Optical switch, optical cross-connect, and switching system

Abstract

The present invention increases the number of simultaneously usable optical paths among optical paths formed between a plurality of optical switches, and improves the utilization efficiency of the entire facility. This optical switch (SW) comprises a plurality of input ports (Q1 to Q3) and a plurality of output ports (P1 to P3). The plurality of input ports are disposed at equal intervals around a rotation axis (AS) and the plurality of output ports are disposed at equal intervals around the rotation axis. Combinations of connections between the input ports and the output ports are switched by rotation around the rotation axis. The plurality of input ports and the plurality of output ports are simultaneously connected and an optical signal propagates between the connected input ports and output ports.

Description

Optical switches, optical cross-connects, and switching systems

[0001] The present disclosure relates to optical switches, optical cross-connects, and switching systems.

[0002] Non-Patent Document 1 discloses a system comprising an optical fiber network (multi-stage loop network) consisting of multiple loop networks, an optical node (in-station node) installed in an environment where commercial power can be used within a communication building, and one or more optical nodes (out-station node) installed outdoors. In the out-station node of the system, an optical switch of an optical cross-connect is controlled based on a control signal superimposed on a power feed light via an optical fiber, and the power obtained by photoelectric conversion of the power feed light is used as a power source to switch between the core wires of the optical fiber.

[0003] Non-Patent Document 2 discloses a rotating ferrule optical switch that achieves power saving and miniaturization in an optical cross-connect that switches between optical fiber cores. In this rotating ferrule optical switch, optical fibers are arranged in a circular shape in a ferrule used in an optical connector, and the rotation of the ferrule switches the channel of the optical switch, changing the connection destination of the optical fiber.

[0004] 2021 IEICE Society Conference, BK-2-3, 2021, "Remote Optical Path Switching Node Operating in Multistage Loop-Type Optical Access Networks" IEICE Optical Fiber Application Technology Study Group OFT2022-6, 2022, "Study on Multi-Core Cylindrical Ferrules for Remotely Controlled Optical Fiber Rotary Switches"

[0005] According to the technology described in Non-Patent Document 1, six optical paths are formed by mesh-connecting four 1 × 3 optical switches. However, each 1 × 3 optical switch can select only one of the three channels, and the number of optical paths that can be used simultaneously is limited to two of the six optical paths.

[0006] Furthermore, according to the technology described in Non-Patent Document 2, 24 optical paths are formed by mesh-connecting six 1x6 optical switches. However, each 1x6 optical switch can select only one of the six channels, and the number of optical paths that can be used simultaneously is limited to six out of the 24 optical paths.

[0007] As such, the number of optical paths that can be used simultaneously is limited compared to the number of optical paths formed between multiple optical switches, which poses a problem in that it is not possible to improve the utilization efficiency of the entire facility.

[0008] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide an optical switch, an optical cross-connect, and a switching system that can increase the number of optical paths that can be used simultaneously among the optical paths formed between multiple optical switches, thereby improving the utilization efficiency of the entire facility.

[0009] In order to solve the above-mentioned problems, the optical switch according to the present disclosure has a plurality of input ports and a plurality of output ports, the plurality of input ports being arranged at equal intervals around the rotation axis, and the plurality of output ports being arranged at equal intervals around the rotation axis, and the combination of connections of the input ports and output ports being switched by rotation around the rotation axis, the plurality of input ports and the plurality of output ports being connected simultaneously, and optical signals being propagated between the connected input ports and output ports.

[0010] According to the present disclosure, it is possible to increase the number of optical paths that can be used simultaneously among the optical paths formed between a plurality of optical switches, thereby improving the utilization efficiency of the entire facility.

[0011] Fig. 1 is a diagram illustrating an example of the configuration of an optical cross connect according to the present disclosure. Fig. 2 is a diagram illustrating an example of the configuration of an optical switch according to the present disclosure. Fig. 3 is a schematic diagram illustrating a communication path within an optical cross connect according to the present disclosure. Fig. 4 is a schematic diagram illustrating a communication path within an optical cross connect according to a comparative example. Fig. 5 is a diagram illustrating an example of the configuration of a switching system according to the present disclosure. Fig. 6 is a diagram illustrating an example of a management table. Fig. 7 is a diagram illustrating a flowchart of a switching system according to the present disclosure.

[0012] Next, embodiments of the present disclosure will be described in detail with reference to the drawings. In the description, the same components are designated by the same reference numerals and redundant description will be omitted.

[0013] [Configuration of Optical Cross Connect] Fig. 1 is a diagram showing an example of the configuration of an optical cross connect according to the present disclosure. The optical cross connect XC includes a plurality of optical switches for connecting optical fibers.

[0014] In Figure 1, optical fibers FB1 to FB4 are shown, and are respectively connected to optical switches SW1 to SW4. The optical fibers FB1 to FB4 are connected by an optical cross connect XC. The number of optical switches provided in the optical cross connect XC is not limited to four, and may be two or more. Furthermore, multiple optical switches may be installed for each path in which an optical fiber is installed. The number of optical fibers connected by the optical cross connect XC is not limited to four, and may be two or more.

[0015] Optical wiring paths GL are provided between the optical switches SW1 to SW4, and the optical switches SW1 to SW4 are connected to one another. In Figure 1, the optical wiring path GL is shown to be composed of six optical paths. Each optical switch has three optical paths, and each optical switch is connected to other optical switches via the optical paths.

[0016] 2 is a diagram illustrating an example of the configuration of an optical switch according to the present disclosure. The optical switches SW (optical switches SW1 to SW4) have multiple input ports and multiple output ports. The input ports are connected to optical fibers external to the optical cross-connect XC, and the output ports are connected to output ports of other optical switches via optical paths.

[0017] 2 shows input ports Q1 to Q3 connected to the optical fiber FB and output ports P1 to P3 connected to the optical path. For example, the input ports Q1 to Q3 are connected to the cores of the optical fiber FB and are configured to be able to transmit and receive optical signals propagating through the cores of the optical fiber FB. The number of output ports P1 to P3 is the same as the number of input ports Q1 to Q3.

[0018] The optical fiber FB may be a multi-core optical fiber. Cores included in the multi-core optical fiber may be connected to the input ports Q1 to Q3, and the optical cross connect XC may input and output optical signals to and from an external device via the multi-core optical fiber. Alternatively, the optical fiber FB may be one multi-core optical fiber having three cores, and one multi-core optical fiber having three cores, each of which is connected to the input ports Q1 to Q3, may be connected.

[0019] The input ports Q1 to Q3 are arranged at equal intervals around the rotation axis AS, and the output ports P1 to P3 are arranged at equal intervals around the rotation axis AS.

[0020] For example, as shown in Fig. 2, the optical switch SW may have a rotation mechanism, and the input ports Q1 to Q3 and the output ports P1 to P3 may be arranged at equal intervals along the direction of rotation of the rotation mechanism. In Fig. 2, the input ports Q1 to Q3 are arranged at 120-degree intervals around the rotation axis AS of the rotation mechanism. Similarly, the output ports P1 to P3 are arranged at 120-degree intervals around the rotation axis AS of the rotation mechanism.

[0021] The rotation mechanism rotates gears using, for example, a motor (not shown) or the like, to change the angular positions of the input ports Q1 to Q3 relative to the output ports P1 to P3 around the rotation axis AS. In Figure 2, the input ports Q1 to Q3 are arranged to face the output ports P1 to P3, respectively, in the direction of the rotation axis AS of the rotation mechanism. In the state shown in Figure 2, optical signals input to and output from the input ports Q1 to Q3 are input to and output from the optical path via the output ports P1 to P3, respectively.

[0022] 2, if the angular positions of the input ports Q1 to Q3 are changed by 120 degrees in the direction of rotation by the rotation mechanism, the input ports Q3, Q1, and Q2 will face the output ports P1, P2, and P3. As a result, the optical signals input to and output from the input ports Q1, Q2, and Q3 are input to and output from the optical path via the output ports P2, P3, and P1, respectively.

[0023] 2, when the angular positions of the input ports Q1 to Q3 are changed by 240 degrees in the direction of rotation by the rotation mechanism, the input ports Q2, Q3, and Q1 come to face the output ports P1, P2, and P3. As a result, the optical signals input to and output from the input ports Q1, Q2, and Q3 are input to and output from the optical path via the output ports P3, P1, and P2, respectively.

[0024] In this way, the combination of input and output port connections is switched by rotation around the rotation axis AS, and multiple input ports and multiple output ports are connected simultaneously, allowing optical signals to propagate between the connected input and output ports.

[0025] [Communication Paths in the Optical Cross-Connect] Fig. 3 is a schematic diagram showing communication paths in the optical cross-connect according to the present disclosure. Like the optical switch SW shown in Fig. 2, the optical switches SW1 to SW4 are configured so that the positional relationship of the output ports with respect to the input ports can be changed.

[0026] 3, in the optical switch SW1, optical signals input to and output from input ports Q11 to Q13 are input to and output from the optical path via output ports P11 to P13, respectively. In the optical switch SW2, optical signals input to and output from input ports Q21 to Q23 are input to and output from the optical path via output ports P21 to P23, respectively.

[0027] In the optical switch SW3, optical signals input to and output from input ports Q31 to Q33 are input to and output from the optical path via output ports P31 to P33, respectively. In the optical switch SW4, optical signals input to and output from input ports Q41 to Q43 are input to and output from the optical path via output ports P41 to P43, respectively.

[0028] 3 can change depending on the state of the optical switches SW1 to SW4. Meanwhile, the output ports of the optical switches SW1 to SW4 are interconnected, and the connection between the output ports is fixed (fixed connection). By changing the positional relationship between the input ports and the output ports in the optical switch, the connections between the multiple optical switches are switched.

[0029] In Fig. 3, output port P11 and output port P43 are connected. Output port P12 and output port P32 are connected. Output port P13 and output port P21 are connected. Output port P22 and output port P42 are connected. Output port P23 and output port P31 are connected. Output port P33 and output port P41 are connected.

[0030] Focusing on each optical switch, three optical paths are formed for each optical switch, the same number as the number of input ports. Therefore, six optical paths are formed between optical switches SW1 to SW4 (3 paths x 4 / 2 = 6 paths).

[0031] Each optical switch in the optical cross connect XC is provided with a plurality of ports to which optical fibers are connected, and each optical switch has the same number of optical paths as the number of ports. As a result, the optical cross connect XC can simultaneously form a maximum of the same number of communication paths as the number of optical paths that make up the optical wiring line GL.

[0032] The number of input ports provided in the optical switch SW is not limited to three and may be two or more. The number of output ports provided in the optical switch SW is not limited to three and may be two or more.

[0033] Fig. 4 is a schematic diagram showing communication paths within an optical cross connect according to a comparative example. Unlike the optical cross connect XC shown in Fig. 3, the optical cross connect XC in Fig. 4 has a different structure from the optical switches SW1 to SW4 included in the optical cross connect XC.

[0034] Each of the optical switches SW1 to SW4 shown in FIG. 4 has only one input port and three output ports.

[0035] For example, the optical switch SW1 has an input port QS1 and output ports P11 to P13. The optical switch SW2 has an input port QS2 and output ports P21 to P23. The optical switch SW3 has an input port QS3 and output ports P31 to P33. The optical switch SW4 has an input port QS4 and output ports P41 to P43.

[0036] Each optical switch connects an input port to one of the output ports, so that each of the optical switches SW1 to SW4 shown in Fig. 4 can form the same number of communication paths as the number of input ports.

[0037] Therefore, with the optical cross connect XC shown in Fig. 4, one optical path can be formed for each optical switch, and the optical cross connect XC can form two communication paths simultaneously (1 path x 4 / 2 = 2 paths). Therefore, compared to the optical cross connect XC shown in Fig. 3, with the optical cross connect XC shown in Fig. 3, it can be seen that the number of communication paths that can be formed simultaneously is greatly limited.

[0038] Therefore, it can be seen that the optical cross-connect XC shown in Figure 3 can increase the number of optical paths that can be used simultaneously among the optical paths formed between multiple optical switches, thereby improving the utilization efficiency of the entire facility.

[0039] [Configuration of Switching System] Fig. 5 is a diagram showing an example of the configuration of a switching system according to the present disclosure, and Fig. 6 is a diagram showing an example of a management table.

[0040] 5, the optical switches SW1 and SW2 are connected to the optical fiber of the upper loop LP1 located on the side of the communication building BL, and the optical switches SW3 and SW4 are connected to the optical fiber of the lower loop LP2. In particular, the optical switches SW3 and SW4 are shown connected to the terminals TM1 and TM2, respectively. In this way, the optical cross-connect XC establishes a connection between the upper loop LP1 and the lower loop LP2.

[0041] The optical cross connect XC may be managed by a controller provided in a server SV or the like. Here, the controller is a general-purpose computer equipped with a CPU (Central Processing Unit), memory, and input / output units. The location where the controller managing the optical cross connect XC is located is not limited to the communication building BL, and may be any location that can be connected to the optical cross connect XC. In addition, the management table shown in FIG. 6 may also be stored in the controller.

[0042] For example, if a communication path needs to be connected via the optical switches SW1 to SW4, the controller records information that identifies an input port on the communication path.

[0043] 6, in accordance with the situation in Fig. 5, the controller records information that identifies input port Q11 and input port Q43, linking them to communication path "1." The controller may also record information that identifies communication path "1" as the main path (first communication path).

[0044] The controller also records the time limit for maintaining the connection of the main route. Here, the "time limit" refers to the operational time limit for which the communication service is guaranteed to be continuously provided via the main route. When the "time limit" has passed, the connection of the main route is switched and the communication service can be provided via another communication route. Note that the "time limit" is merely a guideline and may be changed based on external instructions.

[0045] 5, the controller records information that identifies input port Q23 and input port Q31 in association with communication path "5." The controller may also record information that identifies communication path "5" as the main path (first communication path).

[0046] Alternatively, the controller may record information that identifies input port Q12 and input port Q32 as unused communication paths or communication paths for temporary communication, and that associates them with communication path "2." The controller may also record information that identifies communication path "2" as a sub-path (second communication path).

[0047] Similarly, the controller may record information that identifies an input port by linking each of the communication paths "3," "5," and "6" as an unused communication path or a communication path for temporary communication. The controller may also record information that identifies the communication paths "3," "5," and "6" as sub-paths (second communication paths).

[0048] The controller may record contact information associated with the sub-route. The "contact information" is contact information for a user related to the sub-route, such as an administrator who manages the sub-route or a user who uses the sub-route. The "contact information" may be an email address or a telephone number. Alternatively, the "contact information" may be information for identifying a user related to the sub-route and notifying the user of information.

[0049] For example, a user associated with a sub-route may notify the controller of his or her "contact information," and the controller may record the notified "contact information" in association with the sub-route.

[0050] Next, we will explain the process before the main route connection is switched. The sub-route connection is maintained until the earliest scheduled deadline among the deadlines associated with the main route. Therefore, it is possible to use the sub-route as a communication route with a shorter usage time than the main route.

[0051] Since the connection of the main route will not be switched until the deadline, there will be no interruption of the communication service provided on the main route. However, there may be cases where the communication service provided on the sub-route is interrupted due to the switching of the connection of the main route.

[0052] To avoid unintentional interruption of the communication service provided on the sub-route, the controller sends a switch notification to the contacts associated with the sub-route before switching the main route. The switch notification is information about the main route, informing the user that the main route connection will be switched. By sending the switch notification, the user of the sub-route can be prompted to stop using the service on the sub-route.

[0053] The controller executes the switching of the main route after the expiration of the time limit for the main route after transmitting the switching notification. For example, the controller may execute the switching of the main route after a predetermined time has elapsed since transmitting the switching notification.

[0054] In addition, to avoid unintentional interruption of the communication service provided on the sub-route, the controller may check the presence or absence of communication light on the sub-route. More specifically, based on an instruction from the controller, a port monitoring function provided on a port on the sub-route may check the presence or absence of communication light propagating on the sub-route. Alternatively, a port on the sub-route may be equipped with a photodetector capable of detecting communication light, and the presence or absence of communication light may be checked based on the detected information.

[0055] The controller may then switch the main path after it has been confirmed that there is no communication light on the sub-path. Note that instead of transmitting a switch notification, the controller may switch the main path after it has been confirmed that there is no communication light on the sub-path.

[0056] On the other hand, if it is confirmed that there is communication light on the sub-path, the controller may repeatedly check for the presence or absence of communication light on the sub-path after a predetermined time has elapsed.

[0057] [Processing of the Switching System] Fig. 7 is a diagram showing a flowchart of the switching system according to the present disclosure. The processing shown in the flowchart of Fig. 7 may be repeatedly executed while the controller controls the optical cross-connect.

[0058] In step S101, the controller establishes a first communication path and a second communication path. For example, the controller controls an optical switch provided in the optical cross connect XC for providing a communication service based on an instruction from the server SV or the like to establish the first communication path (main path).

[0059] When the first communication path is established, a second communication path (sub-path) is also established as a secondary path.

[0060] In step S103, the controller records the input port and the time limit for the first communication path. More specifically, the controller records information identifying the input port on the first communication path and the time limit for which the connection of the first communication path is maintained.

[0061] In step S105, the controller records the contact information related to the second communication path.

[0062] The controller may record the input port associated with the second communication path. More specifically, the controller may record information identifying the input port on the second communication path.

[0063] In step S107, the controller determines whether or not there is a plan to switch the first communication path. For example, the controller may determine that there is a plan to switch the first communication path when the time remaining until the deadline for the first communication path arrives is less than a predetermined time.

[0064] If it is determined that there is no plan to switch the first communication path (NO in step S107), the controller may repeatedly execute step S107 at a predetermined interval.

[0065] If it is determined that the first communication path is scheduled to be switched (YES in step S107), the controller transmits a switching notification before the deadline in step S109. Specifically, the controller transmits the switching notification to the contact.

[0066] The controller may check whether or not communication light is present on the sub-path.

[0067] In step S111, the controller switches the first communication path after the time limit has elapsed. The controller may switch the first communication path after transmitting a switching notification, after a predetermined time has elapsed since transmitting the switching notification, or when it is confirmed that there is no communication light on the sub-path.

[0068] [Effects of the embodiment] As described in detail above, the optical switch according to the present disclosure includes a plurality of input ports and a plurality of output ports, the plurality of input ports being arranged at equal intervals around the rotation axis, and the plurality of output ports being arranged at equal intervals around the rotation axis, and the combination of connections of the input ports and the output ports is switched by rotation around the rotation axis, and the plurality of input ports and the plurality of output ports are connected simultaneously, and optical signals are propagated between the connected input ports and output ports.

[0069] This increases the number of optical paths that can be used simultaneously among the optical paths formed between multiple optical switches, thereby improving the utilization efficiency of the entire facility. In particular, the optical switch can simultaneously establish the same number of communication paths as the number of input ports provided in the optical switch. As a result, the number of communication paths that can be simultaneously established can be increased compared to optical switches that can establish only one communication path.

[0070] The optical cross-connect according to the present disclosure may include a plurality of the optical switches described above, with output ports of different optical switches fixedly connected to each other, and the connections between the plurality of optical switches may be switched by rotation around a rotation axis. This increases the number of optical paths that can be simultaneously used among the optical paths formed between the plurality of optical switches, thereby improving the utilization efficiency of the entire facility.

[0071] For example, the optical cross-connect XC shown in Fig. 4 can form one optical path for each optical switch, and the optical cross-connect XC can form two communication paths simultaneously (1 path x 4 / 2 = 2 paths). In contrast, the optical cross-connect XC shown in Fig. 3 can form multiple optical paths for each optical switch. As a result, all of the optical paths formed between multiple optical switches can be used simultaneously.

[0072] The optical cross connect according to the present disclosure may be configured such that a core included in a multi-core optical fiber is connected to an input port, and optical signals are input / output to / from an external device via the multi-core optical fiber. This reduces the number of optical fibers connected to the optical cross connect XC, thereby enabling efficient use of the space around the optical cross connect XC. In particular, this reduces the need for additional cables and reduces the pressure on the conduit space around the optical cross connect XC.

[0073] A switching system according to the present disclosure includes the optical cross connect and a controller. The controller records, for a first communication path and a second communication path provided by the optical cross connect, an input port on the first communication path and a time limit for maintaining the connection of the first communication path, and records a contact associated with the second communication path different from the first communication path. The controller then switches the first communication path after transmitting a switching notification for the first communication path to the contact, or after confirming that there is no communication light on the second communication path and the time limit has elapsed.

[0074] This allows the transmission of a switching notification to prompt the user of the sub-route to stop using the service of the sub-route, thereby preventing the communication service provided via the second communication route from being unintentionally interrupted. Also, since the switching of the first communication route is performed after confirming that there is no communication light, it is possible to prevent the communication service provided via the second communication route from being unintentionally interrupted. Furthermore, it becomes possible to manage and operate the timing of the communication route switching.

[0075] Although the contents of the present disclosure have been described above based on the embodiments, the present disclosure is not limited to these descriptions, and various modifications and improvements are possible, which will be apparent to those skilled in the art. The descriptions and drawings that form part of this disclosure should not be understood as limiting the present disclosure. Various alternative embodiments, examples, and operating techniques will be apparent to those skilled in the art from this disclosure.

[0076] Of course, the present disclosure includes various embodiments not described herein. Therefore, the technical scope of the present disclosure is defined only by the invention-specifying matters according to the scope of the claims that are appropriate from the above description.

[0077] AS Rotation axis BL Communications building FB Optical fiber GL Optical distribution path LP1 Upper loop LP2 Lower loop P1 to P3, P11 to P13, P21 to P23, P31 to P33, P41 to P43 Output ports Q1 to Q3, Q11 to Q13, Q21 to Q23, Q31 to Q33, Q41 to Q43 Input ports SV Server SW, SW1 to SW4 Optical switches TM1, TM2 Terminals XC Optical cross connect

Claims

1. An optical switch having a plurality of input ports and a plurality of output ports, wherein the plurality of input ports are arranged at equal intervals around a rotation axis, and the plurality of output ports are arranged at equal intervals around the rotation axis, and the combination of connections of the input ports and the output ports is switched by rotation around the rotation axis, and the plurality of input ports and the plurality of output ports are connected simultaneously, and optical signals are propagated between the connected input ports and output ports.

2. An optical cross-connect comprising a plurality of optical switches according to claim 1, wherein the output ports of different optical switches are fixedly connected to each other, and the connections between the plurality of optical switches are switched by rotation around the rotation axis.

3. The optical cross connect according to claim 2, wherein a core included in a multi-core optical fiber is connected to the input port, and the optical signal is input / output to / from an external device via the multi-core optical fiber.

4. A switching system comprising an optical cross connect according to claim 2 or 3 and a controller, wherein the controller, for a first communication path and a second communication path provided by the optical cross connect, records the input port on the first communication path and a time limit for which the connection of the first communication path is maintained, records a contact associated with the second communication path different from the first communication path, and executes switching of the first communication path after sending a switching notification for the first communication path to the contact, or after confirming that there is no communication light on the second communication path and after the time limit has elapsed.

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