WO2023238317A1 - Optical transmission device and optical transmission management method - Google Patents

Abstract

Functions of an all optical wavelength conversion (AO-WC) unit (13) are equipped in an optical transmission device (43) at the location of each relay node disposed in an optical communication network that transmits optical signals in a long distance optical communication channel. The all optical wavelength conversion unit (13) extracts a component of unnecessary light other than a main optical signal of the same wavelength (λ1) as that before wavelength conversion and converts the extracted component into an electrical signal in an internal detector (11A). The main optical signal of which the converted wavelength is (λ2) is not electrically terminated and is transmitted to a downstream-side transmission channel as a relay output. A case in which a WDM optical signal into which a plurality of wavelengths are multiplexed is treated is also processed in the same manner. The main optical signal to be relayed is wavelength-converted and efficiently relayed without delay and degradation. Transmission quality data is acquired on the basis of the electrical signal generated from the unnecessary light simultaneously with the relay of the main optical signal. Low delay, large capacity power saving in a network can be achieved, and the separation of a trouble generation section or a failure prediction is enabled with the transmission quality data at the locations of the relay nodes.

Description

Optical transmission equipment and optical transmission management method

The present invention relates to an optical transmission device and an optical transmission management method.

In optical transmission systems that connect transmitting nodes and receiving nodes with relatively long-distance optical fiber cables to transmit optical signals, the optical signals may be significantly attenuated in the middle of the transmission path, or the transmission quality may deteriorate. is expected to occur. Therefore, in order to ensure that the optical signal transmitted from the transmitting node reaches the receiving node, one or more relay nodes are generally placed in the middle of the transmission path to amplify the attenuated optical signal and It is necessary to correct bit errors that occur during the process.

In addition, since it is usually necessary to place relay nodes at regular intervals, when performing long-distance optical transmission, many relay nodes are connected to the middle of the transmission path between the sending node and the receiving node. .

Each relay node in an optical transmission system usually has an electrical termination function. That is, the received optical signal is once converted into an electrical signal, and the information of the converted electrical signal is relayed. Furthermore, when processing electrical signal information, transmission quality data (Pre-FEC BER, dispersion compensation amount, polarization mode dispersion amount, polarization dependent loss) at the relay node can be obtained.

However, if electrical termination processing is performed at each relay node, an increase in delay time associated with the relay processing of electrical signals is unavoidable. Furthermore, power consumption increases with the relay processing of electrical signals. Furthermore, there are restrictions on wavelength resources that can be used during optical transmission, which hinders expansion of transmission capacity.

On the other hand, in recent years, the functionality of optical fiber cables and optical transmitters has improved. Therefore, there is a tendency to increase the interval at which relay nodes equipped with electrical termination processing functions are arranged. This reduces the number of relay nodes while performing electrical termination processing, making it possible to save power, increase capacity, and reduce delay in the network.

On the other hand, for example, Non-Patent Document 1 discloses a technology for an optical transport network that omits electrical termination processing in an optical node device. Furthermore, Non-Patent Document 1 discloses the introduction of a wavelength conversion function for converting the wavelength of an optical signal to another wavelength in an optical node device passing through in order to efficiently use limited wavelength resources.

By the way, when a failure occurs in the optical transmission system, it is necessary to identify the location of the failure. To do this, it is first necessary to divide the entire length of a long-distance transmission line into a plurality of sections for each relay node, and to determine whether or not a failure has occurred in each section.

If each relay node is equipped with an electrical termination function, transmission quality data can be obtained for each relay node. Therefore, by comparing the transmission quality data of each relay node, it is possible to determine whether or not a failure has occurred in each section.

However, for relay nodes that do not have the electrical termination function installed, transmission quality data at that point cannot be obtained. Therefore, a situation arises in which a large number of optical transmission devices are included in each section in which it is possible to determine whether there is a failure or not, and the length of the optical fiber cable for each section becomes extremely long. This makes it difficult to identify the location of the failure.

Therefore, it is conceivable to arrange an optical splitter at the relay node, for example. In other words, one optical signal received by a relay node is split into two paths using an optical splitter, and the main signal on one path is relayed as an optical signal, while the optical signal on the other path is converted into an electrical signal. It is used to obtain transmission quality data. Thereby, the signal delay of the optical main signal due to relaying can be reduced. However, when the input optical signal passes through the optical splitter, the optical intensity of the optical main signal to be relayed decreases, resulting in deterioration of transmission quality at the relay node.

The present invention has been made in view of the above-mentioned situation, and is an optical fiber that can acquire transmission quality data for each relay node without affecting the delay of the optical main signal relayed by the relay node or the deterioration of the transmission quality. The purpose of the present invention is to provide a transmission device and an optical transmission management method.

(1) An optical transmission node capable of transmitting optical signals and an optical reception node capable of receiving optical signals are connected via an optical transmission line, and one or more An optical transmission device that can be installed in at least one optical relay node of an optical transmission system to which optical relay nodes are connected,
an all-optical wavelength conversion device that converts the wavelength of an optical signal relayed by at least one optical relay node;
an unnecessary light extraction unit that extracts unnecessary light components other than the optical main signal having the same wavelength as the optical main signal to be relayed before wavelength conversion;
a photoelectrical signal converter that converts the unnecessary light component light extracted by the unnecessary light extractor into an electrical signal;
An optical transmission device comprising:

(2) An optical transmitting node capable of transmitting optical signals and an optical receiving node capable of receiving optical signals are connected via an optical transmission line, and one or more An optical transmission management method for managing an optical transmission system to which optical relay nodes are connected, the method comprising:
In at least one of the optical relay nodes of the optical transmission system,
a step of converting the wavelength of the received optical signal and transmitting the wavelength-converted optical signal as a relay output;
a step of extracting, from the received optical signal, unnecessary optical components other than the optical main signal having the same wavelength as the optical main signal to be relayed before wavelength conversion;
a step of converting the extracted unnecessary light component light into an electrical signal;
generating transmission quality data based on the electrical signal;
Optical transmission management method to implement.

According to the optical transmission device and optical transmission management method of the present invention, there is no need for electrical termination processing at the relay node, and the relay node It becomes possible to acquire transmission quality data at each time. Therefore, when a fault occurs on the optical network, it becomes easy to identify the location of the fault. Furthermore, even if no failure has occurred, information useful for predicting failures on optical networks can be obtained.

FIG. 1 is a block diagram showing an example of the configuration of a general optical transmission system. FIG. 1 is a block diagram showing an example of the configuration of a general optical transmission system. FIG. 3 is a block diagram showing a modification of the optical transmission system. FIG. 3 is a block diagram showing a modification of the optical transmission system. FIG. 2 is a schematic diagram showing an example of the relationship between optical communication links and wavelength bands in multiband networking technology. 1 is a block diagram showing a configuration example of an optical transmission system in an embodiment of the present invention. 7 is a block diagram showing a configuration example of an all-optical wavelength conversion section included in the optical transmission system of FIG. 6. FIG. 8 is a graph showing a list of optical signal wavelength distributions in each part of the all-optical wavelength conversion section in FIG. 7. FIG. 7 is a block diagram showing the configuration of a modification example of FIG. 6. FIG. 10 is a block diagram showing a first configuration example of an all-optical wavelength conversion section included in the optical transmission system of FIG. 9. FIG. 11 is a graph showing a list of optical signal wavelength distributions in each part of the all-optical wavelength conversion section in FIG. 10; 10 is a block diagram showing a second configuration example of an all-optical wavelength conversion section included in the optical transmission system of FIG. 9. FIG. 13 is a graph showing a list of optical signal wavelength distributions in each part of the all-optical wavelength conversion section in FIG. 12. FIG. 3 is a flowchart showing an example of a processing procedure of the optical transmission management method of the present invention. FIG. 3 is a block diagram showing a modification of the configuration of the all-optical wavelength conversion section.

<Description of the technology that is the premise of the present invention>
In order to facilitate understanding of the present invention, the technology on which it is based will be explained.
-<Optical transmission system configuration>
FIG. 1 shows a configuration example of a general optical transmission system 100A. FIG. 1 shows a configuration example of a general optical transmission system 100B. Further, modified examples of the optical transmission system shown in FIG. 1 are shown in FIGS. 3 and 4.

In the optical transmission system 100A shown in FIG. 1, seven optical transmission devices 10-1, 10-2, 10-3, 10-4, 10-5, 10-6, and 10-7 are arranged in an example, They are connected to each other in series via a common optical fiber cable 15. Further, a network controller 20 is connected to each of the optical transmission devices 10-1 to 10-7 to manage a communication network including these optical transmission devices 10-1 to 10-7.

For example, when transmitting data from the optical transmission device 10-1 at one end of this communication network to the optical transmission device 10-7 at the other end, the optical transmission device 10-1 becomes a transmission node, and the optical transmission device 10-1 -7 becomes the receiving node. Further, optical transmission devices 10-2 to 10-6 located between these transmitting nodes and receiving nodes are respectively used as relay nodes.

The optical transmission device 10-1 of the transmitting node converts the data to be transmitted from an electrical signal into an optical signal of a predetermined wavelength inside a transponder (TPD) 11, and sends this optical signal to the optical fiber cable 15. The optical transmission device 10-7 of the receiving node receives the optical signal from the optical fiber cable 15, converts the optical signal into an electrical signal with the transponder 11 in the optical transmission device 10-7, and obtains received data.

On the other hand, as the distance of optical signal transmission increases, the optical intensity decreases and transmission quality such as bit error rate (BER) deteriorates. Furthermore, if the optical intensity decreases significantly or the bit error rate increases significantly, the optical transmission device 10-7 of the receiving node will be unable to correctly receive the transmitted data.

Therefore, the optical transmission devices 10-2 to 10-6 of each relay node perform predetermined relay processing. That is, each relay node amplifies the optical intensity of the optical signal received at its respective relay position, and restores the original data free of bit errors through predetermined error correction processing.

However, in order to perform error correction processing, etc., it is necessary to perform electrical termination processing of the optical signal to be transmitted. That is, the optical transmission devices 10-2 to 10-6 convert optical signals into electrical signals within the transponder 11, process data of the obtained electrical signals, and perform error correction processing and the like. Further, the optical transmission devices 10-2 to 10-6 convert the processed electrical signals into optical signals again, and send them as relay outputs to the optical fiber cable 15 on the downstream side.

By performing electrical termination processing as described above, it is possible to reliably correct errors that occur during transmission and restore optical intensity. It is also possible to obtain transmission quality data. However, as the electrical signals are processed, a relatively large delay occurs in the signals inside the transponder 11. Furthermore, as the transmission distance increases, the number of relays increases, resulting in an increase in delay time. In the example of the optical transmission system 100A, since the optical transmission devices 10-3 and 10-5 including the transponder 11 are present as relay nodes between the transmitting node and the receiving node, the relay processing including electrical termination processing is performed only once. The delay time is doubled compared to the case of .

On the other hand, in recent years, the functions of optical fiber cables 15 and transmitters that transmit optical signals have improved, so even when performing relatively long-distance optical transmission, it is possible to reduce the number of relay nodes including electrical termination. is possible. Therefore, the configuration of the optical transmission system 100A shown in FIG. 1 can be improved like the optical transmission system 100B shown in FIG.

In the optical transmission system 100B shown in FIG. 2, the transponders 11 are present in the optical transmission devices 10-1 and 10-7, but the transponders 11 are not present in the other optical transmission devices 10-2 to 10-6. That is, when transmitting an optical signal from the optical transmission device 10-1 of the transmitting node to the optical transmission device 10-7 of the receiving node, relaying including electrical termination processing is not performed even once. Therefore, the delay time associated with optical signal transmission in optical transmission system 100B is significantly reduced compared to optical transmission system 100A.

On the other hand, in the case of the optical transmission system 100B, each of the optical transmission devices 10-2 to 10-6 does not have a transponder 11 and does not perform electrical termination processing, so the relay nodes of each optical transmission device 10-2 to 10-6 Transmission quality data cannot be obtained at the location.

On the other hand, when a communication failure occurs, the network controller 20 normally transmits optical signals to narrow down candidates for the location where the failure has occurred based on transmission quality data detected at the location of each node used for optical signal transmission. Divide into sections. However, in the case of the optical transmission system 100B, transmission quality data at the relay positions of each optical transmission device 10-2 to 10-6 cannot be obtained, so the output of the optical transmission device 10-1 and the input of the optical transmission device 10-7 are It is not possible to isolate in which section the failure is occurring. As a result, it becomes difficult to identify the location where the failure has occurred, and it takes a long time to recover from the failure. In particular, when the distance of the optical fiber cable 15 is very long, it is difficult to find the location where the fault has occurred.

On the other hand, in the case of the optical transmission system 100C in FIG. 3, the optical transmission device 10-4 used as a relay node is equipped with a transponder 11, so the network controller 20 can acquire transmission quality data at this relay position. Therefore, when a failure occurs, the failure location is located in the section from the output of the optical transmission device 10-1 to the input of the optical transmission device 10-4, and from the relay output of the optical transmission device 10-4 to the optical transmission device 10-4. Based on the transmission quality data detected by the optical transmission device 10-4, it can be determined which of the sections up to the input of No. 7 is included.

In other words, by arranging the transponder 11 having an electrical termination function in the optical transmission device 10-4 of the relay node as in the optical transmission system 100C, the location of the failure can be identified compared to the optical transmission system 100B in FIG. This makes it easier to divide sections for However, in the case of the optical transmission system 100C, the optical transmission device 10-4 of the relay node has an electrical termination function, which causes a transmission delay.

On the other hand, in the optical transmission system 100D shown in FIG. 4, the optical transmission device 10-4 of the relay node is equipped with an optical splitter 12. The optical splitter 12 branches the optical signal inputted from the optical fiber cable 15 into two paths in the form of light, and outputs them to optical output ends 12a and 12b, respectively. An optical output end 12a of the optical splitter 12 is connected to an optical fiber cable 15 on the relay output side. Further, the optical output end 12b of the optical splitter 12 is connected to the input of the transponder 11 in the optical transmission device 10-4.

In the case of the optical transmission system 100D, since the optical transmission device 10-4 relays and outputs the optical signal without electrical termination processing as it is, it is possible to prevent transmission delays from occurring at this node position. Furthermore, since the transponder 11 in the optical transmission device 10-4 detects the transmission quality data at this node position, it becomes easy to isolate the faulty section as in the case of the optical transmission system 100C.

However, when the optical splitter 12 is placed inside the optical transmission device 10-4 as in the optical transmission system 100D, the optical signal to be relayed (main signal) is lost due to the loss that occurs when it passes through the optical splitter 12. Light intensity decreases. Therefore, deterioration in transmission quality occurs at the node position of the optical transmission device 10-4.

-<Multi-band networking technology>
FIG. 5 shows an example of the relationship between optical communication links and wavelength bands in multiband networking technology (see Non-Patent Document 1).

In the example shown in FIG. 5, it is assumed that there are three types of wavelength bands of light used for communication: L band, C band, and S band. The L band is a wavelength band of 1565 to 1625 nm. The C-band is a wavelength band from 1530 to 1565 nm. The S-band is a wavelength band from 1460 to 1530 nm.
Further, each of the L band, C band, and S band has a mutually independent optical path. Furthermore, in the example of FIG. 5, it is assumed that there are two mutually independent optical communication links 31 and 32.

The optical signals of each optical communication link 31, 32 are adaptively band-switched depending on the situation, and are switched so as to straddle the optical path of multiple bands. That is, after the optical signal of the optical communication link 31 shown in FIG. It is converted into a band optical signal and enters the S-band optical path. This light is then converted into an L-band optical signal by wavelength conversion, enters the L-band optical path, is converted into an electrical signal by Ph-EX (Photonic Exchange), is processed, and is output. Ph-EX is a component that minimizes electrical processing such as exchange, multiplexing, and switching.

Further, the optical signal of the optical communication link 32 having a C-band wavelength passes through the C-band optical path, is converted into an S-band optical signal by wavelength conversion, enters the S-band optical path, and is converted into an electrical signal by Ph-EX. converted and processed.

By using the technology shown in FIG. 5, the optical transmission system can efficiently use limited wavelength resources. Specifically, the amount of traffic that can be accommodated on the transmission line can be increased by about 30%. Furthermore, since electrical termination processing can be omitted at each communication node and optical signals can be processed as they are, effects such as power savings, increased capacity, and reduced delay in the network can be expected. However, the optical transmission equipment at each node position needs to be equipped with a function to convert the wavelength of the optical signal.

Embodiments of the present invention will be described below with reference to each figure.
<Description of embodiment>
FIG. 6 shows a configuration example of an optical transmission system 100 in an embodiment of the present invention.

The optical transmission system 100 shown in FIG. 6 includes five optical transmission devices 41, 42, 43, 44, and 45 and a network controller 20. The five optical transmission devices 41 to 45 are installed, for example, in a line at locations separated from each other by a certain distance. Further, the optical transmission devices 41 to 45 are connected in series to each other via one optical fiber cable 15 used as a transmission path for optical signals.

The network controller 20 manages the entire optical communication network composed of the optical transmission devices 41 to 45 and the optical fiber cable 15. For example, when a failure occurs on the optical communication network, the network controller 20 can generate information useful for identifying the location of the failure.

For example, when transmitting data from an optical transmission device 41 at one end of this communication network to an optical transmission device 45 at the other end, the optical transmission device 41 becomes a transmitting node and the optical transmission device 45 becomes a receiving node. Further, optical transmission devices 42 to 44 located between these transmitting nodes and receiving nodes are respectively used as relay nodes.

The optical transmission device 41 of the transmitting node converts the data to be transmitted from an electrical signal into an optical signal of a predetermined wavelength inside the transponder 11, and sends this optical signal to the optical fiber cable 15. The optical transmission device 45 of the receiving node receives the optical signal from the optical fiber cable 15, converts the optical signal into an electrical signal with the transponder 11 in the optical transmission device 45, and obtains received data.

In the configuration shown in FIG. 6, an all-optical wavelength conversion unit 13 that implements an AO-WC (All Optical Wavelength Conversion) function is installed inside an optical transmission device 43 used as one relay node. We are prepared.

The all-optical wavelength conversion unit 13 in the optical transmission device 43 performs wavelength conversion processing on the input optical signal Oin, which is inputted to the optical transmission device 43 from the optical fiber cable 15 and has a wavelength of λ1, as an optical signal, and converts it into a signal different from the input. An optical signal with a wavelength λ2 can be generated and sent to the optical fiber cable 15 on the downstream side as an output optical signal Oo2 with a wavelength λ2. Further, the all-optical wavelength converter 13 shown in FIG. 6 extracts an unnecessary optical component different from the optical main signal relayed inside the optical transmission device 43 and inputs it to the detector 11A inside the optical transmission device 43. be able to. The detector 11A has the same electrical termination function as the transponder 11, but does not have the function of transmitting an optical signal. That is, the detector 11A has a function of converting an input optical signal into an electrical signal, and a function of processing this electrical signal to detect transmission quality data.

In other words, the optical transmission device 43 relays the optical main signal to be relayed without electrical termination processing, and transmits the optical signal as it is to the downstream optical fiber cable 15, so it is possible to prevent an increase in delay due to the relay processing. Furthermore, as will be described later, since there is no need to use an optical splitter to extract the optical signal input to the detector 11A, it is possible to prevent the optical main signal from decreasing in optical intensity.

In addition, the all-optical wavelength converter 13 extracts an unnecessary optical component different from the optical main signal to be relayed and inputs it to the detector 11A in the optical transmission device 43, so the detector 11A is located at the node position of the optical transmission device 43 transmission quality data can be detected.

Therefore, the network controller 20 can acquire transmission quality data of relay nodes such as the optical transmission equipment 43 that do not perform electrical termination processing. For example, when a failure occurs, the network controller 20 can determine whether or not a failure has occurred for each section based on transmission quality data at the location of each relay node.

<Configuration of all-optical wavelength conversion section>
FIG. 7 shows a configuration example of the all-optical wavelength conversion section 13 included in the optical transmission system 100 of FIG. 6.
The all-optical wavelength conversion unit 13 shown in FIG. 7 includes an excitation light source 14, an optical fiber 15A, an optical multiplexer 16, a nonlinear optical medium 17, an optical demultiplexer 18, and an optical fiber 15B. The all-optical wavelength conversion unit 13 is an all-optical wavelength conversion device that includes a nonlinear optical medium 17 into which both the main optical signal to be relayed and the excitation light emitted from the excitation light source 14 can be input simultaneously.

The excitation light source 14 generates excitation light Oe with a predetermined wavelength λe. The excitation light Oe generated by the excitation light source 14 passes through the optical fiber 15A and enters the optical multiplexer 16. The wavelength λe of the excitation light Oe is different from the wavelength λ1 of the input optical signal Oin. Furthermore, the optical intensity of the excitation light Oe is sufficiently large compared to the input optical signal Oin.

The optical multiplexer 16 generates light by combining the input optical signal Oin input from the optical fiber cable 15 and the excitation light Oe input from the optical fiber 15A, and sends it to the input end of the nonlinear optical medium 17.

The nonlinear optical medium 17 has nonlinear optical characteristics and can generate an optical signal with a wavelength different from that of the incident light. As a typical example, any one of a highly nonlinear fiber (HNLF), a periodically poled lithium niobate (PPLN), and a semiconductor optical amplifier (SOA) can be used as the nonlinear optical medium 17.

The optical demultiplexer 18 is connected to the light output side of the nonlinear optical medium 17, which is a total light wave conversion device. The output light Oout output from the output end of the nonlinear optical medium 17 is input to the optical demultiplexer 18 . The optical demultiplexer 18 demultiplexes the incident light according to its wavelength selection characteristics, and extracts two types of optical signals. That is, the output optical signal Oo2 with the wavelength λ2 and the output light Oo1 with the wavelength λ1 are output from different output terminals of the optical demultiplexer 18.

The wavelength λ2 of the outgoing optical signal Oo2 is generated based on the wavelength of the input optical signal Oin, the wavelength λe of the excitation light Oe, and the nonlinear optical characteristics of the nonlinear optical medium 17. That is, by passing the input optical signal Oin with the wavelength λ1 through the nonlinear optical medium 17 together with the excitation light Oe, the wavelength λ2 of the wavelength-converted output optical signal Oo2 is generated. Furthermore, the light emitted from the nonlinear optical medium 17 also contains a light component having the same wavelength λ1 as before wavelength conversion.

The output optical signal Oo2 of wavelength λ2 outputted from the optical demultiplexer 18 is sent out from the output of the optical transmission device 43 to the downstream optical fiber cable 15 as a relay output. Further, the output light Oo1 having the wavelength λ1 output from the optical demultiplexer 18 is input to the detector 11A in the optical transmission device 43 via the optical fiber 15B.

Therefore, by using the all-optical wavelength converter 13 shown in FIG. 7, the wavelength of the optical main signal relayed by the optical transmission device 43 is converted from λ1 to λ2 without electrical termination processing. This can prevent an increase in delay. Further, the output light Oo1 having the same wavelength λ1 as before wavelength conversion, which is output from the all-optical wavelength conversion unit 13, that is, unnecessary light components other than the main signal, can be input to the detector 11A. The detector 11A can internally convert the input output light Oo1 of wavelength λ1 into an electrical signal, and perform various processing on the electrical signal. Thereby, transmission quality data at the relay node position of the optical transmission device 43 is obtained. However, the wavelength λ2 of the main optical signal transmitted by the relay node is different from the wavelength λ1 of light other than the main signal input to the detector 11A. Therefore, the correlation between the transmission quality detected for the wavelength λ1 and the transmission quality detected for the wavelength λ2 is specified in advance, and the transmission quality data detected by the detector 11A is determined based on the correlation. and converts it into transmission quality data for the optical signal to be relayed. This conversion process may be performed inside the detector 11A or may be performed on the network controller 20 side.

<Wavelength distribution of optical signals in each part>
FIG. 8 shows a list of optical signal wavelength distributions in each part of the all-optical wavelength conversion section 13 in FIG. 7. The horizontal axis in FIG. 8 represents wavelength, and the vertical axis represents light intensity.

As shown in the graph at the top of FIG. 8, the input optical signal Oin input from the upstream optical fiber cable 15 to the optical transmission device 43 includes only a component of a single wavelength λ1. Furthermore, the excitation light Oe generated by the excitation light source 14 includes only a component of a single wavelength λe. Further, as shown in the second graph, the optical intensity of the excitation light Oe is sufficiently larger than the input optical signal Oin.

On the other hand, the output light Oout output from the nonlinear optical medium 17 includes components of three types of wavelengths λ1, λe, and λ2, as shown in the third graph in FIG. The component of wavelength λ2 is a component generated by wavelength conversion of the input optical signal Oin as it passes through the nonlinear optical medium 17. The light intensity of the wavelength λ2 component included in the output light Oout depends on the nonlinear optical medium and the excitation light intensity, and can be made equal to the input optical signal Oin. In other words, wavelength conversion can be performed without attenuating the light intensity.

Furthermore, the light intensity of the component of wavelength λ1 included in the output light Oout is equivalent to the input optical signal Oin. In other words, an optical signal other than the main signal having the same wavelength λ1 as before wavelength conversion and having a sufficiently high optical intensity can be extracted from the output of the nonlinear optical medium 17.

By the demultiplexing in the optical demultiplexer 18, a transmitted optical signal Oo2 containing only the component of wavelength λ2 is extracted from one output of the optical demultiplexer 18. The fourth graph in FIG. 8 shows the transmitted optical signal Oo2. This outgoing optical signal Oo2 is sent out to the optical fiber cable 15 on the downstream side as a relay output optical main signal.

Furthermore, by the demultiplexing of the optical demultiplexer 18, the output light Oo1 containing only the component of the same wavelength λ1 as that before wavelength conversion is extracted from the other output of the optical demultiplexer 18, and this output light Oo1 passes through the optical fiber 15B. The signal is input to the detector 11A via the sensor. The fifth graph in FIG. 8 shows the output light Oo1.
Here, since the emitted light Oo1 with sufficiently high light intensity is input to the detector 11A, the detector 11A can easily detect transmission quality data at the position of the corresponding relay node. Of course, the detector 11A internally converts the input optical signal into an electrical signal, and detects transmission quality data by processing the electrical signal.

<Modified example of optical transmission system>
-<Configuration of modified example>
FIG. 9 shows a configuration of an optical transmission system 200 that is a modification of the configuration in FIG. 6.

The optical transmission system 200 shown in FIG. 9 includes five optical transmission devices 51, 52, 53, 54, and 55 and a network controller 20. The five optical transmission devices 51 to 55 are installed, for example, in a line at locations separated from each other by a certain distance. Further, each of the optical transmission devices 51 to 55 shown in FIG. 9 has a function of transmitting a WDM (Wavelength Division Multiplexing) optical signal in which optical signals of multiple wavelengths are multiplexed.

The five optical transmission devices 51 to 55 are connected in series to each other via one or more optical fiber cables 15 used as transmission paths for WDM optical signals. Optical transmission devices 51 and 55 located at the end of the network that function as transmitting nodes or receiving nodes are each equipped with a plurality of transponders 11a to 11n that are capable of processing WDM optical signals.

The network controller 20 manages the entire optical communication network composed of the optical transmission devices 51 to 55 and the optical fiber cable 15. For example, when a failure occurs on the optical communication network, the network controller 20 can generate information useful for identifying the location of the failure.

For example, when transmitting data from an optical transmission device 51 at one end of this communication network to an optical transmission device 55 at the other end, the optical transmission device 51 becomes a transmitting node and the optical transmission device 55 becomes a receiving node. Furthermore, optical transmission devices 52 to 54 located between these transmitting nodes and receiving nodes are used as relay nodes, respectively.

The optical transmission device 51 of the transmission node converts the data to be transmitted from an electrical signal into an optical signal of a predetermined wavelength inside each transponder 11a to 11n, and sends out a WDM optical signal multiplexed with multiple wavelengths to the optical fiber cable 15. do. The optical transmission device 55 of the receiving node receives the WDM optical signal from the optical fiber cable 15. The optical transmission device 55 separates the received WDM optical signal for each wavelength, converts the optical signal into an electrical signal in each transponder 11a to 11n, and obtains received data by processing the electrical signal.

In the optical transmission system 200 having the configuration shown in FIG. 9, the optical transmission device 53 used as one relay node includes an all-optical wavelength conversion section 13A that implements the AO-WC function. Further, a plurality of transponders 11a to 11n compatible with WDM optical signals are mounted on the optical transmission device 53.

The all-optical wavelength conversion unit 13A in the optical transmission device 53 performs wavelength conversion processing on the WDM optical signal inputted to the optical transmission device 53 from the upstream optical fiber cable 15 as an optical signal, so that the wavelength is different from the input one. A WDM optical signal can be generated and sent to the downstream optical fiber cable 15. Further, the all-optical wavelength conversion section 13A can extract unnecessary optical components separated from the WDM optical main signal relayed by the optical transmission device 53 and input them to the detectors 11Aa to 11An in the optical transmission device 53.

In other words, the optical transmission device 53 relays the WDM optical main signal to be relayed without electrical termination processing, and relays the optical signal as it is and sends it to the downstream optical fiber cable 15, so it is possible to prevent an increase in delay due to relay processing. . Further, since it is not necessary to use an optical splitter to extract the optical signals input to the detectors 11Aa to 11An, it is possible to suppress a decrease in the optical intensity of the WDM optical main signal.

In addition, the all-optical wavelength converter 13A extracts unnecessary optical components separated from the WDM optical main signal to be relayed and inputs them to the detectors 11Aa to 11An in the optical transmission device 53. Transmission quality data at 53 node locations can be detected.

Therefore, the network controller 20 can acquire transmission quality data of a relay node such as the optical transmission device 53 that does not perform electrical termination processing. For example, when a failure occurs, the network controller 20 can determine whether the failure has occurred in each section based on transmission quality data at the location of each relay node.
Furthermore, the optical transmission device 53 can also replace the transmission signal and the extraction signal. In this case, the optical transmission device 53 transmits each optical component with wavelengths λ11 to λ1n, detects each optical component with wavelengths λ21 to λ2n as an extraction signal, and obtains transmission quality data. As a result, the optical transmission device 53 can acquire transmission quality data even when wavelength conversion is not performed.

-<First configuration example of all-optical wavelength conversion section>
A first configuration example of the all-optical wavelength converter 13A included in the optical transmission system 200 of FIG. 9 is shown in FIG.

The all-optical wavelength conversion section 13A shown in FIG. 10 includes an excitation light source 14, an optical fiber 15A, an optical multiplexer 16, a nonlinear optical medium 17, an optical demultiplexer 18, and an optical fiber 15B.

The excitation light source 14 generates excitation light Oe with a predetermined wavelength λe. The excitation light Oe generated by the excitation light source 14 passes through the optical fiber 15A and enters the optical multiplexer 16. The wavelength λe of the excitation light Oe is different from each of the wavelengths λ1 to λn included in the WDM input optical signal Oin. Further, the optical intensity of the excitation light Oe is sufficiently large compared to the WDM input optical signal Oin.

The optical multiplexer 16 generates light by combining the WDM input optical signal Oin input from the optical fiber cable 15 and the excitation light Oe input from the optical fiber 15A, and sends it to the input end of the nonlinear optical medium 17. do.

The output light Oout output from the output end of the nonlinear optical medium 17 is input to the optical demultiplexer 18. This emitted light Oout includes a WDM optical signal after wavelength conversion. The optical demultiplexer 18 demultiplexes the incident light according to its wavelength selection characteristics, and extracts the outgoing optical signal Oo2, which is the WDM optical main signal to be relayed, and the output lights Oo11 to Oo1n, which are other than the WDM optical main signal. do.

The wavelength of the output optical signal Oo2, which is a WDM optical signal, is generated from each wavelength included in the WDM input optical signal Oin, the wavelength λe of the excitation light Oe, and the nonlinear optical characteristics of the nonlinear optical medium 17. That is, the input optical signal Oin including a plurality of wavelengths λ1 to λn passes through the nonlinear optical medium 17 together with the excitation light Oe, thereby generating an output optical signal Oo2 that is wavelength-converted for each WDM wavelength. Furthermore, the light emitted from the nonlinear optical medium 17 also contains light components having the same plurality of wavelengths λ1 to λn as before wavelength conversion.

The wavelength-converted transmission optical signal Oo2 output from the optical demultiplexer 18 is transmitted from the output of the optical transmission device 53 to the downstream optical fiber cable 15 as a relay output. Furthermore, the WDM output light Oo1 containing the same plurality of wavelengths λ1 to λn as before wavelength conversion, which is output from the optical demultiplexer 18, is sent to the plurality of detectors 11Aa to 11An in the optical transmission device 53 via the optical fiber 15B. The output lights are inputted as output lights Oo11 to Oo1n separated for each wavelength.

Therefore, by using the all-optical wavelength converter 13A shown in FIG. 10, the wavelength of the WDM optical main signal relayed by the optical transmission device 53 can be converted as it is without electrical termination processing, and the wavelength can be delayed. can prevent an increase in Further, the output lights Oo11 to Oo1n of the same wavelengths λ1 to λn as before wavelength conversion outputted from the all-optical wavelength conversion unit 13A, that is, unnecessary light components other than the main signal to be relayed, are sent to the plurality of detectors 11Aa to 11An for each wavelength. can be entered.

Each of the detectors 11Aa to 11An internally converts any of the output lights Oo11 to Oo1n separated for each wavelength into an electrical signal, and can perform various processing in the form of the electrical signal. As a result, transmission quality data for each wavelength at the relay node position of the optical transmission device 53 can be obtained.

-<Wavelength distribution of optical signals in each part of Figure 10>
FIG. 11 shows a list of optical signal wavelength distributions in each part of the all-optical wavelength conversion section 13A in FIG. 10. The horizontal axis in FIG. 11 represents wavelength, and the vertical axis represents light intensity.

As shown in the graph at the top of FIG. 11, the input optical signal Oin input from the upstream optical fiber cable 15 to the optical transmission device 53 includes multiplexed components of multiple wavelengths λ11 to λ1n. . Furthermore, as shown in the second graph, the excitation light Oe generated by the excitation light source 14 includes only a component of a single wavelength λe. Further, the optical intensity of the excitation light Oe is sufficiently larger than the input optical signal Oin.

On the other hand, in the output light Oout emitted from the nonlinear optical medium 17, as shown in the third graph of FIG. include.

The optical components with wavelengths λ21 to λ2n are optical components generated by wavelength conversion of the input optical signal Oin as it passes through the nonlinear optical medium 17. Furthermore, the light intensity of the components of wavelengths λ21 to λ2n included in the output light Oout is equal to that of the input optical signal Oin. In other words, wavelength conversion can be performed without attenuating the light intensity.

Furthermore, the light intensity of the components of wavelengths λ11 to λ1n included in the output light Oout is equal to that of the input optical signal Oin. In other words, optical signals other than the main signal having the same wavelengths λ11 to λ1n as before wavelength conversion can be extracted from the output of the nonlinear optical medium 17 with sufficiently high optical intensity.

By the demultiplexing in the optical demultiplexer 18, an output optical signal Oo2 containing optical components with wavelengths λ21 to λ2n is extracted from one output of the optical demultiplexer 18, and this output optical signal Oo2 becomes the WDM optical main signal of the relay output. The signal is sent out to the optical fiber cable 15 on the downstream side. The fourth graph shows the transmitted optical signal Oo2.

Further, by the demultiplexing of the optical demultiplexer 18, output lights Oo11 to Oo1n containing light components of the same wavelengths λ11 to λ1n as before wavelength conversion are extracted to the other output of the optical demultiplexer 18, and these output lights Oo11 to Oo1n are extracted. oO1n is input to a plurality of detectors 11Aa to 11An for each wavelength via an optical fiber 15B. The fifth graph shows the emitted light Oo11. The sixth graph shows the output light Oo1n.
Here, since the emitted lights Oo11 to Oo1n with sufficiently high light intensity are input to the detectors 11Aa to 11An, the detectors 11Aa to 11An can easily detect transmission quality data for each wavelength at the position of the corresponding relay node. . Of course, each of the detectors 11Aa to 11An internally converts an input optical signal into an electrical signal, and detects transmission quality data by processing the electrical signal.

-<Second configuration example of all-optical wavelength conversion section>
FIG. 12 shows a second configuration example of the all-optical wavelength conversion section 13B that can be implemented in the optical transmission system 200 of FIG. 9.

In the all-optical wavelength conversion section 13B shown in FIG. 12, a wavelength filter 19 is connected to the downstream side of the optical fiber 15B, and a single detector 11A is connected to the output side of the wavelength filter 19.

The wavelength filter 19 can selectively extract the component of the optical signal Oo1x of a specific wavelength from the output light Oo1 in which optical components of multiple wavelengths λ11 to λ1n are multiplexed, and input it to the detector 11A.

As a representative example of the wavelength filter 19, it is assumed that one of the following (1) to (3) is adopted, for example.
(1) A 1×n wavelength selective switch (WSS) is used. In that case, the wavelength of the optical signal passing through each port can be electrically controlled.
(2) Branch the optical signal into multiple ports using a coupler, and install a tunable filter at each port. By electrically controlling each tunable filter, the wavelength to be transmitted can be selected for each port.
(3) When the detector 11A performs coherent detection, the wavelength of the optical signal to be detected can be selected by setting the optical wavelength of the local light within the detector 11A. In this case, the installation of the wavelength filter 19 is omitted, the output light Oo1 is made to enter the detector 11A as a WDM signal, and the wavelength to be processed is selected inside the detector 11A.
The configuration of the all-optical wavelength converter 13B other than the above is the same as that of the all-optical wavelength converter 13A.

-<Wavelength distribution of optical signals in each part of Fig. 12>
FIG. 13 shows a list of optical signal wavelength distributions in each part of the all-optical wavelength conversion section 13B in FIG. 12. The horizontal axis in FIG. 13 represents wavelength, and the vertical axis represents light intensity.

As shown in FIG. 13, the input optical signal Oin input from the upstream optical fiber cable 15 to the optical transmission device 53 includes multiplexed components of multiple wavelengths λ11 to λ1n. Furthermore, the excitation light Oe generated by the excitation light source 14 includes only a component of a single wavelength λe. Further, the optical intensity of the excitation light Oe is sufficiently larger than the input optical signal Oin.

On the other hand, the output light Oout output from the nonlinear optical medium 17 includes light components with wavelengths λ11 to λ1n, λe, and λ21 to λ2n, as shown in FIG.

The optical components with wavelengths λ21 to λ2n are optical components generated by wavelength conversion of the input optical signal Oin as it passes through the nonlinear optical medium 17. Furthermore, the light intensity of the components of wavelengths λ21 to λ2n included in the output light Oout is equal to that of the input optical signal Oin. In other words, wavelength conversion can be performed without attenuating the light intensity.

Furthermore, the light intensity of the components of wavelengths λ11 to λ1n included in the output light Oout is equal to that of the input optical signal Oin. In other words, optical signals other than the main signal having the same wavelengths λ11 to λ1n as before wavelength conversion can be extracted from the output of the nonlinear optical medium 17 with sufficiently high optical intensity.

By the demultiplexing in the optical demultiplexer 18, an output optical signal Oo2 containing optical components with wavelengths λ21 to λ2n is extracted from one output of the optical demultiplexer 18, and this output optical signal Oo2 becomes the WDM optical main signal of the relay output. The signal is sent out to the optical fiber cable 15 on the downstream side.

Further, by the demultiplexing of the optical demultiplexer 18, the output light Oo1 containing the light components of the same wavelengths λ11 to λ1n as before wavelength conversion is extracted to the other output of the optical demultiplexer 18, and this output light Oo1 is filtered by the wavelength filter. 19 is input. The wavelength filter 19 selectively extracts a light component of one wavelength λ1a from the wavelengths λ11 to λ1n and inputs it to the detector 11A.

Therefore, there is no need to install multiple detectors 11A inside the optical transmission device 53. In this case, the single detector 11A sequentially selects each of the wavelengths λ11 to λ1n included in the WDM optical signal of the emitted light Oo1, converts each wavelength into an electrical signal, and processes it. Transmission quality data at each location can be detected for each wavelength.

<Processing procedure of optical transmission management method>
FIG. 14 shows an example of the processing procedure of the optical transmission management method of the present invention. The processing procedure of FIG. 14 will be explained below.

This processing procedure can be used, for example, to manage the optical transmission system 100 as shown in FIG. In this optical transmission system 100, at the node position of the optical transmission device 43 that relays communication, the optical transmission device 43 receives the input optical signal Oin from the upstream optical fiber cable 15 in step S11, and 13 performs wavelength conversion of the input optical signal Oin in step S12.

The optical demultiplexer 18 in the all-optical wavelength converter 13 sends out the wavelength-converted outgoing optical signal Oo2 to the downstream optical fiber cable 15 as a relay output in step S13. Further, the optical demultiplexer 18 in the all-optical wavelength converter 13 extracts the output light Oo1 having the same wavelength as before wavelength conversion, that is, unnecessary light that is not used for relaying communication, in step S14.

The detector 11A in the optical transmission device 43 receives the unnecessary light extracted by the optical demultiplexer 18 in step S15 and converts it into an electrical signal.
The detector 11A may be a receiver equivalent to a transponder, a spectrum analyzer, a polarization monitor, a power meter, or the like. The transponder receiving unit converts unnecessary light into an electrical signal and processes it to obtain transmission quality data in step S16. For spectrum analyzers, obtain the signal-to-noise ratio. In the case of a polarization monitor, the polarization state of the optical signal is obtained, and in the case of a power meter, the optical intensity is obtained.

The optical transmission device 43 associates the transmission quality data detected by the internal detector 11A with the relay node position and notifies the network controller 20 in step S17.
Therefore, by performing the relay processing shown in FIG. 14, the network controller 20 can obtain transmission quality data even for relay nodes that omit electrical termination processing of optical signals to be transmitted.

<Explanation of modification example>
FIG. 15 shows the configuration of the all-optical wavelength conversion section 13C. This all-optical wavelength converter 13C is a modification of the all-optical wavelength converter 13 shown in FIG.

In the total optical wavelength conversion unit 13C in FIG. 15, out of the optical components of wavelengths λ1 and λ2 included in the output light Oout of the nonlinear optical medium 17, the output light Oo1 with the wavelength λ1 is extracted by the optical demultiplexer 18, It is sent out to the optical fiber cable 15 as a relay output. Furthermore, among the optical components of wavelengths λ1 and λ2 included in the output light Oout of the nonlinear optical medium 17, the output optical signal Oo2 of wavelength λ2 is extracted by the optical demultiplexer 18 and sent to the detector 11A via the optical fiber 15B. is input.
The configuration of the all-optical wavelength converter 13C other than the above is the same as that of the all-optical wavelength converter 13 shown in FIG.

In other words, in the relay node using the all-optical wavelength converter 13C in FIG. 15, the wavelength of the optical signal to be relayed is not converted. However, by using the all-optical wavelength converter 13C, unnecessary light other than the optical main signal can be extracted and input to the detector 11A without attenuating the optical intensity of the optical main signal to be relayed.

When using the all-optical wavelength converter 13C in FIG. 15, the wavelength λ1 of the optical main signal to be relayed is different from the wavelength λ2 of the transmission quality data detected by the detector 11A. Therefore, the correlation between the transmission quality data for the wavelength λ1 and the transmission quality data for the wavelength λ2 is grasped in advance. Then, the transmission quality data detected by the detector 11A is converted into transmission quality data of the wavelength λ1 of the optical main signal to be relayed based on the correlation. This conversion process may be performed inside the detector 11A or may be performed on the network controller 20 side.

Further, as a practical configuration of the optical transmission device 43, it is conceivable to configure it so that the optical demultiplexer 18 can selectively control the wavelength of the light outputted to each output port. Thereby, the configuration of the all-optical wavelength converter 13 shown in FIG. 7 and the configuration of the all-optical wavelength converter 13C shown in FIG. 15 can be switched as necessary. This allows the network controller 20 to dynamically switch whether wavelength conversion is to be performed at each relay node depending on the situation.

<Possibility of deformation other than the above>
The total optical wavelength conversion unit 13 shown in FIG. The output light Oo1 having the same wavelength λ1 is extracted by the optical demultiplexer 18 and input to the detector 11A. On the other hand, when reflection or scattering of the input optical signal Oin occurs on the light incidence side of the nonlinear optical medium 17, there is a possibility that reflected light or scattered light can be extracted on the incidence side of the nonlinear optical medium 17. In that case, an optical demultiplexer (unnecessary light extraction section) is connected to the light incidence side of the nonlinear optical medium 17 to extract the light component having the same wavelength as the wavelength of the main optical signal to be relayed before wavelength conversion as unnecessary light. The extracted unnecessary light may be input to the detector 11A. Thereby, the degree of freedom in connecting the optical demultiplexer can be improved.

Furthermore, an optical demultiplexer (unnecessary light extraction section) is connected to the light output side of the nonlinear optical medium 17, and from the light output from the nonlinear optical medium 17, the wave of the optical main signal to be relayed is converted. The light component of wave (2) may be extracted as unnecessary light.

It is generally assumed that the network controller 20 of the optical transmission system 100 uses "Pre-FEC BER" as transmission quality data detected by the transponder 11 of each optical relay node. On the other hand, the detector 11A and the transponder 11 can obtain data such as chromatic dispersion compensation amount, polarization mode dispersion, polarization dependent loss, etc. in addition to "Pre-FEC BER" by electrical signal processing of communication data. Therefore, the network controller 20 also collects data such as the amount of chromatic dispersion compensation, polarization mode dispersion, and polarization dependent loss from each optical relay node that implements the detector 11A or the transponder 11, and uses the data as learning data for machine learning. Can be used. This helps in predicting failures in optical networks without electrical termination.

<Characteristics of optical transmission equipment>
Characteristic matters regarding the optical transmission device and optical transmission management method of the present invention are listed in [1] to [8] below.
[1] An optical transmission node capable of transmitting optical signals and an optical reception node capable of receiving optical signals are connected via an optical transmission line, and one or more An optical transmission device that can be installed in at least one optical relay node of an optical transmission system (100) to which optical relay nodes are connected,
an all-optical wavelength conversion device (all-optical wavelength conversion unit 13) that converts the wavelength of an optical signal relayed by at least one of the optical relay nodes;
an unnecessary light extraction unit (optical demultiplexer 18) that extracts an unnecessary light component (output light Oo1) other than the optical main signal having the same wavelength as the optical main signal to be relayed before wavelength conversion;
a photoelectric signal converter (detector 11A) that converts the unnecessary light component light extracted by the unnecessary light extractor into an electrical signal;
An optical transmission device (43) comprising:

According to the optical transmission device configured in [1] above, unnecessary optical components other than the optical main signal relayed by the optical relay node are extracted and converted into electrical signals, so it is necessary to electrically terminate the optical main signal. Therefore, the unnecessary optical component can be extracted and converted into an electrical signal without affecting the delay, optical intensity, transmission quality, etc. of the optical main signal. Therefore, it becomes possible to detect transmission quality data at the position of each relay node, and it becomes easy to identify the section where a fault has occurred. Furthermore, by equipping an optical relay node with a wavelength conversion function for optical signals, it becomes possible to effectively utilize limited wavelength resources, and the effect of increasing the amount of accommodated traffic can be obtained.

[2] The unnecessary light extraction section is connected to the light output side of the all-optical wavelength conversion device, and extracts a wavelength of a main optical signal to be relayed before wavelength conversion from among the light emitted from the all-optical wavelength conversion device. Extracts the light component with the same wavelength.

According to the optical transmission device having the configuration [2] above, since the unnecessary light component contained in the light that has passed through the all-optical wavelength conversion device is extracted and utilized, the unnecessary light with a sufficiently high light intensity is Components can be extracted. Therefore, the opto-electrical signal converter can easily convert the unnecessary optical component into an electrical signal with less deterioration.

[3] The optical transmission device includes a pumping light source (pumping light source 14) that emits pumping light of a different wavelength from the wavelength of the optical main signal to be relayed before wavelength conversion,
The all-optical wavelength conversion device is a nonlinear optical medium into which both the optical main signal to be relayed and the excitation light emitted from the excitation light source can enter simultaneously,
The unnecessary light extraction section separates the light emitted from the nonlinear optical medium into a light component having a wavelength after wavelength conversion and a light component having a wavelength before wavelength conversion.

According to the optical transmission device having the configuration described in [3] above, wavelength conversion can be performed without deteriorating the optical intensity of the optical main signal to be relayed. Furthermore, an optical signal having a sufficiently high light intensity can be obtained from the unnecessary light component extracted by the unnecessary light extraction section.

[4] The optical transmission device includes at least one of a highly nonlinear fiber, periodically poled lithium niobate, and a semiconductor optical amplifier as the nonlinear optical medium.

According to the optical transmission device having the configuration described in [4] above, it is possible to efficiently perform wavelength conversion of an optical signal using the nonlinear optical medium.

[5] The optical transmission device includes a transmission quality detection section (detector 11A) that generates transmission quality data based on the electrical signal output from the opto-electrical signal conversion section.

According to the optical transmission device having the configuration described in [5] above, by utilizing the transmission quality data generated by the transmission quality detection section, it is possible to detect deterioration in transmission quality due to differences in the positions of relay nodes. Therefore, when a failure occurs, it is possible to determine whether or not there is a failure in each section, and to predict failure.

[6] In an optical transmission device, an optical multiplexer that multiplexes WDM signal light including optical main signals of multiple wavelengths (λ11 to λ1n) having different wavelengths and pump light used for wavelength conversion is the all-optical wavelength converter. connected to the light input side of the device,
An optical demultiplexer is connected to the light output side of the all-optical wavelength conversion device, and extracts unnecessary optical components divided into wavelengths that are the same as wavelengths before wavelength conversion of a plurality of optical main signals included in the WDM signal light. ,
A plurality of the photoelectric signal converters (a plurality of detectors 11Aa to 11An) are connected to the output of the optical demultiplexer, and the plurality of photoelectric signal converters convert the plurality of unnecessary light components having different wavelengths from each other. The light (outgoing light Oo11 to Oo1n) is individually converted into electrical signals.

According to the optical transmission device having the configuration [6] above, when the WDM signal light is relayed at each optical relay node, the transmission quality at the corresponding relay node position is determined for each wavelength of the optical main signal included in the WDM signal light. Data can be detected at all times.

[7] In an optical transmission device, an optical multiplexer that combines WDM signal light including optical main signals of multiple wavelengths (λ11 to λ1n) with different wavelengths and pump light used for wavelength conversion is the all-optical wavelength converter. connected to the light input side of the device,
The unnecessary light extractor is connected to the light output side of the all-optical wavelength conversion device, and the unnecessary light extractor extracts the same wavelength (λ11 to It has the function of extracting unnecessary light components of λ1n),
An optical wavelength selection section (wavelength filter 19) is arranged between the output of the unnecessary light extraction section and the input of one of the photoelectric signal conversion sections (detector 11A).

According to the optical transmission device having the configuration [7] above, when the WDM signal light is relayed at each optical relay node, transmission quality data for each wavelength of the optical main signal included in the WDM signal light can be sequentially detected. Furthermore, the number of opto-electrical signal converters mounted on each optical relay node can be reduced. This makes it possible to reduce power consumption and cost.

[8] In the optical transmission device, the unnecessary light extraction section is connected to the light output side of the all-optical wavelength conversion device, and extracts a main optical signal to be relayed from the light emitted from the all-optical wavelength conversion device. The light component of the wave ■ after the wave ■ conversion is extracted as unnecessary light.

[9] An optical transmission node capable of transmitting optical signals and an optical reception node capable of receiving optical signals are connected via an optical transmission line, and one or more An optical transmission management method for managing an optical transmission system (100) to which optical relay nodes are connected, the method comprising:
In at least one of the optical relay nodes (optical transmission device 43 or 53) of the optical transmission system,
a step of converting the wavelength of the received optical signal and transmitting the wavelength-converted optical signal as a relay output (step S13);
a step of extracting, from the received optical signal, unnecessary optical components other than the optical main signal having the same wavelength as the optical main signal to be relayed before wavelength conversion (step S14);
a step of converting the extracted unnecessary light component into an electrical signal (step S15);
a step of generating transmission quality data based on the electrical signal (step S16);
Optical transmission management method to implement.

According to the optical transmission management method of [9] above, unnecessary optical components other than the optical main signal relayed by the optical relay node are extracted and converted into electrical signals, so there is no need to electrically terminate the optical main signal. Therefore, the unnecessary optical component can be extracted and converted into an electrical signal without affecting the delay, optical intensity, transmission quality, etc. of the optical main signal. Therefore, it becomes possible to detect transmission quality data at the position of each relay node, and it becomes easy to identify the section where a fault has occurred. Further, by performing wavelength conversion of optical signals within the optical relay node, it becomes possible to effectively utilize limited wavelength resources, and the effect of increasing the amount of accommodated traffic can be obtained.

10-1, 10-2, 10-3, 10-4, 10-5 Optical transmission device 11 Transponder 11A, 11Aa to 11An Detector 12 Optical splitter 12a, 12b Optical output end 13, 13A, 13B, 13C All optical wavelengths Conversion section (all-optical wavelength conversion device)
14 Excitation light source 15 Optical fiber cable 15A, 15B Optical fiber 16 Optical multiplexer 17 Nonlinear optical medium 18 Optical demultiplexer (unnecessary light extraction section)
19 Wavelength filter 20 Network controller 31, 32 Optical communication link 41, 42, 43, 44, 45 Optical transmission device 51, 52, 53, 54, 55 Optical transmission device 100, 100A, 100B, 100C, 100D, 200 Optical transmission system Oe Pumping light Oin Input optical signal Oo2 Outgoing optical signal Oo1, Oo11 to Oo1n, Oout Outgoing light Oo1x Optical signal λ1, λ11, λ1n, λ2, λ21, λ2n, λe Wavelength

Claims (9)

1. An optical transmitting node capable of transmitting optical signals and an optical receiving node capable of receiving optical signals are connected via an optical transmission line, and one or more optical relay nodes are provided at an intermediate position of the optical transmission line. An optical transmission device that can be installed in at least one optical relay node of an optical transmission system connected to
   an all-optical wavelength conversion device that converts the wavelength of an optical signal relayed by at least one optical relay node;
   an unnecessary light extraction unit that extracts unnecessary light components other than the optical main signal having the same wavelength as the optical main signal to be relayed before wavelength conversion;
   a photoelectrical signal converter that converts the unnecessary light component light extracted by the unnecessary light extractor into an electrical signal;
   An optical transmission device comprising:
2. The unnecessary light extractor is connected to the light output side of the all-optical wavelength conversion device, and extracts a wavelength same as the wavelength of the optical main signal to be relayed before wavelength conversion from among the light emitted from the all-optical wavelength conversion device. extracting the light components of
   The optical transmission device according to claim 1.
3. Equipped with a pumping light source that emits pumping light of a different wavelength from the wavelength of the optical main signal to be relayed before wavelength conversion,
   The all-optical wavelength conversion device is a nonlinear optical medium into which both the optical main signal to be relayed and the excitation light emitted from the excitation light source can enter simultaneously,
   The unnecessary light extraction unit separates the light emitted from the nonlinear optical medium into a light component with a wavelength after wavelength conversion and a light component with a wavelength before wavelength conversion.
   The optical transmission device according to claim 1.
4. The nonlinear optical medium includes at least one of a highly nonlinear fiber, periodically poled lithium niobate, and a semiconductor optical amplifier.
   The optical transmission device according to claim 3.
5. comprising a transmission quality detection unit that generates transmission quality data based on the electrical signal output from the opto-electrical signal conversion unit;
   The optical transmission device according to claim 1.
6. An optical multiplexer that multiplexes WDM signal light including optical main signals of multiple wavelengths different from each other and excitation light used for wavelength conversion is connected to the light incidence side of the all-optical wavelength conversion device,
   An optical demultiplexer is connected to the light output side of the all-optical wavelength conversion device, and extracts unnecessary optical components divided into wavelengths that are the same as wavelengths before wavelength conversion of a plurality of optical main signals included in the WDM signal light. ,
   A plurality of the photoelectric signal converters are connected to the output of the optical demultiplexer, and the plurality of photoelectric signal converters individually convert the plurality of unnecessary light components having different wavelengths into electrical signals. ,
   The optical transmission device according to claim 1.
7. An optical multiplexer that multiplexes WDM signal light including optical main signals of multiple wavelengths different from each other and excitation light used for wavelength conversion is connected to the light incidence side of the all-optical wavelength conversion device,
   The unnecessary light extraction section is connected to the light output side of the all-optical wavelength conversion device, and the unnecessary light extraction section extracts unnecessary light having the same wavelength as the wavelength of a plurality of optical main signals included in the WDM signal light before wavelength conversion. It has the function of extracting ingredients,
   an optical wavelength selection section is disposed between the output of the unnecessary light extraction section and the input of one of the photoelectric signal conversion sections;
   The optical transmission device according to claim 1.
8. The unnecessary light extraction section is connected to the light output side of the all-light wavelength conversion device,
   Extracting the optical components of the wave of the optical main signal to be relayed and the converted wave from among the light emitted from the all-optical wavelength conversion device as unnecessary light;
   The optical transmission device according to claim 1.
9. An optical transmitting node capable of transmitting optical signals and an optical receiving node capable of receiving optical signals are connected via an optical transmission line, and one or more optical relay nodes are provided at an intermediate position of the optical transmission line. An optical transmission management method for managing an optical transmission system connected to
   In at least one of the optical relay nodes of the optical transmission system,
   a step of converting the wavelength of the received optical signal and transmitting the wavelength-converted optical signal as a relay output;
   a step of extracting, from the received optical signal, unnecessary optical components other than the optical main signal having the same wavelength as the optical main signal to be relayed before wavelength conversion;
   a step of converting the extracted unnecessary light component light into an electrical signal;
   generating transmission quality data based on the electrical signal;
   Optical transmission management method to implement.

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