JP2016111480A - Optical path changeover device and multicore fiber network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To put to practical use an optical path changeover device which is compact and low in manufacturing cost even when transmission capacity increases, and adaptive to a multi-fiber network.SOLUTION: An optical path changeover device is provided with: (1) an optical switch module which directly switches an optical path between a plurality of multicore fibers; (2) a multicore fiber-adaptive communication fault monitoring circuit which detects the level of an in-use light signal propagated in one core of a multicore fiber of an in-use system and/or the level of a monitor light signal propagated in one core of a multi-core fiber of a standby system; (3) a light source for optical path switching control signal which generates an optical path switching control signal; and (4) an optical path switching control circuit which monitors a detection signal of the multicore fiber-adaptive communication fault monitoring circuit, and outputs the optical path switching control signal when detecting a communication fault so as to switch the optical path from the multicore fiber of the in-use system to the multicore fiber of the standby system.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a network system constructed using a multi-core fiber having a plurality of cores in one fiber, and an optical path switching device corresponding to the system.

  Today, application services using optical fiber communication are becoming broadband. As a result, the amount of Internet traffic has increased at about twice the rate in two years, and this trend is expected to continue. In the future, in addition to relatively long distance networks of several kilometers or more, such as backbone, metro, and access systems, optical fiber communications will include information communication technology (ICT: Information and Information Technology) such as servers installed in data centers. Communication Technology) It is considered to be applied to extremely short-distance communications between devices (several meters to several hundreds of meters) and within devices (several centimeters to tens of centimeters). This is because optical fiber communication is superior in speeding up and lowering power consumption compared to electrical wiring.

  Up to now, the increase in communication capacity has been realized by a combination of wavelength multiplexing technology and multi-level modulation / demodulation technology, but there is a limit to further increase in capacity (Non-Patent Document 1). As a technology to overcome this limitation, an optical communication technology using a multi-core fiber (MCF) in a transmission line is expected. A conventional fiber has only one core in one fiber (hereinafter, this fiber is referred to as “single-core fiber”). On the other hand, the multi-core fiber has a plurality of cores in one fiber. For this reason, multi-core fibers are attracting attention as a transmission medium capable of high capacity and high density transmission. Currently, research on applying multi-core fibers from a backbone system to a short-distance network is being actively conducted in each organization (Non-Patent Documents 1 and 2).

  On the other hand, in a large-capacity and high-density transmission network, damage caused when a failure occurs in a transmission line due to a disaster or disconnection is immeasurable, and means for increasing reliability is required. Therefore, the following optical path switching devices are being developed as optical path switching devices that improve the reliability of optical networks that use multi-core fibers for transmission lines (Patent Document 1, Non-Patent Document 3).

  A proposed optical path switching device compatible with a multi-core fiber network will be described with reference to FIG. This optical path switching device 1 includes a fan-in / fan-out device 4 that connects a multi-core fiber 2 and a single-core fiber 3, an optical switch module 5 that has an input / output port compatible with a single-core fiber, an optical path switching control circuit 6, a communication A failure determination circuit 10 (comprising a tap photodiode 7, a current / voltage conversion circuit 8, and an analog / digital conversion circuit 9), an optical switch module drive control circuit 11, and an optical switching control signal light source 12 .

  The optical path switching control circuit 6 determines the presence / absence of a communication fault based on the signal input from the communication fault determination circuit 10 and sends an optical path switching control signal to another optical path switching device according to the determination result. At this time, the optical path is switched while synchronizing with the other optical path switching apparatus 1 as necessary. In this conventional optical path switching device 1, an optical signal propagating through the multicore fiber 2 is branched into a plurality of single core fibers 3 and connected to each port of the optical switch module 5. For this reason, in addition to the switching of the optical path between the cores of different multicore fibers, the optical path can be switched between the cores in the same multicore fiber.

JP 2014-165595 A

Morioka et al .: “Future innovative optical transport network technology”, NTT Technology Journal (2011.3) p. 32. Benjamin G. Lee, et. Al., “End-to-End Multicore Fiber Optic Link Operating up to 120 Gb / s”, JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 30, NO. 6, P. 886, MARCH 15, 2012 Yong. Lee, et. Al., “Experimental Demonstration of a Highly Reliable Multicore-Fiber-Based Optical Network”, IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 26, NO. 6, P.538, MARCH 15, 2014.

  However, the conventional optical path switching apparatus 1 has a communication failure determination circuit that increases the number of ports of the optical switch module 5, increases the number of fan-in / fan-out devices 4, and increases the number of tap photodiodes when the transmission capacity increases. In addition to the increase in size of 10, it becomes difficult to accommodate the single core fiber 3 in the optical path switching device 1. These technical problems lead to high price and large size of the optical path switching device 1. Therefore, even if the transmission capacity increases, it is desired to put into practical use an inexpensive and small optical path switching device compatible with a multi-core fiber network.

  In order to solve the above problems, in a typical optical path switching device of the present invention, an optical switch module that directly switches an optical path between a plurality of multi-core fibers and one core of an active multi-core fiber are propagated. Multi-core fiber compatible communication fault monitoring circuit for detecting the level of an active optical signal and / or the level of a monitor optical signal propagating through one core of a standby multi-core fiber, and an optical path switching control signal for generating an optical path switching control signal Monitoring the detection signal of the communication light source and the communication failure monitoring circuit corresponding to the multi-core fiber, and providing the optical path switching control signal to the optical switch module when the communication failure is detected, thereby changing the optical path to the active multi-core. And an optical path switching control circuit for switching from the fiber to the standby multi-core fiber.

  According to the present invention, it is possible to put to practical use an optical path switching device compatible with a multi-fiber network that is small in size and low in manufacturing cost even if the transmission capacity increases. Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

The figure explaining the conventional structure of the optical path switching apparatus corresponding to a multi-core fiber network. The figure which shows the structure of the optical path switching apparatus corresponding to a multi-core fiber network which concerns on a 1st Example. The figure which shows the structural example of the communication failure monitoring circuit corresponding to a multi-core fiber suitable for an active system. The figure explaining the reflectance characteristic of an optical band pass filter. The figure which shows the structural example of the communication failure monitoring circuit corresponding to a multi-core fiber suitable for use in a backup system. The figure which shows the structural example of the communication failure monitoring circuit corresponding to a multi-core fiber suitable for use in a backup system. The figure explaining the reflectance characteristic of an optical band pass filter. The figure which shows the structure of the optical switch module which concerns on a 1st Example. The figure explaining the switching operation | movement of the optical path at the time of communication failure generation | occurrence | production. The figure explaining the positional relationship of the core used for propagation of a control signal, the core used for propagation of an active optical signal, and the core for fault monitoring in an active multi-core fiber. The figure explaining the positional relationship of the core used for propagation of a control signal, and the core where a monitor optical signal propagates in a standby multi-core fiber. The figure explaining the positional relationship of the core used for propagation of a control signal, the core used for propagation of an active optical signal, and the core for fault monitoring in the working multi-core fiber after path switching. The figure which shows the structure of the optical path switching apparatus corresponding to the multi-core fiber network which concerns on a 2nd Example. The figure which shows the structure of the optical switch module which incorporates the communication failure monitoring circuit for multi-core fiber transmission which concerns on a 2nd Example. The figure explaining a P2P type multi-core fiber network system. The figure explaining a ring type multi-core fiber network system. The figure explaining a mesh type multi-core fiber network system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment of the present invention is not limited to the embodiments described later, and various modifications are possible within the scope of the technical idea.

[Example 1]
FIG. 2 shows a configuration of the optical path switching device 13 according to the present embodiment corresponding to the multi-core fiber network. The optical path switching device 13 includes a multi-core fiber 2, a multi-core fiber adapter 16, an optical switch module 14 having an input / output port compatible with a multi-core fiber, an optical path switching control circuit 6, a multi-core fiber compatible communication fault monitoring circuit 15, and an optical switch module. It comprises a drive control circuit 11 and an optical path switching control signal light source 12.

  FIG. 3 shows a configuration example of the multi-core fiber compatible communication failure monitoring circuit 15. Hereinafter, it is simply referred to as “monitoring circuit”. The monitoring circuit corresponding to the multicore fiber for the working optical signal (hereinafter also referred to as “working system”) includes the multicore fiber 2, the multicore fiber adapter 16, the collimator lens 17, the optical bandpass filter 18, the optical path conversion prism 19, and the photodiode. 20, a current / voltage conversion circuit 8, an analog / digital conversion circuit 9, and a single core fiber adapter 21. The multi-core fiber 2 includes a plurality of cores. In the case of this embodiment, a part 23 of the working optical signal 22 (assuming the wavelength is λ2) propagating through one of the plurality of cores is extracted by the optical bandpass filter 18 for monitoring of communication failure.

  The optical bandpass filter 18 converts the optical path of a part 23 of the working optical signal 22 by 90 degrees with respect to the propagation direction of the working optical signal 22. Thereafter, a part 23 of the working optical signal 22 passes through the optical path conversion prism 19 and enters the photodiode 20. The photodiode 20 converts the received light level (optical power) of the portion 23 of the working optical signal 22 into a current magnitude and outputs it to the current / voltage conversion circuit 8. The current / voltage conversion circuit 8 outputs a voltage corresponding to the magnitude of the input current. This voltage is converted into a digital signal by the analog / digital conversion circuit 9. This digital signal is output to the optical path switching control circuit 6 as information indicating the level of the working optical signal 22.

  Transmission / reception of the optical path switching control signal between the plurality of optical path switching devices 13 is performed through at least one core of the multi-core fiber 2. The optical path switching control signal provided from the optical path switching control circuit 6 is converted from an electric signal to an optical signal in the light switching control signal light source 12 and then output to the optical bandpass filter 18 through the collimator lens 17. The optical bandpass filter 18 converts the optical path of the optical path switching control signal 24 (assuming the wavelength is λ1) inputted in the form of an optical signal by 90 degrees, and determines a predetermined one of the plurality of cores of the multicore fiber 2. Output to one core.

For example, in the case of a multi-core fiber having a structure in which a plurality of cores are arranged concentrically, a core at a center position where crosstalk is relatively large is used for propagation of the optical path switching control signal 24. FIG. 4 shows the reflectance characteristics of the optical bandpass filter 18 used in this embodiment. The reflectance characteristic of the optical bandpass filter 18 is selected to be low reflectance (that is, transmission) with respect to the working optical signal 22 (λ2), while being highly reflective with respect to the optical path switching control signal 24 (λ1). Selected. The optical bandpass filter 18 having such characteristics is, for example, a dielectric multilayer filter having a structure in which titanium dioxide (TiO ₂ ) and silicon dioxide (SiO ₂ ) layers are alternately laminated, or gallium arsenide (GaAs). This can be realized by a semiconductor multilayer filter having a structure in which layers of aluminum and aluminum gallium arsenide (AlGaAs) are alternately stacked.

  The configuration of the monitoring circuit corresponding to the standby (hereinafter also referred to as “standby system”) multi-core fiber differs depending on whether it is arranged on the right side or the left side of the optical switch module 14 in FIG.

  FIG. 5A shows the configuration of the former monitoring circuit. The monitoring circuit includes a multi-core fiber 2, a multi-core fiber adapter 16, a collimating lens 17, an optical band pass filter 18, an optical band pass filter 32, an optical path switching control signal light source 12, a single core fiber adapter 21, and a monitor optical signal light source. 34 (assuming the wavelength is λ3).

  FIG. 5B shows the configuration of the latter monitoring circuit. The monitoring circuit includes a multi-core fiber 2, a multi-core fiber adapter 16, a collimating lens 17, an optical bandpass filter 18, an optical path conversion prism 19, a photodiode 20, a current / voltage conversion circuit 8, an analog / digital conversion circuit 9, and an optical path switching. The light source 12 for control signals and the single core fiber adapter 21 are comprised.

  5A and 5B, members corresponding to those in FIG. 3 are denoted by the same reference numerals. Therefore, the members unique to FIG. 5A are the optical bandpass filter 32 and the monitor light signal light source 34. FIG. 6 shows the reflection characteristics of the optical bandpass filter 32. Here, λ1, λ2, and λ3 are wavelengths of the optical path switching control signal 24, the working optical signal 22, and the monitor optical signal 33, respectively. As shown in FIG. 6, the reflectance characteristic of the optical bandpass filter 32 is selected to be a high reflectance only for the monitor optical signal 33, and is a low reflectance for the optical path switching control signal 24 and the working optical signal 22. Selected for rate. For this reason, the optical bandpass filter 32 passes most of the optical path switching control signal 24 and the working optical signal 22 and reflects the monitor optical signal 33.

  The configuration of the monitoring circuit shown in FIG. 5B is basically the same as that of the monitoring circuit shown in FIG. However, the reflectance characteristic of the optical bandpass filter 18 here is selected so as to reflect the optical path switching control signal 24 (λ1) while extracting a portion 35 of the monitor optical signal 33 (λ3). The monitoring circuit shown in FIG. 5B is used for monitoring the working optical signal 22 (λ2) after the multi-core fiber 2 to be monitored is switched from the standby system to the working system. Therefore, the optical bandpass filter 18 exhibits the reflectance characteristic shown in FIG. 4 with respect to the working optical signal 22 (λ2).

  Returning to the description of FIG. The optical path switching control circuit 6 generates an optical path switching control signal when the light reception level of the working optical signal 22 or the portions 22 and 35 of the monitor optical signal 33 falls below the set communication failure level. The optical path switching control signal 24 is given to the optical switch module drive control circuit 11. The optical switch module drive control circuit 11 drives the optical switch module 14 based on the optical path switching control signal 24 and switches the optical path so that communication can be recovered. Specifically, the optical path of the working optical signal 22 propagated by the working multicore fiber 2 is switched to the standby multicore fiber 2.

  FIG. 7 shows a configuration example of the optical switch module 14. A three-dimensional MEMS (Micro Electro Mechanical Systems) optical switch is applied to the optical switch module 14. The optical switch module 14 includes a multicore fiber array 25 in which a plurality of multicore fibers 2 are connected to each port, a microlens array 26 in which a microlens is arranged corresponding to each port, and light corresponding to each port. The MEMS tilt mirror array 27 is an assembly of microlenses capable of individually switching optical paths of signals. The light beam 28 emitted from one multi-core fiber 2 on the input port side is converted into a collimated light beam by the microlens array 26, and then reflected by the MEMS tilt mirror array 27, so that the multi-core fiber 2 on the desired output port side is obtained. Is incident on. The inclination of each micromirror of the MEMS tilt mirror array 27 is individually controlled by a voltage supplied from the optical switch module drive control circuit 11. Switching of the optical path (recombination of the output port connected to the input port) is executed by controlling the inclination of each micromirror.

  8A to 8D, the relationship between the active optical signal 22 (λ2) and the optical path switching control signal 24 (λ1) propagated by the active multicore fiber 2 and each core, and the standby multicore fiber 2 The relationship between the optical path switching control signal 24 (λ1) and the monitor optical signal 33 (λ3) propagated by each of the cores will be described. FIG. 8A schematically shows a state in which the optical path is switched from the active multi-core fiber 40 in which a communication failure has occurred to the standby multi-core fiber 41 by the optical path switching devices 38 and 39.

  As shown in FIGS. 8B to 8D, each of the active multicore fiber 40 and the standby multicore fiber 41 in the present embodiment has one core at the center and six cores around the core. FIG. 8B shows the positional relationship between each core of the active multi-core fiber 40 and the optical signal before switching of the optical path. In the present embodiment, the optical path switching control signal 24 (λ1) is propagated to the central core 42, and the working optical signal 22 (λ2) is propagated to the surrounding six cores. The core 43, which is one of the six cores through which the working optical signal 22 propagates, is used for fault monitoring of the working multi-core fiber 40. However, a core other than the core 43 may be monitored.

  FIG. 8C shows the positional relationship between each core of the standby multi-core fiber 41 and the optical signal before switching of the optical path. In the present embodiment, the optical path switching control signal 24 (λ1) is propagated to the central core 44, and the monitor optical signal 33 (λ3) is propagated to the core 45, which is one of the six peripheral cores. . The core 45 is used for fault monitoring of the standby multi-core fiber 41. However, cores at positions other than the core 45 may be monitored.

  For example, when a communication failure occurs in the active multi-core fiber 40, the optical path switching devices 38 and 39 transmit the optical path switching control signal 24 (λ1) to execute switching of the optical path. By switching the optical path, the input signal 36 propagates through the standby multi-core fiber 41 and the output signal 37 is recovered. After the path switching, the working optical signal 22 (λ2) is propagated using the peripheral core of the multi-core fiber 41 that was the standby system before the switching, and the optical path switching control signal 24 (λ1) is transmitted using the central core 46. Propagated. As a result, the core 47 corresponding to the core 45 to which the monitor optical signal 33 (λ3) has been propagated before the switching of the optical path is used for monitoring a communication failure. The position of the core 43 used for fault monitoring of the active multicore fiber 40 and the position of the core 45 (47) used for fault monitoring of the standby multicore fiber 41 can be arbitrarily selected. That is, the core 43 and the core 45 (47) may be at the same position or different.

  As described above, when the optical path switching device 13 according to the present embodiment is used, a plurality of optical signals propagating in the multicore fiber can be directly switched to another multicore fiber. For this reason, the fan-in / fan-out device 4 and the single core fiber 3 which are essential in the conventional apparatus can be eliminated.

  In addition, the optical path switching device 13 according to the present embodiment realizes monitoring of the occurrence of communication failure in the active and standby multi-core fibers by monitoring optical signals propagating through one core. Therefore, even if the transmission capacity increases, the optical path switching device 13 according to the present embodiment increases the number of signal level monitoring elements, the number of optical switch module ports, and the number of single-core fiber wirings. There is no increase. Therefore, an inexpensive and small optical path switching device 13 compatible with the multi-core fiber network can be realized.

[Example 2]
FIG. 9 shows a configuration of an optical path switching device 29 corresponding to the multi-core fiber network according to the present embodiment. In FIG. 9, parts corresponding to those in FIG. The optical path switching device 29 includes the multi-core fiber 2, the multi-core fiber adapter 16, an input / output port corresponding to the multi-core fiber, and an optical switch module 30 including a communication failure monitoring circuit corresponding to the multi-core fiber, the optical path switching control circuit 6 , An optical switch module drive control circuit 11 and an optical switching control signal light source 12.

  FIG. 10 shows a configuration example of the optical switch module 30 including a communication failure monitoring circuit. In FIG. 10, the same reference numerals are given to the corresponding parts to FIG. The optical switch module 30 includes a multi-core fiber 2, a multi-core fiber array 25, a micro lens array 26, a MEMS tilt mirror array 27, a collimator lens 17, an optical bandpass filter 18, an optical path conversion prism 19, a photodiode 20, and a current / voltage conversion circuit. 8, an analog / digital conversion circuit 9, and a single core fiber adapter 21. The reflection characteristics of the optical bandpass filter 18 are equivalent to the characteristics described in the first embodiment.

  In the case of the present embodiment, the optical system used for monitoring the working optical signal 22 (λ2) propagating through the working multicore fiber 2 and the monitoring optical signal 33 (λ3) propagating through the standby multicore fiber 2 are used. The same optical system is shared with the optical system. An optical system for introducing the optical path switching control signal 24 (λ1) into the active multicore fiber and an optical system for introducing the optical path switching control signal 24 (λ1) into the standby multicore fiber are provided. Shared by the same optical system. Therefore, it is possible to realize the optical path switching device 29 having a smaller apparatus configuration than that of the first embodiment.

[Example 3]
11A to 11C show an example of a multi-core fiber network system constructed using the optical path switching device 31 (that is, the optical path switching device 13 and / or the optical path switching device 29) according to the above-described embodiment as a node. . FIG. 11A shows a system in which two optical path switching devices 31 are connected by a P2P network using multi-core fibers. FIG. 11B shows a system in which four optical path switching devices 31 are connected by a ring network using multi-core fibers. FIG. 11C shows a system in which four optical path switching devices 31 are connected by a multi-core fiber 2 through a mesh network. By constructing a multi-core fiber network system using the optical path switching device 31 according to each of the embodiments described above, high reliability of the network system is realized.

[Other embodiments]
The present invention is not limited to the above-described embodiments, and includes various modifications. For example, the present invention need not include all the configurations described in the above embodiments. In addition, a part of one embodiment can be replaced with the configuration of another embodiment. Moreover, the structure of another Example can also be added to the structure of a certain Example. In addition, with respect to a part of the configuration of each embodiment, a part of the configuration of another embodiment can be added, deleted, or replaced.

1 Optical path switching device (conventional)
2 Multi-core fiber 3 Single-core fiber 4 Fan-in / fan-out device 5 Optical switch module 6 Optical path switching control circuit 7 Tap photodiode 8 Current / voltage conversion circuit 9 Analog / digital conversion circuit 10 Communication failure determination circuit 11 For optical switch module Drive control circuit 12 Light source for light switching control signal 13 Light path switching device (Example 1)
14 optical switch module 15 communication failure monitoring circuit for multi-core fiber 16 multi-core fiber adapter 17 collimating lens 18 optical band pass filter 19 optical path conversion prism 20 photodiode 21 single-core fiber adapter 22 working optical signal 23 part of working optical signal 24 switching optical path Control signal 25 Multi-core fiber array 26 Micro lens array 27 MEMS tilt mirror array 28 Light beam 29 Optical path switching device 30 Optical switch module (built-in communication failure monitoring circuit for multi-core fiber)
31 Optical path switching device 32 Optical band pass filter 33 Monitor optical signal 34 Monitor light signal light source 35 Monitor optical signal part 36 Input signal 37 Output signal 38 Optical path switching device 39 Optical path switching device 40 Active multi-core fiber 41 Preliminary -Based multi-core fiber 42 The core (central core) through which the optical path switching control signal propagates
43 Core (peripheral core) through which the working optical signal to be monitored propagates
44 Core where optical path switching control signal propagates (central core)
45 Core that transmits monitor optical signal before switching optical path (peripheral core)
46 Core for transmitting optical path switching control signal (central core)
47 Core through which the working optical signal to be monitored propagates after switching the optical path

Claims (6)

An optical switch module that directly switches an optical path between a plurality of multi-core fibers;
A communication fault monitoring circuit for a multicore fiber that detects the level of an active optical signal propagating through one core of an active multicore fiber and / or the level of a monitor optical signal propagating through one core of a standby multicore fiber;
A light source for an optical path switching control signal for generating an optical path switching control signal;
The detection signal of the communication failure monitoring circuit corresponding to the multi-core fiber is monitored, and when the communication failure is detected, the optical path switching control signal is given to the optical switch module, so that the optical path is changed from the active multi-core fiber to the standby line. An optical path switching device having an optical path switching control circuit for switching to a multi-core fiber of the system. The optical path switching device according to claim 1,
The optical switch module is
A plurality of multi-core fiber arrays each having a plurality of ports to which one multi-core fiber is connected;
The optical path switching device according to claim 1, further comprising: a plurality of microlens arrays configured by a plurality of micromirrors corresponding to each port, and individually switching an optical path of an optical signal corresponding to each port. The optical path switching device according to claim 1,
The multi-core fiber compatible communication failure monitoring circuit is located between the optical switch module and an input port of the optical path switching device,
The multi-core fiber compatible communication failure monitoring circuit is:
A first adapter connected to the first multi-core fiber on the input port side;
A second adapter connected to a second multi-core fiber on the optical switch module side;
The working optical signal that is located in a space between the first adapter and the second adapter and propagates in the space from the first adapter to the second adapter has a first light amount. The first adapter is configured to separate light into reflected light having a second light amount (<the first light amount) and reflect the light path switching control signal input from the light path switching control signal light source. An optical bandpass filter that propagates in the direction of
A photodiode for detecting a level of the working optical signal reflected by the optical bandpass filter;
A current / voltage conversion element for converting an analog current signal output from the photodiode into an analog voltage signal;
An analog / digital conversion element that converts the analog voltage signal into a digital voltage signal and outputs the digital voltage signal to the optical path switching control circuit;
An optical path switching device further comprising: The optical path switching device according to claim 1,
A monitor light signal light source for generating the monitor light signal;
The multi-core fiber compatible communication failure monitoring circuit has a first monitoring circuit and a second monitoring circuit,
The first monitoring circuit is located between the optical switch module and an input port of the optical path switching device,
The first monitoring circuit includes:
A first adapter connected to the first multi-core fiber on the input port side;
A second adapter connected to a second multi-core fiber on the optical switch module side;
Located in a space between the first adapter and the second adapter, and passes an optical signal propagating from the second adapter in the direction of the first adapter, and is input from the light source for the monitor optical signal A first optical bandpass filter that reflects the transmitted monitor light signal and propagates it in the direction of the first adapter;
The light source for the optical path switching control signal is located in a space between the first adapter and the second adapter, passes an optical signal propagating from the second adapter in the direction of the first adapter, and is used for the optical path switching control signal light source. A second optical bandpass filter that reflects and propagates the optical path switching control signal input from the direction of the first adapter;
Further comprising
The second monitoring circuit includes:
A third adapter connected to a third multi-core fiber on the input port side;
A fourth adapter connected to a fourth multi-core fiber on the optical switch module side;
The monitor light signal that is located in a space between the third adapter and the fourth adapter and propagates in the space from the third adapter toward the fourth adapter has a first light amount. The third adapter separates light into reflected light having a second light quantity (<the first light quantity) and reflects the light path switching control signal input from the light path switching control signal light source. A third optical bandpass filter that propagates in the direction of
A photodiode for detecting a level of the monitor optical signal reflected by the third optical bandpass filter;
A current / voltage conversion element for converting an analog current signal output from the photodiode into an analog voltage signal;
An optical path switching device further comprising: an analog / digital conversion element that converts the analog voltage signal into a digital voltage signal and outputs the digital voltage signal to the optical path switching control circuit. The optical path switching device according to claim 1,
A monitor light signal light source for generating the monitor light signal;
The optical switch module incorporating the communication failure monitoring circuit for the multi-core fiber,
A first multicore fiber array terminating a plurality of multicore fibers on the first port side;
A second multi-core fiber array terminating a plurality of multi-core fibers on the second port side;
A set of tilt mirror arrays that reflect an optical signal between the first multi-core fiber array and the second multi-core fiber array and switch the path of the optical signal in units of multi-core fibers;
A space between one of the set of tilt mirror arrays and the first or second multi-core fiber array is located, and the space is moved from the first or second multi-core fiber array to the other multi-core fiber. The working optical signal propagating in the direction of the array is separated into a passing light having a first light amount and a reflected light having a second light amount (<the first light amount), and inputted from the monitor light signal light source. A first optical bandpass filter that reflects the monitor optical signal and propagates it in the direction of the other multi-core fiber array;
A space between one of the set of tilt mirror arrays and the first or second multi-core fiber array is located, and the space is moved from the first or second multi-core fiber array to the other multi-core. The working optical signal or the monitor optical signal propagating in the direction of the fiber array is separated into a passing light having a third light amount and a reflected light having a fourth light amount (<the third light amount), and the optical path A second optical bandpass filter that reflects the optical path switching control signal input from the switching control signal light source and propagates it in the direction of the other multi-core fiber array;
A photodiode for detecting a level of the working optical signal or the monitor optical signal reflected by the second optical bandpass filter;
A current / voltage conversion element for converting an analog current signal output from the photodiode into an analog voltage signal;
An analog / digital conversion element that converts the analog voltage signal into a digital voltage signal and outputs the digital voltage signal to the optical path switching control circuit;
An optical path switching device. A plurality of nodes including the optical path switching device according to claim 1;
An optical network system comprising: a P2P type, ring type, or mesh type optical network that connects the plurality of nodes by a multi-core fiber.

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