JP7734640B2 - Optical transmission line connectivity verification system - Google Patents

Description

The present invention relates to an optical transmission path connectivity confirmation system.

In recent years, space-division multiplexing (SDM) technology using multi-core fiber (MCF), which has multiple cores through which light propagates, has been the subject of vigorous research and development as a technology to overcome the physical limitations of transmission capacity in single-mode fiber (SMF).

When building an SDM system, it is necessary to construct an optical transmission line using MCF (hereafter referred to as an MCF optical transmission line) to connect the transmitting and receiving ends of the SDM system. To build an MCF optical transmission line, it is necessary to fusion-splice MCFs of a certain length. From a system operation perspective, it is ideal to fusion-splice MCFs with the same core numbers. This uniquely determines the MCF core numbers and connection relationships at the transmitting and receiving ends of the SDM system, avoiding complicated operation and management of the optical transmission line.

However, some MCFs have markers for identifying the core numbers, while others do not. When an MCF has markers, the core numbers can be identified, making it possible to align the core numbers when fusion splicing. However, providing markers to an MCF increases the cost of the fiber. Furthermore, the procedure for aligning the core numbers during fusion splicing takes time, which has the disadvantage of increasing labor costs. Furthermore, when an MCF does not have markers, it is difficult to identify the core numbers, making it difficult to align the core numbers when fusion splicing. Thus, when fusion splicing MCFs, it is difficult to align the core numbers when splicing. For these reasons, if fusion splicing without regard to the MCF core numbers were permitted in the construction of optical transmission lines, it would be easier to build MCF optical transmission lines, leading to a reduction in the time and cost required for constructing transmission lines.

Patent Document 1 discloses a link connectivity confirmation method for confirming the connectivity of the physical link between a cross-connect device and a transmission device.

JP 2008-022446 A

However, because Patent Document 1 uses an optical transmission line based on SMF, it is assumed that the relationship between the input and output ports of the optical transmission line for checking connectivity is uniquely determined, and there is no need to specify how the input and output ports for checking connectivity are connected. As a result, it does not take into account the possibility that the core numbers of the MCFs at the transmitting and receiving ends and their connection relationships may not be uniquely determined, which can occur in SDM systems.

On the other hand, in an SDM system, for example, if the MCF core numbers are not aligned when fusion splicing MCFs, an incident may occur where signal light is input to MCF core 1 (core number 1) at the transmitting end, but output light is obtained from MCF core 3 (core number 3) at the receiving end. In such a case, if the signal light is set based on the core number in an SDM system, the signal light will not reach the desired path (transmitting end: MCF core 1 - receiving end: MCF core 1).

The present invention was developed in light of these circumstances, and aims to provide an optical transmission path connectivity verification system that clarifies how input and output ports are connected, as well as the MCF core numbers and connection relationships at the transmitting and receiving ends of the system.

(1) In order to achieve the above object, the present invention employs the following measures. Specifically, the optical transmission line connectivity verification system of the present invention is an optical transmission line connectivity verification system that verifies the connectivity of an optical transmission line in a multi-core fiber that is fusion-spliced at at least one location, and is characterized by comprising at least an optical transmitter that transmits signal light emitted from a light source to the optical transmission line, an optical receiver that receives the signal light from the optical transmission line, an input device and an output device having multiple ports and connected to both ends of each core of the optical transmission line, a control and management information exchange function unit that acquires, via a separate network, connectivity information for a first port that is any port connected to the optical transmitter and a second port that is any port connected to the optical receiver, and a connectivity determination function unit that measures the optical power in the optical transmission line and determines the connectivity between the first port and the second port.

(2) Furthermore, in the optical transmission path connectivity confirmation system of the present invention, the controller is characterized by further including a setting storage function unit that stores the correspondence between the port numbers of the first port and the second port for which connectivity has been confirmed in the connectivity determination function unit.

(3) Furthermore, in the optical transmission path connectivity confirmation system of the present invention, the connectivity determination function unit determines that the correspondence between the first port and the second port is inappropriate if the optical power in the optical receiver is less than a threshold value, and determines that the correspondence between the input port and the output port is appropriate if the optical power in the optical receiver is equal to or greater than the threshold value.

(4) Furthermore, in the optical transmission line connectivity confirmation system of the present invention, the optical transmitter and the optical receiver are respectively arranged at both ends of the optical transmission line, and the connectivity determination function unit determines whether the signal light input from the optical transmitter to the first port corresponds to the signal light output from the second port and received by the optical receiver.

(5) Furthermore, in the optical transmission line connectivity confirmation system of the present invention, the optical transmitter and the optical receiver are arranged on one side of the optical transmission line, and an isolator arranged on the other side of the optical transmission line returns the signal light transmitted from the optical transmitter and received via a first optical transmission line to a second optical transmission line different from the first optical transmission line at a return port, and the optical receiver receives the signal light returned at the return port via the second optical transmission line , and the connectivity determination function unit determines whether the signal light transmitted from the optical transmitter to the first optical transmission line corresponds to the signal light received by the optical receiver via the second optical transmission line.

(6) In the optical transmission line connectivity confirmation system of the present invention, the optical transmitter and the optical receiver are arranged on one side of the optical transmission line, and a patch cord arranged on the other side of the optical transmission line transmits the signal light transmitted from the optical transmitter and received via a first optical transmission line by looping it back at a return port to a second optical transmission line different from the first optical transmission line, and the optical receiver receives the signal light that has been looped back at the return port via the second optical transmission line, and the connectivity determination function unit determines whether the signal light input from the optical transmitter to the first port corresponds to the signal light output from an output port arranged on the other side of the optical transmission line via the first optical transmission line, and whether the signal light looped back by the patch cord corresponds to the signal light received by the optical receiver.

(7) The present invention also provides an optical transmission line connectivity confirmation program for confirming the connectivity of an optical transmission line in a multi-core fiber fusion-spliced at at least one location, the program comprising: an optical transmitter transmitting signal light emitted from a light source to the optical transmission line; an optical receiver receiving the signal light from the optical transmission line; a controller having multiple ports and connecting an input device and an output device to both ends of each core of the optical transmission line; and a controller acquiring, via a separate network, connection information for a first port connected to the optical transmitter and a second port connected to the optical receiver in a control and management information exchange function unit, and measuring the optical power in the optical transmission line and determining the connectivity between the first port and the second port in a connectivity determination function unit.

(8) The present invention also provides an optical transmission line connectivity confirmation method for confirming the connectivity of an optical transmission line in a multi-core fiber fusion-spliced at at least one location, the method comprising at least the following steps: an optical transmitter transmitting signal light emitted from a light source to the optical transmission line; an optical receiver receiving the signal light from the optical transmission line; a controller having multiple ports and connecting an input device and an output device to both ends of each core of the optical transmission line; and a controller acquiring, via a separate network, connection information for a first port connected to the optical transmitter and a second port connected to the optical receiver in a control and management information exchange function unit; and a connectivity determination function unit measuring the optical power in the optical transmission line and determining the connectivity between the first port and the second port.

According to the present invention, it is possible to check the optical transmission path connectivity of each core after fusion splicing a multicore fiber and clarify the correspondence. As a result, fusion splicing can be performed without having to consider the presence or absence of core numbers or their arrangement in the multicore fiber, reducing the difficulty of constructing an MCF optical transmission path and enabling a reduction in the time and cost required to construct a transmission path.

1 is a diagram illustrating a schematic configuration of an optical transmission line connectivity confirmation system according to a first embodiment. FIG. 10 is a flowchart showing a procedure for determining the connectivity of an MCF optical transmission line in the first embodiment. FIG. 10 is a sequence diagram showing a procedure for determining the connectivity of an MCF optical transmission line in the first embodiment. FIG. 10 is a sequence diagram showing a procedure for determining the connectivity of an MCF optical transmission line in the first embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an optical transmission line connectivity confirmation system according to a second embodiment. FIG. 10 is a flowchart showing a procedure for determining the connectivity of an MCF optical transmission line in the second embodiment. FIG. 10 is a sequence diagram showing a procedure for determining the connectivity of an MCF optical transmission line in the second embodiment. FIG. 10 is a sequence diagram showing a procedure for determining the connectivity of an MCF optical transmission line in the second embodiment. FIG. 10 is a diagram illustrating a schematic configuration of an optical transmission line connectivity confirmation system according to a third embodiment. FIG. 11 is a flowchart showing a procedure for determining the connectivity of an MCF optical transmission line in the third embodiment. FIG. 11 is a sequence diagram showing a procedure for determining the connectivity of an MCF optical transmission line in the third embodiment. FIG. 11 is a sequence diagram showing a procedure for determining the connectivity of an MCF optical transmission line in the third embodiment.

The inventors focused on the issue that may arise in SDM systems, where the core numbers and connection relationships of the MCFs at the transmitting and receiving ends cannot be uniquely determined, and discovered a method for confirming the optical transmission path connectivity of each core after fusion splicing the multicore fiber, thereby clarifying the correspondence relationships, resulting in the present invention. As a result, fusion splicing is possible without having to consider the presence or arrangement of core numbers in the multicore fiber, making it easier to build MCF optical transmission paths and enabling a reduction in the time and cost required to build transmission paths.

In other words, the optical transmission line connectivity verification system of the present invention is an optical transmission line connectivity verification system that verifies the connectivity of an optical transmission line in a multi-core fiber that is fusion-spliced at at least one location, and is characterized by comprising at least an optical transmitter that transmits signal light emitted from a light source to the optical transmission line, an optical receiver that receives the signal light from the optical transmission line, an input device and an output device having multiple ports and connected to both ends of each core of the optical transmission line, a control and management information exchange function unit that acquires, via a separate network, connectivity information for a first port that is any port connected to the optical transmitter and a second port that is any port connected to the optical receiver, and a connectivity determination function unit that measures the optical power in the optical transmission line and determines the connectivity between the first port and the second port.

Each embodiment of the present invention will be described in detail below with reference to the drawings. First, the elements (common elements) that make up the optical transmission path connectivity confirmation system according to each embodiment will be described. To facilitate understanding of the description, the same reference numbers will be used to designate the same components in the drawings of each embodiment, and duplicate descriptions will be omitted.

The optical transmitter is equipped with a light source that emits signal light and has the ability to transmit light (signal light) of a set wavelength at a set power. Note that the wavelength and power settings are within the specified range of the target SDM (Space-Division Multiplexing) system. The optical transmitter also has a control management interface, allowing it to be controlled from an external controller.

The optical receiver is equipped with a power meter and has the ability to measure the power of the received light (hereinafter also referred to as received optical power). The optical receiver also has a control management interface, allowing the optical receiver to be controlled from an external controller, and receiving optical power information to be sent to the external controller via the control interface.

The optical switch has m x n (m and n are positive integers) input and output ports and has the ability to connect any port between the input and output. For ease of explanation, each embodiment in this specification will use an optical switch with 1 x n input and output ports as an example, but this is not limiting. The number of input and output ports needs to be at least one on the optical transmitter and optical receiver sides. Furthermore, the number of ports on the optical switch connected to the input and output devices described below must be at least equal to the number of ports on the input and output devices. Furthermore, the optical switch has a control and management interface and is capable of externally configuring settings such as port switching.

An input device (Fan-In device: FI device) is a device that connects a single-core fiber (SCF: Single-Core Fiber) and a multi-core fiber (MCF: Multi-Core Fiber), and is called an input device when it is used on the input side of an MCF optical transmission line. In the case of a 4-core fiber (4CF) input device, this means that four SCFs are connected.

An output device (Fan-Out device: FO device) is a device that connects a single-core fiber (SCF: Single-Core Fiber) and a multi-core fiber (MCF: Multi-Core Fiber), and is called an output device when used on the output side of an MCF optical transmission line. In the case of a four-core fiber (4CF) output device, this means that four SCFs are connected.

A multi-core fiber (MCF) is an optical fiber in which multiple cores through which light propagates are arranged within a single cladding. In each embodiment in this specification, an optical transmission path is constructed using an MCF. Furthermore, each embodiment in this specification describes an example in which a four-core fiber (4CF) is used, but this is not limited to this. It may also be a 2CF, or may have more cores. Furthermore, the multi-core fiber in this specification includes both uncoupled and coupled multi-core fibers, and the present invention is applicable to either type of multi-core fiber.

The controller has communications capabilities and can access each device via a control and management network or a public network. The controller also has at least a settings storage unit, a connectivity determination unit, and a control and management information exchange unit to control and manage each device in a data communication network, including optical transmission paths. The settings storage unit includes storage means for storing information about devices (optical transmitters, optical receivers, optical switches, input devices, output devices, etc.) configured at the transmitting and receiving ends of the MCF optical transmission path, including, for example, the correspondence between FI ports and FO port port numbers for which connectivity has been confirmed. The connectivity determination unit includes means for determining the connectivity of the MCF transmission path based on device settings and information acquired from the devices. The device settings and information acquired from the devices include, for example, information about the signal light power set by the optical transmitter, information about the received optical power received by the optical receiver, information about the optical power within the MCF optical transmission path, and information about thresholds for determining connectivity. The control and management information exchange function unit is equipped with communication means for exchanging (acquiring) information between the transmitting and receiving ends of the MCF optical transmission path via a control and management network or public network.

In each embodiment of this specification, a data communications network refers to a communications network through which data used by users flows, i.e., a communications network through which signal light passes. Elements that make up a data communications network include optical transmitters, optical receivers, optical switches, MCF optical transmission lines (multicore fibers), input devices, and output devices.

In each embodiment of this specification, the control and management network is a network separate from the data communication network, a communication network that connects the controller and the network devices that make up the data communication network, and refers to a control and management communication network that utilizes dedicated lines or public networks for control and management. Elements that make up the control and management network include optical transmitters, optical receivers, optical switches, and controllers.

Next, the method for determining core connectivity of an MCF optical transmission line will be explained in detail in each embodiment below.

[First embodiment]
[1] Schematic Configuration of Optical Transmission Path Connectivity Check System Fig. 1 is a diagram showing a schematic configuration of an optical transmission path connectability check system according to a first embodiment. The optical transmission path connectability check system 1 is composed of at least an optical transmitter 10, an optical receiver 20, optical switches 51 and 61, an MCF optical transmission path (multi-core fiber) 40, an input device 53, an output device 63, and a controller 30. The optical transmitter 10 is connected to the input end of the MCF optical transmission path via the optical switch 51 and the input device 53. The optical receiver 20 is connected to the output end of the MCF optical transmission path via the optical switch 61 and the output device 63.

[2] Connectivity Determination Procedure for MCF Optical Transmission Line Fig. 2 is a flow diagram showing the connectivity determination procedure for the MCF optical transmission line in the first embodiment. Figs. 3A and 3B are sequence diagrams showing the connectivity determination procedure for the MCF optical transmission line in the first embodiment. The connectivity determination procedure for the MCF optical transmission line in the first embodiment will be described with reference to Figs. 2, 3A, and 3B.

First, an initialization process is performed (step S1). During the initialization process, the controller performs the following processes on the optical transmitter, optical receiver, optical transmitter-side optical switch, and optical receiver-side optical switch: The controller turns off the output light of the optical transmitter and sets the initial wavelength. The controller then turns off the receiving operation of the optical receiver. The controller then performs a process to cancel the switch settings of the optical transmitter-side optical switch and the optical receiver-side optical switch. If a setting error occurs during the initialization process, it is determined to be a device malfunction and execution is halted.

Next, connectivity is confirmed. In this connection confirmation, first, the port of the optical switch connected to the optical transmitter (first port) is connected to FI port 1, and switching is performed (step S2). Next, the port of the optical switch connected to the optical receiver (second port) is connected to FO port 1, and switching is performed (step S3). After switching is performed, the controller turns on optical reception, and the optical receiver begins receiving (step S4). The optical receiver begins measuring the received optical power, and notifies the controller of the measurement information of the received optical power.

The controller checks the acquired measurement information for the received optical power (step S5). If the received optical power is equal to or greater than the threshold in step S5, the process terminates as a configuration abnormality (step S6). This is because step S5 is before the controller turns on the optical transmitter's transmission light. Therefore, if the optical receiver measures received optical power equal to or greater than the threshold, this means that some kind of optical power due to other causes is being detected, rather than optical power due to optical propagation, and this is not the intended setting. Therefore, the process terminates as a configuration abnormality. If the received optical power is less than the threshold in step S5, it can be determined that a transmission path between the optical receiver and one of the FI ports has been established. The threshold used as the judgment criterion can be set arbitrarily and is preset in the controller's connectivity determination function.

Next, the controller turns on the optical output of the optical transmitter at the set output, and the optical transmitter transmits the signal light (step S7). The controller acquires measurement information of the received optical power from the optical receiver (step S8).

The controller checks the acquired measurement information for the received optical power (step S9). If the received optical power is equal to or greater than the threshold, it can be determined that signal light has arrived from the optical transmitter to the optical receiver between the currently connected cores, and a transmission path has been established. This completes the confirmation of connectivity between FI port 1 and FO port 1 (step S10). The controller's setting storage function stores the correspondence between FI port 1 and each port number of FO port 1 for which connectivity has been confirmed. Note that optical fiber loses different optical power depending on factors such as the wavelength of the light and the length of the optical fiber cable. Therefore, the threshold used as the judgment criterion can be set arbitrarily for each optical fiber and is preset in the controller's connectivity judgment function.

To check the connectivity of the next FI port and FO port, the controller initializes the optical transmitter, optical receiver, optical transmitter-side optical switch, and optical receiver-side optical switch, as in step S1 (step S11). The controller then checks whether there are any remaining ports for which connectivity checks are required, and checks whether there are any transmitting or receiving ports for which connectivity checks have not yet been completed (step S12).

In step S12, if the result of checking whether there are any transmitting and receiving ports for which connectivity check has not been completed indicates that there are no ports remaining for which connectivity check is to be performed, the connectivity check process is terminated (step S13). In step S12, if the result of checking whether there are any transmitting and receiving ports for which connectivity check has not been completed indicates that there are ports remaining for which connectivity check is to be performed, the controller increments the connection port number of the optical transmitter and connects it (step S14). In this embodiment, the optical switch port connected to the optical transmitter is connected to FI port 2, the incremented connection port number, from FI port 1. Next, the controller sets the connection port number of the optical receiver to the smallest number of ports for which connectivity check has not been performed, and connects it (step S15). In this embodiment, the optical switch port connected to the optical receiver is connected to FO port 2, the smallest number of ports for which connectivity check has not been performed. After the optical transmitter and optical receiver are connected to each optical switch port, steps S4 to S9 are repeated.

In step S9, if the received optical power is less than the threshold, FI port 1 and FO port 1 are not connected, so the controller sets the connection port number of the optical receiver to the smallest number of ports for which connectivity check has not been completed and connects them. In this embodiment, the port of the optical switch connected to the optical receiver is connected to FO port 2, which is the smallest number of ports for which connectivity check has not been completed.

With the new FO port set, the controller performs initialization processing, as in step S1. The controller initializes the optical transmitter, optical receiver, optical transmitter-side optical switch, and optical receiver-side optical switch (step S16).

Next, the port of the optical switch connected to the optical transmitter is connected to the FI port that was connected before initialization in step S16 (step S17). In this embodiment, the FI port that was connected before initialization in step S16 is FI port 1.

Next, the connection port number of the optical receiver is incremented and connected (step S18). In this embodiment, the port of the optical switch connected to the optical receiver is connected from FO port 1 to FO port 2, the connection port number of which is incremented. Return to the procedure in step S4 and repeat the process. By repeating the above process, it is possible to confirm the connectivity of all cores that make up the MCF optical transmission path.

Second Embodiment
[1] Schematic Configuration of Optical Transmission Path Connectivity Check System FIG. 4 is a diagram showing a schematic configuration of an optical transmission path connectability check system according to a second embodiment. The basic configuration of the optical transmission path connectability check system 2 according to this embodiment is the same as that of the first embodiment. In the optical transmission path connectability check system 2 according to this embodiment, an optical transmitter 10 and an optical receiver 20 are connected to the input end of an MCF optical transmission path via an optical switch 51 and an input device 53. An isolator 71 is provided at the output end of the MCF optical transmission path via an output device 63 and an optical switch 61. In this way, by providing the isolator 71 in the optical switch 61 on the output end side and creating a loopback configuration, connectivity can be checked from one end. Note that the loopback port of the optical switch 61 is fixed. Furthermore, an isolator is used for loopback to limit the traveling direction of light. This makes it possible to clarify the inter-core connectivity of the MCF optical transmission line (the relationship between the core numbers connected between the input end, which is the near end, and the output end, which is the far end. For example, it is possible to clarify the relationship between the connected core numbers, such as "core 1 at the near end is connected to core 2 at the far end, and core 2 at the near end is connected to core 1 at the far end."

On the other hand, without using the isolator 71, only connectivity can be confirmed, but it may not be possible to clarify the relationship between the connected core numbers between the near end and the far end. For example, if light is input to core 1 at the near end, is returned between the far ends, and is received by core 2 at the near end, it is not possible to determine whether the path at the return point is core 1 → core 2 or core 2 → core 1. Therefore, while it is possible to confirm the inter-core connectivity of an MCF optical transmission line without using the isolator 71, it is more preferable to use the isolator 71 in order to also clarify the correspondence between core numbers.

[2] Connectivity Determination Procedure for MCF Optical Transmission Line Fig. 5 is a flow diagram showing the connectivity determination procedure for the MCF optical transmission line in the second embodiment. Figs. 6A and 6B are sequence diagrams showing the connectivity determination procedure for the MCF optical transmission line in the second embodiment. The connectivity determination procedure for the MCF optical transmission line in the second embodiment will be described with reference to Figs. 5, 6A, and 6B.

First, an initialization process is performed (step T1). During the initialization process, the controller performs the following processes on the optical transmitter, optical receiver, near-end (input end) optical switch, and far-end (output end) optical switch: The controller turns off the output light of the optical transmitter and sets the initial wavelength. The controller then turns off reception of the optical receiver. The controller then performs a process to cancel the switch settings of the near-end optical switch and far-end optical switch. If a setting error occurs during the initialization process, it is determined to be an equipment malfunction and execution is halted.

Next, connectivity is confirmed. In this connection confirmation, the port of the optical switch connected to the optical transmitter (first port) is first connected to FI port 1, and the port of the optical switch connected to the optical receiver (second port) is connected to FI port 2, and switching is set up (step T2). Next, FO ports 1 and 2 at the far end are connected to return ports 1 and 2 of the optical switch, respectively, and switching is set up (step T3). After switching is set up, the controller turns on optical reception, and the optical receiver begins receiving (step T4). The optical receiver begins measuring optical power and notifies the controller of the measurement information of the received optical power.

The controller checks the acquired measurement information for the received optical power (step T5). If the received optical power is equal to or greater than the threshold in step T5, the controller concludes that the configuration is abnormal and terminates the process (step T6). Because step T5 is before the controller turns on the optical transmitter, if the optical receiver measures received optical power equal to or greater than the threshold, this indicates that the optical power measured is not due to optical propagation, but rather some other optical power due to some other cause, and is not the intended configuration. Therefore, the controller determines that the correspondence between the FI port and the FO port is inappropriate, and terminates the process as an abnormal configuration. If the received optical power is less than the threshold in step T5, the controller determines that the correspondence between the FI port and the FO port is appropriate, meaning that a transmission path between the optical receiver and any of the FI and FO ports has been established. The threshold used as the judgment criterion can be set arbitrarily and is preset in the controller's connectivity determination function.

Next, the controller turns on the optical output of the optical transmitter at the set output, and the optical transmitter transmits the signal light (step T7). The controller acquires measurement information of the received optical power from the optical receiver (step T8).

The controller checks the acquired measurement information for the received optical power (step T9). If the received optical power is equal to or greater than the threshold, it can be determined that signal light has arrived from the optical transmitter to the optical receiver between the currently connected cores, and that a transmission path has been established. This completes the connectivity check between FI Port 1 and FO Port 1, and between FI Port 2 and FO Port 2 (step T10). The controller's setting storage function stores the correspondence between the port numbers of FI Port 1 and FO Port 1, and FI Port 2 and FO Port 2, for which connectivity has been confirmed. Note that optical fiber loses optical power due to factors such as the optical wavelength and the length of the optical fiber cable. Therefore, the threshold used as the judgment criterion can be set arbitrarily for each optical fiber and is preset in the controller's connectivity judgment function.

In addition, because an isolator is inserted between the return ports of the optical switch on the far end, the directionality of the light can also be uniquely identified. In other words, it can be seen that light travels from FI port 1 to FO port 1 in the direction from the near end to the far end, and from FO port 2 to FI port 2 in the direction from the far end to the near end. From this, it is possible to confirm the connection relationship of the cores of the MCF optical transmission line between the near end and the far end, namely the connectivity between FI port 1 and FO port 1, and the connectivity between FI port 2 and FO port 2.

To check the connectivity of the next FI port and FO port, the controller initializes the optical transmitter, optical receiver, near-end optical switch, and far-end optical switch, as in step S1 (step T11). The controller then checks whether there are any remaining ports for which connectivity check is required, and checks whether there are any transmitting or receiving ports for which connectivity has not yet been completed (step T12).

In step T12, if the result of checking whether there are any transmitting and receiving ports whose connectivity has not been completed indicates that there are no ports remaining for which connectivity check is required, the connectivity check process is terminated (step T13). In step S12, if the result of checking indicates that there are ports remaining for which connectivity check is required, the controller selects and connects two connection ports for the optical transceiver, i.e., port numbers of the near-end optical switch, from those for which connectivity check has not been completed (step T14). One method for selecting connection ports for the optical transceiver is to select them in ascending order of port number. Of the selected port numbers, the optical transmitter may be connected to the one with the lowest port number, and the remaining ports may be connected to the optical receiver. In this embodiment, the port of the optical switch connected to the optical transmitter is connected to FI port 3, and the port of the optical switch connected to the optical receiver is connected to FI port 4.

Next, the controller selects two of the connection port numbers of the far-end optical switch for which connectivity has not yet been confirmed and connects them to the loopback port (step T15). In this embodiment, the controller connects the ports in ascending order of port number. In other words, FO ports 3 and 4 are connected to loopback ports 1 and 2, respectively. After the ports are connected, steps T4 to T9 are repeated.

If the received optical power is less than the threshold in step T9, FI port 1 and FO port 1, and FI port 2 and FO port 2 are not connected, so the same initialization process as in step T1 is performed (step T16). The controller checks whether the connection port number can be incremented when connecting the near-end optical receiver and the FI port (step T17).

If it is not possible to increment the connection port number in step T17, two of the connection port numbers of the near-end optical transceiver for which connectivity check has not been completed are selected and connected (step T18). The connection ports may be selected in ascending order of port number. In this case, the optical transmitter is connected to the selected port number with the lowest port number, and the remaining ports are connected to the optical receiver. Furthermore, for the connection ports of the far-end optical switch, the FO port connected to loopback port 1 is incremented and connected, and for the FO port connected to loopback port 2, one of the FO ports for which connectivity check has not been completed is selected and connected. In this case, the port numbers are selected in ascending order.

In this embodiment, an isolator is inserted in the return section, so the directionality is unique. Therefore, if connectivity cannot be confirmed when FI Port 1 and FO Port 1 are connected, and FI Port 2 and FO Port 2 are connected in the first step and connectivity is checked, a procedure is required in which FI Port 1 and FO Port 2, and FI Port 2 and FO Port 1 are connected and connectivity is checked again.

In step T17, if the connection port number can be incremented, the connection between the near-end optical transmitter and FI port via the optical switch is set to the same connection setting as immediately before, and the connection between the near-end optical receiver and FI port via the optical switch is connected by incrementing the connection port number, and switching settings are performed (step T19). In this embodiment, the optical transmitter is connected to FI port 1, and the optical receiver is connected to FI port 3, and switching settings are performed.

Then, the connection ports of the far-end optical switch are set to the same settings as immediately before (step T20). In this embodiment, FO ports 1 and 2 at the far end are connected to return ports 1 and 2 on the optical switch, respectively, and switching settings are performed. Return to the procedure in step S4 and repeat the process. By repeating the above process, it is possible to confirm the connectivity of all cores that make up the MCF optical transmission line.

[Third embodiment]
[1] Schematic Configuration of Optical Transmission Path Connectivity Check System FIG. 7 is a diagram illustrating a schematic configuration of an optical transmission path connectability check system according to a third embodiment. The basic configuration of the optical transmission path connectability check system 3 according to this embodiment is the same as that of the first embodiment. In the optical transmission path connectability check system 3 according to this embodiment, an optical transmitter 10 and an optical receiver 20 are connected to the input end of an MCF optical transmission path via an optical switch 51 and an input device 53. A patch cord 81 is connected to the output end of the MCF optical transmission path via an output device 63 and an optical switch 61. In this manner, by providing a patch cord to the optical switch at the output end and forming a loopback configuration, connectivity can be checked from one end. The optical switch is equipped with a function for monitoring optical power at each port. Although this embodiment does not include the isolator provided in the second embodiment, a procedure for checking core connectivity of the MCF optical transmission path is implemented by using the optical power monitoring function at each port of the optical switch.

[2] Connectivity Determination Procedure for MCF Optical Transmission Line Fig. 8 is a flow diagram showing the connectivity determination procedure for the MCF optical transmission line in the third embodiment. Figs. 9A and 9B are sequence diagrams showing the connectivity determination procedure for the MCF optical transmission line in the third embodiment. The connectivity determination procedure for the MCF optical transmission line in the third embodiment will be described with reference to Figs. 8, 9A, and 9B.

First, initialization processing is performed (step P1). In initialization processing, the controller performs the following processing on the optical transmitter, optical receiver, near-end (input end) optical switch, and far-end (output end) optical switch: The controller turns off the output light of the optical transmitter and sets the initial wavelength. The controller then turns off reception of the optical receiver. The controller then performs processing to cancel the switch settings of the near-end optical switch and far-end optical switch. If a setting error occurs during initialization processing, it is determined to be an equipment malfunction and execution is halted.

Next, connectivity is confirmed. In this connection confirmation, the port of the optical switch connected to the optical transmitter (first port) is first connected to FI port 1, and the port of the optical switch connected to the optical receiver (second port) is connected to FI port 2, and switching is performed (step P2). After switching is performed, the controller turns on the optical output at the set output in the optical transmitter, and the optical transmitter transmits the signal light (step P3).

Next, the connectivity of the core from the near end to the far end is confirmed in the following steps P4 to P7. The controller checks the received optical power at the optical switch on the far end (step P4). Here, the controller uses the optical power monitoring function of the optical switch on the far end to check whether optical power is detected at all ports connected to the FO port. This identifies the port where received optical power is being detected.

If the port where the received optical power is detected cannot be identified in step P4, this means that none of the cores in the optical transmission path are connected to the far end, and the process ends with a configuration error (step P6).

If the port where the received optical power is detected can be identified in step P4, the controller acquires the measurement information of the received optical power. The controller then checks the acquired measurement information of the received optical power (step P5). If the received optical power of the port where the received optical power is detected is below the threshold, it is assumed that a transmission path loss greater than expected is occurring. Therefore, the connection is determined to be inappropriate, and the process is terminated with a setting abnormality (step P6). The threshold used as the judgment criterion can be set arbitrarily and is preset in the controller's connectivity judgment function unit.

In step P5, if the received optical power of the port where the received optical power is detected is equal to or greater than the threshold, it can be determined that signal light has arrived at the optical receiver from the optical transmitter between the currently connected cores, and a transmission path has been established. In this embodiment, connectivity has been confirmed between FI port 1 of the optical transmitter set in step P2 and the FO port on the receiving end where the received optical power was detected in step P4. This completes the core connectivity confirmation from the near end to the far end (step P7). The controller's setting storage function stores the correspondence between FI port 1 for which connectivity has been confirmed and each port number of the FO port. Note that optical fiber loses optical power depending on the optical wavelength, the length of the optical fiber cable, and other factors. Therefore, the threshold used as the judgment criterion can be set arbitrarily for each optical fiber and is preset in the controller's connectivity judgment function.

Next, the connectivity of the core from the far-end to the near-end is confirmed in the following steps P8 to P16. First, the controller performs the initialization process, as in step P1 (step P8). Then, it connects the port of the far-end optical switch whose connectivity was confirmed in step P7 to return port 1 of the far-end optical switch (step P9).

The controller checks whether there are any ports on the far-end optical switch for which connectivity check has not been completed on the FO side that are to be connected to loopback port 2 (step P10). If there are no ports for which connectivity check has not been completed in step P10, the connectivity check cannot continue, and the process is terminated with a configuration error (step P11). If there are ports for which connectivity check has not been completed in step P10, one of the ports for which connectivity check has not been completed is selected from the FO side port numbers of the far-end optical switch and connected to loopback port 2 (step P12). The loopback port is selected in ascending order of port number.

Next, the controller turns on the optical output of the optical transmitter at the set output, and the optical transmitter transmits the signal light (step P13). If the received optical power is confirmed at the optical receiver, the controller acquires measurement information of the received optical power from the optical receiver (step P14) and confirms the acquired measurement information of the received optical power (step P15). If the received optical power is below the threshold in step P15, it is determined that the core does not have a connection established with the FO port, and the process returns to step P12. On the other hand, if the received optical power is above the threshold in step P15, it is determined that the signal light has arrived. Therefore, connectivity between the far-end FO port set in step P12 and the near-end FI port confirmed in the previous procedure (step P2 or step P19) has been confirmed. This completes the core connectivity confirmation from the far-end to the near-end (step P16). The controller's setting storage function stores the correspondence between FI port 1 for which connectivity has been confirmed and each port number of the FO port. Optical fiber loses optical power depending on the wavelength of the light, the length of the optical fiber cable, etc. Therefore, the threshold value that serves as the judgment criterion can be set arbitrarily for each optical fiber and is preset in the controller's connectivity judgment function unit.

Next, to check the connectivity of another core, initialization processing is performed similarly to step P1 (step P17). The controller checks whether any far-end or near-end ports for which connectivity check has not been completed remain (step P18). If any far-end or near-end ports for which connectivity check has not been completed remain, two of the near-end optical transceiver connection port numbers for which connectivity check has not been completed are selected and connected (step P19). The optical transceiver connection port may be selected, for example, in ascending order of port number. After selecting the optical transceiver connection port, the process returns to step P3 and repeats. By repeating the above process, it is possible to check the connectivity of all cores that make up the MCF optical transmission line. If no far-end or near-end ports for which connectivity check has not been completed remain in step P18, all connectivity has been confirmed, and the process ends (step P20).

As described above, according to the above embodiment, it is possible to check the optical transmission path connectivity of each core after fusion splicing the multicore fiber and clarify the correspondence. As a result, fusion splicing can be performed without having to consider the presence or absence of core numbers or the arrangement of the multicore fiber, making it easier to construct an MCF optical transmission path and reducing the time and cost required to construct the transmission path.

1, 2, 3 Optical transmission line connectivity confirmation system 10 Optical transmitter 20 Optical receiver 30 Controller 301 Setting storage function unit 303 Connectivity determination function unit 305 Control management information exchange function unit 40 MCF optical transmission lines 51, 61 Optical switch 53 Input device 63 Output device 71 Isolator 81 Patch cord

Claims (8)

An optical transmission line connectivity confirmation system for confirming connectivity of an optical transmission line in a multi-core fiber fusion-spliced at at least one location, comprising:
an optical transmitter that transmits signal light emitted from a light source to the optical transmission line;
an optical receiver that receives the signal light from the optical transmission line;
an input device and an output device each having a plurality of ports and connected to both ends of each core of the optical transmission line,
a control management information transfer function unit that acquires connection information of a first port, which is any port connected to the optical transmitter, and a second port, which is any port connected to the optical receiver, via a separate network; and a controller having a connectivity determination function unit that measures optical power in the optical transmission path and determines connectivity between the first port and the second port. The optical transmission path connectivity confirmation system of claim 1, wherein the controller further comprises a setting storage function unit that stores the correspondence between the port numbers of the first port and the second port for which connectivity has been confirmed in the connectivity determination function unit. The optical transmission path connectivity confirmation system of claim 1 or 2, characterized in that the connectivity determination function unit determines that the correspondence between the first port and the second port is inappropriate if the optical power in the optical receiver is below a threshold, and determines that the correspondence between the first port and the second port is appropriate if the optical power in the optical receiver is above the threshold. the optical transmitter and the optical receiver are disposed at both ends of the optical transmission line,
4. The optical transmission path connectivity confirmation system according to claim 3 , wherein the connectivity determination function unit determines whether the signal light input from the optical transmitter to the first port corresponds to the signal light output from the second port and received by the optical receiver. the optical transmitter and the optical receiver are disposed on one side of the optical transmission line,
an isolator disposed on the other side of the optical transmission line returns the signal light transmitted from the optical transmitter and received via the first optical transmission line to a second optical transmission line different from the first optical transmission line at a return port, and transmits the returned signal light;
the optical receiver receives the signal light that is returned at the return port and via the second optical transmission line;
4. The optical transmission line connectivity confirmation system according to claim 3, wherein the connectivity determination function unit determines whether the signal light transmitted from the optical transmitter to the first optical transmission line corresponds to the signal light received by the optical receiver via the second optical transmission line. the optical transmitter and the optical receiver are disposed on one side of the optical transmission line,
a patch cord disposed on the other side of the optical transmission line, the signal light transmitted from the optical transmitter and received via the first optical transmission line, is returned at a return port to a second optical transmission line different from the first optical transmission line, and transmitted;
the optical receiver receives the signal light that is returned at the return port and via the second optical transmission line;
4. The optical transmission line connectivity confirmation system according to claim 3, wherein the connectivity determination function unit determines whether the signal light input from the optical transmitter to the first port corresponds to the signal light output from an output port arranged on the other side of the optical transmission line via the first optical transmission line, and whether the signal light returned by the patch cord corresponds to the signal light received by the optical receiver. An optical transmission line connectivity confirmation program for confirming connectivity of an optical transmission line in a multi-core fiber fusion-spliced at at least one location,
a process in which an optical transmitter transmits signal light emitted from a light source to the optical transmission line;
a process in which an optical receiver receives the signal light from the optical transmission line;
a process of connecting an input device and an output device having a plurality of ports to both ends of each core of the optical transmission line, respectively;
an optical transmission path connectivity confirmation program, characterized in that a controller acquires, via a separate network, in a control management information exchange function unit, connection information of any input port connected to the optical transmitter and any output port connected to the optical receiver; and, in a connectivity determination function unit, measures the optical power in the optical transmission path and determines the connectivity between the input port and the output port. 1. A method for verifying connectivity of an optical transmission line in a multi-core fiber fusion-spliced at at least one location, comprising:
an optical transmitter transmitting signal light emitted from a light source to the optical transmission line;
an optical receiver receiving the signal light from the optical transmission line;
connecting an input device and an output device having a plurality of ports to both ends of each core of the optical transmission line, respectively;
a controller, via a separate network, in a control management information transfer function unit, acquiring connection information of any of the input ports connected to the optical transmitter and any of the output ports connected to the optical receiver; and, in a connectivity determination function unit, measuring the optical power in the optical transmission path and determining the connectivity between the input port and the output port.