JP2017168916A - Optical switch, optical path switching system, and optical path switching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the surge of an optical amplifier at a time of switching an optical path without requiring a large additional circuit and prevent communication from being disrupted at the time of switching the optical path.SOLUTION: The optical switch is so configured that a path of an optical signal is switched between a plurality of input ports and a plurality of output ports, dummy light input from one input port is output to an output port, which is a switching destination of the optical signal, the output of the optical signal is switched to the output port of the switching destination, and the output of the dummy light from the switching destination output port is stopped.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical switch, an optical path switching system, and an optical path switching method, and more particularly to an optical path switching by an optical switch.

  Super Hi-Vision (SHV) broadcasting, which is expected for the next-generation high-intensity broadcasting system, is an ITU-R recommendation BT. It was approved in 2012 as 2020, and development is being promoted mainly by NHK with the aim of starting commercial broadcasting in 2018. The full-spec SHV is 7,680 x 4,320 (8K4K), the frame frequency is 120, the gradation is 16 times the number of pixels of 1,920 x 1,080 high-definition broadcasts that have been put into practical use. It is an ultra-high accuracy system that realizes 12 and 22.2 ch three-dimensional sound. Full-spec SHV transmission requires an extremely large transmission capacity of 144 Gpbs when uncompressed. The video to be broadcast is delivered to each home after compression, but as shown in FIG. 11, in a broadcasting station, a large-scale network called a network and a routing switcher is used as a non-compressed signal between a studio, an editing room, and a video storage room. Exchange takes place via electrical switches.

  In Hi-Vision so far, the required transmission bandwidth per material is 12 Gbps, and transmission is performed using electric cables using four 3 Gbps SDI (Serial Digital Interface). However, in the full-spec SHV, the necessary transmission bandwidth is as high as 144 Gbps, so that it is difficult to transmit using an electric cable. For example, transmission over an electric cable using a transmission capacity exceeding 10 Gbps is insufficient for the transmission distance, so it is necessary to use a transmission rate of about 3 Gbps as before. When a transmission rate of about 3 Gbps is used, 48 electrical cables are actually required for transmission per material, and wiring work becomes extremely difficult. Therefore, as shown in FIG. 12, studies have been made on transmission using an optical fiber capable of high-speed transmission compared to electrical transmission. For example, Non-Patent Document 1 shows that full-spec SHV transmission is possible in a configuration using a 10 Gbps × 12 ch optical transceiver and a multimode fiber.

  As described above, the study of optical transmission is currently underway, but the routing switcher remains an electrical switch. For this reason, it is necessary to convert it to electricity once before input to the routing switcher, then switch it with the routing switcher, re-optically transmit it, and transmit an optical transceiver for photoelectric conversion before and after input to the routing switcher. It becomes. On the other hand, as shown in FIG. 13, by replacing the routing switcher with an optical switch, there is an advantage that an optical transceiver for photoelectric conversion becomes unnecessary.

  Next, FIG. 14 shows a configuration example of the optical switch. For example, a routing switcher must have a multicast function that simultaneously distributes from one studio to a plurality of editing rooms or video storages. Therefore, an optical switch that realizes the multicast function also requires a multicast function. There are several methods for realizing multicast. Here, a switch configuration called a split and select type shown in FIG. 14 will be described. In FIG. 14, the optical signal from the input port is branched into eight by the 1 × 8 splitter, and only the optical signal that needs to be connected to the output port is selected by the 8 × 1 selector in the next stage, thereby enabling switching including multicast. It becomes possible.

  Note that in an optical switch that realizes multicast, it is necessary to branch an optical signal inside the optical switch, so that the optical signal level decreases inside the switch. For example, as shown in FIG. 14, in an 8 × 8 switch configuration, if an optical signal from one input port is multicast to all eight output ports, eight branches are required, resulting in a 12 dB optical signal level drop. . Since the decrease in the optical signal level affects the reception sensitivity of the optical transceiver on the reception side, it is necessary to compensate for the loss by installing an optical amplifier after the routing switcher, as shown in FIG.

  Next, operations for switching video materials using a routing switcher are shown in FIGS. 16 (a) and 16 (b). FIG. 16B shows an operation of switching the optical signal from the input port (1) from the output port (1) to the output port (4). FIG. 16B shows the optical signal levels at the output port (1) and the output port (4) at this time. The light level of the output port (1) is changed from a certain level to 0 by switching, and the light level of the output port (4) is changed from 0 to a certain level by switching. At this time, the energy accumulated in the optical amplifier during the light interruption time when the optical signal is not input to the optical amplifier is released all at once when the input of the optical signal is resumed, thereby generating a surge.

  As a first method for preventing the surge of the optical amplifier, a change in the level of the input optical signal to the optical amplifier as shown in FIG. 17 is detected, and a surge is generated in the gain of the optical amplifier according to the detected change in the optical level. There is something that controls to a level that does not. For example, when the input optical signal rises from 0 to a certain level, a PD (Photo Detector) detects the change, and the excitation light source while the input optical signal passes through the delay line installed in the preceding stage of the optical amplifier. By reducing the current applied to the optical amplifier, the gain of the optical amplifier is lowered to an appropriate value to prevent surges.

  Further, as a second method for preventing the surge of the optical amplifier, there is a method of once decreasing the gain when the switch is switched as shown in FIG. For example, before switching the optical signal input to the input port (1) from the output port (1) to the output port (2), the control system indicates the gain of the optical amplifier once connected to the output port (2). To lower. Then, after switching, the surge is prevented by gradually increasing the gain of the optical amplifier to an appropriate value.

  Further, as a third method for preventing the surge of the optical amplifier, there is a method using dummy light as shown in FIG. At the time of switching the optical switch, the optical signal is once cut off and then recovered.At that time, by detecting the interruption of the optical signal with the PD and inserting the dummy light instead of the optical signal during the interruption of the optical signal, Prevents sudden light level changes and prevents surges in the optical amplifier. Patent Document 1 relates to an optical communication system in which transmission lines are duplicated, and it has been proposed to use dummy light in order to prevent the occurrence of an optical surge caused by switching of transmission lines.

  Patent Document 2 relates to an optical amplifier, and prevents the occurrence of an optical surge pulse by detecting that the output of signal light from the optical amplifier is below a predetermined level and inserting dummy light into the optical fiber. It has been proposed to do. Patent Document 3 relates to an optical transmission device, and proposes to suppress the occurrence of an optical surge by configuring signal light or dummy light to be input to an optical amplifier disposed between nodes. Yes. Patent Document 4 relates to an optical transmission device, which suppresses the occurrence of an optical surge by inserting a dummy signal in a period in which no optical packet exists in an optical amplifier that amplifies an optical packet generated intermittently. Proposed.

Japanese Patent No. 3905083 JP-A-9-321373 Japanese Patent Laid-Open No. 11-88270 JP 2003-258729 A

“Development and standardization trend of optical interface in 8K Super Hi-Vision”, NHK R & D No. 146, 20144.8

  However, the optical path switching system described above has the following problems.

  The first problem is that an additional circuit is required. The reason for this is that in the method of detecting the level change of the input optical signal to the optical amplifier and controlling the gain of the optical amplifier to a level at which no surge occurs according to the detected light level change, the following elements are required. That is, the delay line for preventing the optical signal from being input to the optical amplifier, the PD for detecting the optical level change, and a part of the optical signal are input to the PD from the detection of the optical level change to the control of the gain of the optical amplifier This is an optical coupler.

  The second problem is not suitable for a system that distributes real-time video. The reason for this is that when the switch is switched, the gain of the optical amplifier is temporarily reduced to a level that does not cause surge, and the optical amplifier gain is gradually increased to an appropriate value because communication is interrupted before the gain of the optical amplifier is restored. It is.

  The third problem is that an additional circuit is required. The reason for this is that in the method of detecting optical signal interruption by PD and inserting dummy light during optical signal interruption to prevent optical amplifier surge, PD for detecting light level change, part of optical signal This is because an optical coupler for inputting the signal to the PD is required.

  In Patent Literature 2, Patent Literature 3, and Patent Literature 4, there is no disclosure regarding specific contents and methods of optical path switching using an optical switch.

  An object of the present invention is to provide an optical switch, an optical path switching system, which can prevent a surge of an optical amplifier at the time of switching an optical path without requiring a large additional circuit and without interrupting communication at the time of switching the optical path. And providing an optical path switching method.

In order to achieve the above object, the optical switch according to the present invention is configured such that optical signal paths are switched between a plurality of input ports and a plurality of output ports.
After the dummy light input from one input port is output to the output port that is the switching destination of the optical signal, the output of the optical signal is switched to the output port that is the switching destination, and the dummy light from the output port that is the switching destination Stop the output of.

  In the optical path switching system according to the present invention, optical signal paths are switched between a plurality of input ports and a plurality of output ports, and dummy light input from one input port is used as an output port to which the optical signal is switched. After output, the optical signal output is switched to the switching destination output port, and the dummy switch from the switching destination output port is stopped, and the optical switch is output from the output port of the optical switch. And an optical amplifier for amplifying the optical signal.

The optical path switching method according to the present invention includes an optical switch that switches an optical signal path between a plurality of input ports and a plurality of output ports, and an optical that amplifies the optical signal output from the output port of the optical switch. An optical path switching method for a system including an amplifier,
After the dummy light input from one input port of the optical switch is output to the output port to which the optical signal is switched, the output of the optical signal is switched to the output port of the switching destination, and the output port of the switching destination The output of the dummy light from is stopped.

  The present invention can prevent a surge of the optical amplifier at the time of switching the optical path without requiring a large additional circuit and without interrupting communication at the time of switching the optical path.

It is a functional block diagram for demonstrating the optical switch switching system by 1st Embodiment of this invention. (A) is a block diagram which shows an example of an optical switch, (b) is a block diagram which shows an example of the optical switch system containing an optical amplifier. It is a block diagram for demonstrating the aspect which comprised the optical switch with the MZ interferometer type | mold optical switch. It is a flowchart which shows switching operation | movement of the optical switch by 1st Embodiment of this invention. (A) is an operation | movement figure which shows the example of a switching of an optical switch system, (b) is a graph which shows the optical level of the output port (1) and output port (4) at the time of switching. It is a block diagram of the optical switch system containing the optical amplifier in 2nd Embodiment of this invention. FIG. 7 is an operation diagram illustrating a switching example of the optical switch system in FIG. 6. (A) is a block diagram of the optical switch system containing the optical amplifier in 3rd Embodiment of this invention, (b) is the optical signal output from the output port (1) and output port (2) before switching. It is a graph which shows a light level and the light level of the dummy light output from an output port (3) and an output port (4). (A) is an operation | movement diagram which shows the example of switching of the optical switch system of FIG. 8, (b) is a graph which shows the optical level of the output port (3) and output port (4) at the time of switching. 1 is a configuration diagram illustrating an optical switch according to an embodiment of the highest concept of the present invention. FIG. It is a block diagram of a broadcast video system. 1 is a configuration diagram of a broadcast video system using optical transmission. It is a block diagram of a broadcast video system using optical transmission and an optical switch. It is a block diagram of an optical switch. It is a block diagram of the optical switch system containing an optical amplifier. (A) is an operation | movement diagram which switches the optical switch system of FIG. 15, (b) is a graph which shows the optical level of the output port (1) and output port (4) at the time of switching. It is a block diagram which shows the 1st background art which prevents the surge of an optical amplifier. It is a block diagram which shows the 2nd background art which prevents the surge of an optical amplifier. It is a block diagram which shows the 3rd background art which prevents the surge of an optical amplifier.

  An optical switch, an optical path switching system, and an optical path switching method according to embodiments of the present invention will be described with reference to the drawings. In addition, the direction of the arrow in a drawing shows an example and does not limit the direction of the signal between blocks.

[First Embodiment]
An optical switch, an optical path switching system, and an optical path switching method according to a first embodiment of the present invention will be described. FIG. 1 is a functional block diagram for explaining an optical switch switching system according to a first embodiment of the present invention. FIG. 1 shows an example of functional blocks of an entire routing switcher system using optical switches.

  The optical path switching system of FIG. 1 includes a system controller 100, an optical transceiver 101 that converts an electrically transmitted video material into an optical signal, and an optical switch that switches an optical signal from the optical transceiver 101 to a desired path. Further, the optical path switching system of FIG. 1 includes a drive circuit 104 that changes the port connection state of the optical switch, a drive circuit control unit 105 that controls the drive circuit 104, and an optical amplifier that amplifies the optical signal output from the optical switch. Including. Further, the optical path switching system of FIG. 1 is connected to the optical transmission path 106 for transmitting the optical signal from the optical amplifier and the input port of the optical switch, and outputs dummy light to the switching destination port in advance when the optical switch is switched. It includes a light source 107.

An optical switch for switching the optical signal from the optical transceiver 101 to the desired path includes an optical switch 102 ₁ as an example of a transmission side optical switch, an optical switch 102 ₂ as an example of a reception side optical switch, the. An optical amplifier for amplifying an optical signal output from the optical switch includes an optical amplifier 103 ₁ as an example of the transmission side optical amplifier, the optical amplifier 103 ₂ as an example of the receiving-side optical amplifier, a.

  FIG. 2A is a configuration diagram illustrating an example of an optical switch, and FIG. 2B is a configuration diagram illustrating an example of an optical switch system including an optical amplifier. As an example, an example of an optical switch system including an optical switch and an optical amplifier when an 8 × 8 split & select optical switch is used will be described. The optical switch system includes an optical switch 102 and an optical amplifier 103. The optical switch 102 includes an input port (1) to an input port (8) and an output port (1) to an output port (8). The optical switch 102 in FIG. 2A selects a 1 × 8 splitter 201 that splits an optical signal from an input port into 8 branches, and 8 × that selects one of 8 optical signals input from the 1 × 8 splitter. 1 selector 202 is included. Further, the optical switch 102 in FIG. 2A includes an optical waveguide 203 that connects between the 1 × 8 splitter 201 and the 8 × 1 selector 202. Also, here, an example is shown in which dummy light is input from the input port (8) among the input ports (1) to (8). Any port of the input port (8) may be used. In addition to the 8 × 8 configuration, in addition to the input port (1) to the input port (8) and the output port (1) to the output port (8), a 9 × 8 configuration having an input port dedicated to dummy light input may be used. .

  In a split & select type optical switch, it is necessary to integrate a large number of switch elements, and switches using various technologies have been developed. As a switch element used for a switch, there is a MEMS (Micro Electro Mechanical Systems) optical switch that switches an optical path by changing an angle of a micromirror formed on a silicon substrate. In addition, there is an LCOS (Liquid Crystal On Silicon) optical switch that switches an optical path by changing a refractive index of a liquid crystal layer formed on a silicon substrate and changing a reflection angle of incident light. There is also a PLC (Planar Lightwave Circuit) optical switch that configures a Mach-Zehnder interferometer with a quartz optical waveguide on a silicon substrate and controls the passage / non-passage of light. Furthermore, there is a silicon optical switch that configures a Mach-Zehnder interferometer (MZ Zehnder interferometer) with a silicon optical waveguide on a silicon substrate and controls the passage / non-passage of light.

  In the embodiment of the present invention, a silicon optical switch capable of high-speed switching of several tens of μs necessary for realizing surge prevention of an optical amplifier is used. The silicon optical switch can perform high-speed switching so that the optical amplifier at the subsequent stage does not follow the path switching operation of the optical signal.

  Next, a switching element using the MZ interferometer used in the above-described silicon optical switch will be described. FIG. 3 is a configuration diagram for explaining an aspect in which an optical switch is configured by the MZ interferometer type optical switch 301. One MZ interferometer-type optical switch 301 in FIG. 3 includes two optical couplers 302, an equal-length optical waveguide 303 connecting the optical couplers 302, and a phase shifter 304 that changes the refractive index of the optical waveguide 303. Composed. The input optical signal is branched into two (50:50) by the front-stage optical coupler 302 and joined again by the rear-stage optical coupler 302. As a switching operation, a 100% optical signal is output from the cross port when the phase shifter 304 is not driven. Further, when the phase shifter 304 is driven, the speed of the optical signal traveling through the optical waveguide 303 changes, and a phase difference is generated when the optical signal is joined by the optical coupler 302 at the subsequent stage. By optimizing this phase difference, a 100% optical signal can be output from the bar port. Further, by changing the phase difference, it is possible to output to the bar port and the cross port at an arbitrary branching ratio. The phase shifter 304 includes a thermo-optic effect type that changes the refractive index of the optical waveguide 303 using a heater or the like, and an electrical engineering effect type that changes the refractive index by applying a voltage to the optical waveguide 303. Since silicon has a small electrical engineering effect, a thermo-optic effect type is usually used.

  Next, the thermo-optic effect type phase shifter 304 will be described. The thermo-optic effect phase shifter 304 is composed of a resistor formed in a thin film on or in the vicinity of the optical waveguide 303. By passing a current through the resistor, the temperature of the optical waveguide 303 is raised and the refractive index is changed. As a structural example, a pair of thin film resistors corresponding to two optical waveguides 303 connecting between the optical couplers 302 in the MZ interferometer type optical switch 301 are formed, and one side is grounded and one side is used as a power source. It is often connected to a change-over switch to be connected. That is, when the changeover switch of the phase shifter 304 whose phase is to be changed is turned on, a current flows through the phase shifter 304 and the temperature of the thin film resistor rises, whereby the MZ interferometer type optical switch 301 is changed over.

(Description of operation)
Next, the optical path switching method using the optical switch of the present embodiment will be described with reference to FIGS. 1, 4, and 5. FIG. 4 is a flowchart showing the switching operation of the optical switch, and FIG. 5A is an operation diagram showing a switching example of the optical switch. In FIG. 5A, the optical path before switching is indicated by a solid line, and the optical path after switching is indicated by a dotted line. FIG. 5B is a graph showing the light levels of the output port (1) and the output port (4) at the time of switching. Here, in the optical switch 102 as one example of a transmission side optical switches 102 _1, the state in which the optical signal inputted to the input port (1) is output from the output port (1), the output from the output port (4) The switching operation to the state to be performed will be described. Since the operation is the same on the receiving side, the operation on the receiving side is omitted.

  When changing the distribution destination of the video material, first, an optical signal switch port switching request is received from the system controller 100 (S1). Specifically, the drive circuit control unit 105 receives an optical signal switch port switching request from the system controller 100. Optical signal switching information is set in the drive circuit controller 105 (S2).

  Next, the connection between the optical signal switching destination output port (output port (4)) and the dummy light source input port (input port (8)) is set in the drive circuit control unit 105 (S3).

  Next, the drive circuit 104 connects between the optical signal switching output port and the dummy light source input port (S4). Specifically, based on the information set in the drive circuit control unit 105, the drive circuit 104 is driven, the optical signal switching destination output port (output port (4)) and the dummy light source input port (input port). (8)) are connected. As a result, the dummy light is output from the output port (4).

  Next, the output port of the optical signal is switched by the drive circuit 104 (S5). Specifically, at time T when the optical signal output port is switched, the drive circuit 104 is driven to switch the optical signal output port from (1) to (4) and to the dummy light output port (4). Disconnect output. Here, the disconnection of the dummy light output to the output port means that the dummy light is not output from the output port of the optical switch by switching the switch element. Also, the operation of the dummy light output stop does not change either at the same time as the switch switching or after a certain time after the switch switching.

(Explanation of effect)
Referring to FIG. 5B, until time T, an optical signal is output from the output port (1) and a dummy light is output from the output port (4). When the optical signal output port is switched at time T, the optical level of the output port (1) becomes 0, and the optical output from the output port (4) is switched from the dummy light to the optical signal. At this time, since the switching time is as short as several tens of μs in a silicon optical switch capable of high-speed switching, the optical amplifier 103 in the subsequent stage feels almost continuous. Thereby, according to the optical switch, the optical path switching system, and the optical path switching method according to the present embodiment, it is possible to prevent a surge of the optical amplifier that occurs when the optical switch is switched.

  According to the present embodiment, a surge of the optical amplifier at the time of switching the optical path can be prevented without requiring a large additional circuit and without interrupting communication when the optical path is switched by the optical switch.

[Second Embodiment]
Next, an optical switch, an optical path switching system, and an optical path switching method according to a second embodiment of the present invention will be described. Since the present embodiment and the first embodiment are different only in the configuration for inputting dummy light, the description of the same configuration of the optical path switching system will be omitted, and only the different portion will be described.

  FIG. 6 is a configuration diagram showing an example of an optical switch system including an optical amplifier when an 8 × 8 split & select type optical switch is used as an example. The optical switch system includes an optical switch 102 and an optical amplifier 103, and is used in the optical path switching system and the optical path switching method of the present embodiment. The optical switch 102 includes an input port (1) to an input port (8) and an output port (1) to an output port (8). The optical switch 102 includes a 1 × 8 splitter 201 that divides an optical signal from an input port into eight, and an 8 × 1 selector 202 that selects one of eight optical signals input from the 1 × 8 splitter. Further, the optical switch 102 includes an optical waveguide 203 that connects between the 1 × 8 splitter 201 and the 8 × 1 selector 202. Here, the dummy light is input from the input port (8) among the input ports (1) to (8), is branched inside the optical switch 102, and is output to the output port (3) that is the switching destination of the optical signal. It is output to port (4) by the multicast method. Here, the output of the 1: 2 multicast method is used, but the number of output ports is not particular to this, such as 1: 3.

  The branching ratio of the dummy light in the 8 × 8 split & select type optical switch 102 can be made variable. In addition, when an optical switch is configured by a plurality of MZ interferometer type optical switches 301 as shown in FIG. 3, the branching ratio of the dummy light can be made variable by adjusting the phase difference of the phase shifter 304 of the optical switch 301. it can.

  In this example, dummy light is input from the input port (8). However, any port from the input port (1) to the input port (8) may be used as long as it is an unused port. In addition to the 8 × 8 configuration, in addition to the input port (1) to the input port (8) and the output port (1) to the output port (8), a 9 × 8 configuration having an input port dedicated to dummy light input may be used. .

(Description of operation)
Next, the optical path switching method by the optical switch of the second embodiment will be described with reference to FIG. FIG. 7 is a diagram illustrating an example of switching optical paths by the optical switch of the second embodiment. The optical path before switching is indicated by a solid line, and the optical path after switching is indicated by a dotted line. Here, an operation of switching the output ports of the two optical signals input to the input port (1) and the input port (2) in the transmission side optical switch 102 will be described. Specifically, the operation of switching from the state output from the output port (1) and the output port (2) to the state output from the output port (3) and the output port (4) will be described. Since the switching operation is the same on the receiving side, the operation on the receiving side is omitted.

  When changing the distribution destination of the video material, first, an optical signal switch port switching request is received from the system controller 100 (S1). Specifically, the drive circuit control unit 105 receives an optical signal switch port switching request from the system controller 100. Further, optical signal switching information is set in the drive circuit controller 105 (S2).

  Next, the connection between the optical signal switching destination output port (output port (3) and output port (4)) and the dummy light source input port (input port (8)) is set in the drive circuit control unit 105 (S3). ).

  Next, the drive circuit 104 connects between the optical signal switching destination output port and the dummy light source input port (S4). Specifically, the drive circuit 104 is driven based on the information set in the drive circuit control unit 105, the optical signal switching destination output ports (output port (3) and output port (4)), and the dummy light source. Are connected to each other (input port (8)). Thereby, the dummy light is output from the output port (3) and the output port (4).

  Next, the output port of the optical signal is switched by the drive circuit 104 (S5). Specifically, at time T when the optical signal output port is switched, the drive circuit 104 is driven to switch the optical signal output port from (1) to (3) and from (2) to (4). The optical output port (3) and the output port (4) are disconnected. As a result, the output of the optical signal and the dummy light is switched. Note that the optical level at each output port of the optical signal and the dummy light and the principle for preventing the surge of the optical amplifier are the same as in the operation of the first embodiment, and therefore will be omitted.

(Explanation of effect)
According to the optical switch, the optical path switching system, and the optical path switching method of the present embodiment, by using the multicast function of the optical switch, a single dummy light source can prevent an optical amplifier surge when switching a plurality of optical signals. Can do.

  According to the present embodiment, as in the first embodiment, a large additional circuit is not required, and communication is not interrupted when the optical path is switched by the optical switch, and the surge of the optical amplifier at the time of switching the optical path is prevented. Can do.

[Third Embodiment]
Next, an optical path switching system and an optical path switching method according to a third embodiment of the present invention will be described. Note that the present embodiment and the first embodiment differ only in the configuration for adjusting the light level of the dummy light, so the same configuration portion is omitted and only the different portion is described.

  FIG. 8A is a configuration diagram showing an example of an optical switch system including an optical amplifier when an 8 × 8 split & select type optical switch is used as an example. The optical switch system includes an optical switch 102 and an optical amplifier 103, and is used in the optical path switching system and the optical path switching method of the present embodiment. The optical switch 102 includes an input port (1) to an input port (8) and an output port (1) to an output port (8). The optical switch 102 includes a 1 × 8 splitter 201 that divides an optical signal from an input port into eight, and an 8 × 1 selector 202 that selects one of eight optical signals input from the 1 × 8 splitter. Further, the optical switch 102 includes an optical waveguide 203 that connects between the 1 × 8 splitter 201 and the 8 × 1 selector 202. Here, the dummy light is input from the input port (8), branched inside the optical switch 102, and output to the output port (3) and the output port (4), which are optical signal switching destinations, in a multicast manner. Here, the output of the 1: 2 multicast method is used, but the number of output ports is not particular to this, such as 1: 3. The branching ratio of the dummy light in the 8 × 8 split & select type optical switch can be made variable. In this example, dummy light is input from the input port (8). However, any port may be used as long as it is an unused port. Further, the split & select type optical switch may not have an 8 × 8 configuration, but may have a 9 × 8 configuration having a dedicated port for a dummy optical input port.

  Next, the light level adjustment of the dummy light according to the present embodiment will be described. FIG. 8B shows the optical level of the optical signal output from the output port (1) and output port (2) before switching, and the dummy light output from the output port (3) and output port (4). It is a graph which shows a light level. When transmitting using the wavelength multiplexing method, the optical level of the optical signal differs depending on the number of wavelength multiplexing. Here, the dummy light input from the input port (8) and output to the output port (3) and the output port (4) by the multicast method is the light input from the input port (1) and the input port (2). It is controlled to be similar to the optical level of the signal. The light level of the dummy light branched in the optical switch can be adjusted by adjusting the phase difference of the phase shifter in the optical switch 102 and changing the branching ratio. The light level may be adjusted by other methods such as incorporating an optical attenuator inside the optical switch.

(Description of operation)
Next, an optical path switching method by the optical switch of the present embodiment will be described with reference to FIGS. 9A and 9B. FIG. 9A is an operation diagram showing an example of switching of the optical switch. In FIG. 9A, the optical path before switching is indicated by a solid line, and the optical path after switching is indicated by a dotted line. FIG. 9B is a graph showing the light levels of the output port (3) and the output port (4) at the time of switching. Here, an operation of switching the output ports of the two optical signals input to the input port (1) and the input port (2) in the transmission side optical switch 102 will be described. Specifically, the operation of switching from the state output from the output port (1) and the output port (2) to the state output from the output port (3) and the output port (4) will be described. Since the operation is the same on the receiving side, the operation on the receiving side is omitted.

  When changing the distribution destination of the video material, first, an optical signal switch port switching request is received from the system controller 100 (S1). Specifically, the drive circuit control unit 105 receives an optical signal switch port switching request from a system controller (not shown). Further, optical signal switching information is set in the drive circuit controller 105 (S2).

  Next, the connection between the optical signal switching destination output port (output port (3) and output port (4)) and the dummy light source input port (input port (8)) is set in the drive circuit control unit 105 (S3). ). In the present embodiment, at this time, the light level of the dummy light is set to match the light level of the optical signal. That is, the optical level of the dummy light branched in the optical switch and output from the output port (3) is matched with the optical level of the optical signal output from the output port (1). Furthermore, the optical level of the dummy light branched in the optical switch and output from the output port (4) is matched with the optical level of the optical signal output from the output port (2).

  Next, the drive circuit 104 connects between the optical signal switching destination output port and the dummy light source input port (S4). Specifically, the drive circuit 104 is driven based on the information set in the drive circuit control unit 105, the optical signal switching destination output ports (output port (3) and output port (4)), and the dummy light source. Are connected to each other (input port (8)). Thereby, the dummy light is output from the output port (3) and the output port (4).

  Next, the output port of the optical signal is switched by the drive circuit 104 (S5). Specifically, at time T when the optical signal output port is switched, the drive circuit 104 is driven to switch the optical signal output port from (1) to (3) and from (2) to (4). The optical output port (3) and the output port (4) are disconnected. As a result, the output of the optical signal and the dummy light is switched. Note that the optical level at each output port of the optical signal and the dummy light and the principle for preventing the surge of the optical amplifier are the same as the operation of the first embodiment, and thus the description is omitted. By using the multicast function of the optical switch as in this embodiment, it is possible to prevent an optical amplifier surge at the time of switching a plurality of optical signals with one dummy light source.

  Furthermore, according to the present embodiment, it is possible to match the optical output of the dummy light to the optical signals having different optical levels by changing the multicast function and the branching ratio of the optical switch. Thereby, it is possible to prevent an optical amplifier surge at the time of switching a plurality of optical signals having different optical outputs with one dummy light source.

  The optical switch according to the embodiment of the present invention can be configured by the optical switch of the embodiment according to the highest concept of the present invention shown in FIG. The optical switch in FIG. 10 is an optical switch in which the path of an optical signal is switched between a plurality of input ports and a plurality of output ports. Among the plurality of input ports, dummy light is input from one input port and output to the output port to which the optical signal is switched, and then the output of the optical signal is switched to the output port to be switched and the switching is performed. Stop the dummy light output from the previous output port. The optical switch of FIG. 10 can prevent surge of the optical amplifier at the time of switching the optical signal path without interrupting communication at the time of switching the path of the optical signal.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to this. It goes without saying that various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention.

A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Appendix 1) Optical signal paths are switched between a plurality of input ports and a plurality of output ports,
After the dummy light input from one input port is output to the output port to which the optical signal is switched, the output of the optical signal is switched to the output port of the switching destination, and the dummy light from the output port of the switching destination The optical switch to stop the output of.
(Appendix 2) After outputting dummy light input from one input port to a plurality of output ports to which the optical signal is switched, the output of the optical signal is switched to the plurality of output ports to which the switching is performed, and The optical switch according to appendix 1, wherein output of dummy light from a plurality of output ports to be switched is stopped.
(Supplementary note 3) The optical switch according to supplementary note 2, wherein the dummy light input from the one input port is branched internally and output to a plurality of output ports to which the optical signal is switched.
(Additional remark 4) The optical switch of Additional remark 3 which makes variable the branching ratio of the said dummy light.
(Appendix 5) Provided with a plurality of switch elements having phase shifters,
The optical switch according to appendix 4, wherein the phase difference of the phase shifter is adjusted to make the branch ratio of the dummy light variable.
(Supplementary note 6) The optical switch according to any one of supplementary notes 2 to 5, wherein the optical signals of the plurality of output ports of the switching destination have different optical levels.
(Supplementary note 7) An optical path switching system including the optical switch according to any one of supplementary notes 1 to 6, and an optical amplifier that amplifies an optical signal output from an output port of the optical switch.
(Supplementary Note 8) A system including an optical switch that switches an optical signal path between a plurality of input ports and a plurality of output ports, and an optical amplifier that amplifies an optical signal output from the output port of the optical switch. The optical path switching method of
After the dummy light input from one input port of the optical switch is output to the output port to which the optical signal is switched, the output of the optical signal is switched to the output port of the switching destination, and the output port of the switching destination Optical path switching method to stop the output of dummy light from
(Supplementary Note 9) After outputting dummy light input from one input port of the optical switch to a plurality of output ports to which the optical signal is switched, the output of the optical signal is output to the plurality of output ports to be switched The optical path switching method according to appendix 6, wherein switching is performed and output of dummy light from the plurality of output ports to be switched is stopped.
(Supplementary note 10) The optical path switching method according to supplementary note 9, wherein the dummy light input from the one input port is internally branched and output to a plurality of output ports to which the optical signal is switched.
(Supplementary note 11) The optical path switching method according to supplementary note 10, wherein the branching ratio of the dummy light is variable.
(Supplementary Note 12) The optical switch includes a plurality of switch elements having phase shifters,
12. The optical path switching method according to appendix 11, wherein the phase difference of the phase shifter is adjusted to make the branch ratio of the dummy light variable.
(Supplementary note 13) The optical path switching method according to any one of supplementary notes 8 to 12, wherein the optical signals of the plurality of output ports at the switching destination have different optical levels.

100 system controller 101 optical transceiver 102, 102 _1, 102 ₂ optical switches 103 and 103 _1, 103 ₂ optical amplifier 104 driving circuit 105 driving circuit control unit 106 the optical transmission line 107 dummy light source 201 1 × 8 splitter 202 8 × 1 selector 203 Optical waveguide 301 MZ interferometer type optical switch 302 Optical coupler 303 Optical waveguide 304 Phase shifter

Claims (10)

The optical signal path is switched between multiple input ports and multiple output ports,
After the dummy light input from one input port is output to the output port to which the optical signal is switched, the output of the optical signal is switched to the output port of the switching destination, and the dummy light from the output port of the switching destination The optical switch to stop the output of.   After the dummy light input from one input port is output to the plurality of output ports to which the optical signal is switched, the output of the optical signal is switched to the plurality of output ports to which the switching is performed, and the plurality of switching destinations The optical switch according to claim 1, wherein output of dummy light from the output port is stopped.   The optical switch according to claim 2, wherein the dummy light input from the one input port is branched internally and output to a plurality of output ports to which the optical signal is switched.   The optical switch according to claim 3, wherein a branching ratio of the dummy light is variable. Comprising a plurality of switching elements having phase shifters;
The optical switch according to claim 4, wherein a branching ratio of the dummy light is made variable by adjusting a phase difference of the phase shifter.   6. The optical switch according to claim 2, wherein the optical signals of the plurality of output ports to be switched have different optical levels.   An optical path switching system including the optical switch according to claim 1 and an optical amplifier that amplifies an optical signal output from an output port of the optical switch. Optical path switching of a system including an optical switch that switches an optical signal path between a plurality of input ports and a plurality of output ports, and an optical amplifier that amplifies an optical signal output from the output port of the optical switch A method,
After the dummy light input from one input port of the optical switch is output to the output port to which the optical signal is switched, the output of the optical signal is switched to the output port of the switching destination, and the output port of the switching destination Optical path switching method to stop the output of dummy light from   The dummy light input from one input port of the optical switch is output to the plurality of output ports to which the optical signal is switched, and then the output of the optical signal is switched to the plurality of output ports to which the switching is performed. The optical path switching method according to claim 8, wherein output of dummy light from a plurality of output ports as switching destinations is stopped.   The optical path switching method according to claim 9, wherein the optical signals of the plurality of output ports to be switched have different optical levels.

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