by connecting the upstream port 31U of the first multiplexer / demultiplexer 31 to the first fiber 11 and connecting the upstream port 32U of the second multiplexer / demultiplexer 32 to the second fiber 12, it is possible to support the core network 10 related to single-core bidirectional transmission.

[0077] Second Modified Example In the optical gateway device 30 according to the second embodiment, the optical fiber connected to the downstream side performs single-core bidirectional transmission, but is not limited to this. For example, the optical fiber connected to the downstream side of the optical gateway device 30 according to another embodiment may perform single-core unidirectional transmission. Fig. 10 is a diagram showing the configuration of the optical gateway device 30 according to a second modification of the second embodiment. When the optical fiber connected to the downstream side performs single-core unidirectional transmission, the optical gateway device 30 according to the second modification of the second embodiment includes N up-down separators 39 on the downstream side of the optical switch 33. The up-down separator 39 includes an upstream port 39U, a downstream input port 39DI, and a downstream output port 39DO. The upstream port 39U is connected to the optical switch 33. The downstream input port 39DI and the downstream output port 39DO are connected to the service device 50. The up-down separator 39 outputs an optical signal input to the downstream input port 39DI from the upstream port 39U. The up-down separator 39 outputs an optical signal input to the upstream port 39U from the downstream output port 39DO. The up-down separator 39 may be configured, for example, by an optical circulator. The up-down separator 39 may be configured, for example, by a wavelength multiplexing / demultiplexing module.

[0078] Third Modification The optical gateway device 30 according to the second embodiment includes a first circulator 37 and a second circulator 38 connected to a first coupler 35 and a second coupler 36, but is not limited to this. For example, the optical gateway device 30 according to another embodiment may include a third coupler 40 and a fourth coupler 41 instead of the first circulator 37 and the second circulator 38. Fig. 11 is a diagram showing a configuration of an optical gateway device 30 according to a third modification of the second embodiment.

[0079] The third coupler 40 according to the third modified example of the second embodiment transmits the signals of the first wavelength group input from the first coupler 35 to the upstream port 32U of the second multiplexer / demultiplexer 32. The third coupler 40 also transmits the signals of the second wavelength group, among the signals input from the upstream port 32U of the second multiplexer / demultiplexer 32, to the second coupler 36.

[0080] The fourth coupler 41 according to the third modified example of the second embodiment transmits the signal of the second wavelength group input from the first coupler 35 to the upstream port 32U of the second multiplexer / demultiplexer 32. The fourth coupler 41 also transmits the signal of the first wavelength group, among the signals input from the upstream port 32U of the second multiplexer / demultiplexer 32, to the second coupler 36.

[0081] Fourth Variation The optical gateway device 30 according to the second embodiment includes two multiplexers 31 and 32 with a periodicity M of [N / 2], but the periodicity M of the multiplexers and demultiplexers according to other embodiments is not limited to this and may be less than [N / 2].

[0082] FIG. 12 is a diagram showing a configuration of an optical gateway device 30 according to a fourth modification of the second embodiment. The optical gateway device 30 according to the fourth modification of the second embodiment includes four multiplexers / demultiplexers 31A, 31B, 32A, and 32B with a periodicity M of [N / 4], and two couplers 31C and 32C. The upstream port of the multiplexer / demultiplexer 31A and the upstream port of the multiplexer / demultiplexer 31B are connected to the downstream port of the coupler 31C. All of the multiplexers / demultiplexers 31A, 31B, 32A, and 32B have wavelength cyclicity. The first circulator 37 is connected to the upstream port of the coupler 31C. The upstream port of the multiplexer / demultiplexer 32A and the upstream port of the multiplexer / demultiplexer 32B are connected to the downstream port of the coupler 32C. The second circulator 38 is connected to the upstream port of the coupler 32C.

[0083] FIG. 13 is a diagram showing the relationship between a multiplexer / demultiplexer according to a fourth modified example of the second embodiment and wavelengths. For example, when the number of wavelengths N is 16, the periodicity M of each multiplexer / demultiplexer is 4. If the 16 wavelengths are referred to as the first wavelength to the 16th wavelength in order from the shortest, the following cyclicity holds: At the first downstream port of each multiplexer / demultiplexer, the first wavelength, the fifth wavelength, the ninth wavelength, and the thirteenth wavelength have cyclicity with each other. At the second downstream port of each multiplexer / demultiplexer, the second wavelength, the sixth wavelength, the tenth wavelength, and the fourteenth wavelength have cyclicity with each other. At the third downstream port of each multiplexer / demultiplexer, the third wavelength, the seventh wavelength, the eleventh wavelength, and the fifteenth wavelength have cyclicity with each other. At the fourth downstream port of each multiplexer / demultiplexer, the fourth wavelength, the eighth wavelength, the twelfth wavelength, and the sixteenth wavelength have cyclicity with each other.

[0084] As shown in Fig. 13, the control device 33C assigns wavelengths to the upstream and downstream signals, which are offset from each other by 2M (=[N / 2]), to each downstream port of each multiplexer / demultiplexer. The control device 33C assigns wavelengths so that they do not overlap between multiplexer / demultiplexer 31A and multiplexer / demultiplexer 31B. Specifically, the control device 33C assigns the first wavelength to the [N / 4]th wavelength to the downstream signal of multiplexer / demultiplexer 31A, and the [1+N / 4]th wavelength to the [N / 2]th wavelength to the downstream signal of multiplexer / demultiplexer 31B. The control device 33C also assigns wavelengths so that they do not overlap between multiplexer / demultiplexer 32A and multiplexer / demultiplexer 32B. Specifically, control device 33C assigns the [1+N / 2]th wavelength to the [3N / 4]th wavelength to the downstream signal of multiplexer / demultiplexer 32A, and assigns the [1+3N / 4]th wavelength to the Nth wavelength to the downstream signal of multiplexer / demultiplexer 32B.

[0085] In this case, the couplers 31C and 32C switch the input / output ports every [N / 4] period. For example, the couplers 31C and 32C according to the fourth modification of the second embodiment are configured by an MZ filter, an MZ filter with a ring resonator, or the like.

[0086] As a result, the optical gateway device 30 according to the fourth variant of the second embodiment can make the wavelengths of the optical signal transmitted in both directions over a single core in the service device 50 different in the upstream and downstream directions, and can utilize the same wavelength components in each transmission path of the core network 10.

[0087] Fifth Modification An optical gateway device 30 according to a fifth modification of the second embodiment has a similar configuration to that of the fourth modification, but the wavelengths assigned to the ports of each multiplexer / demultiplexer are different. Fig. 14 is a diagram showing the relationship between multiplexers / demultiplexers and wavelengths according to the fifth modification of the second embodiment. As shown in Fig. 14, the control device 33C assigns wavelengths to the upstream and downstream signals, which are offset by M (=[N / 4]) from each other, to each downstream port of each multiplexer / demultiplexer. The control device 33C assigns wavelengths so that they do not overlap between multiplexer / demultiplexer 31A and multiplexer / demultiplexer 31B. Specifically, the control device 33C assigns the first wavelength to the [N / 4]th wavelength to the downstream signal of multiplexer / demultiplexer 31A, and the [1+N / 2]th wavelength to the [3N / 4]th wavelength to the downstream signal of multiplexer / demultiplexer 31B. The control device 33C also assigns wavelengths so that they do not overlap between multiplexer / demultiplexer 32A and multiplexer / demultiplexer 32B. Specifically, control device 33C assigns the [1+N / 4]th wavelength to the [N / 2]th wavelength to the downstream signal of multiplexer / demultiplexer 32A, and assigns the [1+3N / 4]th wavelength to the Nth wavelength to the downstream signal of multiplexer / demultiplexer 32B.

[0088] In this case, the couplers 31C and 32C switch the input / output ports between a wavelength group of [N / 2] or more wavelengths and a wavelength group of less than [N / 2] wavelengths. For example, the couplers 31C and 32C according to the fifth modification of the second embodiment are configured by WDM filters.

[0089] On the other hand, the first coupler 35 and the second coupler 36 switch the input / output ports every [N / 4] period. For example, the first coupler 35 and the second coupler 36 according to the fifth modified example of the second embodiment are configured with an MZ filter, an MZ filter with a ring resonator, or the like.

[0090] Sixth Variation The optical gateway 30 according to the fourth and fifth modified examples of the second embodiment transmits optical signals to the service device 50 in a single-core unidirectional manner. In contrast, the optical gateway 30 according to the sixth modified example transmits optical signals to the service device 50 in a single-core bidirectional manner. FIG. 15 is a diagram showing the configuration of an optical gateway according to the sixth modified example of the second embodiment. In the optical gateway 30 according to the sixth modified example, the service device 50 is connected to the downstream port 33D of the optical switch 33 without the upstream / downstream separator 39. That is, the optical gateway 30 according to the sixth modified example of the second embodiment does not need to include the upstream / downstream separator 39.

[0091] Other Embodiments Although one embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design modifications and the like are possible.

[0092] The first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 according to the above-described embodiment are configured by AWGs, but are not limited to this. For example, the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 according to other embodiments may be realized by an MZ filter or may use a WSS (Wavelength Selective Switch).

[0093] In addition, WSS is usually used for multiplexing or branching in single-core unidirectional transmission, and cannot transmit single-core bidirectional transmission as it is, but handles it after splitting optical signals into up and down unidirectional signals. This is because some WSSs do not have wavelength selectivity and may mix wavelengths other than the intended wavelengths into the ports. Therefore, if one WSS is used instead of the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32, there is a possibility that the upstream signal will be conducted as it is even if it contains wavelengths other than the intended wavelengths, and there is a possibility that signals addressed to other service devices 50 will be mixed into the downstream signal. In some configurations, only one wavelength is selected. For example, the WSS module includes a wavelength multiplexer / demultiplexer 1 provided corresponding to a port that inputs and outputs wavelength-multiplexed optical signals, multiple wavelength multiplexers / demultiplexers 2 provided corresponding to each port on the splitting side, and an optical switch that connects the port of each wavelength on the splitting side of the wavelength multiplexer / demultiplexer 1 to one of the multiple wavelength multiplexers / demultiplexers 2. Therefore, it is not possible to transmit different wavelengths in the up and down directions. Therefore, when using this type of WSS, it is necessary to create a new WSS that differs from general WSSs by using a cyclic AWG as a wavelength multiplexer / demultiplexer, and to assign appropriate wavelengths and routes to the service device 50 in the optical switch 33.

[0094] In another embodiment, the optical switch 33 may be realized by using a multicast switch that realizes a transponder aggregator, or may be realized by using a WSS module. In the multicast switch that realizes a transponder aggregator, the optical switch 33 includes, for example, L couplers corresponding to the upstream port 33U and N switches corresponding to the downstream port 33D. The coupler includes one first port and N second ports. The switch includes one first port and L second ports. The second ports of each coupler and the second ports of each switch are fully connected to each other. That is, the optical switch 33 has L×N ports. However, in this configuration, since the optical signals are multiplexed and split by the couplers, there is a possibility that wavelengths other than the target may be conducted for the upstream signal, and wavelengths other than the target are blocked by the filter for the downstream signal. For this reason, if the optical switch 33 is configured on the upstream side, there is a possibility that wavelengths other than the target may be conducted. On the other hand, if the optical switch 33 is configured on the downstream side, only wavelengths previously set by the filter can be passed. Therefore, in order to make a multicast switch compatible with both directions over a single core, it is necessary to create a new multicast switch equipped with a filter that can select and transmit multiple wavelengths for the upstream and downstream directions using a cyclic AWG or the like, and to assign the upstream and downstream wavelengths in the same way as in the configuration using a cyclic AWG or the like of the present application.

[0095] Further, although the optical switch 33 according to the embodiment described above is an example configured with an optical switch such as an FXC switch, the present invention is not limited to this and may be configured with an optical switch of another configuration. The first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32 in the above-described embodiment handle signals in the same wavelength range, but are not limited to this. For example, in another embodiment, the first multiplexer / demultiplexer 31 may handle signals with wavelengths from λ1 to λ10, and the second multiplexer / demultiplexer 32 may handle signals with wavelengths from λ6 to λ15. In this case, the wavelength components at least related to wavelengths λ6 to λ10 travel in opposite directions in the first multiplexer / demultiplexer 31 and the second multiplexer / demultiplexer 32. Even with such a configuration, it is possible to achieve the effect of enabling both upstream and downstream conduction using the same wavelength for at least some wavelengths. [Explanation of symbols]

[0096] REFERENCE SIGNS LIST 1...optical network 10...core network 11...first fiber 12...second fiber 30...optical gateway device 31...first multiplexer / demultiplexer 32...second multiplexer / demultiplexer 33...optical switch 33C...control device 34...upper / lower separator 35...first coupler 36...second coupler 37...first circulator 38...second circulator 39...upper / lower separator 50...service device 51...third fiber

Claims

1. a first multiplexer / demultiplexer including a first port and a plurality of second ports, which demultiplexes an optical signal inputted from the first port and outputs the demultiplexed optical signal from the plurality of second ports, and multiplexes the optical signals inputted from the plurality of second ports and outputs the multiplexed optical signal from the first port; a second multiplexer / demultiplexer including a third port and a plurality of fourth ports, which demultiplexes an optical signal inputted from the third port and outputs the demultiplexed optical signal from the plurality of fourth ports, and multiplexes the optical signals inputted from the plurality of fourth ports and outputs the multiplexed optical signals from the third port; an optical switch including a plurality of fifth ports and a plurality of sixth ports, the second port and the fourth port being connected to the fifth ports, and the fifth ports being connected only to the sixth ports; Equipped with A direction in which a wavelength component having a first wavelength of the optical signal passing through the first port advances is opposite to a direction in which a wavelength component having the first wavelength of the optical signal passing through the third port advances. Optical gateway device.

2. Among the optical signals passing through the first port, wavelength components related to a first wavelength group including the first wavelength travel in a first direction, and the remaining wavelength components related to a second wavelength group travel in a second direction opposite to the first direction, Of the optical signals passing through the third port, the wavelength components related to the first wavelength group travel in the second direction, and the wavelength components related to the second wavelength group travel in the first direction.

2. The optical gateway device according to claim 1.

3. all wavelength components of the optical signal passing through the first port travel in a first direction; All wavelength components of the optical signal passing through the third port travel in a second direction opposite to the first direction.

2. The optical gateway device according to claim 1.

4. the first multiplexer / demultiplexer and the second multiplexer / demultiplexer have wavelength cyclicity; a direction in which a wavelength component of a second wavelength in a circular relationship with the first wavelength of the optical signal passing through the first port advances is opposite to a direction in which a wavelength component of the first wavelength advances; The direction in which the wavelength component of the second wavelength of the optical signal passing through the third port advances is opposite to the direction in which the wavelength component of the first wavelength advances.

4. An optical gateway device according to claim 1.

5. a plurality of up / down separators including a seventh port, an eighth port and a ninth port, which output from the eighth port an optical signal traveling in a first direction among the optical signals input from the seventh port, and which output from the seventh port an optical signal traveling in a second direction among the optical signals input from the ninth port; the first multiplexer / demultiplexer and the second multiplexer / demultiplexer do not have wavelength cyclicity, The seventh port of each of the upper and lower separators is connected to the sixth port, respectively, or the second port and the fourth port, respectively.

4. An optical gateway device according to claim 1.

6. a control device for allocating wavelengths to be used for optical signals to service devices connected to the optical gateway device; The control device includes: Assigning different wavelengths to the upstream and downstream signals of the service device 6. An optical gateway device according to claim 1, wherein the optical gateway device comprises:

7. A first multiplexer / demultiplexer comprising a first port and a plurality of second ports, which separates an optical signal input from the first port and outputs the separated optical signal from the plurality of second ports, and which multiplexes the optical signals input from the plurality of second ports and outputs the multiplexed optical signals from the first port; a second multiplexer / demultiplexer including a third port and a plurality of fourth ports, which demultiplexes an optical signal inputted from the third port and outputs the demultiplexed optical signal from the plurality of fourth ports, and multiplexes the optical signals inputted from the plurality of fourth ports and outputs the multiplexed optical signals from the third port; an optical switch including a plurality of fifth ports and a plurality of sixth ports, the second port and the fourth port being connected to the fifth port, and transmitting an optical signal input to the fifth port to the sixth port and transmitting an optical signal input to the sixth port to the fifth port; Equipped with A direction in which a wavelength component having a first wavelength of the optical signal passing through the first port advances is opposite to a direction in which a wavelength component having the first wavelength of the optical signal passing through the third port advances. Optical gateway device.

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