Optical switch

Abstract

Provided is an optical switch which includes an output port for a monitoring optical signal for determining whether the optical switch is operating normally, thereby enabling failures to be detected, and which does not give rise to excessive optical losses in optical signals used for communication. An optical switch (20) according to the present disclosure comprises at least one switch functional unit (221 to 223) in which a plurality of one-input two-output optical switches (211a to c, 212a to c, 213a to c) are connected in cascade, optical coupler functional units (251 to 253) in which a plurality of two-input one-output optical couplers (231a to 233a, 231b to 233b) for accepting input of optical signals output from the switch functional units (221 to 223) are connected in cascade, and at least either first monitoring output ports (261 to 263) or second monitoring output ports (271 to 273), wherein: the first monitoring output ports (261 to 263) are ports for delivering first monitoring optical signals output from the switch functional units (221 to 223) to the outside; and the second monitoring output ports (271 to 273) are ports for delivering, to the outside, second monitoring optical signals output from two-input two-output optical couplers (241a to c) provided instead of the two-input one-output optical couplers (231b to 233b) positioned at output side ends of the plurality of two-input one-output optical couplers.

Description

[Technical Field]

[0001] The present disclosure relates to optical switches. [Background technology]

[0002] With the spread of the Internet, the demand for data communication networks is rapidly increasing. To meet this rapidly increasing demand, optical communication networks that can transmit large amounts of data with low power consumption are being widely constructed.

[0003] In optical communication networks, optical switches are used to realize flexible route configuration in addition to the function of directly connecting two points. Among these optical switches, a multicast switch that controls multiplexing and demultiplexing functions in a CDC-ROADM (Colorless, Directionless, Contentionless-Reconfigurable Optical Add Drop Multiplexer) is an example of a switch device that has been widely used in recent years (see, for example, Non-Patent Document 1).

[0004] 1 is a conceptual diagram illustrating the configuration of a conventional multicast switch 10. This conventional multicast switch 10 includes N (N=3, for example) 1-input, 3 (=M)-output optical switches 121-123, each of which is composed of M (M=3, for example) 1-input, 2-output optical switches 111a-c, 112a-c, and 113a-c, each of which is cascaded; M N-input, 1-output optical couplers 141-143, each of which is composed of N-1 2-input, 1-output optical couplers 131a-b, 132a-b, and 133a-b, each of which has a merging ratio of 1:1, 1:2, . . . , 1:(N-1); 3 (=N) input ports 151-153; and 3 (=M) output ports 161-163. Here, M and N are integers greater than or equal to 2. In addition, the paths of optical signals are indicated by arrows in FIG.

[0005] In optical switches 121-123, one output of optical switches 111a-b, 112a-b, and 113a-b is connected to the input of the optical switch adjacent to the output side (for example, one output of 111a is connected to the input of 111b). However, the optical switches (111c-113c in FIG. 1) located at the end of the output side (farthest from input ports 151-153) do not have an adjacent optical switch on the output side, so one output of these switches is not connected to any optical switch.

[0006] On the other hand, the other outputs of optical switches 111a-c, 112a-c, and 113a-c are connected as outputs of optical switches 121-123 to the inputs of optical couplers 131a-b, 132a-b, and 133a-b arranged within optical couplers 141-143. The outputs of optical couplers 131a-133a are connected to the inputs of adjacent optical couplers 131b-133b, and the outputs of optical couplers 131b-133b are connected to output ports 161-163, respectively, as outputs of optical couplers 141-143.

[0007] The multicast switch 10 according to the prior art having such a configuration has the function of outputting optical signals input from an input port from any output port. In addition, when the signal wavelengths input from different input ports are different, it is possible to wavelength-division multiplex and output the optical signals input from the different input ports without interference.

[0008] Not only with multicast switches, but with optical switches in general, it is difficult to determine whether they are operating normally, i.e., to detect a fault. For this reason, a circuit that branches and outputs a portion of the optical signal is provided outside the optical switch, and a portion of the input optical signal and output optical signal is observed to detect a fault. The objects of this observation can be, for example, the presence or absence of a signal, the optical level of the signal, the wavelength of the signal, etc. These observations then obtain information such as the presence or absence of an optical signal that should be present, changes in the optical level of a signal that should be generated, and the presence or absence of an optical signal of a wavelength that should be present, and based on this information, it is possible to determine whether the optical switch is operating normally.

[0009] However, when a circuit for branching and outputting a portion of such an optical signal is provided, there is a problem that a portion of the optical signal used for communication is lost due to branching, resulting in a decrease in the optical signal level and a decrease in the quality of the optical signal. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] T. Watanabe, K. Suzuki and T. Takahashi, “Silica-based PLC transponder aggregators for colorless, directionless, and contentionless ROADM”, Optical Fiber Communication Conference(OFC), Paper OTh3D.1(2012). Summary of the Invention

[0011] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide an optical switch that has the functions of a multicast switch or a tree-type optical switch equivalent to a multicast switch with one input port, that further includes an output port for a monitor optical signal to determine whether it is operating normally, thereby enabling detection of a fault, and that does not cause excessive optical loss in the optical signal used for optical signal communication.

[0012] In response to the above-described problems, the present disclosure provides an optical switch comprising at least one switch function unit in which a plurality of 1-input 2-output optical switches are cascaded, an optical coupler function unit in which a plurality of 2-input 1-output optical couplers are cascaded to receive an optical signal output from the switch function unit, and at least one of a first monitor output port and a second monitor output port, wherein the first monitor output port is a port for sending to the outside the first monitor optical signal output from the switch function unit, and the second monitor output port is a port for sending to the outside the second monitor optical signal output from a 2-input 2-output optical coupler that is provided in place of the 2-input 1-output optical coupler that is located at the output end of the plurality of 2-input 1-output optical couplers. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram conceptually illustrating the configuration of a multicast switch 10 according to the prior art. [Figure 2] 1 is a diagram conceptually illustrating the configuration of an optical switch 20 according to the present disclosure. [Figure 3] 1 is a diagram conceptually illustrating the configuration of an optical switch 30 according to the present disclosure. [Figure 4] 1 is a diagram conceptually illustrating the configuration of an optical switch 40 according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Various embodiments of the present disclosure will be described in detail below with reference to the drawings. The same or similar reference numerals indicate the same or similar elements, and redundant description may be omitted. Materials and numerical values ​​are for illustrative purposes only and are not intended to limit the technical scope of the present disclosure. The following description is an example, and some configurations may be omitted or modified, or additional configurations may be added, as long as they do not deviate from the gist of one embodiment of the present disclosure.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The optical switch according to this embodiment is a multicast switch having N input ports and M output ports (where M and N are integers of 2 or more), and further including first and / or second output ports from which monitor optical signals are output to determine whether the optical switch is operating normally.

[0016] Fig. 2 is a diagram conceptually illustrating the configuration of an optical switch 20 according to the present disclosure. Fig. 2 shows an example in which M=3 and N=3, with three inputs and three outputs, but the numbers M and N are not limited to this.

[0017] As shown in FIG. 2, the optical switch 20 includes switch function units 221-223 in which three (=M) one-input, two-output optical switches 211a-c, 212a-c, and 213a-c are cascade-connected, and optical coupler function units 251-25 in which one (=N-2) two-input, one-output optical coupler 231a-c and one two-input, two-output optical coupler 241a-c are cascade-connected, each of which is connected to the output of the optical coupler 231a-c. 3, first monitor output ports 261-263 which are connected to the outputs of the optical switches 211c-213c and are ports for sending monitor optical signals to the outside, second monitor output ports 271-273 which are connected to the outputs of the optical couplers 241a-c and are ports for sending monitor optical signals to the outside, optical signal input ports 281-283, and optical signal output ports 291-293.

[0018] In the switch function units 221-223, one of the outputs of the optical switches 211a-b, 212a-b, and 213a-b is connected to the input of the optical switch adjacent to it on the output side (for example, one of the outputs of 211a is connected to the input of 211b). However, one of the outputs of the optical switch located at the end of the output side, in other words, the optical switch farthest from the input ports 281-283 (corresponding to the optical switches 211c-213c in FIG. 2), is connected to the first monitor output ports 261-263. In contrast, the other outputs of the optical switches 211a-c, 212a-c, and 213a-c are connected to the inputs of the optical couplers 231a-c in the optical coupler function units 251-253 as outputs of the switch function units 221-223.

[0019] In the optical coupler function units 251-253, the outputs of the optical couplers 231a-c are connected to the inputs of the optical couplers 241a-c, respectively. One output of each of the optical couplers 241a-c is connected to the output ports 291-293, respectively, as in the prior art, while the other output is connected to the second monitor output ports 271-273, respectively.

[0020] In the optical switch 20 according to this embodiment having such a configuration, it is assumed that an optical signal is input from an input port (e.g., input port 282), and an arbitrary optical switch (e.g., optical switch 212b) of the switch function units 221-223 is connected to an output port (e.g., output port 292). In this case, the optical signal passing through the optical switch 212b is guided to the output port 292 via the optical coupler function unit 252, and therefore no optical signal is output from the first monitor output port 262. Therefore, if an optical signal is observed by monitoring the first monitor output port 262 under such conditions, it can be detected that the optical switch 212b is faulty.

[0021] Furthermore, in the optical switch 20, for example, when an optical signal is input from the input port 282 and the optical switch 212b is connected to the output port 292, an optical signal is also output from the second monitor output port connected to the optical coupler 241b. Therefore, by monitoring the optical signal output from the second monitor output port, if no optical signal is observed, it can be detected that the optical switch 212b is faulty.

[0022] The optical switch 20 can be fabricated using silica-based planar lightwave circuit technology on a silicon substrate, and is expected to achieve excellent optical characteristics. In this case, the optical switch 20 is a waveguide-type optical switch that can be driven using the thermo-optic effect.

[0023] Furthermore, by installing photoelectric conversion elements (e.g., pn junction photodiodes) in the first monitor output ports 261-263 and the second monitor output ports 271-273, it is possible to obtain the output of an electrical signal, and obtain the presence or absence of an optical signal, the level of the optical signal, etc. from the electrical signal.

[0024] As described above, in the optical switch 20 according to this embodiment, the connection function between the input ports 281-283 and the output ports 291-293 is the same function provided by a multicast switch according to conventional technology, so the conventional functionality of the optical switch is maintained. Furthermore, by separately installing the first monitor output ports 261-263 and the second monitor output ports 271-273 and monitoring the optical signals output from these ports, it is possible to achieve the effect of detecting a failure in the optical switch. In addition, the optical switch 20 according to this embodiment is not configured to branch a portion of the optical signal as in the conventional technology, and therefore it is possible to suppress excessive loss of the optical signal due to failure detection.

[0025] Although this embodiment is described as including both the first monitor output ports 261-263 and the second monitor output ports 271-273, the optical switch according to the present disclosure can achieve the same effect even if it is configured to include only the second monitor output ports 271-273, as in the optical switch 30 shown in FIG.

[0026] In addition, the same effect can be achieved even in a configuration including only the first monitor output ports 261-263, as in optical switch 40 shown in Fig. 4. In this case, N-1 two-input, one-output optical couplers 231b-233b are also installed as the terminal (closest to the output side) optical couplers in optical coupler function units 251-253. This makes it possible to set N=1, which corresponds to a tree-type switch with one input and M outputs. [Industrial Applicability]

[0027] As described above, the optical switch according to the present disclosure includes a mechanism for determining whether the optical switch is operating normally without causing excessive optical loss to the optical signal. Therefore, the optical switch is expected to be applied to optical communication networks as a highly efficient optical switch.

Claims

1. An optical switch, at least one switch function unit in which a plurality of 1-input 2-output optical switches are cascade-connected; an optical coupler function unit in which a plurality of 2-input 1-output optical couplers are cascade-connected to receive the optical signal output from the switch function unit; a first monitor output port and a second monitor output port; the first monitor output port is a port for transmitting a first monitor optical signal output from the switch function unit to the outside, the second monitor output port is a port for transmitting to the outside a second monitor optical signal output from a 2-input 2-output optical coupler provided in place of the 2-input 1-output optical coupler located at the end of the output side of the plurality of 2-input 1-output optical couplers, an optical switch configured to identify a faulty one-input two-output optical switch according to a combination of a result of monitoring the first monitor optical signal and a result of monitoring the second monitor optical signal.

2. 2. The optical switch according to claim 1, further comprising a photoelectric conversion element that converts an optical signal sent from at least one of said first monitor output port and said second monitor output port into an electrical signal.

3. It is formed on a silicon substrate and has SiO 2 It is a waveguide type optical switch manufactured using planar lightwave circuit technology including silica-based glass whose main component is 3. The optical switch according to claim 1, which is driven using the thermo-optic effect.

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