Optical transceiver and setting method

Abstract

This optical transceiver is attachable to a host device, and includes: an optical transmission unit which wavelength-multiplexes a first optical signal, which is a main signal, and a second optical signal, which is a control signal, and transmits the wavelength-multiplexed signals as a first wavelength-multiplexed signal; an optical reception unit which receives a second wavelength-multiplexed signal obtained by wavelength-multiplexing a third optical signal, which is a main signal, and a fourth optical signal, which is a control signal; and a connection unit for connecting to a port of the host device.

Description

Optical Transceiver and Setting Method

[0001] The present disclosure relates to an optical transceiver and a setting method. This application claims priority based on Japanese Patent Application No. 2025-26828 filed on February 21, 2025, and incorporates all of its disclosure herein.

[0002] Patent Document 1 discloses a multi-rate PON (Passive Optical Network) system in which signals with a transmission speed of 1 Gbps class and signals with a transmission speed of 10 Gbps class are mixed. The master station device (multi-rate PON master station device) in the system disclosed in Patent Document 1 includes a 10G optical transceiver that transmits and receives signals (signals with a transmission speed of 10 Gbps class) in a 10G-PON system, and a 1G optical transceiver that transmits and receives signals (signals with a transmission speed of 1 Gbps class) in a 1G-PON system.

[0003] Some optical communication devices (for example, master station devices, slave station devices) used in an optical network including PON are configured by mounting an optical transceiver for transmitting and receiving optical signals on a port provided in a communication device main body (host device). Patent Document 2 discloses an optical transceiver (optical communication module) in which an optical transmission sub-assembly (TOSA: Transmitter Optical Sub-Assembly) and an optical reception sub-assembly (ROSA: Receiver Optical Sub-Assembly) are mounted in a housing.

[0004] Japanese Unexamined Patent Application Publication No. 2010-161568, Japanese Unexamined Patent Application Publication No. 2021-118210

[0005] An optical transceiver according to one aspect of the present disclosure is an optical transceiver that can be attached to a host device, comprising: an optical transmitting unit that wavelength-multiplexes a first optical signal which is a first main signal and a second optical signal which is a first control signal and transmits it as a first wavelength-multiplexed signal; an optical receiving unit that receives a second wavelength-multiplexed signal which is a wavelength-multiplexed signal obtained by wavelength-multiplexing a third optical signal which is a second main signal and a fourth optical signal which is a second control signal; and a connecting unit for connecting to a port of the host device, wherein the optical transmitting unit comprises: a first light-emitting unit that outputs the first optical signal in a first direction; a second light-emitting unit that outputs the second optical signal in a second direction intersecting the first direction; and the first light-emitting unit The optical receiver includes a wavelength multiplexing unit that wavelength-multiplexes the first optical signal input in one direction and the second optical signal input from the second light-emitting unit in the second direction, and outputs the first wavelength-multiplexed signal in the first direction, and the optical receiver includes a separation unit that wavelength-separates the second wavelength-multiplexed signal input in the first direction into a third optical signal and a fourth optical signal, outputs the third optical signal in the first direction and outputs the fourth optical signal in the second direction, a first light-receiving unit that receives the third optical signal output from the separation unit in the first direction, and a second light-receiving unit that receives the fourth optical signal output from the separation unit in the second direction.

[0006] Figure 1 is a diagram showing an example of the configuration of a remote control system according to an embodiment. Figure 2 is a block diagram showing an example of the hardware configuration of an optical transceiver according to an embodiment. Figure 3 is a perspective view showing an example of the internal layout of the housing of an optical transceiver according to an embodiment. Figure 4 is a plan view showing an example of the internal layout of the housing of an optical transceiver according to an embodiment. Figure 5 is a side view showing an example of the schematic configuration of a two-wavelength TOSA. Figure 6 is a side view showing an example of the schematic configuration of a two-wavelength ROSA. Figure 7 is a diagram schematically showing an example of the configuration of a main control board. Figure 8 is a plan view schematically showing an example of the configuration of a sub-control board. Figure 9 is a diagram showing an example of the pin settings of an inter-board connector mounted on the main control board. Figure 10 is a diagram showing an example of the pin settings of an inter-board connector mounted on the sub-control board. Figure 11 is a diagram for explaining the power supply of the main control board and the sub-control board. Figure 12 is a diagram for explaining the FPGA configuration using a setting device. Figure 13 is a flowchart showing an example of the procedure for configuring the FPGA of the sub-control board 370.

[0007] For example, in optical communication equipment used in optical networks where low-speed and high-speed signals coexist, such as multi-rate PON systems, if existing optical transceivers are used, it is necessary to install separate optical transceivers for transmitting and receiving low-speed optical signals and optical transceivers for transmitting and receiving high-speed optical signals on separate ports. Optical communication equipment equipped with two optical transceivers has the problem of being larger overall.

[0008] According to this disclosure, the overall size of the optical communication device can be reduced.

[0009] The embodiments of this disclosure are outlined below.

[0010] (1) The optical transceiver according to this embodiment is an optical transceiver that can be attached to a host device and comprises: an optical transmitting unit that wavelength-multiplexes a first optical signal which is a first main signal and a second optical signal which is a first control signal and transmits it as a first wavelength-multiplexed signal; an optical receiving unit that wavelength-multiplexes a third optical signal which is a second main signal and a fourth optical signal which is a second control signal and receives a second wavelength-multiplexed signal; and a connecting unit for connecting to a port of the host device, wherein the optical transmitting unit comprises: a first light-emitting unit that outputs the first optical signal in a first direction; a second light-emitting unit that outputs the second optical signal in a second direction intersecting the first direction; and the first The optical receiver includes a wavelength multiplexing unit that wavelength-multiplexes the first optical signal input in the first direction and the second optical signal input from the second light-emitting unit in the second direction, and outputs the first wavelength-multiplexed signal in the first direction, and the optical receiver includes a separation unit that wavelength-separates the second wavelength-multiplexed signal input in the first direction into a third optical signal and a fourth optical signal, outputs the third optical signal in the first direction and the fourth optical signal in the second direction, a first light-receiving unit that receives the third optical signal output from the separation unit in the first direction, and a second light-receiving unit that receives the fourth optical signal output from the separation unit in the second direction. By configuring the transmission and reception of the main signal and control signal with a single optical transceiver, the number of ports occupied by the host device can be reduced. There is no need to install an optical transceiver for each main signal and control signal in the host device, and the overall size of the optical communication device can be reduced.

[0011] (2) In the above (1), the optical transceiver may further be provided with a housing defined in the standard form factor, and the optical transmitting unit, the optical receiving unit, and the connection unit may be housed in the housing. This makes it possible to mount the optical transceiver on a host device having a port conforming to the standard form factor.

[0012] (3) In (1) or (2) above, the first optical signal may be faster than the second optical signal, and the third optical signal may be faster than the fourth optical signal. This makes it possible to transmit the main signal faster than the control signal.

[0013] (4) In (2) or (3) above, the optical transmitting unit and the optical receiving unit may be arranged in a third direction intersecting the first direction and the second direction, respectively. This arranges the optical transmitting unit and the optical receiving unit in a third direction, the second light emitting unit is positioned in a second direction relative to the first light emitting unit, and the second light receiving unit is positioned in a second direction relative to the first light receiving unit. Thus, it is possible to prevent the optical transceiver from becoming larger in only the second direction or only in the third direction.

[0014] (5) In (4) above, the optical transceiver further comprises a first control board on which a first control circuit for controlling the first light-emitting unit and the first light-receiving unit is mounted, and a second control board on which a second control circuit for controlling the second light-emitting unit and the second light-receiving unit is mounted, wherein the first control board and the second control board are stacked in the second direction, the first control board includes a first board-to-board connector arranged on the surface facing the second control board, and the second control board may include a second board-to-board connector arranged on the surface facing the first control board and connectable to the first board-to-board connector. This makes it possible to align the arrangement direction of the second light-emitting unit and the second light-receiving unit with respect to the first light-emitting unit and the first light-receiving unit, and the arrangement direction of the second control board with respect to the first control board, thereby reducing the space required for arranging the optical transmitting unit and the optical receiving unit, and the first control board and the second control board. Power or signals can be transmitted between the first control board and the second control board by the first board-to-board connector and the second board-to-board connector, eliminating the need for space for arranging power lines or signal lines.

[0015] (6) In (5) above, the first board connector may include a first pin for first serial communication and a second pin for second serial communication, and the second board connector may include a third pin for first serial communication that can be connected to the first pin and a fourth pin for second serial communication that can be connected to the second pin. This allows signals to be transmitted between the first control board and the second control board by first serial communication and second serial communication.

[0016] (7) In (6) above, in the first serial communication, the first control circuit may be the master and the second control circuit may be the slave, and in the second serial communication, the second control circuit may be the master and the second control circuit may be the slave. This allows the first control circuit to control the second control circuit via the first serial communication, and the second control circuit to control the first control circuit via the second serial communication.

[0017] (8) In any one of (5) to (7) above, the second board connector may include a fifth pin for inputting a reception loss signal indicating that the intensity of the fourth optical signal received by the second light receiving unit is below a predetermined threshold, and a sixth pin for inputting a transmission fault signal indicating that an error has occurred in the second optical signal transmitted by the second light emitting unit, and the first board connector may include a seventh pin for outputting the reception loss signal input to the fifth pin to the first control circuit, and an eighth pin for outputting the transmission fault signal input to the sixth pin to the first control circuit. This makes it possible to quickly notify the first control circuit of any transmission or reception abnormalities in the second optical signal and the fourth optical signal, which are control signals.

[0018] (9) In any one of (5) to (8) above, the first board connector includes a ninth pin for inputting power of the first voltage from the host device via the connection part, the second board connector includes a tenth pin connected to the ninth pin, and the second control board further includes a power conversion unit that converts the power output from the tenth pin from the first voltage to the second voltage. This eliminates the need to provide pins for sending and receiving power of the second voltage in the first board connector and the second board connector, and prevents an increase in the number of pins in the first board connector and the second board connector.

[0019] (10) In any one of (5) to (9) above, the second board connector may include an eleventh pin for inputting setting information of the second control circuit. This allows the second control circuit to be configured from a setting device (hereinafter also referred to as the "external connector") by connecting the second board connector of the second control board to a connector provided on the setting device for configuring the second control circuit, for example, when the second control board is not connected to the first control board, such as during the manufacturing or inspection of an optical transceiver. It is also possible to configure the second control circuit from the first control circuit by providing a pin on the first board connector that is connected to the eleventh pin.

[0020] (11) In any one of (5) to (10) above, the optical transceiver further comprises a flexible substrate connecting the second light-emitting unit and the second light-receiving unit to the second control board, and a heat conduction unit that conducts heat generated from the first light-emitting unit to the housing, wherein the heat conduction unit is superimposed on the first light-emitting unit in the second direction, and the flexible substrate may have a recess to avoid the heat conduction unit. This allows the heat conduction unit and the flexible substrate to be arranged without interfering with each other.

[0021] (12) The setting method according to this embodiment is a setting method for setting a control circuit mounted on the second control board for controlling the second light-emitting unit and the second light-receiving unit, which are mounted on the optical transceiver for transmitting and receiving an optical signal that is a main signal, and a second control board for controlling a second light-emitting unit and a second light-receiving unit, which are mounted on the optical transceiver for transmitting and receiving an optical signal that is a control signal, which can be mounted on the optical transceiver, and the setting method includes the steps of: connecting a second inter-board connector provided on the second control board, which is connectable to a first inter-board connector provided on the first control board, to a third inter-board connector provided on a connecting device; outputting setting information for setting the control circuit from the connecting device to the second inter-board connector through the third inter-board connector; outputting the setting information input to the second inter-board connector to the control circuit; and setting the control circuit using the setting information input to the control circuit. This makes it possible to set the control circuit using a connecting device.

[0022] This disclosure can be achieved not only as an optical transceiver having the characteristic configuration described above and a setting method including characteristic steps, but also as an optical communication device including the optical transceiver, or as part or all of the optical transceiver being a semiconductor integrated circuit.

[0023] <Details of Embodiments of the Disclosure> Details of embodiments of the disclosure will be described below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0024] [1. Remote Control System] Figure 1 is a diagram showing an example of the configuration of a remote control system according to the embodiment. The remote control system 100 shown in Figure 1 is a part of an optical communication system which is an APN (All-Photonics Network). The remote control system 100 includes an optical wavelength division multiplexer 10 and optical transceivers 30A, 30B, and 30C. Each of the optical transceivers 30A, 30B, and 30C is installed in user devices 40A, 40B, and 40C, respectively. Hereinafter, user devices 40A, 40B, and 40C will be collectively referred to as "user device 40," and optical transceivers 30A, 30B, and 30C will be collectively referred to as "optical transceiver 30." Hereinafter, the optical wavelength division multiplexer will also be referred to as "optical wavelength division multiplexer SW."

[0025] The optical transceiver 30 is a pluggable module that can be attached to and detached from the user device 40 (host device). In Figure 1, a pair of optical transceivers 30 and the user device 40 are assigned a common subnumber. For example, optical transceiver 30A is installed in user device 40A, and optical transceiver 30B is installed in user device 40B. In Figure 1, one optical transceiver 30 is installed in one user device 40, but this is not the only configuration. Multiple optical transceivers 30 may be installed in one user device 40.

[0026] The optical transceiver 30 includes an optical transmitter with a tunable transmission wavelength. The transmission wavelength of the optical transmitter is remotely controllable. The configuration of the optical transceiver 30 will be described later.

[0027] Each optical transceiver 30 is assigned a transmission wavelength. The optical transceiver 30 transmits an optical signal (main signal) of the assigned wavelength. For example, optical transceivers 30A, 30B, and 30C are each assigned different wavelengths. The wavelength of the main signal is selected from, for example, the C-band (Conventional-band, a wavelength band from 1530 nm to 1565 nm). Optical transceivers 30 whose transmission signals are not multiplexed may be assigned the same wavelength. The wavelength of the main signal is selected from the wavelength range excluding the wavelength for control signals, which will be described later. The main signal is transmitted in the optical communication system at a transmission speed of 25 Gbps class.

[0028] The user device 40 is located within the user's home or facility. The user device 40 may be, for example, a relay device such as a router for connecting the user's LAN (Local Area Network) to an optical network. For example, the first user device 40 (e.g., user device 40A) may be a RU (Radio Unit) in a mobile fronthaul (MFH), and the second user device (not shown), which is the counterpart device to the first user device, may be a DU (Distributed Unit).

[0029] An optical communication system includes, for example, a metro network connected to a telecommunications carrier's base in a city, and an access network connected to a user's base (user's home or user's facility).

[0030] The optical wavelength division multiplexer (WDM) SW 10 is an optical gateway that connects a metro network (not shown) and an access network 200, and relays optical signals between the metro network and the access network 200. In the metro network, multiple WDM SW 10s are interconnected by multiple optical transmission lines 60A, 60B. The metro network is a two-core transmission network, and the optical transmission lines 60A, 60B are two-core optical transmission lines (the transmission directions of the two cores are opposite to each other). Hereinafter, a two-core optical transmission line will also be referred to as a "two-core transmission line". For example, the metro network is a ring topology network, and one example is a ROADM (Reconfigurable Optical Add / Drop Multiplexer). The configuration of the metro network is not limited to this, and it may also be a mesh topology network.

[0031] The optical wavelength division multiplexer (WDM) SW10 includes multiple ports MP1 and MP2 connected to a metro network (hereinafter also referred to as "metro ports"), and multiple ports AP1, AP2, and AP3 connected to an access network (hereinafter also referred to as "access ports").

[0032] Each of the Metroport MP1 and MP2 includes an output interface and an input interface. The output interface of Metroport MP1 is connected to the first transmission line of the 2-core transmission line 60A (the transmission line in the direction of exiting the optical wavelength division multiplexing SW 10), and the input interface of Metroport MP1 is connected to the second transmission line of the 2-core transmission line 60A (the transmission line in the direction of going toward the optical wavelength division multiplexing SW 10). The output interface of Metroport MP2 is connected to the second transmission line of the 2-core transmission line 60B (the transmission line in the direction of exiting the optical wavelength division multiplexing SW 10), and the input interface of Metroport MP2 is connected to the first transmission line of the 2-core transmission line 60B (the transmission line in the direction of going toward the optical wavelength division multiplexing SW 10).

[0033] In the example shown in Figure 1, an optical splitter 20 is positioned between the optical wavelength division multiplexer (WDM) SW 10 and the optical transceivers 30A, 30B, and 30C. The WDM SW 10 may be directly connected to the optical transceivers 30A, 30B, and 30C (i.e., an optical splitter does not need to be positioned between the WDM SW 10 and the optical transceivers 30A, 30B, and 30C).

[0034] The optical wavelength division multiplexer (WDM) SW10 can be connected to a two-core transmission line at each of the access ports AP1, AP2, and AP3.

[0035] The optical wavelength division multiplexing switch (SW) 10 includes a wavelength selection switch (hereinafter also referred to as "WSS") 12 and a wavelength division multiplexing separation unit (hereinafter also referred to as "Add / Drop") 13.

[0036] WSS12 is connected to each metro port MP1 and MP2 by optical transmission lines. WSS12 is connected to Add / Drop13 by optical transmission lines. Add / Drop13 is connected to each access port AP1, AP2, and AP3 by multiple optical transmission lines.

[0037] WSS12 determines whether to pass or drop the optical signal input to the input interface of Metroport MP1 for each wavelength, and outputs the optical signals of the wavelengths to be passed to the output interface of Metroport MP2. WSS12 outputs the optical signals of the wavelengths to be dropped to Add / Drop13. WSS12 determines whether to pass or drop the optical signal input to the input interface of Metroport MP2 for each wavelength, and outputs the optical signals of the wavelengths to be passed to the output interface of Metroport MP1. WSS12 outputs the optical signals of the wavelengths to be dropped to Add / Drop13.

[0038] WSS12 outputs the optical signals input from Add / Drop13 to either the output interface of Metroport MP1 or Metroport MP2 for each wavelength.

[0039] Add / Drop 13 separates the optical signal input from WSS 12 by wavelength and outputs the optical signal of each wavelength to access port AP1, AP2, or AP3. Add / Drop 13 wavelength-multiplexes the optical signals input from access ports AP1, AP2, and AP3 and outputs the wavelength-division multiplexed signal (hereinafter also referred to as the "WDM signal") to WSS 12.

[0040] Optical transmission lines 61A, 61B, and 61C, each composed of optical fibers, are connected to the access ports AP1, AP2, and AP3 of the optical wavelength division multiplexer SW10, respectively. Optical transmission line 61A is connected to the optical branching device 20. Optical transceivers 30A, 30B, and 30C are connected to the optical branching device 20 via optical transmission lines 62A, 62B, and 62C.

[0041] The optical branching device 20 separates the WDM signal of the main signal transferred by the optical wavelength division multiplexer (WDM) SW 10 for each wavelength and transfers the separated optical signals (main signals) to the corresponding optical transceivers 30 for each wavelength. The optical branching device 20 wavelength-multiplexes the main signals transmitted from each optical transceiver 30 and transfers the resulting WDM signal to the optical wavelength division multiplexer SW 10. The optical branching device 20 multiplexes or separates the optical signals within the device without converting them to electrical signals and transfers them to the desired path.

[0042] The optical transceiver 30 and the optical wavelength multiplexer SW10 may be connected via a plurality of optical branching devices 20. In this case, one wavelength range multiplexed by the upper (near the optical wavelength multiplexer SW10) optical branching device 20 includes the wavelength range of the lower (near the optical transceiver 30) optical branching device 20. The optical branching device 20 may be a power coupler. In this case, since the optical transceiver 30 receives main signals of a plurality of wavelengths, the optical transceiver 30 includes a wavelength selection filter for selecting and receiving only the corresponding wavelength.

[0043] The optical branching device 20 is a branching device that connects the upstream direction and the downstream direction in a 1:n ratio. That is, in the upstream direction, the optical branching device 20 is connected to a single optical wavelength multiplexer SW10 by an optical transmission line 61A, and in the downstream direction, the optical branching device 20 is connected to a plurality of optical transceivers 30A, 30B, 30C by optical transmission lines 62A, 62B, 62C. Here, n is set to 3, but n may be an integer of 2 or 4 or more.

[0044] In the example shown in FIG. 1, the optical transmission line 61A is a two-core transmission line.

[0045] The optical branching device 20 separates the downstream main signal input from the two-core transmission line 61A connected to the trunk line for each downstream wavelength, and distributes the separated downstream main signals of each system to the two-core transmission lines 62A, 62B, 62C connected to each branch line. When three upstream main signals of upstream wavelengths are input from the two-core transmission lines 62A, 6​​The optical transmission lines 61A, 61B, and 61C of the access network 200 may be single-core (bidirectional multiplexed communication using one core) optical transmission lines. In single-core transmission, different wavelengths are assigned to the upstream main signal and the downstream main signal. The optical transmission lines 62A, 62B, and 62C may be single-core transmission lines. For example, the entire access network 200 may be a single-core transmission network or a two-core transmission network.

[0047] The remote control system 100 is a system for remotely controlling the optical transceivers 30A, 30B, and 30C. The remote control system 100 may include a management device 50.

[0048] The optical wavelength multiplexer SW10 includes an optical remote control module 11 and a control signal multiplexing unit 14 in addition to the WSS12 and Add / Drop 13.

[0049] The management device 50 centrally manages the optical communication system. The management device 50 is communicably connected to the optical wavelength multiplexer SW10 via a transmission path 65 (shown by a broken line in the figure) using a known technology such as an electrical signal line, an optical signal line, or a wireless network.

[0050] The optical remote control module 11 can communicate with the management device 50 via the transmission path 65 using a communication protocol such as the Ethernet protocol ( "Ethernet" is a registered trademark). The management device 50 transmits setting information including the transmission path and wavelength of the optical signal, and the optical remote control module 11 receives the setting information from the management device 50.

[0051] The optical remote control module 11 analyzes the received setting information and sets the WSS12 and Add / Drop 13 according to the transmission path and wavelength included in the setting information. In FIG. 1, the optical connections between multiple elements are shown by solid lines, the electrical connections between multiple elements are shown by broken lines, and the connections (optical connections, electrical connections, etc.) between multiple elements regardless of the connection form are shown by two-dot chain lines.

[0052] The optical remote control module 11 is capable of transmitting and receiving optical signals. Based on the received configuration information, the optical remote control module 11 outputs an optical signal (hereinafter also referred to as "control signal") of a predetermined control wavelength, which includes the configuration information of the optical transceiver 30. The control signal is transmitted in the optical communication system at a transmission speed of 1 Gbps class.

[0053] In the example shown in Figure 1, a single optical remote control module 11 is connected to multiple optical transceivers 30A, 30B, and 30C (point-to-multipoint (PtoMP) connection). In the example shown in Figure 1, the optical transceivers 30 are remotely controlled using TDM-PON (TDM: Time Division Multiplexing). The optical remote control module 11 functions as an OLT. In the example shown in Figure 1, each of the optical transceivers 30 functions as an ONU. That is, in the example shown in Figure 1, the optical remote control module 11 transmits and receives control signals including PON frames.

[0054] The optical remote control module 11 communicates individually with the optical transceivers 30A, 30B, and 30C under its control, and remotely controls the optical transceivers 30A, 30B, and 30C individually. The optical wavelength division multiplexing switch 10 is an example of a "control device". Hereinafter, the direction from the optical wavelength division multiplexing switch 10 (optical remote control module 11) to the optical transceivers 30A, 30B, and 30C will be referred to as the "downstream direction", and the direction from the optical transceivers 30A, 30B, and 30C to the optical wavelength division multiplexing switch 10 (optical remote control module 11) will be referred to as the "upstream direction". The control wavelength is different from the wavelength of the main signal.

[0055] A control signal multiplexing unit 14 is located in the middle of the optical transmission path between Add / Drop 13 and access ports AP1, AP2, and AP3. In the example shown in Figure 1, the optical transmission paths 61A, 61B, and 61C are 2-core transmission paths, and the optical signals are handled as 2-core transmissions in WSS 12, Add / Drop 13, and the control signal multiplexing unit 14. Three sets of 2-core transmission paths 61A, 61B, and 61C extend from Add / Drop 13. Each of the 2-core transmission paths 61A, 61B, and 61C includes a downstream optical transmission path 61AA, 61BA, and 61CA (hereinafter also referred to as the "downstream transmission path") and an upstream optical transmission path 61AB, 61BB, and 61CB (hereinafter also referred to as the "upstream transmission path"). The control signal multiplexer 14 includes WDM couplers 14AA, 14BA, and 14CA positioned in the middle of each of the downlink transmission lines 61AA, 61BA, and 61CA, and WDM couplers 14AB, 14BB, and 14CB positioned in the middle of each of the uplink transmission lines 61AB, 61BB, and 61CB.

[0056] In the example shown in Figure 1, the optical remote control module 11 outputs a downlink multiplexed control signal, which is time-division multiplexed with the setting information of the optical transceivers 30A, 30B, and 30C. The downlink multiplexed control signal output from the optical remote control module 11 is distributed to each branch line by optical couplers (power couplers) (not shown) placed on the transmission line extending from the optical remote control module 11. The WDM couplers 14AA, 14BA, and 14CA wavelength-multiplex the distributed downlink multiplexed control signals with the downlink main signal transmitted through each downlink transmission line 61AA, 61BA, and 61CA. Each of the two-core transmission lines 61A, 61B, and 61C extending from the control signal multiplexing unit 14 extends to the outside from the access ports AP1, AP2, and AP3.

[0057] Wavelength division multiplexed signals (hereinafter also referred to as "downstream optical multiplexed signals") consisting of a downlink main signal and a downlink multiplexed control signal are output from the access ports AP1, AP2, and AP3 of the optical wavelength division multiplexing switch SW10.

[0058] The optical branching device 20 is connected to the downlink transmission line 61AA and the uplink transmission line 61AB of the two-core transmission line 61A. A WDM coupler 22A is placed in the middle of the downlink transmission line 61AA, and a WDM coupler 22B is placed in the middle of the uplink transmission line 61AB. The WDM coupler 22A separates the downlink main signal (WDM signals of three downlink main signals) and the downlink multiplexing control signal from the downlink optical multiplexed signal transmitted through the downlink transmission line 61AA. The downlink main signal is input to the WDM coupler 21A. The WDM coupler 21A separates the input downlink main signal by wavelength and distributes the separated main signals of each system to each branch line.

[0059] Each of the two-core transmission lines 62A, 62B, and 62C includes downlink transmission lines 62AA, 62BA, and 62CA, and uplink transmission lines 62AB, 62BB, and 62CB. The downlink multiplexed control signals separated by the WDM coupler 22A are distributed to multiple systems by the optical coupler 23A. Each of the downlink transmission lines 62AA, 62BA, and 62CA is equipped with a WDM coupler 24AA, 24AB, and 24AC. Each of the WDM couplers 24AA, 24AB, and 24AC receives the downlink main signal output from the WDM coupler 21 and the downlink multiplexed control signal output from the optical coupler 23A. Each of the WDM couplers 24AA, 24AB, and 24AC combines the input downlink main signal and downlink multiplexed control signal and outputs it as a WDM signal (optical multiplexed signal).

[0060] The optical transceiver 30 includes a dual-wavelength TOSA 305, which is an optical transmitting unit, and a dual-wavelength ROSA 306, which is an optical receiving unit. The dual-wavelength TOSA 305 transmits an uplink WDM signal obtained by combining an uplink main signal and an uplink multiplex control signal. The dual-wavelength ROSA 306 receives a downlink WDM signal obtained by combining a downlink main signal and a downlink multiplex control signal. Details of the dual-wavelength TOSA 305 and the dual-wavelength ROSA 306 will be described later.

[0061] The optical transceiver 30 includes a port PA for receiving optical signals and a port PB for transmitting optical signals. Port PA is connected to a two-wavelength ROSA 306 by an optical transmission line, and port PB is connected to a two-wavelength TOSA 305 by an optical transmission line.

[0062] Downstream WDM signals output from the optical branching device 20 and transmitted through the downstream transmission lines 62AA, 62BA, and 62CA are input to the two-wavelength ROSA 305 from the port PA of the optical transceivers 30A, 30B, and 30C.

[0063] Optical transceivers 30x (x is A through C) receive a control signal (frame) addressed to optical transceiver 30x from the downlink multiplexed control signal and execute the command contained in the control signal. Optical transceivers 30A, 30B, and 30C each transmit an uplink control signal containing the frame with the execution result at different timings. The dual-wavelength TOSA 305 combines the uplink main signal and the uplink control signal and outputs an uplink WDM signal. The uplink WDM signal is output from port PB to the uplink transmission lines 62AB, 62BB, and 62CB.

[0064] Within the optical branching device 20, WDM couplers 24BA, 24BB, and 24BC are arranged in each of the uplink transmission lines 62AB, 62BB, and 62CB. Uplink WDM signals transmitted through each of the uplink transmission lines 62AB, 62BB, and 62CB are input to each of the WDM couplers 24BA, 24BB, and 24BC. Each of the WDM couplers 24BA, 24BB, and 24BC separates the uplink main signal and the uplink control signal from the uplink WDM signal by wavelength. Each of the three uplink main signals is input to the WDM coupler 21B. The WDM coupler 21B combines the three input uplink main signals and outputs a WDM signal to the uplink transmission line 61AB.

[0065] The three uplink control signals output from the WDM couplers 24BA, 24BB, and 24BC are input to the optical coupler 23B. The optical coupler 23B combines the three input uplink control signals. As described above, since the optical transceivers 30A, 30B, and 30C transmit frames at different timings, the three uplink control signals are time-division multiplexed in the optical coupler 23B.

[0066] The WDM coupler 22B combines the uplink WDM signal output from the WDM coupler 21 with the uplink multiplexing control signal (TDM signals of three control signals) output from the optical coupler 23B, and outputs a wavelength division multiplexed signal (hereinafter also referred to as the "uplink optical multiplexed signal") which is a combination of the three main WDM signals and the uplink multiplexing control signal. The uplink optical multiplexed signal is transmitted through the uplink transmission path 61AB of the two-core transmission path 61A and input to the access port AP1 of the optical wavelength division multiplexing switch 10. The uplink optical multiplexed signal transmitted through the uplink transmission path 61BB is input to the access port AP2. The uplink optical multiplexed signal transmitted through the uplink transmission path 61CB is input to the access port AP3.

[0067] The control signal multiplexing unit 14 separates the uplink optical multiplexed signals transmitted through the uplink transmission lines 61AB, 61BB, and 61CB into an uplink main signal and an uplink multiplexed control signal using WDM couplers 14AB, 14BB, and 14CB, respectively. The uplink multiplexed control signals output from the WDB couplers 14AB, 14BB, and 14CB are multiplexed by an optical coupler (not shown) and input to the optical remote control module 11. The optical remote control module 11 extracts the execution result of a command from the uplink multiplexed control signal and generates response information including the extracted command execution result. The optical remote control module 11 transmits the response information to the management device 50 either as is or together with the response to the setting commands of WSS 12 and Add / Drop 13.

[0068] [2. Optical Transceiver] Figure 2 is a block diagram showing an example of the hardware configuration of an optical transceiver according to the embodiment.

[0069] In addition to the two-wavelength TOSA 305 and two-wavelength ROSA 306 described above, the optical transceiver 30 includes an ONU function unit 31, a microcontroller unit (MCU) 32, a drive circuit 302, a digital signal processor (DSP) 303, a laser diode driver (LDD) and limiting amplifier (LA) unit (LDD / LA) 312, a connector 33, a wavelength control circuit 363, and a laser current control circuit 364.

[0070] The dual-wavelength TOSA 305 includes a light-emitting unit 301T that transmits an uplink main signal and a light-emitting unit 311T that transmits an uplink control signal. The light-emitting unit 301T is capable of transmitting optical signals in the 25 Gbps class. The light-emitting unit 311T is capable of transmitting optical signals in the 1 Gbps class. The dual-wavelength TOSA 305 is an example of an "optical transmission unit".

[0071] The dual-wavelength ROSA 306 includes a light-receiving unit 301R that receives a downlink main signal and a light-receiving unit 311R that receives a downlink multiplexed control signal. The light-receiving unit 301R is capable of receiving optical signals of the 25 Gbps class. The light-receiving unit 311R is capable of receiving optical signals of the 1 Gbps class. The dual-wavelength ROSA 306 is an example of an "optical receiving unit". In this embodiment, the main signal is an optical signal of the 25 Gbps class, and the control signal is an optical signal of the 1 Gbps class.

[0072] Connector 33 can be connected to connector 401 (see Figure 1) of the user device 40. Connector 33 includes a number of terminals (not shown). Connector 33 conforms to SFP28, one of the standard form factors for optical transceivers.

[0073] The DSP 303 is connected to connector 33. The DSP 303 performs signal processing such as frame processing on the upstream main signal output from the user device 40 and input to connector 33.

[0074] The output terminals of the DSP 303 are connected to the input terminals of the drive circuit 302, the wavelength control circuit 363, and the laser current control circuit 364, respectively. For example, the light-emitting unit 301T converts electrical signals into optical signals using an electro-absorption modulated laser (EAM). The drive circuit 302 is connected to the light-emitting unit 301T and drives and controls the EAM according to the electrical signal output from the DSP 303. The wavelength control circuit 363 controls the wavelength of the light output from the light-emitting unit 301T according to the electrical signal from the DSP 303, and the laser current control circuit 364 supplies current to the light-emitting unit 301T to output the laser according to the electrical signal from the DSP 303. As a result, the light-emitting unit 301T outputs an optical signal corresponding to the electrical signal output by the DSP 303.

[0075] The light-receiving unit 301R converts the optical signal into a current signal using, for example, an avalanche photodiode (APD). The light-receiving unit 301R includes a transimpedance amplifier (TIA), which converts the current signal output from the pin-PD into a voltage signal.

[0076] The input terminal of the DSP 303 is connected to the light receiving unit 301R, and the electrical signal (downlink main signal) output from the light receiving unit 301R is input to the DSP 303. The DSP 303 performs signal processing such as frame processing on the downlink main signal output from the light receiving unit 301R. The downlink main signal processed by the DSP 303 is output externally through the connector 33.

[0077] The light-emitting unit 311T and the light-receiving unit 311R are each connected to the LDD / LA 312. The light-emitting unit 311T is connected to the LDD. The light-receiving unit 311R is connected to the LA.

[0078] The light receiving unit 311R converts an optical signal (downlink multiplex control signal) into a current signal using, for example, a pin-PD, and then converts the current signal output from the pin-PD into a voltage signal using a TIA.

[0079] An electrical signal is output from the light receiving unit 311R to the LA. The LA adjusts the output amplitude of the TIA, which changes according to the intensity of the received optical signal, to obtain an electrical signal of the corresponding amplitude. The LDD / LA 311 is connected to the ONU function unit 31, and the electrical signal output from the LA is input to the ONU function unit 31.

[0080] The ONU function unit 31 is configured, for example, by an FPGA (Field Programmable Gate Array). The FPGA constituting the ONU function unit 31 includes a circuit that functions as a frame processing unit 313, a processor 314, and a memory 315.

[0081] The frame processing unit 313 performs frame processing on the downlink multiplexed control signals output from the LA. The frame processing unit 313 is a MAC (Media Access Control) circuit for PON and processes PON frames as defined in IEEE 802.3ah. It can generate frames or obtain information from PON frames. In one example, the frame processing unit 313 can handle OAM frames for PON. Any frame other than an OAM frame may be used, as long as it contains control information including a Request or Response. For example, instead of EPON as defined in IEEE 802.3ah, GPON (Gigabit PON) as defined in ITU-T G. 984 may be used. In this case, an OMCI (ONU Management and Control Interface) frame is used instead of an OAM frame. The optical transceiver 30 may be remotely controlled using a frame defined by the user.

[0082] The frame processing unit 313 extracts downlink control signals addressed to the frame processing unit 313, specifically frames addressed to the frame processing unit 313, from the downlink multiplexing control signals received by the light receiving unit 311R. Each ONU function unit 31 is assigned identification information called LLID (Logical Link ID). The LLID is stored in the frame's preamble. The frame processing unit 313 obtains the LLID from the frame's preamble and identifies frames addressed to the frame processing unit 313 by determining whether it matches the LLID of the frame processing unit 313 or the broadcast LLID. The frame processing unit 313 obtains the frames that it has determined to be addressed to the frame processing unit 313 based on the LLID and discards frames that are not addressed to the frame processing unit 313.

[0083] The frame processing unit 313 is connected to the processor 314, which is connected to the memory 315. The frame processing unit 313 outputs the acquired frames to the processor 314. The processor 314 obtains configuration information from the input frames.

[0084] The MCU 32 includes a processor 321, a memory 322, a digital-to-analog converter (DAC) 323, and an analog-to-digital converter (ADC) 324. The processor 314 of the ONU function unit 31 outputs the configuration information acquired from the frame to the processor 321. The processor 321 converts the configuration information into instructions. The processor 321 executes the obtained instructions and obtains the execution result.

[0085] Processor 314 receives the instruction execution result output from processor 321 and generates a frame containing the received instruction execution result. Processor 314 outputs the generated frame to frame processing unit 313.

[0086] The frame processing unit 313 outputs the frame input from the processor 314 to the LDD as a downlink control signal (voltage signal).

[0087] The LDD converts the voltage signal into a current signal and outputs the resulting current signal to the light-emitting unit 311T. This drives the laser in the light-emitting unit 311T, and a burst light signal corresponding to the current signal is output (transmitted).

[0088] [3. Internal Layout of Optical Transceiver Housing] Figure 3 is a perspective view showing an example of the internal layout of the optical transceiver housing according to the embodiment, and Figure 4 is a plan view thereof.

[0089] The optical transceiver 30 includes a housing 340. The housing 340 has a shape conforming to SFP28. The housing 340 is roughly a rectangular prism shape that is elongated in one direction. Hereinafter, as shown in Figure 3, the longitudinal direction of the housing 340 is referred to as the "front-to-back direction," the horizontal direction perpendicular to the front-to-back direction is referred to as the "left-to-right direction," and the direction perpendicular to both the front-to-back and left-to-right directions is referred to as the "up-and-down direction." "Right" refers to the right when facing forward, and "left" refers to the left when facing forward. The above directions are for convenience based on the illustrated state and do not limit the directions. For the sake of explanation, the housing 340 is assumed to be horizontally positioned. That is, the top and bottom surfaces of the housing 340 are horizontal planes.

[0090] Figure 3 shows the housing 340 as indicated by a dashed line, and the internal layout of the housing is shown through the housing 340. Figure 4 shows a plan view of the housing 340 with the top plate removed.

[0091] The housing 340 has an opening 341 at its front end and an opening 342 at its rear end. The opening 341 is an insertion point for the optical fiber cable connector. The opening 342 is a connection port for the host device.

[0092] Two wavelength TOSA 305 and two wavelength ROSA 306 are arranged at the front interior end of the housing 340. The two wavelength TOSA 305 and two wavelength ROSA 306 are arranged side by side in the left-right direction. In the examples of Figures 3 and 4, the two wavelength TOSA 305 is on the right side and the two wavelength ROSA 306 is on the left side.

[0093] Figure 5 is a side view showing an example of a schematic configuration of a two-wavelength TOSA, and Figure 6 is a side view showing an example of a schematic configuration of a two-wavelength ROSA.

[0094] Optical connectors 351 and 361, to which optical fiber cables can be connected, are provided at the front ends of the dual-wavelength TOSA 305 and the dual-wavelength ROSA 306, respectively. The front end of the dual-wavelength TOSA 305 is connected to an optical fiber cable (not shown) for upstream signals, and the dual-wavelength ROSA 306 is connected to an optical fiber cable (not shown) for downstream signals.

[0095] Referring to Figure 5, a light-emitting section 301T is positioned at the rear end of the dual-wavelength TOSA 305. The light-emitting surface of the light-emitting section 301T is directed forward. In the dual-wavelength TOSA 305, a WDM coupler housing 304Bh containing a WDM coupler 304B is positioned between the optical connector 351 and the light-emitting section 301T. A light-emitting section 311T is positioned above the upper end of the dual-wavelength TOSA 305 and above the WDM coupler housing 304Bh. The light-emitting surface of the light-emitting section 311T is directed downward.

[0096] A main signal, which is a 25 Gbps class optical signal, is output forward from the light-emitting unit 301T. A control signal, which is a 1 Gbps class optical signal, is output downward from the light-emitting unit 311T. The main signal and the control signal are wavelength-multiplexed in the WDM coupler 304B, and the wavelength-multiplexed signal is output forward from the optical connector 351. The WDM coupler 304B is an example of a "wavelength-multiplexed unit". 25 Gbps and 1 Gbps are examples, and the transmission rates of the main signal and control signal are not limited to 25 Gbps and 1 Gbps.

[0097] The dual-wavelength TOSA 305 has a roughly cylindrical optical connector 351 with a small diameter, positioned so that its central axis aligns with the front-to-back direction, and a roughly rectangular WDM coupler housing 304Bh is provided behind the optical connector 351. A light-emitting section 301T is positioned on the rear end face of the WDM coupler housing 304Bh. The light-emitting section 301T includes a rectangular laser diode 301TL and a roughly cylindrical light guide section 301TG with a large diameter. The light guide section 301TG is connected to the rear end face of the WDM coupler housing 304Bh so that its central axis aligns with the front-to-back direction. The laser diode 301TL is positioned behind the light guide section 301TG. A short cylindrical light-emitting section 311T is positioned on the upper end face of the WDM coupler housing 304Bh so that its central axis aligns with the vertical direction. In other words, the two-wavelength TOSA 305 has a shape in which the light-emitting portion 311T protrudes upward.

[0098] Referring to Figure 6, a light-receiving unit 301R is positioned at the rear end of the dual-wavelength ROSA 306. The light-receiving surface of the light-receiving unit 301R is oriented forward. In the dual-wavelength ROSA 306, a WDM coupler housing 304A, which houses the WDM coupler 304A, is positioned between the optical connector 361 and the light-receiving unit 301R. A light-receiving unit 311R is positioned at the upper end of the dual-wavelength ROSA 306, above the WDM coupler housing 304Ah. The light-receiving surface of the light-receiving unit 311R is oriented downward.

[0099] A wavelength-multiplexed signal, consisting of a main signal and a control signal, is input to the optical connector 361 from the rear. The wavelength-multiplexed signal travels backward and is input to the WDM coupler 304A, where it is wavelength-separated into the main signal and the control signal. The WDM coupler 304A is an example of a "separation unit". The main signal is output backward from the WDM coupler 304A and received by the light receiving unit 311R. The control signal is output upward from the WDM coupler 304A and received by the light receiving unit 311R.

[0100] The dual-wavelength ROSA 306 has a roughly cylindrical optical connector 361 with a small diameter, positioned so that its central axis aligns with the front-to-back direction, and a roughly rectangular WDM coupler housing 304Ah is provided behind the optical connector 361. A roughly cylindrical light-receiving section 301R with a large diameter is positioned on the rear end face of the WDM coupler housing 304Ah so that its central axis aligns with the front-to-back direction. A short cylindrical light-receiving section 311R is positioned on the upper end face of the WDM coupler housing 304Ah so that its central axis aligns with the vertical direction. In other words, the dual-wavelength ROSA 306 has a shape in which the light-receiving section 311R protrudes upward.

[0101] Since the two-wavelength TOSA 305 and two-wavelength ROSA 306, which have shapes that protrude upward, are arranged side by side, the space required to accommodate the two-wavelength TOSA 305 and two-wavelength ROSA 306 can be reduced in the left-right direction. The height of the WDM coupler housings 304Ah and 304Bh is smaller than the total width occupied by the two WDM coupler housings 304Ah and 304Bh arranged side by side, and by arranging the light-emitting section 311T and light-receiving section 311R above the WDM coupler housings 304Ah and 304Bh, the space can be used efficiently to arrange the two-wavelength TOSA 305 and two-wavelength ROSA 306.

[0102] Referring to Figure 5, a heat conduction section 301TH, made of a metal material with high thermal conductivity such as a copper alloy or an aluminum alloy, is attached to the upper end surface of the laser diode 301TL. The heat conduction section 301TH is rectangular, and its upper end surface is in contact with the lower surface of the upper plate of the housing 340. The heat generated from the laser diode 301TL is released to the housing 340 by the heat conduction section 301TH.

[0103] Referring to Figure 3, inside the housing 340, the main control board 360 and the sub-control board 370 are arranged behind the two-wavelength TOSA 305 and the two-wavelength ROSA 306. The main control board 360 is a board for controlling the main signal light-emitting unit 301T and the light-receiving unit 301R, and the sub-control board 370 is a board for controlling the optical signal light-emitting unit 311T and the light-receiving unit 311R.

[0104] The main control board 360 and the sub-control board 370 are stacked vertically. The main control board 360 is positioned on the lower side, and the sub-control board 370 is positioned on the upper side. In other words, the orientation of the set of light-emitting unit 301T and light-receiving unit 301R that transmit and receive the main signal, and the set of light-emitting unit 311T and light-receiving unit 311R that transmit and receive the control signal, is aligned with the orientation of the main control board 360 and the sub-control board 370. Therefore, the wiring connecting each of the light-emitting unit 301T and light-receiving unit 301R to the main control board 360, and the wiring connecting each of the light-emitting unit 311T and light-receiving unit 311R to the sub-control board 370 can be efficiently arranged.

[0105] Figure 7 is a schematic diagram showing an example of the configuration of the main control board. The light-emitting unit 301T and the light-receiving unit 301R are connected to the front end of the main control board 360 via two flexible printed circuits (FPCs) 362T and 362R. FPC 362T connects the light-emitting unit 301T to the main control board 360. FPC 362R connects the light-receiving unit 301R to the main control board 360. Each of the FPCs 362T and 362R includes signal lines and power lines, and transmits signals and power between the light-emitting unit 301T and the main control board 360, and between the light-receiving unit 301R and the main control board 360.

[0106] The main control board 360 is equipped with an MCU 32, a DSP 303, a drive circuit 302, a connector 33, a wavelength control circuit 363, a laser current control circuit 364, a power supply circuit 365, and an inter-board connector 366. The MCU 32 is a circuit that controls the light-emitting unit 301T and the light-receiving unit 301R, and is an example of a "first control circuit". The main control board 360 is an example of a "first control board".

[0107] The connector 33 is located at the rear end of the main control board 360. The connector 33 is located near the opening 342 of the housing 340. When the rear end of the optical transceiver 30 is inserted into the host device, the connector 33 is connected to a port provided in the host device via the opening 342. The connector 33 is an SFP28 compliant connector. Therefore, the connector 33 can be connected to a port of a host device that complies with SFP28.

[0108] The drive circuit 302, wavelength control circuit 363, and laser current control circuit 364 are each connected to the light-emitting unit 301T. The drive circuit 302 drives and controls the laser diode 301TL. The wavelength control circuit 363 outputs a control current to the light-emitting unit 301T to control the wavelength of the optical signal. The laser current control circuit 364 outputs a current to the laser diode 301TL to output the laser.

[0109] The board-to-board connector (BtoB connector) 366 is a connector for electrically connecting the main control board 360 to the sub-control board 370.

[0110] The power supply circuit 365 converts the voltage of the DC power supplied from the host device through the connector 33 and supplies the converted DC power to each component of the main control board 360. Details of the power supply circuit 365 will be described later.

[0111] Figure 8 is a schematic plan view showing an example of the configuration of a sub-control board. The light-emitting unit 311T and the light-receiving unit 311R are connected to the front end of the sub-control board 370 via a single FPC 371. The FPC 371 includes signal lines and power lines and transmits signals and power between the light-emitting unit 311T and the sub-control board 370, and between the light-receiving unit 311R and the sub-control board 370. The FPC 371 is positioned above the FPCs 362T and 362R.

[0112] The sub-control board 370 is equipped with an ONU function unit 31, an LDD / LA 312, a power supply circuit 372, and an inter-board connector 373. The ONU function unit 31 is a circuit that controls the light-emitting unit 311T and the light-receiving unit 311R, and is an example of a "second control circuit" and a "control circuit". The sub-control board 370 is an example of a "second control board".

[0113] The board-to-board connector 373 is a connector for electrically connecting the sub-control board 370 to the main control board 360. Board-to-board connector 373 and board-to-board connector 366 are connectable to each other.

[0114] The power supply circuit 372 converts the voltage of the DC power supplied from the main control board 360 via the board-to-board connectors 366 and 373, and supplies the voltage-converted DC power to each component of the sub-control board 370. Details of the power supply circuit 372 will be described later.

[0115] [4. FPC for Sub-Control Board] Refer to Figures 4 and 5. The heat conduction section 301TH connects the laser diode 301TL to the upper plate of the housing 340. The sub-control board 370 is positioned at the same height as the heat conduction section 301TH and behind the heat conduction section 301TH. The light-emitting section 311T is positioned in front of the heat conduction section 301TH. Thus, the heat conduction section 301TH exists between the light-emitting section 311T and the sub-control board 370. The FPC 371 for the sub-control board 370 has a rectangular recess 371R on its right side that corresponds to the size of the heat conduction section 301TH. The recess 371R allows the FPC 371 to avoid the heat conduction section 301TH.

[0116] [5. Electrical connection relationship between the main control board and the sub-control board] Figure 9 shows an example of the pin settings for the inter-board connector mounted on the main control board.

[0117] In the example shown in Figure 9, the board-to-board connector 366 has 24 pins. Pin 1 is assigned to the power enable signal for the FPGA (ONU function unit 31). Pins 2 and 3 are not used. Pin 4 is assigned to the FPGA reset signal, and pin 5 is assigned to the FPGA's GPIO (General Purpose Input / Output). Pin 6 is assigned to the input of the UART (Universal Asynchronous Receiver Transmitter), and pin 7 is assigned to the output of the UART. UART is one of the asynchronous serial communication standards.

[0118] Pins 8 through 12 are unused. Pins 13 through 16 are assigned to the 3.3V power supply. Pin 17 is assigned to the receive loss (Rx_LOS) signal of the light receiver 311R, and pin 18 is assigned to the transmit fault (Tx_Fault) signal of the light emitter 311T. The Rx_LOS signal indicates that the intensity of the optical signal received by the light receiver 311R is below a predetermined threshold. The Rx_LOS signal may also indicate that the light receiver 311R is not receiving an optical signal. The Tx_Fault signal indicates that an error has occurred in the optical signal transmitted by the light emitter 311T. The Tx_Fault signal may indicate that the intensity of the optical signal transmitted by the light emitter 311T is below a predetermined threshold, or it may indicate that the light emitter 311T is not transmitting an optical signal.

[0119] Pins 19 and 20 are assigned to I2C (Inter-Integrated Circuit). I2C is a serial communication standard. Pins 21 through 24 are assigned to GND (ground).

[0120] Refer to Figure 7. Connector 33 and DSP 303 are connected by signal line 366A for the upstream main signal and signal line 366B for the downstream main signal. A signal line 366C for the upstream main signal extends from DSP 303 to drive circuit 302, and a signal line 366D for the drive signal of light-emitting unit 301T extends from drive circuit 302 to light-emitting unit 301T. A signal line 366E for the downstream main signal extends from light-receiving unit 301R to DSP 303. Here, "extends" indicates that the signal line 366E, which is an electrical wire, connects the light-receiving unit 301R and DSP 303, and does not limit the direction of signal transmission.

[0121] Signal lines 366F for control and monitoring and signal line 366G for I2C extend from connector 33 to MCU 32. Signal line 366H for wavelength control extends from MCU 32 to wavelength control circuit 363, and signal line 366I for wavelength control current extends from wavelength control circuit 363 to light-emitting unit 301T. Signal line 366J for laser current control extends from MCU 32 to laser current control circuit 364, and signal line 366K for laser current extends from laser current control circuit 364 to light-emitting unit 301T.

[0122] UART signal lines 366L extend from the UART input pin (pin 6) and UART output pin (pin 7) of the board-to-board connector 366 to the MCU 32.

[0123] I2C signal lines 366M extend from the I2C pins (pins 19 and 20) of the board-to-board connector 366 to the MCU 32. The MCU 32 and the DSP 303 are connected by an I2C signal line 366N.

[0124] A signal line 366P for the Rx_LOS signal of the light receiving unit 311R extends from the Rx_LOS pin (pin 17) of the board-to-board connector 366 to the MCU 32, and a signal line 366Q for the Tx_Fault signal of the light emitting unit 311T extends from the Tx_Fault pin (pin 18) to the MCU 32.

[0125] A signal line 366R for power-enabling the ONU function unit 31 (hereinafter, "ONU function unit 31" is also referred to as "FPGA 31") extends from the FPGA power-enable pin (pin 1) of the board-to-board connector 366 to the MCU 32. A signal line 366S for resetting the FPGA 31 extends from the FPGA reset pin (pin 4) of the board-to-board connector 366 to the MCU 32. A signal line 366T for GPIO extends from the FPGA GPIO pin (pin 5) of the board-to-board connector 366 to the MCU 32.

[0126] Figure 10 shows an example of the pin settings for an inter-board connector mounted on a sub-control board.

[0127] In the example shown in Figure 10, the board-to-board connector 373 has 24 pins. The assignments of pins 1, 4 through 7, and 13 through 24 are the same as those of the board-to-board connector 366 for the main control board 360.

[0128] Pin 2 of the board-to-board connector 373 is assigned to the input of the UART for FPGA debugging, and pin 3 is assigned to the output of the UART for FPGA debugging.

[0129] Pins 8 through 12 are assigned to JTAG for FPGA configuration. JTAG is a serial communication standard defined in IEEE 1149.1.

[0130] Refer to Figure 8. Signal lines 373A for the uplink control signal and 373B for the downlink control signal extend from FPGA 31 to LDD / LA 312. Signal line 373C for the drive signal of the light-emitting unit 311T extends from LDD / LA 312 to light-emitting unit 311T. Signal line 373D for the downlink control signal extends from light-receiving unit 311R to LDD / LA 312.

[0131] Signal lines 373E for UART extend from the UART input pin (pin 6) and UART output pin (pin 7) of the board-to-board connector 373 to the FPGA 31.

[0132] Signal lines 373F for I2C extend from the I2C pins (pins 19 and 20) of the board-to-board connector 373 to the FPGA 31. Signal lines 373F branch off midway and connect to the LDD / LA312.

[0133] A signal line 373G for the Rx_LOS signal (pin 18) of the light receiving unit 311R extends from the Rx_LOS pin (pin 17) of the board-to-board connector 373 to the FPGA 31, and a signal line 373H for the Tx_Fault signal of the light emitting unit 311T extends from the Tx_Fault pin to the FPGA 31.

[0134] A signal line 373I for JTAG extends from the JTAG pins (pins 8 to 12) of the board-to-board connector 373 to the FPGA 31.

[0135] A signal line 373J for enabling the power of FPGA 31 extends from the FPGA power enable pin (pin 1) of the board-to-board connector 373 to the power supply circuit 372. A signal line 373K for resetting FPGA 31 extends from the FPGA reset pin (pin 4) of the board-to-board connector 373 to FPGA 31. A signal line 373L for GPIO extends from the FPGA GPIO pin (pin 5) of the board-to-board connector 373 to FPGA 31.

[0136] The MCU 32 and FPGA 31 are connected by signal line 366L, board-to-board connectors 366 and 373, and signal line 373E. Therefore, the MCU 32 and FPGA 31 can communicate via UART. In this embodiment, FPGA 31 is set as the UART master, and MCU 32 is set as the UART slave. This allows FPGA 31 to control the main control board 360 (main signal). For example, FPGA 31 can read values ​​from the registers of MCU 32 or write values ​​to the registers. For example, FPGA 31 can read the value of the main signal's set wavelength from the register of MCU 32 and transmit it to the management device 50 as a control signal. FPGA 31 can write the main signal's set wavelength to the register of MCU 32 in accordance with the wavelength setting command included in the control signal received from the management device 50.

[0137] The MCU 32 and FPGA 31 are connected by signal line 366M, board-to-board connectors 366 and 373, and signal line 373F. Therefore, the MCU 32 and FPGA 31 can communicate via I2C. In this embodiment, the MCU 32 is set as the I2C master and the FPGA 31 is set as the I2C slave. As a result, the MCU 32 can control the sub-control board 370 (control signals). For example, the MCU 32 can read values ​​from the FPGA 31's registers or write values ​​to the registers. The MCU 32 can also control the LDD / LA 312 via I2C through signal line 366M, board-to-board connectors 366 and 373, and signal line 373F.

[0138] The host device connected to connector 33 is connected to MCU 32 via control and monitoring signal line 366F. Therefore, the host device can control and monitor the optical transceiver 30. The host device connected to connector 33 is also connected to MCU 32 via I2C signal line 366G. Therefore, the host device can control MCU 32 via I2C and DSP 303 connected to MCU 32 via signal line 366N.

[0139] The MCU 32 and FPGA 31 are connected by signal lines 366P and 366Q, board connectors 366 and 373, and signal lines 373G and 373H. Therefore, if a signal reception loss occurs due to the light receiving unit 311R, FPGA 31 can notify MCU 32 of the signal reception loss by sending an Rx_LOS signal. If a signal transmission fault occurs due to the light emitting unit 311T, FPGA 31 can notify MCU 32 of the signal transmission fault by sending a Tx_Fault signal.

[0140] The MCU 32 is connected to the power supply circuit 372 by signal line 366R, board-to-board connectors 366 and 373, and signal line 373J. Therefore, the MCU 32 can start up the FPGA 31 by sending a power enable signal to the power supply circuit 372, and can stop the FPGA 31 by stopping the transmission of the power enable signal.

[0141] The MCU 32 and FPGA 31 are connected by signal line 366S, board-to-board connectors 366 and 373, and signal line 373K. Therefore, the MCU 32 can reset the FPGA 31.

[0142] [6. Power Supply for Optical Transceiver] Refer to Figure 7. In Figure 7, signal lines are indicated by solid arrows, and power lines are indicated by dashed arrows. Connector 33 includes a 3.3V power supply pin and a GND pin (not shown). Power lines and GND lines for the 3.3V power supply are provided on the main control board 360 by printed circuit boards (copper foil). Hereinafter, power lines that transmit xV current will also be called "xV power lines". From the 3.3V power supply pin and GND pin of connector 33, 3.3V power lines and GND lines extend to the power supply circuit 365. From connector 33, the 3.3V power lines extend to the 3.3V power supply pins (pins 13 to 16) of the board-to-board connector 366, and the GND lines extend to the GND pins (pins 21 to 24).

[0143] Refer to Figure 8. In Figure 8, signal lines are indicated by solid arrows, and power lines are indicated by dashed arrows. 3.3V power lines and GND lines extend from the 3.3V power supply pins (pins 13 to 16) and GND pins (pins 21 to 24) of the board-to-board connector 373 to the power supply circuit 372, respectively.

[0144] Figure 11 is a diagram illustrating the power supply for the main control board and the sub-control board.

[0145] 3.3V power is supplied from the host device to the main control board 360 via connector 33. The 3.3V power is supplied to the MCU 32 and DSP 303 without being stepped down. The 3.3V power is supplied to the sub-control board 370 via inter-board connectors 366 and 373.

[0146] In the main control board 360, the power supply circuit 365 steps down the 3.3V power to 3.0V, 1.8V, 0.9V, and -3.3V. The 3.0V power is supplied to the light receiving unit 301R. The 1.8V power is supplied to the wavelength control circuit 363 and the DSP 303. The 0.9V power is supplied to the DSP 303. The -3.3V power is supplied to the drive circuit 302.

[0147] The 3.3V power output from the board-to-board connector 373 is supplied to the FPGA 31 and LDD / LA 312 without being stepped down.

[0148] In the sub-control board 370, the power supply circuit 372 steps down the 3.3V power to 3.0V, 1.2V, and 2.5V. The 3.0V power is supplied to the light receiving unit 311R. The 1.2V and 2.5V power are supplied to the FPGA 31.

[0149] As a variation, a 3.0V power supply pin may be provided on each of the board-to-board connectors 366 and 373, and the 3.0V power output from the power supply circuit 365 may be supplied from the sub-control board 370 to the light receiving unit 311R via the board-to-board connectors 366 and 373. In this case, the power supply circuit 372 of the sub-control board 370 does not need to convert the 3.3V power to 3.0V.

[0150] [7. FPGA Configuration] During the manufacturing stage of the optical transceiver 30, the configuration data for FPGA 31 is stored on a sub-control board 370 that is not assembled into the housing 340. Hereinafter, the storage of configuration data on the sub-control board 370 will also be referred to as "FPGA 31 configuration".

[0151] A connection device is used to configure FPGA 31. Figure 12 is a diagram illustrating the FPGA configuration using the configuration device.

[0152] The connection device 400 includes a plurality of board-to-board connectors 410, a switch 420, a connector 430, and a power supply circuit 440.

[0153] In the example shown in Figure 12, the connection device 400 includes four board-to-board connectors 410. Each of the board-to-board connectors 410 can be connected to a board-to-board connector 373 on the sub-control board 370.

[0154] The board-to-board connector 410 has 24 pins. Pin 1 of the board-to-board connector 410 is assigned to the power enable signal for the FPGA. Pin 4 is assigned to the FPGA reset signal. Pin 5 is assigned to the GPIO for the FPGA. Pin 2 is assigned to the input of the UART for FPGA debugging. Pin 3 is assigned to the output of the UART for FPGA debugging. Pins 8 through 12 are assigned to the JTAG for FPGA configuration. Pins 13 through 16 are assigned to the 3.3V power supply. Pins 21 through 24 are assigned to GND.

[0155] Connector 430 is connectable to a configuration device 500 configured by a computer. The configuration device 500 has an external connector (not shown) to which a signal cable 501 can be connected. Connector 430 includes pins for FPGA power enable signals, FPGA reset signals, FPGA GPIO pins, JTAG pins, UART pins, and switch 420 control pins. The signal cable 501 includes a connector 502 at its end, which is connectable to connector 430.

[0156] The power supply circuit 440 is connected to the commercial AC power supply. The power supply circuit 440 converts the commercial AC power into 3.3V DC power.

[0157] The switch 420 includes one first terminal 420A and four second terminals 420B. The first terminal 420A is connected to the setting device 500, and the JTAG pins of the connector 430 are connected to the first terminal 420A by JTAG signal lines. The four second terminals 420B are connected to the sub-control board 370, and each of the four second terminals 420B is connected via signal lines to each of the JTAG pins (pins 8 to 12) of the four board-to-board connectors 410. The power supply circuit 440 is connected via power lines to each of the 3.3V power supply pins (pins 13 to 16) of the four board-to-board connectors 410 (shown by dashed lines in the figure). Although not shown in the figure, a signal line for the FPGA reset signal is connected in parallel from connector 430 to pin 4 of each of the four board-to-board connectors 410.

[0158] The switch 420 can switch the connection between one first terminal 420A and four second terminals 420B. Since each of the four second terminals 420B is connected to multiple JTAG pins in each of the four board-to-board connectors 410, the switch 420 can switch the connection of multiple JTAG pins of the board-to-board connectors 410 to the connector 430 all at once. Each of the four second terminals 420B is assigned a number from 1 to 4. Each of the four board-to-board connectors 410 is also assigned a number from 1 to 4, and the second terminal 420B with the same number is connected to the board-to-board connector 410.

[0159] Figure 13 is a flowchart showing an example of the FPGA configuration procedure for the sub-control board 370.

[0160] During the manufacturing stage of the optical transceiver 30, the worker connects the board-to-board connector 373 of the sub-control board 370, before it is assembled into the housing 340, to the board-to-board connector 410 of the connection device 400. At this time, the worker connects four sub-control boards 370 to each of the four board-to-board connectors 410 (step S101). As a result, 3.3V DC power output from the power supply circuit 440 is supplied to each of the four sub-control boards 370 connected to the board-to-board connectors 410.

[0161] With the initial value of the integer variable i set to "1", the setting device 500 connects the first terminal 420A of the switch 420 to the i-th second terminal 420B (step S102).

[0162] The operator operates the setting device 500 to output configuration data for FPGA 31 from the setting device 500 to the connection device 400. In the connection device 400, the configuration data is output from the JTAG pins (pins 8 to 12) of the board-to-board connector 410 to the JTAG pins (pins 8 to 12) of the board-to-board connector 373. The configuration data input to the board-to-board connector 373 is stored, for example, in the memory 315 of the sub-control board 370 to be configured (step S103). The operator operates the setting device 500 to input a configuration execution instruction to the setting device 500. The configuration execution instruction is output from the setting device 500 to the FPGA 31 of the sub-control board 370 to be configured, and the configuration of FPGA 31 is executed (step S104).

[0163] The setting device 500 determines whether the value of variable i is "4" (step S105). If the value of variable i is not "4" (NO in step S105), the setting device 500 increments variable i (step S106) and returns to step S102.

[0164] If the value of variable i is "4" (YES in step S105), the setting device 500 displays that the FPGA configuration of the four sub-control boards 370 is complete (step S107). When the operator recognizes from the display of the setting device 500 that the FPGA configuration of the four sub-control boards 370 is complete, they remove the four sub-control boards 370 from the connection device 400 (step S108). This completes the configuration of the FPGA 31 of the sub-control boards 370.

[0165] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and includes the meaning of equivalents to the claims and all modifications within that scope.

[0166] 100 Remote control system 200 Access network 10 Optical wavelength division multiplexing switch (Optical Wavelength Division Multiplexing SW) 11 Optical remote control module 12 Wavelength selector switch (WSS) 13 Wavelength division multiplexing separation unit (Add / Drop) 14 Control signal multiplexing unit 14AA, 14AB, 14BA, 14BB, 14CA, 14CB WDM coupler 20 Optical branching device 21A, 21B, 22A, 22B, 24AA, 24AB, 24AC, 24BA, 24BB, 24BC WDM coupler 23A, 23B Optical coupler 30, 30A, 30B, 30C Optical transceiver 301T Light emitting unit 301TL Laser diode 301TG Light guide unit 301TH Heat conduction unit 301R Light receiving unit 302 Drive circuit 303 Digital signal processor (DSP) 304A, 304B WDM coupler 304Ah, 304Bh WDM coupler housing 305 Dual-wavelength TOSA (optical transmitter) 306 Dual-wavelength ROSA (optical receiver) 31 ONU function unit (FPGA) 311T Light-emitting unit 311R Light-receiving unit 312 LDD / LA 313 Frame processing unit 314 Processor 315 Memory 32 Microcontroller unit (MCU) 321 Processor 322 Memory 323 Digital-to-analog converter (DAC) 324 Analog-to-digital converter (ADC) 33 Connectors 33A, 33B, 33C, 33D, 33E, 33F, 33G Terminals 340 Enclosure 341, 342 Aperture 351, 361 Optical connector 360 Main control board 362T, 362R Flexible printed circuit board (FPC) 363 Wavelength control circuit 364 Laser current control circuit 365 Power supply circuit 366 Inter-board connectors 366A, 366B, 366C, 366D, 366E, 366F, 366G, 366H, 366I, 366J, 366K, 366L, 366M, 366N, 366P, 366Q, 366R, 366S, 366T Signal line 370 Sub-control board 371 Flexible printed circuit board (FPC) 371R Recess 372 Power supply circuit 373 Inter-board connector 373A, 373B, 373C, 373D, 373E, 373F, 373G, 373H, 373I, 373J, 373K, 373L Signal line 40, 40A,40B, 40C User equipment (host equipment) 401 Connector 400 Connection device 410 Inter-board connector 420 Switch 420A First terminal 420B Second terminal 430 Connector 440 Power supply circuit 50 Management device 500 Setting device 501 Signal cable 502 Connector 60A, 60B Optical transmission line 61A, 61B, 61C Optical transmission line 61AA, 61AB, 61BA, 61BB, 61CA, 61CB Optical transmission line 62A, 62B, 62C Optical transmission line 62AA, 62AB, 62BA, 62BB, 62CA, 62CB Optical transmission line 65 Transmission line AP1, AP2, AP3 Access port MP1, MP2 Metro port PA, PB Port,

Claims

1. An optical transceiver that can be attached to a host device, comprising: an optical transmitting unit that wavelength-multiplexes a first optical signal which is a first main signal and a second optical signal which is a first control signal and transmits it as a first wavelength-multiplexed signal; an optical receiving unit that receives a second wavelength-multiplexed signal which is a wavelength-multiplexed signal obtained by wavelength-multiplexing a third optical signal which is a second main signal and a fourth optical signal which is a second control signal; and a connecting unit for connecting to a port of the host device, wherein the optical transmitting unit includes: a first light-emitting unit that outputs the first optical signal in a first direction; a second light-emitting unit that outputs the second optical signal in a second direction intersecting the first direction; a wavelength-multiplexing unit that wavelength-multiplexes the first optical signal input from the first light-emitting unit in the first direction and the second optical signal input from the second light-emitting unit in the second direction and outputs the first wavelength-multiplexed signal in the first direction, and the optical receiving unit is An optical transceiver comprising: a separation unit that wavelength-separates the second wavelength-multiplexed signal input in the first direction into a third optical signal and a fourth optical signal, outputs the third optical signal in the first direction and outputs the fourth optical signal in the second direction; a first light-receiving unit that receives the third optical signal output from the separation unit in the first direction; and a second light-receiving unit that receives the fourth optical signal output from the separation unit in the second direction.

2. The optical transceiver according to claim 1, further comprising a housing defined in a standard form factor, wherein the optical transmitting unit, the optical receiving unit, and the connecting unit are housed in the housing.

3. The optical transceiver according to claim 1 or 2, wherein the first optical signal is faster than the second optical signal, and the third optical signal is faster than the fourth optical signal.

4. The optical transceiver according to claim 2 or 3, wherein the optical transmitting unit and the optical receiving unit are arranged in a third direction intersecting the first direction and the second direction, respectively.

5. The optical transceiver according to claim 4, further comprising: a first control board on which a first control circuit for controlling the first light-emitting unit and the first light-receiving unit is mounted; and a second control board on which a second control circuit for controlling the second light-emitting unit and the second light-receiving unit is mounted, wherein the first control board and the second control board are stacked in the second direction; the first control board includes a first inter-board connector disposed on the surface facing the second control board; and the second control board includes a second inter-board connector disposed on the surface facing the first control board and connectable to the first inter-board connector.

6. The optical transceiver according to claim 5, wherein the first board-to-board connector includes a first pin for first serial communication and a second pin for second serial communication, and the second board-to-board connector includes a third pin for first serial communication connectable to the first pin and a fourth pin for second serial communication connectable to the second pin.

7. The optical transceiver according to claim 6, wherein in the first serial communication, the first control circuit is the master and the second control circuit is the slave, and in the second serial communication, the second control circuit is the master and the second control circuit is the slave.

8. The optical transceiver according to any one of claims 5 to 7, wherein the second board-to-board connector includes a fifth pin for inputting a received loss signal indicating that the intensity of the fourth optical signal received by the second light-receiving unit is below a predetermined threshold, and a sixth pin for inputting a transmitted fault signal indicating that an error has occurred in the second optical signal transmitted by the second light-emitting unit, and the first board-to-board connector includes a seventh pin for outputting the received loss signal input to the fifth pin to the first control circuit, and an eighth pin for outputting the transmitted fault signal input to the sixth pin to the first control circuit.

9. The optical transceiver according to any one of claims 5 to 8, wherein the first board-to-board connector includes a ninth pin for inputting power of a first voltage from the host device via the connection part, the second board-to-board connector includes a tenth pin connected to the ninth pin, and the second control board further includes a power conversion unit for converting power output from the tenth pin from the first voltage to the second voltage.

10. The optical transceiver according to any one of claims 5 to 9, wherein the second board connector includes an eleventh pin for inputting setting information of the second control circuit.

11. The optical transceiver according to any one of claims 5 to 10, further comprising: a flexible substrate connecting the second light-emitting unit and the second light-receiving unit to the second control board; and a heat conduction unit for conducting heat generated from the first light-emitting unit to the housing, wherein the heat conduction unit is superimposed on the first light-emitting unit in the second direction, and the flexible substrate has a recess for avoiding the heat conduction unit.

12. A setting method for setting a control circuit mounted on the second control board for controlling the second light-emitting unit and the second light-receiving unit, wherein the optical transceiver is capable of mounting a first control board for controlling a first light-emitting unit and a first light-receiving unit mounted on the optical transceiver for transmitting and receiving an optical signal which is a main signal, and a second control board for controlling a second light-emitting unit and a second light-receiving unit mounted on the optical transceiver for transmitting and receiving an optical signal which is a control signal, the setting method comprising: connecting a second inter-board connector provided on the second control board, which is connectable to a first inter-board connector provided on the first control board, to a third inter-board connector provided on a connecting device; outputting setting information for setting the control circuit from the connecting device to the second inter-board connector through the third inter-board connector; outputting the setting information input to the second inter-board connector to the control circuit; and setting the control circuit using the setting information input to the control circuit.

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