Optical communication device and method for activating an optical communication path

Abstract

This optical communication device comprises: a first optical multiplexing / demultiplexing unit that branches and outputs a control signal and main signal light transmitted at different wavelengths from at least one subscriber device that is newly connected; an optical distribution unit that has a plurality of first ports and a plurality of second ports, and that inputs at least the main signal light branched at the first optical multiplexing / demultiplexing unit from one first port of the plurality of first ports, and performs output thereof from one second port of the plurality of second ports; a detecting unit that is provided inside or outside of the optical distribution unit and detects the main signal light; a subscriber device management control unit that recognizes the port of the optical distribution unit to which the at least one subscriber device that is newly connected is connected, on the basis of the main signal light detected by the detecting unit; and an optical distribution control unit that controls connection between ports of the optical distribution unit, such that the main signal light transmitted from the at least one subscriber device that is newly connected is transferred to a subscriber device that is a communicating party.　

Description

Technical Field

[0001] The present invention relates to an optical communication device and an optical communication path opening method.

Background Art

[0002] In a conventional optical communication system, a subscriber device needs to open an optical path for connecting to a subscriber device that is a communication partner in order to perform communication. FIGS. 8 and 9 are diagrams for explaining a method of opening an optical path in a conventional optical communication system 100. As shown in FIG. 8, a conventional optical communication system 100 includes a plurality of subscriber devices 200-1 to 200-3, a plurality of subscriber devices 300-1 to 300-3, a plurality of control units 400-1 to 400-2, a plurality of optical oscillator units 500-1 to 500-2, and a plurality of wavelength multiplexing / demultiplexing units 550-1 to 550-2.

[0003] Note that the subscriber device 200-1 is not connected to the optical oscillator unit 500-1, the subscriber devices 200-2 to 200-3 are connected to the optical oscillator unit 500-1 via an optical transmission line, and the subscriber devices 300-1 to 300-3 are connected to the optical oscillator unit 500-2 via an optical transmission line. The optical oscillator unit 500-1 and the optical oscillator unit 500-2 are connected via an optical communication NW600 composed of an optical transmission line and the wavelength multiplexing / demultiplexing units 550-1 to 550-2. The control unit 400-1 manages the subscriber device 200 and controls the operation of the optical oscillator unit 500-1. The control unit 400-2 manages the subscriber device 300 and controls the operation of the optical oscillator unit 500-2.

[0004] When a user attempts to initiate communication via subscriber device 200-1, assume that subscriber device 200-1 is newly connected to the optical distribution unit 500-1. During the initial connection of subscriber device 200-1, the optical distribution unit 410 sets up the connection between the ports of the optical distribution unit 500-1 so that subscriber device 200-1 can communicate with subscriber device management control unit 420. This allows for the exchange of information necessary for the registration and authentication of subscriber device 200-1 between subscriber device 200-1 and subscriber device management control unit 420, and allows subscriber device management control unit 420 to instruct subscriber device 200-1 on the emission wavelength to be used for transmission and reception. A control signal called AMCC (Auxiliary Management and Control Channel) can be used as a signal for the management and control of subscriber devices. The AMCC signal includes status information such as the transmission and reception wavelengths of the optical transceiver, the transmitted light intensity, and the temperature.

[0005] Once registration and authentication of subscriber device 200-1, wavelength setting, etc., are completed, the optical distribution control unit 410 changes the port connection settings of the optical distribution unit 500-1 so that the optical signal transmitted from subscriber device 200-1 is forwarded to the subscriber device 300 (for example, subscriber device 300-1), which is the communication partner, as shown in Figure 9. Similarly, the control unit 400-2 changes the port connection settings of the optical distribution unit 500-2 so that the optical signal transmitted from subscriber device 200-1 is forwarded to the subscriber device 300 (for example, subscriber device 300-1), which is the communication partner. As a result, an optical path connecting subscriber device 200-1 and subscriber device 300-1 can be opened, as shown in Figure 9.

[0006] However, in the configuration of the optical communication system 100 shown in Figures 8 and 9, once the optical path is established, there is no control channel for transmitting control signals between the control unit 400 and the subscriber devices 200 and 300. In contrast, with the configuration of the optical communication system 150 shown in Figure 10, even after the optical path is established, the control unit 400 can exchange control signals with multiple subscriber devices 200 and 300.

[0007] Figure 10 shows an example configuration of a conventional optical communication system 150. As shown in Figure 10, the conventional optical communication system 150 comprises a plurality of subscriber devices 200-1 to 200-3, a plurality of subscriber devices 300-1 to 300-3, a plurality of control units 400-1 to 400-2, a plurality of optical distribution units 500-1 to 500-2, a plurality of wavelength multiplexing and demultiplexing units 550-1 to 550-2, a plurality of first optical multiplexing and demultiplexing units 610-1 to 610-3, a second optical multiplexing and demultiplexing unit 620, a plurality of first optical multiplexing and demultiplexing units 630-1 to 630-3, and a second optical multiplexing and demultiplexing unit 640. The optical communication system 150 is configured in addition to the optical communication system 100 shown in Figures 8 and 9, by adding a plurality of first optical combining and demultiplexing units 610-1 to 610-3, a second optical combining and demultiplexing unit 620, a plurality of first optical combining and demultiplexing units 630-1 to 630-3, and a second optical combining and demultiplexing unit 640.

[0008] Multiple first optical combining and demultiplexing units 610-1 to 610-3 are provided between multiple subscriber devices 200-1 to 200-3 and the optical distribution unit 500-1. A second optical combining and demultiplexing unit 620 is provided between multiple first optical combining and demultiplexing units 610-1 to 610-3 and the control unit 400-1. Multiple first optical combining and demultiplexing units 630-1 to 630-3 are provided between multiple subscriber devices 300-1 to 300-3 and the optical distribution unit 500-2. A second optical combining and demultiplexing unit 640 is provided between multiple first optical combining and demultiplexing units 630-1 to 630-3 and the control unit 400-2.

[0009] Subscriber devices 200-1 to 200-3 output uplink control signals to the control unit 400-1 at a different wavelength from the optical carrier carrying the main signal (hereinafter referred to as "main signal light"). Multiple first optical multiplexers and demultiplexers 610-1 to 610-3 transfer the uplink control signals transmitted from subscriber devices 200-1 to 200-3 to the second optical multiplexer and demultiplexer 620. The second optical multiplexer and demultiplexer 620 multiplexes the uplink control signals transferred from the multiple first optical multiplexers and demultiplexers 610-1 to 610-3 and outputs them to the control unit 400-1. The control unit 400-2 outputs downlink control signals to multiple subscriber devices 300-1 to 300-3 at a different wavelength from the main signal light. The second optical multiplexer and demultiplexer 640 branches the downlink control signals output from the control unit 400-2 and outputs them to multiple first optical multiplexers and demultiplexers 630-1 to 630-3. Multiple first optical multiplexers 630-1 to 630-3 wavelength-multiplex the downlink control signal and the main signal light and output them to multiple subscriber devices 300-1 to 300-3.

[0010] With the above configuration, the control units 400-1 to 400-2 exchange information with subscriber devices 200 and 300 before optical path activation, including registration, authentication, and information necessary for optical path activation, via multiple first optical multiplexers / demultiplexers 610-1 to 610-3 and a second optical multiplexer / demultiplexer 620, or multiple first optical multiplexers / demultiplexers 630-1 to 630-3 and a second optical multiplexer / demultiplexer 640. Similarly, the control units 400-1 to 400-2 can exchange control information with subscriber devices 200 and 300 after optical path activation, via multiple first optical multiplexers / demultiplexers 610-1 to 610-3 and a second optical multiplexer / demultiplexer 620, or multiple first optical multiplexers / demultiplexers 630-1 to 630-3 and a second optical multiplexer / demultiplexer 640. [Prior art documents] [Non-patent literature]

[0011] [Non-Patent Document 1] Takuya Kanai, Kazuaki Honda, Yasunari Tanaka, Shin Kaneko, Kazuki Hara, Junichi Kani, and Tomoaki Yoshida, “Photonic Gateway Supporting All-Photonics Networks,” IEICE General Conference, B-8-20, March 2021. [Overview of the project] [Problems that the invention aims to solve]

[0012] In order to open an optical path to a newly connected subscriber device, the optical distribution control unit must configure the inter-port connections of the optical distribution unit so that the main signal light transmitted from the newly connected subscriber device is forwarded to the subscriber device that will be communicating with the new subscriber device, once the registration and authentication of the newly connected subscriber device and wavelength settings are completed. At this time, in order for the optical distribution control unit to appropriately change the inter-port connection settings of the optical distribution unit, the control unit needs to know which port of the optical distribution unit the newly connected subscriber device is connected to via the optical transmission path. However, in the conventional configuration shown in Figure 10, the control unit cannot know which port of the optical distribution unit the newly connected subscriber device is connected to via the optical transmission path, which is the problem that prevents the opening of the optical path.

[0013] In view of the above circumstances, the present invention aims to provide a technology that enables the opening of an optical path to enable communication between a newly connected subscriber device and a subscriber device to communicate with, in an optical communication system equipped with an optical multiplexer / demultiplexer between an optical distribution unit or control unit and a subscriber device. [Means for solving the problem]

[0014] One aspect of the present invention is an optical communication device comprising: a first optical multiplexer / demultiplexer that splits and outputs a control signal and a main signal light transmitted at different wavelengths from at least one newly connected subscriber device; an optical distribution unit having a plurality of first ports and a plurality of second ports, which inputs at least the main signal light split by the first optical multiplexer / demultiplexer from a first port of any of the plurality of first ports and outputs it from a second port of any of the plurality of second ports; a detection unit provided inside or outside the optical distribution unit for detecting the main signal light; a subscriber device management control unit that recognizes the port of the optical distribution unit to which the at least one newly connected subscriber device is connected based on the main signal light detected by the detection unit; and an optical distribution control unit that controls the connections between ports of the optical distribution unit so that the main signal light transmitted from the at least one newly connected subscriber device is transferred to a subscriber device that is to communicate with the other party.

[0015] One aspect of the present invention is an optical communication path opening method comprising: an optical distribution unit having a plurality of first ports and a plurality of second ports, which splits and outputs control signals and main signal light transmitted at different wavelengths from at least one newly connected subscriber device, inputs at least the split main signal light from one of the plurality of first ports and outputs it from one of the plurality of second ports, detects the main signal light inside or outside the optical distribution unit, recognizes the port of the optical distribution unit to which the newly connected at least one subscriber device is connected based on the detected main signal light, and controls the connection between ports of the optical distribution unit so that the main signal light transmitted from the newly connected at least one subscriber device is forwarded to the subscriber device that will be the communication partner. [Effects of the Invention]

[0016] The present invention makes it possible to open an optical path that enables communication between a newly connected subscriber device and a subscriber device in an optical communication system equipped with an optical multiplexer / demultiplexer between an optical distribution unit or control unit and a subscriber device. [Brief explanation of the drawing]

[0017] [Figure 1] It is a diagram showing a configuration example of an optical communication system in the first embodiment. [Figure 2] It is a sequence diagram showing the flow of the optical path opening process of the optical communication system in the first embodiment. [Figure 3] It is a sequence diagram showing the flow of the optical path opening process of the optical communication system in the first embodiment. [Figure 4] It is a diagram showing a configuration example of an optical communication system in Modification 1 of the first embodiment. [Figure 5] It is a diagram showing a configuration example of an optical communication system in Modification 2 of the first embodiment. [Figure 6] It is a diagram showing a configuration example of an optical communication system in the second embodiment. [Figure 7] It is a diagram showing a configuration example after the optical path is opened in the optical communication system in the second embodiment. [Figure 8] It is a diagram for explaining a method of opening an optical path in a conventional optical communication system. [Figure 9] It is a diagram for explaining a method of opening an optical path in a conventional optical communication system. [Figure 10] It is a diagram showing a configuration example of a conventional optical communication system.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] (First Embodiment) Figure 1 shows an example configuration of the optical communication system 1 in the first embodiment. The optical communication system 1 comprises a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing and demultiplexing units 20 (e.g., first optical multiplexing and demultiplexing units 20-1 to 20-3), a second optical multiplexing and demultiplexing unit 30, a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of wavelength multiplexing and demultiplexing units 50 (e.g., wavelength multiplexing and demultiplexing units 50-1 to 50-2), a plurality of first optical multiplexing and demultiplexing units 60 (e.g., first optical multiplexing and demultiplexing units 60-1 to 60-3), a second optical multiplexing and demultiplexing unit 70, and a management control device 80. In the first embodiment, the case in which subscriber device 10 transmits an optical signal and subscriber device 15 receives the optical signal transmitted from subscriber device 10 will be described as an example.

[0020] In the following description, the direction from subscriber devices 10 and 15 toward the management control device 80 is referred to as the upstream direction, and the direction from the management control device 80 toward subscriber devices 10 and 15 is referred to as the downstream direction. The number of subscriber devices 10, subscriber devices 15, first optical multiplexing and demultiplexing units 20 and 60, second optical multiplexing and demultiplexing units 30 and 70, optical distribution unit 40, and wavelength multiplexing and demultiplexing unit 50 provided in the optical communication system 1 is not limited to the number shown in Figure 1.

[0021] The following connections are made using an optical transmission path: between the subscriber device 10 and the first optical multiplexer / demultiplexer unit 20, between the first optical multiplexer / demultiplexer unit 20 and the second optical multiplexer / demultiplexer unit 30, between the second optical multiplexer / demultiplexer units 30 and 70 and the management control device 80, between the first optical multiplexer / demultiplexer unit 20 and the optical distribution unit 40-1, between the optical distribution unit 40-1 and the wavelength multiplexer / demultiplexer unit 50-1, between the wavelength multiplexer / demultiplexer unit 50-1 and the wavelength multiplexer / demultiplexer unit 50-2, between the wavelength multiplexer / demultiplexer unit 50-2 and the optical distribution unit 40-2, between the optical distribution unit 40-2 and the first optical multiplexer / demultiplexer unit 60, between the first optical multiplexer / demultiplexer unit 60 and the subscriber device 15, and between the first optical multiplexer / demultiplexer unit 60 and the second optical multiplexer / demultiplexer unit 70. The optical transmission path is, for example, an optical fiber. The space between wavelength combining / demultiplying unit 50-1 and wavelength combining / demultiplying unit 50-2 is connected by an optical communication network NW75.

[0022] The subscriber device 10 is equipped with an optical transceiver. The optical transceiver is, for example, a coherent transceiver. The subscriber device 10 transmits and receives optical signals such as main signals and control signals using the optical transceiver. Before the optical path is activated, the subscriber device 10 transmits light of a wavelength that reaches the optical distribution unit 40-1 at one of the following timings: before it starts exchanging information with the management control unit 80 for registration and authentication and optical path activation, during the exchange, or after the exchange is completed.

[0023] The information required for optical path activation includes, for example, information on the wavelengths used for transmission and reception, and information on the subscriber device 15 to be communicated. Hereinafter, unless otherwise specified, the timing before the start of the exchange of information with the management control device 80 for registration and authentication and optical path activation, during the exchange period, or after the exchange is completed will be referred to as the main signal optical transmission timing. The wavelength of light reaching the optical distribution unit 40-1 is the light within the wavelength range transmitted from the input / output port on the subscriber device 10 side to the port on the optical distribution unit 40-1 side among the input / output ports of the first optical multiplexer / demultiplexer unit 20.

[0024] The subscriber device 10 transmits light of a wavelength that reaches the optical distribution unit 40-1 at the main signal light transmission timing. When the subscriber device 10 transmits light of a wavelength that reaches the optical distribution unit 40 at the main signal light transmission timing, the subscriber device 10 may determine the transmission timing itself, or it may transmit after receiving a transmission command from the management control device 80 via a downstream control signal.

[0025] If the subscriber device 10 itself determines the transmission timing, there is a possibility that two or more subscriber devices 10 may transmit light of the same wavelength simultaneously. On the other hand, if the device transmits after receiving a transmission command via a downlink control signal from the management control device 80, the possibility of simultaneous transmission of light of the same wavelength can be avoided if the management control device 80 sends a transmission command to each subscriber device 10.

[0026] The subscriber device 10 outputs an uplink control signal to the management control device 80 as an optical signal with a different wavelength from the main signal light. The wavelength of the uplink control signal transmitted by the subscriber device 10 is within the wavelength range that is transmitted from the input / output port of the first optical multiplexer / demultiplexer 20 on the subscriber device 10 side to the port on the second optical multiplexer / demultiplexer 30 side. Note that the wavelengths of the uplink control signals transmitted by each subscriber device 10 may all be the same. The subscriber device 10 is, for example, an ONU (Optical Network Unit) installed in the subscriber's premises. In the following description, it is assumed that subscriber device 10-1 is a subscriber device newly connected to the optical distribution unit 40-1.

[0027] The subscriber device 15 is a device that communicates with the subscriber device 10. The subscriber device 15 is equipped with an optical transceiver. The subscriber device 15 transmits and receives optical signals such as main signals and control signals using the optical transceiver. The subscriber device 15 also performs the same processing as the subscriber device 10 in terms of processing before the optical path is opened. The subscriber device 15 receives the downlink control signal transmitted from the management control device 80 and the main signal light that has been transmitted through the optical transmission path 86. The subscriber device 15 is installed, for example, in the subscriber's home.

[0028] The first optical multiplexer / demultiplexer 20 is provided between the subscriber device 10 and the optical distribution unit 40-1. The first optical multiplexer / demultiplexer 20 splits and outputs the uplink control signal and the main signal light transmitted from each subscriber device 10 at different wavelengths. In the following description, the splitting performed by the first optical multiplexer / demultiplexer 20 includes cases where the uplink control signal and the main signal light are separated, and cases where the uplink control signal and the main signal light are split at a predetermined ratio. When separating the uplink control signal and the main signal light, the first optical multiplexer / demultiplexer 20 separates the uplink control signal and the main signal light by wavelength, outputs the separated uplink control signal to the second optical multiplexer / demultiplexer 30, and outputs the separated main signal light to the optical distribution unit 40-1. When splitting the uplink control signal and the main signal light at a predetermined ratio, the first photomultiplier / demultiplier unit 20 splits both the uplink control signal and the main signal light at a predetermined ratio and outputs them to the second photomultiplier / demultiplier unit 30 and the optical distribution unit 40-1. In the first embodiment, the first photomultiplier / demultiplier unit 20 uses a wavelength-selective photomultiplier / demultiplier (for example, a wavelength filter).

[0029] The second photomultiplier / demultiplier unit 30 is provided between the first photomultiplier / demultiplier unit 20 and the control unit 81-1. The second photomultiplier / demultiplier unit 30 multiplexes the uplink control signals transferred from each of the first photomultiplier / demultiplier units 20 and outputs them to the control unit 81-1. The second photomultiplier / demultiplier unit 30 is, for example, an optical coupler.

[0030] The optical distribution unit 40-1 has P (where P is an integer of 2 or more) ports 41-1, Q (where Q is an integer of 2 or more) ports 42-1, and a photodetector 43-1. The optical distribution unit 40-2 has the same configuration as the optical distribution unit 40-1, so the configuration of the optical distribution unit 40-1 will be used as an example for explanation. An optical signal input to one port of the optical distribution unit 40 is output from another port. For example, an optical signal input to port 41-1 of the optical distribution unit 40 is output from port 42-1. The optical distribution unit 40 in the first embodiment is an FXC (Fiber Cross Connect) that outputs the light input from each port to a port that is configured as a connection port to that port, regardless of wavelength. As the optical distribution unit 40 in the first embodiment, for example, a spatial optical switch using MEMS (Micro Electro Mechanical Systems) or a piezo actuator is used. Port 41-1 is an embodiment of the first port, and port 42-1 is an embodiment of the second port.

[0031] The light detection unit 43-1 detects the optical signal input to port 41-1. When the light detection unit 43-1 detects an optical signal, it notifies the management control device 80 of the detection results, including the port to which the optical signal was detected. The notification from the light detection unit 43-1 to the management control device 80 may be made via the electrical wire connecting the management control device 80 and the optical distribution unit 40-1. The notification transmitted from the light detection unit 43-1 allows the management control device 80 to recognize the input of light to the port to which the subscriber device 10 has been newly connected.

[0032] The wavelength combining / demultiplexing unit 50 combines or separates the input optical signal according to its wavelength. For example, the wavelength combining / demultiplexing unit 50-1 combines multiple wavelength optical signals output from the optical distribution unit 40-1 to generate a multiplexed signal. The wavelength combining / demultiplexing unit 50-1 outputs the generated multiplexed signal to the optical transmission path. For example, the wavelength combining / demultiplexing unit 50-2 separates the multiplexed signal input via the optical transmission path for each wavelength and outputs it. The wavelength combining / demultiplexing unit 50 is, for example, an AWG (Arrayed Waveguide Grating) or a WSS (Wavelength Selective Switch).

[0033] The first optical multiplexer / demultiplexer 60 is provided between the subscriber device 15 and the optical distribution unit 40-2. The first optical multiplexer / demultiplexer 60 wavelength-multiplexes the main signal light transmitted through the optical transmission path and the downlink control signal output from the second optical multiplexer / demultiplexer 70 and outputs it to the subscriber device 15. In the first embodiment, the first optical multiplexer / demultiplexer 60 uses a wavelength-selective optical multiplexer / demultiplexer (for example, a wavelength filter).

[0034] The second photomultiplier / demultiplier unit 70 is provided between the first photomultiplier / demultiplier unit 60 and the control unit 81-2. The second photomultiplier / demultiplier unit 70 branches the downlink control signal output from the control unit 81-2 and outputs it to each of the first photomultiplier / demultiplier units 60. The second photomultiplier / demultiplier unit 70 is, for example, an optical coupler.

[0035] The management control device 80 controls at least the subscriber devices 10 and 15 and the optical distribution unit 40. Control of the subscriber devices 10 and 15 includes, for example, controlling the timing of transmission of control signals, assigning emission wavelengths to the subscriber devices 10 and 15, issuing optical stop instructions and wavelength change instructions. Control of the optical distribution unit 40 includes, for example, switching connections between ports of the optical distribution unit 40. The management control device 80 comprises a plurality of control units 81 (for example, control units 81-1 to 81-2). Each control unit 81 controls each optical distribution unit 40 and the subscriber devices 10 and 15 housed in each optical distribution unit 40. For example, control unit 81-1 controls the optical distribution unit 40-1 and the subscriber device 10 housed in the optical distribution unit 40-1. For example, control unit 81-2 controls the optical distribution unit 40-2 and the subscriber device 15 housed in the optical distribution unit 40-2.

[0036] Control unit 81-1 comprises an optical distribution control unit 82-1 and a subscriber equipment management control unit 83-1. Control unit 81-2 has the same configuration as control unit 81-1. Since control units 81-1 and 81-2 perform similar processing except for the difference in the controlled objects, the optical distribution control unit 82-1 and the subscriber equipment management control unit 83-1 will be explained as examples.

[0037] The optical distribution control unit 82-1 sets and switches the connections between ports of the optical distribution unit 40 and sets the optical path.

[0038] When a subscriber device 10 is newly connected to the optical distribution unit 40, the subscriber device management control unit 83-1 sends a search signal to the newly connected subscriber device 10 requesting it to send a response signal. The subscriber device management control unit 83-1 may send the search signal periodically, or it may send the search signal only when it detects the connection of a subscriber device 10 requesting the opening of an optical path. Through the exchange of search signals, response signals, and subsequent signals with the subscriber device 10, the subscriber device management control unit 83-1 measures the round trip time (RTT) between the subscriber device 10 and the subscriber device management control unit 83-1.

[0039] The subscriber device management control unit 83-1 performs photoelectric conversion on the uplink control signal transmitted from the subscriber device 10, and then uses an identifier included in the uplink control signal to recognize the subscriber device 10 that is the source of the received uplink control signal. Examples of identifiers include the ID assigned to the subscriber device 10 by the subscriber device management control unit 83-1, and the MAC (Media Access Control) address of the subscriber device 10.

[0040] If multiple subscriber devices 10 transmit uplink control signals simultaneously, these signals may collide. Therefore, to enable the subscriber device management control unit 83-1 to exchange control signals with multiple subscriber devices 10, a Passive Optical Network (PON) method can be applied, for example. The subscriber device 10 outputs an uplink control signal, including the control signal, only during the time period permitted by the subscriber device management control unit 83-1, and stops outputting the uplink control signal during other times. In other words, the uplink control signal is a burst signal light.

[0041] The subscriber device management control unit 83-1 recognizes the round-trip time (RTT) between itself and each subscriber device 10. Therefore, the subscriber device management control unit 83-1 refers to the RTT value and grants permission to each subscriber device 10 to transmit an uplink control signal, so that the uplink control signal from the subscriber device 10, which is a burst signal light, does not reach the subscriber device management control unit 83-1 at the same time as the uplink control signals from other subscriber devices 10.

[0042] Furthermore, the subscriber device management control unit 83-1 grants permission to transmit an uplink control signal to a subscriber device 10 with an established optical path, by referring to the RTT value between each subscriber device 10 and the subscriber device management control unit 83-1, so that an uplink control signal including a response signal sent back by a subscriber device 10 (e.g., subscriber device 10-1) in response to a search signal from the subscriber device management control unit 83-1 can reach the subscriber device management control unit 83-1 before the optical path is established.

[0043] With the above configuration, the subscriber device management control unit 83-1 exchanges information with the subscriber device 10 before the optical path is activated, via the first optical multiplexer / demultiplexer unit 20 and the second optical multiplexer / demultiplexer unit 30, which is necessary for registration, authentication, and activation of the optical path. Furthermore, the subscriber device management control unit 83-1 exchanges control information with the subscriber device 10 after the optical path is activated, via the first optical multiplexer / demultiplexer unit 20 and the second optical multiplexer / demultiplexer unit 30.

[0044] Furthermore, when a subscriber device 10 is newly connected to the optical distribution unit 40, the subscriber device management control unit 83-1 identifies which port of the optical distribution unit 40 the newly connected subscriber device 10 is connected to, based on the detection result transmitted from the optical distribution unit 40. The subscriber device management control unit 83-1 then performs the process of opening the optical path by switching the connection relationship of the optical distribution unit 40 so that communication is possible between the identified port and the port to which the subscriber device 15 to be communicated is connected.

[0045] In the process of exchanging information necessary for registration, authentication, and optical path activation with the newly connected subscriber device 10, the subscriber device management control unit 83-1 recognizes, based on the detection results obtained from the optical distribution unit 40, that the port of the optical distribution unit 40-1 to which a new optical input has been detected is the port to which the newly connected subscriber device 10 is connected, within a predetermined time before, after, or before / after the reference time when the connection of the new subscriber device 10 is recognized.

[0046] The control unit 81-2 transmits a downlink control signal to the subscriber device 15. The wavelength of the downlink control signal transmitted by the control unit 81-2 is within the wavelength range that is transmitted from the input / output port of the first photomultiplier / demultiplier unit 60 on the side of the second photomultiplier / demultiplier unit 70 to the port on the subscriber device 15 side. The downlink control signal is a signal light obtained by time-multiplying downlink control signals for each subscriber device 15. After photoelectric conversion of the downlink control signal, the subscriber device 15 selectively receives the downlink control signal for itself from the time-multiplyed downlink control signal using an identifier included in the downlink control signal. Examples of identifiers include the ID assigned to the subscriber device 15 by the subscriber device management control unit 83-2 provided in the control unit 81-2, and the MAC address of the subscriber device 15. The functions of the control unit 81 may be realized by one or more processors executing a program.

[0047] Figures 2 and 3 are sequence diagrams showing the flow of the optical path activation process of the optical communication system 1 in the first embodiment. In Figures 2 and 3, the main signal optical transmission timing is described as occurring at some point during the period in which information necessary for registration, authentication, and optical path activation is exchanged between the subscriber device 10 and the management control device 80.

[0048] Assume that the user connects the subscriber device 10-1 to the optical distribution unit 40-1 via the optical transmission path 85-1. As a result, the subscriber device 10 is connected to the optical distribution unit 40-1 via the optical transmission path 85-1 (step S101). The subscriber device management control unit 83-1, which is part of the control unit 81-1, periodically transmits a search signal, or when the connection of the subscriber device 10 is detected (step S102).

[0049] After transmitting the search signal, the subscriber device management control unit 83-1 controls the timing of transmission of the uplink control signals from subscriber devices 10 whose optical paths are open (step S103). Specifically, the subscriber device management control unit 83-1 refers to the RTT value of the subscriber devices 10 whose optical paths are open and grants permission to transmit to each of the subscriber devices 10 whose optical paths are open so that uplink control signals from other subscriber devices 10 do not reach the subscriber device management control unit 83-1 during the period in which the uplink control signal including the response signal that subscriber device 10-1 sends back in response to the search signal can reach the subscriber device management control unit 83-1. This prevents the subscriber device management control unit 83-1 from receiving the uplink control signal including the response signal from subscriber device 10-1 when the subscriber device management control unit 83-1 receives the uplink control signal from other subscriber devices 10, thus preventing the subscriber device management control unit 83-1 from receiving the uplink control signal.

[0050] The search signal transmitted from the subscriber device management control unit 83-1 is input to the second optical multiplexer / demultiplexer 30. The second optical multiplexer / demultiplexer 30 branches the input search signal and outputs it. The search signal branched by the second optical multiplexer / demultiplexer 30 is input to each first optical multiplexer / demultiplexer 20. Each first optical multiplexer / demultiplexer 20 outputs the input search signal to the connected subscriber device 10 via the optical transmission path 85. As a result, each subscriber device 10 receives the search signal transmitted from the subscriber device management control unit 83-1.

[0051] The subscriber device 10-1 generates an uplink control signal, including a response signal, in response to receiving a search signal transmitted from the subscriber device management control unit 83-1. The subscriber device 10-1 transmits the generated uplink control signal to the optical transmission line 85-1 (step S104). The uplink control signal transmitted from the subscriber device 10-1 is input to the first optical multiplexer / demultiplexer 20-1 via the optical transmission line 85-1.

[0052] The first optical combiner / demultiplexer 20-1 outputs the input uplink control signal to the second optical combiner / demultiplexer 30. The wavelength of the uplink control signal transmitted by the subscriber device 10 is within the wavelength range that can be transmitted from the input / output port of the first optical combiner / demultiplexer 20 on the subscriber device 10 side to the port on the second optical combiner / demultiplexer 30 side. Therefore, the uplink control signal input to the first optical combiner / demultiplexer 20-1 is output to the second optical combiner / demultiplexer 30. However, if the wavelength of the uplink control signal transmitted by the subscriber device 10 is not within the wavelength range that can be transmitted from the input / output port of the first optical combiner / demultiplexer 20 on the subscriber device 10 side to the port on the optical distribution unit 40-1 side, the uplink control signal input to the first optical combiner / demultiplexer 20-1 is not output to the optical distribution unit 40-1.

[0053] The second photomultiplexer 30 multiplexes the uplink control signals output from each of the first photomultiplexers 20 and outputs them to the control unit 81-1. As a result, the uplink control signals transmitted from the subscriber device 10-1 are transferred to the control unit 81-1.

[0054] The subscriber equipment management control unit 83-1, which is part of the control unit 81-1, acquires the response signal included in the uplink control signal transmitted from the subscriber equipment 10-1 (step S105). Subsequently, the subscriber equipment management control unit 83-1 exchanges information with the subscriber equipment 10-1 necessary for opening the optical path (step S106). While the subscriber equipment management control unit 83-1 is exchanging information necessary for opening the optical path, it measures the round-trip time (RTT) between the subscriber equipment management control unit 83-1 and the subscriber equipment 10-1 (step S107). The subscriber equipment management control unit 83-1 stores the measured RTT value, associating it with the identifier of the subscriber equipment 10-1.

[0055] The subscriber device 10 transmits a main signal light of a wavelength that reaches the optical distribution unit 40-1 to the optical transmission line 85-1 at some point during the period in which it is exchanging information with the management control device 80 necessary for registration, authentication, and optical path activation (step S108). The main signal light transmitted from the subscriber device 10 is input to the first optical multiplexer / demultiplexer unit 20-1 via the optical transmission line 85-1.

[0056] The first optical multiplexer / demultiplexer 20-1 outputs the input main signal light to the optical distribution unit 40-1. Since the wavelength of the main signal light transmitted by the subscriber device 10 is within the wavelength range that can be transmitted from the input / output port of the first optical multiplexer / demultiplexer 20 on the subscriber device 10 side to the port on the optical distribution unit 40-1 side, the main signal light input to the first optical multiplexer / demultiplexer 20-1 is output to the optical distribution unit 40-1. The photodetector 43 of the optical distribution unit 40-1 detects the main signal light output from the first optical multiplexer / demultiplexer 20-1 (step S109). For example, the photodetector 43 detects the main signal light output from the first optical multiplexer / demultiplexer 20-1 at port 41-1-1. The photodetector 43 transmits the detection result indicating that light has been detected at port 41-1 to the control unit 81-1 (step S110).

[0057] The subscriber device management control unit 83-1, which is part of the control unit 81-1, acquires the detection result transmitted from the optical detection unit 43. Based on the acquired detection result, the subscriber device management control unit 83-1 recognizes the port to which the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected (step S111). Specifically, if the detection result is acquired before, after, or within a predetermined time frame before or after the reference time, the subscriber device management control unit 83-1 recognizes that the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is connected to the port indicated by the port information included in the detection result (for example, port 41-1-1).

[0058] On the other hand, if the subscriber device management control unit 83-1 does not obtain the detection result within a predetermined time before, after, or before / after the reference time, it recognizes that the subscriber device 10-1 newly connected to the optical distribution unit 40-1 is not connected to the port indicated by the port information included in the detection result (for example, port 41-1-1).

[0059] The optical distribution control units 82-1 and 82-2 set the connection relationships between the ports of the optical distribution units 40-1 and 40-2 based on the recognized ports and information about the subscriber device 15 (e.g., subscriber device 15-1) with which the subscriber device 10-1 communicates (step S112). Specifically, the optical distribution control unit 82-1 sets the connection relationships of the optical distribution unit 40-1 to connect port 41-1-1, to which the subscriber device 10-1 is connected, with port 42-1-2, which is connected to the optical distribution unit 40-2 to which the subscriber device 15-1 is connected. The optical distribution control unit 82-1 generates a control signal to connect port 41-1-1 and port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1 (step S113).

[0060] Similarly, the optical distribution control unit of the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-1 is connected to the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit of the control unit 81-2 generates a control signal to connect the port to which the subscriber device 15-1 is connected to the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit of the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0061] The optical distribution units 40-1 and 40-2 set the connection relationships between ports based on the control signals transmitted from the management control device 80 (step S114). This opens an optical path between subscriber device 10-1 and subscriber device 15-1. As a result, communication becomes possible between subscriber device 10-1 and subscriber device 15-1.

[0062] With the optical communication system 1 configured as described above, the control unit 81 can recognize which port of the optical distribution unit 40 the newly connected subscriber device 10 is connected to via the optical transmission path. As a result, the optical distribution control units 82-1 and 82-2 configure the inter-port connections of the optical distribution units 40-1 and 40-2 so that the main signal light transmitted from the newly connected subscriber device 10 is forwarded to the subscriber device 15 that will be the communication partner. This makes it possible to open an optical path that enables communication between the newly connected subscriber device and the subscriber device that will be the communication partner in an optical communication system equipped with an optical multiplexer / demultiplexer between the optical distribution unit or control unit and the subscriber device.

[0063] (Variation 1) In the configuration shown in Figure 1, the main signal light transmitted from subscriber device 10 to subscriber device 15 and the main signal light transmitted from subscriber device 15 to subscriber device 10 flow through the same optical transmission line. In contrast, there may be a configuration in which the main signal light transmitted from subscriber device 10 to subscriber device 15 and the main signal light transmitted from subscriber device 15 to subscriber device 10 each flow through different optical transmission line cores.

[0064] Figure 4 shows an example of the configuration of optical communication system 1a in modified example 1 of the first embodiment. Optical communication system 1a comprises a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing and demultiplexing units 20 (e.g., first optical multiplexing and demultiplexing units 20-1 to 20-3), a second optical multiplexing and demultiplexing unit 30, a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of first optical multiplexing and demultiplexing units 60 (e.g., first optical multiplexing and demultiplexing units 60-1 to 60-3), a second optical multiplexing and demultiplexing unit 70, and a management control device 80. Optical communication system 1a differs from optical communication system 1 in that it does not have a wavelength multiplexing and demultiplexing unit 50. The differences from optical communication system 1 will be explained below.

[0065] In the configuration shown in Figure 4, the optical dispersion unit 40 has the function of being able to set a transmission path for each wavelength. For example, a WSS can be used as the optical dispersion unit 40. This makes the wavelength multiplexing / demultiplexing unit 50 unnecessary.

[0066] If there is a section in the optical transmission path where signal lights of different directions flow through the same optical transmission path, the subscriber equipment management control unit 83-1 either sets the wavelengths of the signal lights of different directions to different wavelengths, or grants transmission permission to the signal lights of different directions at different timings, in order to prevent the reception characteristics of the opposite-direction signal light from deteriorating due to reflection in the optical transmission path. If there is no section in the optical transmission path where signal lights of different directions flow through the same optical transmission path, the wavelengths of the signal lights of different directions can be set to the same wavelength.

[0067] (Modification 2) The optical communication system 1 may be configured to use non-wavelength selective optical multiplexers and demultiplexers as the first optical multiplexer / demultiplexer units 20, 60, rather than wavelength selective optical multiplexers and demultiplexers. Figure 5 shows an example of the configuration of the optical communication system 1b in a modified example 2 of the first embodiment. The optical communication system 1b comprises a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing and demultiplexing units 20b (e.g., first optical multiplexing and demultiplexing units 20b-1 to 20b-3), a second optical multiplexing and demultiplexing unit 30, a plurality of optical distribution units 40 (e.g., optical distribution units 40-1 to 40-2), a plurality of wavelength multiplexing and demultiplexing units 50 (e.g., wavelength multiplexing and demultiplexing units 50-1 to 50-3), a plurality of first optical multiplexing and demultiplexing units 60b (e.g., first optical multiplexing and demultiplexing units 60b-1 to 60b-3), a second optical multiplexing and demultiplexing unit 70, a management control device 80, a wavelength filter 90, and a wavelength filter 91.

[0068] Optical communication system 1b differs in configuration from optical communication system 1 in that it includes first photomultiplier / demultiplier units 20b and 60b instead of the first photomultiplier / demultiplier units 20 and 60, and newly includes wavelength filters 90 and 91. The differences from optical communication system 1 will be explained below.

[0069] The first optical multiplexer / demultiplexer 20b is provided between the subscriber device 10 and the optical distribution unit 40-1. The first optical multiplexer / demultiplexer 20b splits and outputs the uplink control signals and the main signal light transmitted from each subscriber device 10 at different wavelengths. The first optical multiplexer / demultiplexer 20b uses an optical multiplexer / demultiplexer (e.g., an optical coupler) that does not have wavelength selectivity. Therefore, the first optical multiplexer / demultiplexer 20b splits the uplink control signals and the main signal light transmitted from each subscriber device 10 at a predetermined ratio and outputs them to the second optical multiplexer / demultiplexer 30 and the optical distribution unit 40-1.

[0070] The first optical multiplexer / demultiplexer 60b is provided between the subscriber device 15 and the optical distribution unit 40-2. The first optical multiplexer / demultiplexer 60b wavelength-multiplexes the main signal light transmitted through the optical transmission path and the downlink control signal output from the second optical multiplexer / demultiplexer 70 and outputs it to the subscriber device 15. The first optical multiplexer / demultiplexer 60b uses an optical multiplexer / demultiplexer without wavelength selectivity (for example, an optical coupler).

[0071] The wavelength filter 90 is provided between the second photomultiplier / demultiplier unit 30 and the control device 80. The wavelength filter 90 blocks the wavelength of the main signal light.

[0072] The wavelength filter 91 is provided between the second photomultiplier / demultiplier unit 70 and the control device 80. The wavelength filter 91 blocks the wavelength of the main signal light.

[0073] The first optical multiplexer / demultiplexer 20b, after the optical path is established, branches off a portion of the uplink control signal from the subscriber device 10 to the management control device 80 and forwards it to the second optical multiplexer / demultiplexer 30. The first optical multiplexer / demultiplexer 60b, after the optical path is established, wavelength multiplexes the downlink control signal from the management control device 80 to the subscriber device 15 with the main signal light. Since the first optical multiplexer / demultiplexer 20b is a wavelength multiplexer / demultiplexer without wavelength selectivity, the uplink control signal is also forwarded to the wavelength multiplexer / demultiplexer 50.

[0074] However, since the uplink control signal has a different wavelength from the main signal light, it is blocked by the wavelength multiplexing / demultiplexing unit 50 and is not transmitted beyond the wavelength multiplexing / demultiplexing unit 50. Therefore, the uplink control signal and the downlink control signal do not coexist. For this reason, as with the configuration shown in Figure 1, if there is no section in which signal light in different directions flows through the core wire of the same optical transmission path, the wavelengths of the uplink control signal and the downlink control signal can be the same.

[0075] In optical communication systems 1, 1a, and 1b, a second optical distribution unit may be provided instead of the second optical multiplexer / demultiplexer 30 and 70, and the optical distribution control unit 82-1 may be configured to dynamically set the connection relationships between ports of the second optical distribution unit so that the uplink control signal that reaches the second optical multiplexer / demultiplexer 30 is transmitted to the subscriber equipment management control unit 83-1. Specifically, for subscriber equipment 10-1 before the optical path is opened, the management control device 80 does not know in advance whether subscriber equipment 10-1 exists or not. Therefore, the optical distribution unit may periodically set the paths for unopened ports. Alternatively, when the optical detection unit 43 detects optical input at a new port, the optical distribution unit may set the paths for each unopened port and search for subscriber equipment 10 that exchanges control signals.

[0076] (Variation 3) In the optical communication system 1, the first optical multiplexing and demultiplexing unit 20, the second optical multiplexing and demultiplexing unit 30, the optical dispersion unit 40-1, the wavelength multiplexing and demultiplexing unit 50-1, and the control unit 81-1 may be configured as an optical communication device. Similarly, the first optical multiplexing and demultiplexing unit 60, the second optical multiplexing and demultiplexing unit 70, the optical dispersion unit 40-2, the wavelength multiplexing and demultiplexing unit 50-2, and the control unit 81-2 may be configured as an optical communication device.

[0077] In the optical communication system 1a, the first optical multiplexer / demultiplexer 20, the second optical multiplexer / demultiplexer 30, the optical signal splitter 40-1, and the control unit 81-1 may be configured as an optical communication device. Similarly, the first optical multiplexer / demultiplexer 60, the second optical multiplexer / demultiplexer 70, the optical signal splitter 40-2, and the control unit 81-2 may be configured as an optical communication device.

[0078] In the optical communication system 1b, the first optical multiplexer / demultiplexer 20b, the second optical multiplexer / demultiplexer 30, the optical dispersion unit 40-1, the wavelength multiplexer / demultiplexer 50-1, the control unit 81-1, and the wavelength filter 90 may be configured as an optical communication device. Similarly, the first optical multiplexer / demultiplexer 60b, the second optical multiplexer / demultiplexer 70, the optical dispersion unit 40-2, the wavelength multiplexer / demultiplexer 50-2, the control unit 81-2, and the wavelength filter 91 may be configured as an optical communication device.

[0079] (Second embodiment) In the first embodiment, a configuration was shown in which the light detection unit is provided inside the light distribution unit. In the second embodiment, a configuration in which the light detection unit is provided outside the light distribution unit will be described.

[0080] Figure 6 shows an example configuration of the optical communication system 1c in the second embodiment. The optical communication system 1c comprises a plurality of subscriber devices 10 (e.g., subscriber devices 10-1 to 10-3), a plurality of subscriber devices 15 (e.g., subscriber devices 15-1 to 15-3), a plurality of first optical multiplexing and demultiplexing units 20 (e.g., first optical multiplexing and demultiplexing units 20-1 to 20-3), a second optical multiplexing and demultiplexing unit 30, a plurality of optical distribution units 40c (e.g., optical distribution units 40c-1 to 40c-2), a plurality of optical detection units 43 (e.g., optical detection units 43c-1 to 43c-2), a plurality of wavelength multiplexing and demultiplexing units 50 (e.g., wavelength multiplexing and demultiplexing units 50-1 to 50-3), a plurality of first optical multiplexing and demultiplexing units 60 (e.g., first optical multiplexing and demultiplexing units 60-1 to 60-3), a second optical multiplexing and demultiplexing unit 70, and a management control device 80.

[0081] Optical communication system 1c differs from optical communication system 1 in that it has optical distribution units 40c-1 and 40c-2 instead of optical distribution units 40-1 and 40-2, and that it has multiple optical detection units 43 externally. The differences from optical communication system 1 will be explained below.

[0082] The optical distribution unit 40c-1 has P ports 41-1 and Q ports 42-1. The optical distribution unit 40c-2 has the same configuration as the optical distribution unit 40c-1, so the configuration of the optical distribution unit 40c-1 will be used as an example for explanation. The optical distribution unit 40c-1 differs in configuration from the optical distribution unit 40-1 in that it does not have a photodetector unit 43-1. The photodetector unit 43-1 is connected to port 42-1-1 of the optical distribution unit 40c-1. Note that the photodetector unit 43-1 can be connected to any of the ports 42-1. In the following explanation, it will be assumed that the photodetector unit 43-1 is connected to port 42-1-1 of the optical distribution unit 40c-1.

[0083] The optical distribution unit 40c-1, in accordance with the control of the optical distribution control unit 82-1, switches the connection relationships between ports so that each port 41-1 with an unopened optical path is sequentially connected to port 42-1-1 to which the optical detection unit 43-1 is connected. The optical detection unit 43-1 detects the optical signal output from the connected port 42-1-1. When the optical detection unit 43-1 detects an optical signal, it notifies the management control device 80 of the detection result indicating that an optical signal has been detected.

[0084] The configuration and processing of the management control device 80 are basically the same as in the first embodiment. For example, the management control device 80 differs from the first embodiment in the processing from step S111 onwards shown in Figure 3, and in the processing performed by the optical distribution control unit 82-1 after the transmission of the search signal.

[0085] The optical distribution control unit 82-1 controls the connection relationships between the ports of the optical distribution unit 40c-1, for example, after a search signal is transmitted, so that each port 41-1 of the optical distribution unit 40c-1 to which an optical path is not yet opened is sequentially connected to the port 42-1-1 to which the light detection unit 43-1 is connected. Alternatively, the optical distribution control unit 82-1 may control the connection relationships between the ports of the optical distribution unit 40c-1 at all times, rather than controlling them only after a search signal is transmitted.

[0086] When the subscriber device management control unit 83-1 obtains a detection result from the optical detection unit 43-1, it recognizes that the port 41-1 connected to port 42-1-1 to which the optical detection unit 43-1 is connected is the port to which the newly connected subscriber device 10 is connected. In this case, if the detection result is obtained before, after, or within a predetermined time before or after the reference time, the subscriber device management control unit 83-1 recognizes that the subscriber device 10-1, newly connected to the optical distribution unit 40-1, is connected to port 41-1 connected to port 42-1-1 to which the optical detection unit 43-1 is connected.

[0087] For example, if the subscriber device management control unit 83-1 recognizes that port 41-1-1 is the port to which the newly connected subscriber device 10-1 is connected, the optical distribution control units 82-1 and 82-2 set the connection relationships between the ports of the optical distribution units 40-1 and 40-2 based on the recognized port 41-1-1 and information about the subscriber device 15 (e.g., subscriber device 15-1) with which the subscriber device 10-1 communicates. Specifically, the optical distribution control unit 82-1 sets the connection relationships of the optical distribution unit 40-1 to connect port 41-1-1, to which the subscriber device 10-1 is connected, to port 42-1-2, which is connected to the optical distribution unit 40-2 to which the subscriber device 15-1 is connected. The optical distribution control unit 82-1 generates a control signal to connect port 41-1-1 and port 42-1-2. The optical distribution control unit 82-1 transmits the generated control signal to the optical distribution unit 40-1.

[0088] Similarly, the optical distribution control unit of the control unit 81-2 sets the connection relationship of the optical distribution unit 40-2 so as to connect the port to which the subscriber device 15-1 is connected to the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit of the control unit 81-2 generates a control signal to connect the port to which the subscriber device 15-1 is connected to the port connected to the optical distribution unit 40-1 to which the subscriber device 10-1 is connected. The optical distribution control unit of the control unit 81-2 transmits the generated control signal to the optical distribution unit 40-2.

[0089] The optical distribution units 40-1 and 40-2 set the connection relationships between ports based on the control signals transmitted from the management control device 80. As a result, an optical path is opened between subscriber device 10-1 and subscriber device 15-1, as shown in Figure 7. Consequently, communication becomes possible between subscriber device 10-1 and subscriber device 15-1.

[0090] With the optical communication system 1c configured as described above, the same effects as in the first embodiment can be obtained.

[0091] (Variation 1) The optical communication system 1c may be modified to be like the optical communication system 1a or 1b shown in the first embodiment.

[0092] (Modification 2) The optical communication system 1c may be configured to include a header detection unit instead of the optical detection units 43-1 and 43-2. ​​The header detection unit consists of a photoelectric conversion unit and a header information acquisition unit. The header detection unit is one form of a detection unit that detects the main signal light. The photoelectric conversion unit converts the optical signals output from the optical distribution units 40c-1 and 40c-2 into electrical signals. The header information acquisition unit detects and reads the header from the electrical signals. The header information acquisition unit transmits the read header information to the management control device 80 as a detection result. When multiple subscriber devices 10 transmit light of the same wavelength simultaneously, the optical detection unit 43c-1 cannot distinguish between the two lights.

[0093] For example, when transmitting an uplink control signal and a signal carried by light of a wavelength reaching the optical distribution unit 40c-1 in an Ethernet frame, by keeping the source MAC address of the header of each frame containing the respective signals the same, if the source MAC address of the header read by the management control device 80 from the uplink control signal and the source MAC address of the header read by the header information acquisition unit from the signal carried by light of a wavelength reaching the optical distribution unit 40c-1 are the same, the management control device 80 can recognize whether the light of a wavelength reaching the optical distribution unit 40c-1 output by the subscriber device 10 having that source MAC address was input from one of the ports 41-1 of the optical distribution unit 40 and forwarded to the header information acquisition unit. As a result, it is possible to handle cases where multiple subscriber devices 10 transmit the same wavelength simultaneously.

[0094] (Variation 3) In the optical communication system 1c, the first optical multiplexing and demultiplexing unit 20, the second optical multiplexing and demultiplexing unit 30, the optical dispersion unit 40c-1, the photodetector unit 43-1, the wavelength multiplexing and demultiplexing unit 50-1, and the control unit 81-1 may be configured as an optical communication device. Similarly, the first optical multiplexing and demultiplexing unit 60, the second optical multiplexing and demultiplexing unit 70, the optical dispersion unit 40c-2, the photodetector unit 43-2, the wavelength multiplexing and demultiplexing unit 50-2, and the control unit 81-2 may be configured as an optical communication device.

[0095] Some of the functional parts of the management control device 80 in the above-described embodiment may be implemented by a computer. In that case, the program for implementing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. The term "computer system" as used herein includes hardware such as an OS (Operating System) and peripheral devices.

[0096] Furthermore, "computer-readable recording media" refers to portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), and CD-ROMs, as well as storage devices such as hard disks built into computer systems. In addition, "computer-readable recording media" may also include those that dynamically hold programs for a short period of time, such as communication lines used when transmitting programs over networks such as the Internet or communication lines such as telephone lines, and those that hold programs for a certain period of time, such as volatile memory inside computer systems that act as servers or clients in such cases. Moreover, the above-mentioned programs may be for the purpose of realizing some of the functions described above, or they may be able to realize the above-mentioned functions in combination with programs already recorded in the computer system, or they may be realized using programmable logic devices such as FPGAs (Field Programmable Gate Arrays).

[0097] Although embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and includes designs and the like that do not depart from the spirit of this invention. [Industrial applicability]

[0098] This invention can be applied to techniques for opening optical paths. [Explanation of symbols]

[0099] 1, 1a, 1b, 1c…Optical communication system, 10, 15, 10-1~10-3, 15-1~15-3…Subscriber equipment, 20, 20-1~20-3, 60, 60-1~60-3…First optical multiplexing / demultiplexing unit, 30, 70…Second optical multiplexing / demultiplexing unit, 40-1, 40-2, 40c-1, 40c-2…Optical distribution unit, 43-1, 43-2, 43c-1, 43c-2…Optical detection unit, 50-1, 50-2…Wavelength multiplexing / demultiplexing unit, 80…Management control unit, 81-1, 81-2…Control unit, 82-1…Optical distribution control unit, 83-1…Subscriber equipment management control unit, 85-1~85-3, 86-1~86-3…Optical transmission path, 90, 91…Wavelength filter

Claims

1. A first optical multiplexer / demultiplexer that splits and outputs a control signal and a main signal light transmitted at different wavelengths from at least one newly connected subscriber device, An optical distribution unit having a plurality of first ports and a plurality of second ports, which receives at least the main signal light branched by the first optical multiplexer / demultiplexer from one of the plurality of first ports and outputs it from one of the plurality of second ports, A detection unit is provided inside or outside the optical distribution unit to detect the main signal light, A subscriber device management control unit recognizes, based on the main signal light detected by the detection unit, the first port of the optical distribution unit to which at least one newly connected subscriber device is connected, among the plurality of first ports of the optical distribution unit. An optical distribution control unit controls the connection between ports of the optical distribution unit so that the main signal light transmitted from the newly connected at least one subscriber device is transferred to the subscriber device that will be the communication partner, An optical communication device equipped with the following features.

2. If the detection unit is provided inside the optical dispersion unit, The detection unit detects the main signal light input to each of the plurality of first ports of the optical distribution unit, and outputs the detection result, including information of the first port that detected the main signal light, to the subscriber device management control unit. The optical communication device according to claim 1.

3. If the detection unit is located outside the optical distribution unit, the detection unit is connected to one of the second ports among the plurality of second ports. The optical distribution control unit controls the optical distribution unit to sequentially switch and connect between the first port to which the optical path is not open and the second port to which the detection unit is connected, among the plurality of first ports of the optical distribution unit. When the detection unit detects the main signal light, it outputs the detection result to the subscriber device management control unit. The optical communication device according to claim 1.

4. When the subscriber device management control unit receives the detection result output from the detection unit, it recognizes that among the plurality of first ports of the optical distribution unit connected to the second port to which the detection unit is connected, the first port to which the optical path is not opened is the port to which the newly connected at least one subscriber device is connected. The optical communication device according to claim 3.

5. The detection unit is A photoelectric conversion unit that converts the main signal light into an electrical signal, It consists of a header information acquisition unit that detects and reads the header from the aforementioned electrical signal, The header information acquisition unit outputs the read header information as the detection result to the subscriber device management control unit. The subscriber device management control unit recognizes the port of the optical distribution unit to which the newly connected at least one subscriber device is connected, based on the header information included in the detection result and the control signal. The optical communication device according to claim 3.

6. The subscriber device management control unit recognizes that at least one newly connected subscriber device is connected to the optical distribution unit when the detection result detected by the detection unit is obtained within a predetermined time period before, after, or before / after the reference time. The optical communication device according to any one of claims 1 to 5.

7. The subscriber device management control unit transmits a search signal to the newly connected subscriber device and controls the timing of transmitting control signals to the one or more subscriber devices with an open optical path so that control signals from one or more subscriber devices with an open optical path do not arrive during the period in which control signals, including response signals, can arrive in response to the search signal. The optical communication device according to any one of claims 1 to 5.

8. The control signal and the main signal light transmitted at different wavelengths from at least one newly connected subscriber device are split and output. An optical distribution unit having a plurality of first ports and a plurality of second ports receives at least the branched main signal light from one of the first ports of the plurality of first ports and outputs it from one of the second ports of the plurality of second ports. The main signal light is detected inside or outside the optical distribution unit. Based on the detected main signal light, the optical distribution unit recognizes the first port of the optical distribution unit to which at least one newly connected subscriber device is connected, among the plurality of first ports of the optical distribution unit. An optical communication path opening method that controls the connection between ports of the optical distribution unit so that the main signal light transmitted from the newly connected at least one subscriber device is transferred to the subscriber device that will be the communication partner.

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