JP7529037B2 - Optical Node - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act: An invention was made public due to the actions of the rights holder by posting on a website (posting date: October 29, 2020, posting address: https://www.tsukuba-forum.jp) (publisher: Katayama Kazunori, published content: Katayama Kazunori disclosed technology related to "optical nodes" invented by Kawano Tomohiro, Toge Kunihiro, Fukai Chisato, and Katayama Kazunori in the on-demand broadcast of Tsukuba Forum 2020 ONLINE Workshop 2 "Research and Development Efforts on Next-Generation Optical Cable Technology", which is published on the website at the above address), and within one year of the disclosure, the rights holder filed an international application as PCT/JP2020/042521 (filing date: November 13, 2020).

This disclosure primarily relates to optical nodes that perform remote optical path switching in optical fiber networks, and their power supply and control.

In optical fiber networks, particularly in access networks that connect telecommunications carriers and optical terminals, optical line switching is performed at a certain frequency to connect optical fiber cores to desired routes or change routes in order to use the facilities efficiently during installation and maintenance. Normally, such work is performed by going to the site and physically switching the connections, but a technology has been proposed that allows this to be done remotely using optical switches.

For example, non-patent document 1 proposes a system in which a MEMS optical switch is applied to the aforementioned optical line switching, and the operating power of the optical switch is provided by optical power supply via optical fiber, making it possible to supply power to any installation location that does not have a power source.

Furthermore, if we focus only on the optical power supply system mentioned above, the following technologies have been proposed:

Non-patent document 2 proposes a system in which a monitoring device consisting of a laser light source and an optical receiver transmits constant light via optical fiber to a wireless sensor node installed at any remote location, performs photoelectric conversion, obtains driving power for a wireless receiving circuit provided in the wireless sensor node and a modulator that converts the wireless signal into an upstream optical signal, and communicates upstream data to the monitoring device, making it possible to accommodate a large number of sensors over a wide area.

R. Helkey et. al. , “Remortly powered optical switch for remote subscriber aggregation and OTDR measurement in PON”, 33rd European Conference and Exhibition of Optical Communication (2007) Yosuke Tanaka et al., "Wide-area sensor network using optical fiber power supply," IEICE Technical Report, vol. 110, no. 183, ICD2010-52, pp. 71-76, (2010)

Non-Patent Document 1 discloses a system that can drive a remotely installed electrostatic mirror-driven MEMS optical switch with optical power supply. However, Non-Patent Document 1 does not disclose the remote control method required to select and change any port or path of the MEMS optical switch. In other words, the optically powered optical switch of Non-Patent Document 1 has the problem that it is difficult to control remotely.

As for an optical power supply system for remotely driving an optical switch, Non-Patent Document 2 discloses an optical power supply system that converts a portion of downstream stationary light into upstream signal light and transmits it to a monitoring device. However, in this optical power supply system, unlike an optical switch, an instruction to select an arbitrary port and switch the optical path is not given from the monitoring device. In other words, Non-Patent Document 2 does not disclose a method for remotely controlling an optically powered optical device.

As such, the techniques described in these documents have the problem that it is difficult to remotely control optical devices such as optically powered optical switches. Therefore, in order to solve the above problem, the present invention aims to provide an optically powered optical node that can be remotely controlled.

In order to achieve the above objective, the optical node of the present invention is capable of carrying a control signal on the laser light for optical power supply and of receiving the control signal at all times.

Specifically, the optical node according to the present invention comprises:
an input/output unit that receives downstream light including a modulated period and a non-modulated period and outputs upstream light including information;
an input gate switch that transmits the downstream light input to the input/output unit for a given period of time and supplies the downstream light to an optical power supply unit;
an optical receiver that constantly receives the downstream light input to the input/output unit;
a reflective optical switch that performs reflection or non-reflection on the downstream light during the unmodulated period among the downstream light input to the input/output unit based on the information to generate the upstream light;
Equipped with.

The monitoring and control device provides a period in which the laser light for optical power supply is modulated and a period in which it is not modulated. A control signal is transmitted to the optical node during the modulation period. The optical node charges a battery with the laser light, but is provided with an input gate switch to prevent overcharging. The on/off period of this input gate switch is not synchronized with the modulation/non-modulation period. Therefore, if the period in which the input gate switch is off overlaps with the modulation period of the laser light, the optical node will not be able to receive a control signal from the monitoring and control device. Therefore, the optical node according to the present invention is provided with an optical receiver that can constantly receive the laser light for optical power supply. Therefore, the optical node according to the present invention can receive a control signal from the monitoring and control device even if the period in which the input gate switch is off overlaps with the modulation period of the laser light.

Furthermore, the optical node according to the present invention also includes a reflective optical switch that reflects/non-reflects laser light. Therefore, the optical node can modulate the laser light during unmodulated periods with the reflective optical switch and notify the monitoring and control device of its own status. This makes it possible for the optical node to be remotely controlled from the monitoring and control device.

Thus, the present invention can provide a remotely controllable optically powered optical node.

The optical node according to the present invention further comprises an optical path switching unit that operates with power stored in the optical power supply unit and arbitrarily switches among a plurality of optical paths, and the information is a state of the optical paths. In this case, the optical path switching unit is characterized by having a plurality of optical ports to which a plurality of communication optical fibers are respectively connected, an optical path changeover switch that switches the optical paths so that an optical signal input to the optical ports is output to an arbitrary one of the optical ports, and an optical port monitoring unit that monitors the optical signals passing through the optical ports and monitors the state of the optical paths.
This optical node functions as an optical line switch. The state of the optical path includes confirmation of the optical port to be switched, confirmation after the optical path is switched (confirmation of whether the switching is completed correctly), and confirmation of the break of the optical path.

The optical path changeover switch of the optical node according to the present invention is an optical switch having a self-holding function.
No power is required during standby and the switched state can be maintained even when power is lost.

The optical port monitoring unit of the optical node according to the present invention is characterized by having an optical receiver that optically branches and optically receives a part of the optical signal passing through the optical port, and monitors the optical signal.
This optical node can grasp its own status by monitoring the optical signal.

For example, an optical node according to the present invention may include:
a power control function unit that monitors the amount of power stored in the power supply unit;
a downstream frame analysis function unit that analyzes a modulated signal included in the downstream light during the modulation period;
a switching operation control function unit that issues a switching instruction to the input gate switch based on the amount of stored power and issues a switching instruction to the optical path switching unit based on an analysis result of the modulated signal;
an optical port monitoring function unit that sets the state of the optical path as the information;
an upstream signal generating function unit that drives the reflective optical switch based on the information;
Preferably, the device further comprises a microprocessor having:

Moreover, it is preferable that the input gate switch of the optical node according to the present invention outputs the downstream light input to the input/output unit to the outside during a period other than the arbitrary period.
The downstream light outputted to the outside can be used by other optical nodes, and a plurality of optical nodes can be connected in series.

The above inventions can be combined as much as possible.

The present invention can provide a remotely controllable optically powered optical node.
Furthermore, according to the present invention, in a system consisting of a monitoring and control device installed in a power supply environment and one or more optical line switching nodes located remotely, it is possible to simultaneously realize the functions of optical power supply and control of multiple optical switches contained in the node using a single laser, thereby providing an economical optical line switching node system.

1 is a diagram illustrating an optical node remote control system including an optical node according to the present invention. FIG. 2 is a diagram illustrating an optical node according to the present invention. FIG. 2 is a diagram for explaining an overview of communication and power management between an optical node and a monitoring and control device according to the present invention. 4 is a flowchart illustrating the operation of a microprocessor of an optical node according to the present invention. FIG. 2 is a diagram for explaining an overview of communication and power management between an optical node and a monitoring and control device according to the present invention. 4 is a flowchart illustrating the operation of a microprocessor of an optical node according to the present invention. FIG. 2 is a diagram for explaining downstream light received by an optical node according to the present invention. FIG. 2 is a diagram for explaining an overview of communication and power management between an optical node and a monitoring and control device according to the present invention. 4 is a flowchart illustrating the operation of a microprocessor of an optical node according to the present invention. 1 is a diagram illustrating an optical node remote control system including an optical node according to the present invention. FIG. 2 is a diagram illustrating an optical node according to the present invention. FIG. 2 is a diagram for explaining an overview of communication and power management between an optical node and a monitoring and control device according to the present invention. FIG. 2 is a diagram for explaining an overview of communication and power management between an optical node and a monitoring and control device according to the present invention.

An embodiment of the present invention will be described with reference to the attached drawings. The embodiment described below is an example of the present invention, and the present invention is not limited to the following embodiment. Note that components with the same reference numerals in this specification and drawings are assumed to indicate the same components.

(Embodiment 1)
1 is a block diagram illustrating an optical node remote control system 301 including an optical node according to the present embodiment. In this embodiment, an optical line switching node S1-7 that switches an optical signal between a plurality of optical fibers will be described as an optical node.

The monitoring and control device S1-1 is installed in an environment where power can be provided, and comprises a light source S1-2, an optical circulator S1-3, an optical receiver S1-4, and a controller S1-5. Laser light emitted from the light source S1-2 is input to the transmission optical fiber S1-6 via the optical circulator S1-3. For example, the wavelength of the laser light can be 1480 nm to 1490 nm. The power of the laser light output from the light source S1-2 is approximately +10 to 17 dBm.

The optical line switching node S1-7 is installed at any location, such as a location without a power source, and is connected to the monitoring and control device S1-1 via the transmission line optical fiber S1-6. In this way, this embodiment is configured to have a single optical line switching node S1-7 for one monitoring and control device S1-1 via the transmission line optical fiber S1-6.

The optical line switching node S1-7 has the transmission line optical fiber S1-6 and several other transmission line optical fibers (hereinafter referred to as communication optical fibers S1-8 and S1-9 to distinguish them from the transmission line optical fiber S1-6) connected to its input and output.

As will be described in detail later, the downstream light S1-10 propagated from the monitoring and control device S1-1 to each optical line switching node supplies the drive power energy for the optical switch contained in each optical line switching node S1-7, and is characterized by the fact that a control signal for switching any port is also superimposed. The upstream light S1-11 from each optical line switching node S1-7 to the monitoring and control device S1-1 is used to communicate the status of the optical line switching node S1-7 to the monitoring and control device S1-1.

2 is a diagram showing the internal configuration of the optical line switching node S1-7.
an input/output unit S2-0 that receives downstream light S1-10 including a modulated period and a non-modulated period and outputs upstream light S1-11 including information;
an input gate switch S2-2 that transmits the downstream light S1-10 input to the input/output unit S2-0 for a given period of time and supplies the downstream light S1-10 to an optical power supply unit S2-22;
an optical receiver S2-7 that constantly receives the downstream light S1-10 input to the input/output unit S2-0;
a reflective optical switch S2-8 that reflects or non-reflects the downstream light S1-10 during the non-modulation period among the downstream light S1-10 input to the input/output unit S2-0 based on the information, thereby generating an upstream light S1-11;
Equipped with.

In addition, since the optical node has the function of optical path switching, the optical path switching node S1-7 further includes an optical path switching unit S2-30 that operates with power stored in the optical power supply unit S2-22 and arbitrarily switches between multiple optical paths, and is characterized in that the state of the optical path is used as the information.
The optical path switching unit S2-30 is
a plurality of optical ports (S1-80, S1-90) to which a plurality of communication optical fibers (S1-8, S1-9) are respectively connected;
an optical path changeover switch (cross-connect unit S2-16) that operates with power stored in the optical power supply unit S2-22 and switches an optical path so that an optical signal input to an optical port (S1-80, S1-90) is output to an arbitrary optical port (S1-80, S1-90);
an optical port monitor S2-20 that monitors the optical signals passing through the optical ports (S1-80, S1-90) and monitors the state of the optical path;
It further comprises:

The optical line switching node S1-7 is characterized in that it supplies the downstream light S1-10 from the transmission line optical fiber S1-6 via the optical branching section S2-1, the input gate switch S2-2, the photoelectric conversion element S2-3, and the secondary battery S2-4 with driving power S2-5 for all active elements contained in the optical line switching node S1-7. The photoelectric conversion element S2-3 and the secondary battery S2-4 are the "optical power supply section S2-22", and the input gate switch S2-2, the reflection switch S2-8, the cross-connect section S2-16, and the microprocessor S2-13 described below are included in the active elements.

The optical branching section S2-1 is a branching ratio coupler, for example, with a branching ratio of 90:10 or 99:1, and guides more of the optical power of the downstream light S1-10 to the input gate switch S2-2. The input gate switch S2-2 plays the role of a gate switch that can select whether or not to transmit the downstream light S1-10 to the photoelectric conversion element S2-3, and is used to prevent overcharging of the secondary battery S2-4. Since the input gate switch S2-2 operates frequently, it is desirable that it operates at a low voltage and with very small power consumption of a few nW or less. For example, it is possible to use an electrostatically driven MEMS optical switch, which has a low drive power and is generally available, as the input gate switch S2-2.

The photoelectric conversion element S2-3 is capable of receiving the wavelength of the laser light emitted from the light source S1-2. The photoelectric conversion element S2-3 can be an easily available element suitable for the long wavelength band of 1300 nm to 1600 nm for communication, such as an element made of indium gallium arsenide with an open circuit voltage of 5 V or less and a conversion efficiency of about 30%. For example, the photoelectric conversion element S2-3 is an optical power supply converter (https://www.kyosemi.co.jp/resources/ja/products/sensor/nir_photodiode/kpc8_t/kpc8_t_spec.pdf). In addition, if the power of the laser light transmitted by the transmission optical fiber S1-6 is, for example, about 2 mW, it can be used as an optical power supply. Note that the power varies depending on the device used as the optical power supply.

The secondary battery S2-4 is used to store the power energy converted by the photoelectric conversion element S2-3, and may be, for example, an electric double layer capacitor. The voltage supplied to each active element can be adjusted appropriately using a DC/DC converter or the like.

The other end of the optical branching section S2-1 is guided to another optical branching section S2-6 and input to the optical receiver S2-7 and the reflective optical switch S2-8. The optical receiver S2-7 is positioned to always receive the downstream light S1-10 regardless of the path state of the input gate switch S2-2, and accepts a control signal from the monitoring and control device S1-1.

The reflective optical switch S2-8 is an optical switch that can control the ON/OFF control of whether or not a portion of the downstream light S1-10 is totally reflected. The reflective optical switch S2-8 uses the downstream light S1-10 to modulate the upstream communication light toward the monitoring and control device S1-1. It is desirable for the reflective optical switch S2-8 to operate at a low voltage and with very little power consumption of a few nW or less. For example, the reflective optical switch S2-8 can be an electrostatically driven MEMS optical switch that requires little drive power and is generally available.

The optical line switching node S1-7 further includes an optical path switching unit S2-30 that operates with power stored in the optical power supply unit S2-22 and arbitrarily switches between a plurality of optical paths. The optical path switching unit S2-30 includes a plurality of optical ports (S1-80, S1-90) to which a plurality of communication optical fibers (S1-8, S1-9) are respectively connected, an optical path changeover switch (optical cross-connect unit S2-16) that switches the optical path so that an optical signal input to the optical port is output to an arbitrary optical port, and an optical port monitoring unit (S2-20) that monitors the optical signal passing through the optical port and monitors the state of the optical path.

In the example of FIG. 2, the optical cross-connect unit S2-16 includes a plurality of optical switches S2-14. The optical cross-connect unit S2-16 has a plurality of optical switches S2-14(a) with 1 input and N outputs arranged on the optical port S1-80 side, and a plurality of optical switches S2-14(b) with N inputs and 1 output arranged on the optical port S1-90 side, with the optical cross-connect unit S2-16 cross-wiring the optical waveguide wiring S2-15 between them. The optical cross-connect unit S2-16 is an optical cross-connect of N×N ports. The wiring of the optical waveguide wiring S2-15 can be freely determined depending on the application. For example, by folding back any part of the N ports and connecting them to another optical switch S2-14 on the same side, it is possible to perform wiring such as folding back wiring. In addition, the number of input/output ports of the optical cross-connect unit S2-16 does not need to be symmetrical, and an asymmetric configuration such as M×N can also be implemented. In this manner, the optical cross-connect unit S2-16 is characterized in that it is composed of a plurality of optical switches S2-14 as in this embodiment.

However, the standby power consumption of the optical cross-connect unit S2-16 significantly affects the power management of the entire system. For this reason, it is preferable that the optical switch S2-14 is configured as a self-holding optical switch that does not require power in standby mode and maintains its switched state even when power is lost.

The reason why the optical cross-connect unit S2-16 is configured with multiple optical switches S2-14 arranged on each side of the optical ports (S1-80, S1-90) is as follows. Normally, self-holding optical switches with multiple output ports have the potential to output light to an unintended port during a switching operation, which can lead to communication accidents. Providing multiple optical switches on both the input and output sides requires the switching of at least two optical switches to switch one optical path. Even if one optical switch outputs light to an unintended port, the other optical switch can block that light, preventing communication accidents caused by unintended light output.

The optical line switching unit S2-30 also has an optical port monitoring unit S2-20 that monitors the connection information of the optical cross-connect S2-16. The optical port monitoring unit S2-20 is arranged on the optical port S1-80 side and the optical port S1-90 side of the optical cross-connect unit S2-16, and monitors the ports of the multiple optical switches S2-14 in the optical cross-connect unit S2-16 by optically branching and receiving the communication light input from the communication optical fiber S1-8 and the communication light or test light output from the communication optical fiber S1-9. The means by which the optical port monitoring unit S2-20 optically branches the communication light or test light includes, for example, a 99:1 optical coupler that is generally available. The optical receiver that reads the branched light includes, for example, a photodiode that is generally available.

The optical port monitoring unit S2-20 can check the optical port to be switched before switching the optical cross-connect unit S2-16, and check whether the optical port has been switched correctly after switching the optical cross-connect unit S2-16, and can treat these as the "state of the optical path." In addition, by monitoring optical loss with the optical port monitoring units S2-20 of multiple optical line switching nodes S1-7, it is possible to identify which node between which the abnormality occurred when an abnormality such as a disconnection occurs in the optical transmission path composed of communication optical fibers (S1-8 and S1-9). In this way, the location where the abnormality detected by the optical port monitoring units S2-20 of multiple optical line switching nodes S1-7 occurred can also be treated as the "state of the optical path."

The optical line switching node S1-7 includes a microprocessor S2-13 for control.
A power control function unit S2-12 that monitors the amount of power stored in the power supply unit S2-22;
a downstream frame analysis function unit S2-9 that analyzes a modulated signal included in the downstream light during the modulation period;
a switching operation control function unit S2-11 that instructs the input gate switch S2-2 to switch based on the amount of stored power and instructs the optical path switching unit S2-30 to switch based on an analysis result of the modulated signal;
an optical port monitoring function unit S2-21 that uses the "state of the optical path" as the information;
an upstream signal generating function unit S2-10 that drives the reflective optical switch S2-8 based on the information;
has.
These five functional blocks (1) to (5) will now be described.

(1) Downstream frame analysis function unit S2-9
The downstream frame analysis function unit S2-9 is a function that analyzes downstream frames contained in the downstream light S1-10 from the monitoring and control device S1-1 received by the optical receiver S2-7. The light source S1-2 of the monitoring and control device S1-1 adds intensity modulation to the output laser light based on a signal from the controller S1-5, and converts it into an informationized downstream frame such as a TTL (Time to Live) or CMOS signal. The frame includes a request for node information and an execution instruction for switching the switches (input gate switches S2-2 and S2-14).

(2) Upstream signal generating function unit S2-10
The upstream signal generating function unit S2-10 cooperates with the downstream frame analyzing function unit S2-9, and uses the "state of the optical path" as the information to modulate the reflective optical switch S2-8 to generate an upstream signal light S1-11.

(3) Switching operation control function unit S2-11
The switching operation control function unit S2-11, in cooperation with the downstream frame analysis function S2-9, designates the input gate switch S2-2 or any optical switch S2-14 included in the optical cross-connect unit S2-16 to be switched, and issues a switching command to any port. A specific circuit configuration of the switching operation control function unit S2-11 is a circuit that sends an instruction to a driving circuit having an arbitrary address by bus communication (e.g., I2C, etc.) with the microprocessor S2-13 as the master, to a driving circuit attached to each optical switch, and controls the switching operation of any optical switch S2-14.

(4) Power monitoring function unit S2-12
The power monitoring function S2-12 monitors the amount of stored energy in the secondary battery S2-4. The power monitoring function S2-12 constantly monitors the amount of stored energy in the secondary battery S2-4 via a voltage monitor or the like, and notifies the monitoring control device S1-1 via the signal generation function S2-10 based on a set threshold value.

(5) Optical port monitoring function unit S2-21
The optical port monitoring function unit S2-21 monitors the optical port information of the optical port monitoring unit S2-20. When an inquiry is received from the monitoring control device S1-1, the optical port monitoring function unit S2-21 grasps the optical port information via a voltage monitor of an optical receiver provided in the optical port monitoring unit S2-20, and notifies the monitoring control device S1-1 via the signal generation function S2-10.

As described above, the microprocessor S2-13 enables the optical path switching node S1-7 itself to manage the amount of stored energy, to perform upstream communication with the monitoring and control device S1-1, and to perform downstream communication to accept execution instructions from the monitoring and control device S1-1 by coordinating the above five functions with each other.

FIG. 3 is a schematic diagram showing an overview of communication and power management between a monitor and control device and an optical line switching node during standby.
Assume that the input gate switch S2-2 for the gate of the optical line switching node S1-7 is open at time T0. At this time, the secondary battery S2-4 is being charged by the downstream light S1-10 from the monitoring and controlling device S1-1.
At time T1, the monitoring control device S1-1 sends a request (ASK1) to the node to notify the node of its status. When the amount of stored energy in the secondary battery S2-4 reaches a certain threshold, the optical line switching node S1-7 sends a report (REPORT1) to the monitoring control device S1-1.
At time T2, the supervisory control device S1-1 notifies the optical line switching node S1-7 of an execution instruction (GATE1) to close the gate. The optical line switching node S1-7 closes the input gate switch S2-2 via the downstream frame analysis function S2-9 and the switching operation control function S2-11, and notifies the supervisory control device S1-1 of the execution result (GATE ACK2).

Since the optical receiver S2-7 is arranged in the optical line switching node S1-7, regardless of the state of the input gate switch S2-2, the optical line switching node S1-7 can receive a request (ASK) to notify the node of its state at any time, and can report to the monitoring control device S1-1. For example, at time T3, the monitoring control device S1-1 notifies the node of a request (ASK3) to notify the node of its state, and if the amount of stored energy in the secondary battery S2-4 is less than the threshold, the optical line switching node S1-7 notifies the monitoring control device S1-1 of the fact (REPORT3). At time T4, the monitoring control device S1-1 notifies the optical line switching node S1-7 of an execution instruction (GATE3) to open the gate. The optical line switching node S1-7 opens the input gate switch S2-2 and notifies the monitoring control device S1-1 of the execution result (GATE ACK4).
In this way, the supervisory control device S1-1 can always control charging of the optical line switching node S1-7 by exchanging such communications (ASK, REPORT, GATE).

At the time of a request (ASK3) at time T3, the amount of stored energy in the secondary battery S2-4 is assumed to be below a certain threshold (REPORT3). The monitoring and control device S1-1 issues an execution instruction to open the input gate switch S2-2 (GATE3), and the optical line switching node S1-7 starts charging again.

FIG. 4 is a flow chart for explaining the operation (charging control) of the microprocessor S2-13.
The downstream frame analysis function unit S2-9 grasps the request (ASK) from the monitoring control device S1-1 (step S01). The power monitoring function unit S2-12 reports "storage amount" or "storage amount ≧ threshold" as storage information (step S02). The upstream signal generation function S2-10 notifies the storage information to the monitoring control device S1-1 (step S03; REPORT). The monitoring control device S1-1 compares the storage amount with a predetermined threshold (step S04). If the storage amount is equal to or greater than the threshold ("Yes" in step S04), the monitoring control device S1-1 checks whether the input gate switch S2-2 is open or closed (step S05). If the input gate switch S2-2 is closed ("No" in step S05), the process is repeated from step S01. If the input gate switch S2-2 is open ("Yes" in step S05), the supervisory control device S1-1 sends a "GATE close" signal, and the downstream frame analysis function unit S2-9 grasps this (step S06). The switching operation control function unit S2-11 closes the input gate switch S2-2, and the upstream signal generation function unit S2-10 notifies the supervisory control device S1-1 of the execution result (that the input gate switch S2-2 has been closed) (step S07; GATE ACK).

Also, if the amount of stored power is equal to or greater than the threshold ("No" in step S04), the monitoring control device S1-1 checks whether the input gate switch S2-2 is open or closed (step S08). If the input gate switch S2-2 is open ("Yes" in step S08), the process repeats from step S01. On the other hand, if the input gate switch S2-2 is closed ("No" in step S08), the monitoring control device S1-1 sends a "GATE open" signal, and the downstream frame analysis function unit S2-9 grasps this (step S09). The switching operation control function unit S2-11 opens the input gate switch S2-2, and the upstream signal generation function unit S2-10 notifies the monitoring control device S1-1 of the execution result (that the input gate switch S2-2 has been opened) (step S10; GATE ACK).

5 is a schematic diagram showing an overview of communication and power management between a monitor and control device and an optical line switching node when a request for switching an optical line is made. The explanation up to time T3 is the same as that of FIG.
At time T5, before time T3, a designated port switching request Q1 is generated for the optical line switching node S1-7, and the monitoring and control device S1-1 accepts it. At time T6, the monitoring and control device S1-1 sends an execution instruction (GATE5) to open the input gate switch S2-2 again to the optical line switching node S1-7 in response to the switching request Q1, as an interrupt operation of the exchange in Fig. 3. This is to obtain power to drive each optical switch S2-14 of the optical cross-connect S2-16. The optical line switching node S1-7 opens the input gate switch S2-2, and notifies the monitoring and control device S1-1 of the execution result (GATE ACK5).
After confirming GATE ACK5 (time T7), the supervisory control device S1-1 notifies the optical line switching node S1-7 of a designated port switching execution instruction (SWITCH6) together with the port number. After executing switching of the optical switch S2-14 of the optical cross-connect S2-16, the optical line switching node S1-7 notifies the supervisory control device S1-1 of the fact (SWITCH ACK6).

If the amount of stored energy in the secondary battery S2-4 has not yet reached the level at which switching can be performed, the monitoring and control device S1-1 can repeatedly inquire (ASK) and report (REPORT) on the amount of stored energy, and wait for notification of an execution instruction (SWITCH) until the amount of stored energy reaches the level at which optical port switching can be performed. Alternatively, it is also possible to set a threshold for the amount of stored energy in advance so that the amount of energy at which switching can be performed remains as the remaining amount.

Figure 6 is a flow chart explaining the operation (switching control) of the microprocessor S2-13. The switching operation control function unit S2-11 opens the input gate switch S2-2, and the upstream signal generation function unit S2-10 notifies the monitoring control device S1-1 of the execution result (step S11; GATE ACK). The downstream frame analysis function unit S2-9 grasps the designated port switching (SWITCH) signal from the monitoring control device S1-1 (step S12). The switching operation control function unit S2-11 drives the optical switch S2-14 and executes switching to the designated port (step S13). The upstream signal generation function unit S2-10 notifies the execution result (that the optical path switching has been completed) (step S14; SWITCH ACK).

Figure 7 is a diagram explaining the downstream light S1-10. This downstream light S1-10 includes a SWITCH frame that instructs the switching of the specified port, and a part of the period is modulated. Figure 7 (A) is a diagram explaining the modulation state. Figure 7 (B) is a diagram explaining the average power supply. As shown in the figure, the downstream light is steadily supplied to the optical line switching node S1-7 in the "1" state (unmodulated period). On the other hand, during the modulation period, the laser light is intensity modulated at a frequency of, for example, 1 kHz or less to transmit the frame. Note that the ASK and GATE frames are similar except that there is no input/output port ID.

8 is a schematic diagram showing an overview of communication and power management between a monitoring control device and an optical line switching node when an optical port monitoring request is made. The explanation up to time T3 is the same as that of FIG.
At time T8, before time T3, an optical port monitoring request Q2 for a specified port is generated for the optical line switching node S1-7, and the monitoring control device S1-1 accepts it. At time T9, the monitoring control device S1-1 sends an execution instruction (GATE8) to open the input gate switch S2-2 again to the optical line switching node S1-7 in response to the monitoring request Q2, as an interrupt operation of the exchange in Fig. 3. This is to obtain power to drive the optical port monitoring unit S2-20 and the optical port monitoring function unit S2-21. The optical line switching node S1-7 opens the input gate switch S2-2, and notifies the monitoring control device S1-1 of the execution result (GATE ACK8).
After confirming GATE ACK8 (time T10), the supervisory control device S1-1 sends an optical port information inquiry (ASK PORT9) to the optical line switching node S1-7. The optical line switching node S1-7 reads the optical port information and sends the result to the supervisory control device S1-1 (PORT REPORT9).

If the amount of stored energy in the secondary battery S2-4 has not yet reached the level at which reading of optical port information can be performed, the monitoring and control device S1-1 can receive a report while inquiring (ASK) about the amount of stored energy, and wait for notification of an execution instruction (ASK PORT) until the amount of energy reaches a level at which reading of optical port information can be performed. Alternatively, it is also possible to set a threshold for the amount of stored energy in advance so that the amount of energy at which reading of optical port information can be performed is left as the remaining amount.

Figure 9 is a flow chart explaining the operation (port monitoring control) of the microprocessor S2-13. The switching operation control function unit S2-11 opens the input gate switch S2-2, and the upstream signal generation function unit S2-10 notifies the monitoring control device S1-1 of the execution result (step S21; GATE ACK). The downstream frame analysis function unit S2-9 grasps the optical port information inquiry (ASK PORT) signal from the monitoring control device S1-1 (step S22). The optical port monitoring function unit S2-21 reads the optical port information using the optical port monitoring unit S2-20 (step S23). The upstream signal generation function unit S2-10 notifies the execution result (optical port reading result) (step S24; PORT REPORT).

(Embodiment 2)
10 is a block diagram illustrating an optical node remote control system 302 including an optical node according to this embodiment. In this embodiment, an optical line switching node (S7-7, S7-8) that switches an optical signal between multiple optical fibers is also described as an optical node. In this embodiment, differences from the optical node remote control system 301 according to the first embodiment are also described.

The monitoring and control device S7-1 is installed in an environment where power can be provided, and is composed of a light source S7-2, an optical circulator S7-3, an optical receiver S7-4, and a controller S7-5. The laser light emitted from the light source S7-2 is input to the transmission optical fiber S7-60 via the optical circulator S7-3.

The optical line switching node S7-7 is installed at any location, for example, a location without a power source, and is connected to the monitoring and control device S7-1 via the transmission line optical fiber S7-60. The optical line switching node S7-8 is installed at any location, for example, a location without a power source, and is connected to the optical line switching node S7-7 via the transmission line optical fiber S7-61. Furthermore, the optical line switching node S7-8 is connected to another optical line switching node S7-7 via the transmission line optical fiber S7-62. In this way, the optical node remote control system 302 is configured to have multiple optical line switching nodes via the transmission line optical fiber for one monitoring and control device.

At the optical line switching node S7-7, the transmission line optical fiber S7-60 and a number of other transmission line optical fibers (hereafter referred to as communication optical fibers S7-9 and S7-10 to distinguish them from the transmission line optical fiber S7-60) are connected to the input and output. Similarly, communication optical fibers (S7-11 and S7-12) are connected to the optical line switching node S7-8. Here, these communication optical fibers (S7-9, S7-10, S7-11 and S7-12) do not need to be the same optical fibers on the same route, and may be any optical fiber at each optical line switching node.

As will be described in detail later, the downstream light S7-13 propagated from the monitoring and control device S7-1 to each optical line switching node supplies the drive power energy for the optical switches contained in each optical line switching node S7-7 and S7-8, and is characterized by the fact that a control signal for switching any port is also superimposed. The upstream light S7-14 from each optical line switching node S7-7 and S7-8 to the monitoring and control device S7-1 is used to communicate the status of each optical line switching node S7-7 and S7-8 to the monitoring and control device S7-1.

11 is a diagram showing the internal configuration of the optical line switching node (S6-7, S6-8). The optical line switching node (S6-7, S6-8) is characterized in that, compared to the optical line switching node S1-7 in FIG. 2, the input gate switch S7-2 outputs the downstream light S7-13 input to the input/output unit S2-0 to the outside during the period excluding the arbitrary period.
In other words, the optical switch S7-2 is a gate switch that can select whether to transmit the downstream light S7-13 to the photoelectric conversion element S2-3 (cross state) or to transmit it to the optical line switching node S7-8 on the downstream side (the side farther from the monitoring and control device S7-1) (bar state).Other than this, it is the same as the optical node remote control system 301 of the first embodiment.

FIG. 12 is a schematic diagram showing an overview of communication and power management between the monitor and control device and each optical line switching node during standby.
As can be seen from the overall system configuration in Fig. 7 and the internal configuration of the optical line switching node shown in Fig. 8, when the input gate switch S7-2 of the optical line switching node S7-7 on the upstream side (the side closer to the monitoring and control device S7-1) is in a cross state, the downstream light to the optical line switching node S7-8 located on the downstream side of the node (the side farther from the monitoring and control device S7-1) and the upstream signal light from the optical line switching node S7-8 to the monitoring and control device S7-1 are blocked by the optical line switching node S7-7. For this reason, the communication between the monitoring and control device S7-1 and each node belonging to it has a different feature from that of the first embodiment, and has the following conditions.

(Condition 1) Of a plurality of optical line switching nodes, at most one input gate switch is in the cross state.
(Condition 2) Upstream communication is performed only to optical line switching nodes where the input gate switches of all optical line switching nodes are in the bar state or where the input gate switches are in the cross state.
(Condition 3) Downstream communication is performed only to one optical line switching node where the input gate switches of all optical line switching nodes are in the bar state or where the input gate switch is in the cross state.

Condition 1 is a requirement from the viewpoint of power supply efficiency, and by setting each input gate switch to supply power to one destination, the power supply efficiency of the target optical line switching node can be maximized.
Condition 2 is a condition for avoiding collision of upstream communications from a plurality of optical line switching nodes in the time domain and non-delivery of upstream communications due to the gate state of an upstream optical line switching node.
Condition 3 is a condition for avoiding failure of downstream communication due to the gate state of an upstream optical line switching node.

A specific description will be given using FIG. 12 as an example.
At time T0, it is assumed that only the input gate switch S7-2 of the optical line switching node S7-8 located downstream from the monitor and control device S7-1 is in the cross state, and charging is being performed for the optical line switching node S7-8.
At time T1, when the amount of stored energy in the optical line switching node S7-8 reaches a certain threshold, the optical line switching node S7-8 notifies the supervisory control device S7-1 of the fact in a report (REPORT 1). The report always includes information such as the amount of stored energy.
At time T2, the monitor and control device S7-1 notifies the optical line switching node S7-8 of an execution instruction (GATE1) to switch the input gate switch S7-2 to the bar state. The optical line switching node S7-8 switches the input gate switch S7-2 to the bar state and notifies the monitor and control device S7-1 of the execution result (GATE ACK2).
The monitor and control device S7-1 schedules in advance the optical line switching node to be the next power supply target based on the reports received from each optical line switching node in this way.
At time T3, the supervisory control device S7-1 notifies the scheduled optical line switching node S7-7 of an execution instruction (GATE3) to switch the input gate switch S7-2 to the cross state. The optical line switching node S7-7 notifies the supervisory control device S7-1 of the switching result of the input gate switch S7-2 (GATE ACK3).
At time T4, when the amount of stored energy in the optical line switching node S7-7 reaches a certain threshold, the optical line switching node S7-7 notifies the supervisory control device S7-1 of the fact in a report (REPORT4).
At time T5, the monitor and control device S7-1 notifies the optical line switching node S7-7 of an execution instruction (GATE4) to switch the input gate switch S7-2 to the bar state. The optical line switching node S7-7 switches the input gate switch S7-2 to the bar state and notifies the monitor and control device S7-1 of the execution result (GATE ACK5).

The optical node remote control system 302 repeats this type of control. Although it depends on the optical power supply efficiency and the standby power consumption of each node, even if there are three or more optical line switching nodes, the control method is the same, with only the time interval until recharging changing. As can be seen from Figure 12, frames are exchanged based on conditions 1 to 3.

13 is a schematic diagram showing an overview of communication and power management between a monitor and control device and each optical line switching node when a request for switching an optical path is made. The explanation up to time T6 is the same as that of FIG.
At time T9 before time T3, a designated port switching request Q1 is generated for the optical line switching node S7-8, and the monitoring and control device S7-1 accepts the request. The monitoring and control device S7-1 reschedules the switching request Q1 as an interrupt operation of the exchange in FIG.
After time T6, when the input gate switch S7-2 of the optical line switching node S7-8 goes into the cross state, the monitor and control device S7-1 confirms that the amount of stored energy in the optical line switching node S7-8 is sufficient to execute switching (REPORT7).
At time T8, the supervisory control device S7-1 issues a switching execution instruction (SWITCH8) for the designated port together with the port ID. After executing port switching, the optical line switching node S7-8 notifies the supervisory control device S7-1 of this (SWITCH ACK8).

In addition, if the amount of stored energy in the secondary battery S2-4 of the optical line switching node S7-8 has not yet reached the level at which switching can be performed, the monitoring and control device S7-1 repeatedly inquires (ASK) and reports (REPORT) on the amount of stored energy, and waits for notification of an execution instruction (SWITCH) until the amount of stored energy reaches a level at which optical port switching is possible.

In the control of Figure 13, as in the control of Figure 12, it can be seen that frame exchange is carried out based on conditions 1 to 3.

In addition, when an optical port monitoring request is made, the same optical port monitoring interrupt processing as in Figure 13 is performed for communication and power management between the monitoring control device S7-1 and each optical line switching node.

As in embodiment 2, an optical line switching node system having multiple optical line switching nodes for a single monitoring and control device can be provided. According to embodiment 2, as described in non-patent document 2, for example, the number of optical fiber transmission lines required for optical power supply can be reduced to one, compared to the case where multiple nodes (or child devices) are optically powered simultaneously via an optical splitter, and the ease of installing optical nodes in the network is improved. Furthermore, since the downstream optical power is not dispersed, there is an advantage that the required startup voltage for active elements such as a microprocessor can be easily obtained in the photoelectric conversion element S2-3, and remote control is easy.

Other Embodiments
In the above embodiment, the optical node is described as an optical path switching node that switches optical paths. However, the optical node of the present invention is not limited to an optical path switching node. The present invention can be applied to devices that have an optical power supply function and are remotely controlled.

(Effects of the present invention)
According to the optical line switching node and the system using the same of the present invention, the downstream laser light supplied from the monitoring and control device to the optical node can be used not only as driving power but also as a control signal for the optical node by being temporarily intensity modulated in the time domain. The optical node can be controlled using the laser light for power management of the optical node and for controlling the optical switch included in the optical node. Therefore, the present invention can provide an economical optical line switching node system that can simultaneously realize the functions of optical power supply and optical switch control with a single laser.

According to the present invention, the optical line switching node contains multiple types of optical switches, each of which is used as an input gate switch, for generating upstream signals, and for controlling the switching of multiple communication optical fibers. All of the optical switches are controlled in the same way by a microprocessor. The optical switches for the former two applications are non-self-holding optical switches with excellent low power consumption because they perform frequent switching control, while the optical switch for the latter application is preferably a self-holding optical switch that maintains its state even when the power supply is lost due to a failure, etc., because it becomes part of the transmission line that provides the communication service. With this configuration, it is possible to reduce the standby power of the optical line switching node during standby, that is, when there is no request to switch the transmission line.

For example, in embodiment 1, the present invention facilitates expansion to a system in which an optical switch is introduced on the monitoring and control device side (downstream of the optical circulator) to monitor and control remote optical nodes in a cyclical manner, and in embodiment 2, expansion such as increasing the number of optical line switching nodes provided in the system.

S1-1, S7-1: monitoring and control device S1-2, S7-2: light source S1-3, S7-3: optical circulator S1-4, S7-4: optical receiver S1-5, S7-5: controller

Claims (7)

an input/output unit that receives downstream light including a modulated period and a non-modulated period and outputs upstream light including information;
an input gate switch that transmits the downstream light input to the input/output unit for a given period of time and supplies the downstream light to an optical power supply unit;
an optical receiver that constantly receives the downstream light input to the input/output unit;
a reflective optical switch that performs reflection or non-reflection on the downstream light during the unmodulated period among the downstream light input to the input/output unit based on the information to generate the upstream light;
An optical node comprising: an optical path switching unit that operates with the power stored in the optical power supply unit and arbitrarily switches between a plurality of optical paths;
2. The optical node according to claim 1, wherein the information is a state of the optical path. The optical path switching unit includes:
a plurality of optical ports to which a plurality of communication optical fibers are respectively connected;
an optical path changeover switch that switches an optical path so that an optical signal input to the optical port is output to any one of the optical ports;
an optical port monitor that monitors the optical signal passing through the optical port and monitors the state of the optical path;
3. The optical node according to claim 2, further comprising: The optical node according to claim 3, characterized in that the optical path switching switch is an optical switch having a self-holding function. The optical node according to claim 3 or 4, characterized in that the optical port monitoring unit has an optical receiver that optically branches and receives a portion of the optical signal passing through the optical port, and monitors the optical signal. a power control function unit that monitors the amount of power stored in the optical power supply unit;
a downstream frame analysis function unit that analyzes a modulated signal included in the downstream light during the modulation period;
a switching operation control function unit that issues a switching instruction to the input gate switch based on the amount of stored power and issues a switching instruction to the optical path switching unit based on an analysis result of the modulated signal;
an optical port monitoring function unit that sets the state of the optical path as the information;
an upstream signal generating function unit that drives the reflective optical switch based on the information;
6. The optical node according to claim 2, further comprising a microprocessor having a first input and a second input. An optical node as described in any one of claims 1 to 6, characterized in that the input gate switch outputs the downstream light input to the input/output unit to the outside during a period other than the arbitrary period.

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