Optical transmission device and optical transmission management method

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

[Technical Field]

[0001] The present invention relates to an optical transmission device and an optical transmission management method. [Background technology]

[0002] In optical transmission systems that connect a sending node and a receiving node with a relatively long-distance optical fiber cable and transmit optical signals, it is expected that the optical signal will be significantly attenuated along the transmission path, and that degradation in transmission quality will occur. Therefore, to ensure that the optical signal transmitted from the sending node reaches the receiving node reliably, it is generally necessary to place one or more relay nodes along the transmission path to amplify the attenuated optical signal and correct bit errors that occur along the transmission path.

[0003] Furthermore, since relay nodes must usually be placed at regular intervals, when optical transmission over long distances is performed, many relay nodes are connected to intermediate portions of the transmission path between the transmitting node and the receiving node.

[0004] Each relay node in an optical transmission system is usually equipped with an electrical termination function. That is, it converts the received optical signal into an electrical signal and then relays the information of the converted electrical signal. When processing the information of the electrical signal, it is also possible to obtain transmission quality data (Pre-FEC BER, dispersion compensation amount, polarization mode dispersion amount, and polarization dependent loss) at the relay node.

[0005] However, electrical termination at each relay node inevitably increases the delay time associated with the relaying of electrical signals. This also increases power consumption. Furthermore, the wavelength resources available for optical transmission are limited, hindering the expansion of transmission capacity.

[0006] On the other hand, in recent years, the functionality of optical fiber cables and optical transmitters has improved. Therefore, there is a trend to increase the spacing between relay nodes equipped with electrical termination functions. This reduces the number of relay nodes while performing electrical termination, enabling networks to be more energy-efficient, with higher capacity and lower latency.

[0007] On the other hand, for example, Non-Patent Document 1 discloses a technology for an optical transport network that omits electrical termination processing in optical node devices.Non-Patent Document 1 also discloses the introduction of a wavelength conversion function that converts the wavelength of an optical signal to another wavelength in the optical node devices that pass through the network in order to efficiently use limited wavelength resources. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] M. Nakagawa et.al., "Adaptive Link-by-Link Band Allocation: A Novel Adaptation Scheme in Multi-Band Optical Networks," 2021 International Conference on Optical Network Design and Modeling (ONDM) (2021). Summary of the Invention [Problem to be solved by the invention]

[0009] When a fault occurs in an optical transmission system, it is necessary to identify the location of the fault. To do this, it is first necessary to divide the entire length of the long-distance transmission line into multiple sections, each with a relay node, and then determine whether or not a fault has occurred in each section.

[0010] If each relay node is equipped with an electrical termination function, transmission quality data can be acquired for each relay node. Therefore, by comparing the transmission quality data of each relay node, it becomes possible to determine whether or not a fault has occurred in each section.

[0011] However, for relay nodes that do not implement electrical termination processing, it is not possible to obtain transmission quality data at those points. As a result, each section where it is possible to isolate faults may contain many optical transmission devices, and the length of the optical fiber cable per section may become very long, making it difficult to identify the fault location.

[0012] One possible solution is to place an optical splitter at a relay node. That is, the optical splitter splits one optical signal received by the relay node into two paths, relaying the main signal on one path as an optical signal while converting the optical signal on the other path into an electrical signal and using it to acquire transmission quality data. This reduces the signal delay of the optical main signal that occurs during relaying. However, because the optical intensity of the relayed main optical signal decreases when the input optical signal passes through the optical splitter, degradation of transmission quality occurs at the relay node.

[0013] The present invention has been made in consideration of the above situation, and aims to provide an optical transmission device and an optical transmission management method that are capable of acquiring transmission quality data for each relay node without affecting the delay or deterioration of transmission quality of the optical main signal relayed by the relay node. [Means for solving the problem]

[0014] (1) An optical transmission device that can be installed in at least one optical repeater node of an optical transmission system in which an optical transmitting node capable of transmitting an optical signal and an optical receiving node capable of receiving an optical signal are connected via an optical transmission line, and one or more optical repeater nodes are connected to intermediate positions of the optical transmission line, At least one of the optical repeater nodes The optical main signal to be relayed is split into a wavelength after wavelength conversion and the same wavelength as the optical main signal before wavelength conversion, and the same wavelength as the optical main signal before wavelength conversion is used as an unnecessary optical component. Unwanted light extraction section and converting the wavelength of the optical signal relayed by the optical relay node. All-optical wavelength conversion devices 、 an optical-electrical signal conversion unit that converts the light of the unnecessary light component extracted by the unnecessary light extraction unit into an electrical signal; An optical transmission device comprising:

[0015] (2) An optical transmission management method for managing an optical transmission system in which an optical transmitting node capable of transmitting an optical signal and an optical receiving node capable of receiving the optical signal are connected via an optical transmission line, and one or more optical repeater nodes are connected to intermediate positions of the optical transmission line, comprising: In at least one of the optical repeater nodes of the optical transmission system , receiving converting the wavelength of the received optical signal and transmitting the wavelength-converted optical signal as a relay output; The optical main signal to be relayed is split into a wavelength after wavelength conversion and the same wavelength as the optical main signal before wavelength conversion, and the same wavelength as the optical main signal before wavelength conversion is used as an unnecessary optical component. The extraction procedure, converting the extracted unnecessary light component into an electrical signal; generating transmission quality data based on the electrical signal; An optical transmission management method that implements the above. [Effects of the Invention]

[0016] The optical transmission device and optical transmission management method of the present invention eliminate the need for electrical termination at relay nodes, and enable the acquisition of transmission quality data for each relay node without affecting the delay or degradation of transmission quality of the optical main signal relayed by the relay nodes. Therefore, when a fault occurs on the optical network, it becomes easy to identify the location of the fault. Furthermore, even when no fault occurs, information useful for predicting failures on the optical network can be obtained. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a general optical transmission system. [Figure 2] FIG. 1 is a block diagram showing an example of the configuration of a general optical transmission system. [Figure 3] FIG. 10 is a block diagram showing a modified example of the optical transmission system. [Figure 4] FIG. 10 is a block diagram showing a modified example of the optical transmission system. [Figure 5] FIG. 1 is a schematic diagram illustrating an example of the relationship between optical communication links and wavelength bands in multi-band networking technology. [Figure 6] 1 is a block diagram showing an example of the configuration of an optical transmission system according to an embodiment of the present invention. [Figure 7] 7 is a block diagram showing an example of the configuration of an all-optical wavelength conversion unit included in the optical transmission system of FIG. 6. FIG. [Figure 8] 8 is a graph showing a list of optical signal wavelength distributions at each part of the all-optical wavelength conversion part of FIG. 7; [Figure 9] FIG. 7 is a block diagram showing a configuration of a modified example of FIG. 6. [Figure 10] 10 is a block diagram showing a first configuration example of an all-optical wavelength conversion unit included in the optical transmission system of FIG. 9. FIG. [Figure 11] 11 is a graph showing a list of optical signal wavelength distributions at each part of the all-optical wavelength conversion part of FIG. 10. [Figure 12] 10 is a block diagram showing a second configuration example of the all-optical wavelength conversion unit included in the optical transmission system of FIG. 9. FIG. [Figure 13] 13 is a graph showing a list of optical signal wavelength distributions at each part of the all-optical wavelength conversion part of FIG. 12. [Figure 14] 1 is a flowchart illustrating an example of a processing procedure of an optical transmission management method according to the present invention. [Figure 15] FIG. 10 is a block diagram showing a modified example of the configuration of the all-optical wavelength conversion unit. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Explanation of the technology underlying the present invention> To facilitate understanding of the present invention, the underlying technology will be described. -<Optical transmission system configuration> An example of the configuration of a general optical transmission system 100A is shown in Fig. 1. An example of the configuration of a general optical transmission system 100B is shown in Fig. 1. Modifications of the optical transmission system of Fig. 1 are shown in Figs. 3 and 4.

[0019] 1, seven optical transmission devices 10-1, 10-2, 10-3, 10-4, 10-5, 10-6, and 10-7 are arranged in a row and connected in series to each other via a common optical fiber cable 15. A network controller 20 is connected to each of the optical transmission devices 10-1 to 10-7 to manage a communication network including the optical transmission devices 10-1 to 10-7.

[0020] For example, when data is transmitted from optical transmission device 10-1 at one end of this communication network to optical transmission device 10-7 at the other end, optical transmission device 10-1 serves as the transmitting node and optical transmission device 10-7 serves as the receiving node. Furthermore, optical transmission devices 10-2 to 10-6 located between these transmitting and receiving nodes are each used as relay nodes.

[0021] The optical transmission device 10-1 at the sending node converts the data to be transmitted from an electrical signal to an optical signal of a predetermined wavelength inside a transponder (TPD: Transponder) 11, and transmits this optical signal to an optical fiber cable 15. The optical transmission device 10-7 at the receiving node receives the optical signal from the optical fiber cable 15, and converts the optical signal to an electrical signal in the transponder 11 within the optical transmission device 10-7 to obtain the received data.

[0022] On the other hand, as the distance of optical signal transmission increases, the optical intensity decreases and the transmission quality such as the 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 at the receiving node cannot correctly receive the transmitted data.

[0023] Therefore, the optical transmission devices 10-2 to 10-6 at each relay node perform predetermined relay processing, such as amplifying the optical intensity of the optical signal received at each relay position and restoring the original data without bit errors through predetermined error correction processing.

[0024] However, in order to perform error correction and other processes, it is necessary to perform electrical termination processing of the optical signals to be transmitted. That is, the optical transmission devices 10-2 to 10-6 convert the optical signals into electrical signals within the transponder 11, and process the data of the obtained electrical signals to perform error correction and other processes. Furthermore, the optical transmission devices 10-2 to 10-6 convert the processed electrical signals back into optical signals and send them as relay outputs to the downstream optical fiber cable 15.

[0025] By performing the electrical termination process described above, errors that occur during transmission can be reliably corrected and optical intensity can be restored. Transmission quality data can also be obtained. However, the electrical signal processing causes a relatively large delay in the signal inside the transponder 11. Furthermore, as the transmission distance increases, the number of relays increases, resulting in an increased delay time. In the example of the optical transmission system 100A, optical transmission devices 10-3 and 10-5, each including the transponder 11, exist as relay nodes between the transmitting node and the receiving node, so the delay time is doubled compared to when relay processing including electrical termination is performed only once.

[0026] On the other hand, in recent years, the functionality of the optical fiber cable 15 and transmitters that transmit optical signals has improved, making it possible to reduce the number of relay nodes, including electrical termination processing, even in relatively long-distance optical transmission. Therefore, the configuration of the optical transmission system 100A shown in Figure 1 can be improved to become the optical transmission system 100B in the same Figure 1.

[0027] 2, the optical transmission system 100B includes a transponder 11 in the optical transmission devices 10-1 and 10-7, but does not include a transponder 11 in the other optical transmission devices 10-2 to 10-6. That is, when an optical signal is transmitted from the optical transmission device 10-1, which is the transmitting node, to the optical transmission device 10-7, which is the receiving node, no relaying including electrical termination is performed along the way. Therefore, the delay time associated with optical signal transmission in the optical transmission system 100B is significantly reduced compared to the optical transmission system 100A.

[0028] On the other hand, in the optical transmission system 100B, the optical transmission devices 10-2 to 10-6 do not have the transponder 11 and do not perform electrical termination processing, so transmission quality data cannot be obtained at the relay node positions of the optical transmission devices 10-2 to 10-6.

[0029] On the other hand, when a communication failure occurs, the network controller 20 typically isolates the transmission section to narrow down the candidate locations of the failure based on transmission quality data detected at each node used in transmitting the optical signal. However, in the case of the optical transmission system 100B, transmission quality data is not available at the relay locations of the optical transmission devices 10-2 to 10-6, so it is not possible to identify the section between the output of the optical transmission device 10-1 and the input of the optical transmission device 10-7 where the failure has occurred. As a result, it becomes difficult to identify the location of the failure, and recovery from the failure requires a long time. It is particularly difficult to locate the location of the failure when the optical fiber cable 15 is very long.

[0030] 3, the optical transmission system 100C, which is used as a relay node, is equipped with the transponder 11, and therefore the network controller 20 can acquire transmission quality data at this relay position. Therefore, when a fault occurs, it is possible to identify whether the fault location is included in the section from the output of the optical transmission device 10-1 to the input of the optical transmission device 10-4 or in the section from the relay output of the optical transmission device 10-4 to the input of the optical transmission device 10-7, based on the transmission quality data detected by the optical transmission device 10-4.

[0031] That is, by disposing a 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, it becomes easier to isolate the section to identify the location of the fault compared to the optical transmission system 100B in Fig. 2. However, in the case of the optical transmission system 100C, the optical transmission device 10-4 of the relay node has the electrical termination function, which causes a transmission delay.

[0032] 4, an optical transmission system 100D includes an optical transmission device 10-4 as a relay node, and an optical splitter 12 is provided in the optical transmission device 10-4. The optical splitter 12 splits an optical signal input from an optical fiber cable 15 into two paths as light and outputs the two paths to optical output terminals 12a and 12b, respectively. The optical output terminal 12a of the optical splitter 12 is connected to the optical fiber cable 15 on the relay output side. The optical output terminal 12b of the optical splitter 12 is connected to the input of the transponder 11 in the optical transmission device 10-4.

[0033] In the optical transmission system 100D, the optical transmission device 10-4 relays and outputs optical signals without electrical termination, preventing transmission delays at this node. Also, the transponder 11 in the optical transmission device 10-4 detects transmission quality data at this node, making it easy to isolate the faulty section, just like in the optical transmission system 100C.

[0034] However, when the optical splitter 12 is disposed inside the optical transmission device 10-4 as in the optical transmission system 100D, the optical intensity of the relayed optical signal (main signal) decreases due to loss that occurs when the optical signal passes through the optical splitter 12. Therefore, degradation of transmission quality occurs at the node position of the optical transmission device 10-4.

[0035] -<Multi-band networking technology> FIG. 5 shows an example of the relationship between optical communication links and wavelength bands in multi-band networking technology (see Non-Patent Document 1).

[0036] In the example shown in Figure 5, it is assumed that there are three types of optical wavelength bands used for communication: L-band, C-band, and S-band. The L-band is a wavelength band from 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. Furthermore, the L-band, C-band, and S-band each have an optical path that is independent of one another. In the example of Fig. 5, it is assumed that there are two optical communication links 31 and 32 that are independent of one another.

[0037] The optical signals of each optical communication link 31, 32 are adaptively band-switched according to the situation, and are switched across optical paths of multiple bands. That is, the optical signal of the optical communication link 31 shown in Fig. 5 passes through an L-band optical path, is converted to a C-band optical signal by wavelength conversion, enters the C-band optical path, and is further converted to an S-band optical signal by wavelength conversion, enters the S-band optical path. This light is then converted to an L-band optical signal by wavelength conversion, enters the L-band optical path, and is converted to an electrical signal in a Ph-EX (Photonic Exchange), processed, and output. The Ph-EX is a component that minimizes electrical processing such as exchange, multiplexing, and switching.

[0038] In addition, the optical signal of the optical communication link 32 with 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 for processing.

[0039] By utilizing technologies such as those shown in Figure 5, optical transmission systems can efficiently use limited wavelength resources. Specifically, the traffic capacity of transmission paths can be increased by approximately 30%. In addition, electrical termination processing can be omitted at each communication node, allowing optical signals to be processed as they are, which is expected to result in energy savings, increased capacity, and reduced latency in the network. However, the optical transmission equipment at each node must be equipped with a function to convert the wavelength of optical signals.

[0040] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. <Description of the embodiment> FIG. 6 shows an example of the configuration of an optical transmission system 100 according to an embodiment of the present invention.

[0041] 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 spaced a certain distance apart from one another. The optical transmission devices 41 to 45 are connected in series to one another via a single optical fiber cable 15 used as a transmission path for optical signals.

[0042] The network controller 20 manages the entire optical communication network made up of the optical transmission devices 41 to 45 and the optical fiber cable 15. For example, when a fault occurs on the optical communication network, the network controller 20 can generate information that is useful for identifying the location of the fault.

[0043] 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 serves as a transmitting node and the optical transmission device 45 serves as a receiving node. Furthermore, the optical transmission devices 42 to 44 located between these transmitting and receiving nodes are each used as relay nodes.

[0044] The optical transmission device 41 at the sending node converts the data to be transmitted from an electrical signal to 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 at the receiving node receives the optical signal from the optical fiber cable 15, and converts the optical signal to an electrical signal in the transponder 11 within the optical transmission device 45 to obtain the received data.

[0045] In the configuration shown in FIG. 6, an optical transmission device 43 used as one relay node is provided with an all-optical wavelength conversion unit 13 that implements the function of AO-WC (All Optical Wavelength Conversion).

[0046] The all-optical wavelength converter 13 in the optical transmission device 43 performs wavelength conversion on the input optical signal Oin having a wavelength of λ1 input to the optical transmission device 43 from the optical fiber cable 15 while the signal is still an optical signal, generating an optical signal with a wavelength λ2 different from the input, and transmitting the generated optical signal Oo2 having a wavelength λ2 to the downstream optical fiber cable 15. The all-optical wavelength converter 13 shown in FIG. 6 can also extract unwanted optical components separate from the optical main signal relayed within the optical transmission device 43 and input them to the detector 11A in the optical transmission device 43. 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 the function of converting the input optical signal into an electrical signal and the function of processing the electrical signal to detect transmission quality data.

[0047] That is, the optical transmission device 43 does not perform electrical termination processing on the optical main signal to be relayed, but relays the optical signal as it is and sends it to the downstream optical fiber cable 15, thereby preventing an increase in delay due to relay processing. Also, as will be described later, there is no need to use an optical splitter to extract the optical signal to be input to the detector 11A, which prevents a decrease in the optical intensity of the optical main signal.

[0048] In addition, the all-optical wavelength converter 13 extracts unnecessary optical components separate from the optical main signal to be relayed and inputs them to the detector 11A in the optical transmission device 43, so that the detector 11A can detect transmission quality data at the node position of the optical transmission device 43.

[0049] Therefore, the network controller 20 can acquire transmission quality data of relay nodes such as the optical transmission device 43 that does not perform electrical termination. For example, if a failure occurs, the network controller 20 can determine whether or not a failure has occurred for each section based on the transmission quality data at the position of each relay node.

[0050] <Configuration of all-optical wavelength conversion unit> FIG. 7 shows an example of the configuration of the all-optical wavelength converter 13 included in the optical transmission system 100 of FIG. 7 includes a pumping 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 converter 13 is an all-optical wavelength conversion device including a nonlinear optical medium 17 onto which both the optical main signal to be relayed and the pumping light emitted from the pumping light source 14 can be simultaneously incident.

[0051] The pumping light source 14 generates pumping light Oe having a predetermined wavelength λe. The pumping light Oe generated by the pumping light source 14 passes through an optical fiber 15A and enters the optical multiplexer 16. The wavelength λe of the pumping light Oe is different from the wavelength λ1 of the input optical signal Oin. Furthermore, the optical intensity of the pumping light Oe is sufficiently greater than that of the input optical signal Oin.

[0052] The optical multiplexer 16 multiplexes the input optical signal Oin input from the optical fiber cable 15 and the pumping light Oe input from the optical fiber 15 A to generate light, and sends it to the input end of the nonlinear optical medium 17 .

[0053] The nonlinear optical medium 17 has nonlinear optical properties and can generate an optical signal with a wavelength different from that of the incident light. As a representative 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.

[0054] The optical demultiplexer 18 is an all-optical long The optical fiber 10 is connected to the light output side of a nonlinear optical medium 17, which is a conversion device. The output light Oout output from the output end of the nonlinear optical medium 17 is input to an optical demultiplexer 18. The optical demultiplexer 18 demultiplexes the incident light using its wavelength selection characteristics and extracts two types of optical signals. That is, an outgoing optical signal Oo2 with a wavelength λ2 and an output light Oo1 with a wavelength λ1 are output from different output terminals of the optical demultiplexer 18.

[0055] 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 pumping light Oe, and the nonlinear optical characteristics of the nonlinear optical medium 17. That is, the wavelength λ2 of the wavelength-converted outgoing optical signal Oo2 is generated by the input optical signal Oin having a wavelength λ1 passing through the nonlinear optical medium 17 together with the pumping light Oe. In addition, the light emitted from the nonlinear optical medium 17 also contains an optical component having the same wavelength λ1 as before the wavelength conversion.

[0056] The outgoing optical signal Oo2 having a wavelength λ2 output from the optical demultiplexer 18 is transmitted as a relay output from the output of the optical transmission device 43 to the downstream optical fiber cable 15. In addition, the outgoing light Oo1 having a 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.

[0057] 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 can be converted from λ1 to λ2 without electrical termination, thereby preventing an increase in delay. Furthermore, the output light Oo1 with the same wavelength λ1 as before wavelength conversion, i.e., unnecessary optical components other than the main signal, can be input to the detector 11A. The detector 11A internally converts the input output light Oo1 with wavelength λ1 into an electrical signal and performs various processes in the form of an electrical signal. This allows transmission quality data at the relay node position of the optical transmission device 43 to be obtained. However, the wavelength λ2 of the optical main signal transmitted by the relay node is different from the wavelength λ1 of the 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 determined in advance, and the transmission quality data detected by the detector 11A is converted to transmission quality data of the optical signal to be relayed based on the correlation. This conversion process may be performed inside the detector 11A or on the network controller 20 side.

[0058] <Wavelength distribution of optical signals at each part> A list of optical signal wavelength distributions at each part of the all-optical wavelength conversion unit 13 in Fig. 7 is shown in Fig. 8. In Fig. 8, the horizontal axis represents wavelength, and the vertical axis represents optical intensity.

[0059] 8, the input optical signal Oin input to the optical transmission device 43 from the upstream optical fiber cable 15 contains only a single component of wavelength λ1. Also, the pumping light Oe generated by the pumping light source 14 contains only a single component of wavelength λe. Also, as shown in the second graph, the optical intensity of the pumping light Oe is sufficiently greater than that of the input optical signal Oin.

[0060] On the other hand, the output light Oout output from the nonlinear optical medium 17 contains three wavelength components, λ1, λe, and λ2, as shown in the third graph of Fig. 8. The wavelength λ2 component is a component generated by wavelength conversion of the input optical signal Oin as it passes through the nonlinear optical medium 17. The optical intensity of the wavelength λ2 component contained in the output light Oout depends on the nonlinear optical medium and the pump light intensity, and can be made equal to that of the input optical signal Oin. In other words, wavelength conversion can be performed without attenuating the optical intensity.

[0061] Furthermore, the optical intensity of the component of wavelength λ1 contained in the output light Oout is equal to that of the input optical signal Oin. That is, an optical signal other than the main signal having the same wavelength λ1 as before the wavelength conversion can be extracted from the output of the nonlinear optical medium 17 with sufficiently high optical intensity.

[0062] As a result of the demultiplexing in the optical demultiplexer 18, an outgoing optical signal Oo2 containing only the component of wavelength λ2 is extracted from one output of the optical demultiplexer 18. The outgoing optical signal Oo2 is shown in the fourth graph of Figure 8. This outgoing optical signal Oo2 is sent to the downstream optical fiber cable 15 as the optical main signal of the relay output.

[0063] Furthermore, due to the demultiplexing by the optical demultiplexer 18, output light Oo1 containing only components with the same wavelength λ1 as before the wavelength conversion is extracted at the other output of the optical demultiplexer 18, and this output light Oo1 is input to the detector 11A via the optical fiber 15B. The fifth graph in Figure 8 shows the output light Oo1. Here, since the output light Oo1 with a sufficiently high optical intensity is input to the detector 11A, the detector 11A can easily detect the transmission quality data at the position of the relevant relay node. Of course, the detector 11A internally converts the input optical signal into an electrical signal and detects the transmission quality data by processing the electrical signal.

[0064] <Modification of Optical Transmission System> -<Configuration of modified example> FIG. 9 shows the configuration of an optical transmission system 200, which is a modification of the configuration of FIG.

[0065] 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 row at locations spaced a certain distance apart from each other. Each of the optical transmission devices 51 to 55 shown in Fig. 9 has the function of transmitting a WDM (Wavelength Division Multiplexing) optical signal in which optical signals of multiple wavelengths are multiplexed.

[0066] The five optical transmission devices 51 to 55 are connected in series with one another via one or more optical fiber cables 15 used as transmission paths for WDM optical signals. The optical transmission devices 51 and 55, which are located at the ends of the network and function as transmitting or receiving nodes, are each equipped with a plurality of transponders 11a to 11n capable of processing WDM optical signals.

[0067] The network controller 20 manages the entire optical communication network made up of the optical transmission devices 51 to 55 and the optical fiber cable 15. For example, when a fault occurs on the optical communication network, the network controller 20 can generate information that is useful for identifying the location of the fault.

[0068] For example, when data is transmitted from optical transmission device 51 at one end of this communication network to optical transmission device 55 at the other end, optical transmission device 51 serves as the transmitting node and optical transmission device 55 serves as the receiving node. Furthermore, optical transmission devices 52 to 54 located between these transmitting and receiving nodes are each used as relay nodes.

[0069] The optical transmission device 51 at the sending node converts data to be transmitted from an electrical signal into an optical signal of a predetermined wavelength within each of the transponders 11a to 11n, and transmits a WDM optical signal in which multiple wavelengths are multiplexed onto the optical fiber cable 15. The optical transmission device 55 at 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 into individual wavelengths, and converts the optical signal into an electrical signal in each of the transponders 11a to 11n, and obtains the received data by processing the electrical signal.

[0070] 9, an optical transmission system 200 includes an all-optical wavelength converter 13A that implements the AO-WC function inside an optical transmission device 53 used as one relay node. Also, a plurality of transponders 11a to 11n that are compatible with WDM optical signals are implemented in the optical transmission device 53.

[0071] The all-optical wavelength converter 13A in the optical transmission device 53 can wavelength convert the WDM optical signal input to the optical transmission device 53 from the upstream optical fiber cable 15 while it is still an optical signal, generate a WDM optical signal having a wavelength different from that of the input, and send it to the downstream optical fiber cable 15. In addition, the all-optical wavelength converter 13A can extract unnecessary optical components separated from the WDM optical main signal relayed by the optical transmission device 53, and input the extracted components to the detectors 11Aa to 11An in the optical transmission device 53.

[0072] That is, the optical transmission device 53 does not perform electrical termination processing on the WDM optical main signal to be relayed, but relays the signal as an optical signal and sends it to the downstream optical fiber cable 15, thereby preventing an increase in delay due to relay processing. Also, since there is no need to use an optical splitter to extract the optical signal to be input to the detectors 11Aa to 11An, a decrease in the optical intensity of the WDM optical main signal can be suppressed.

[0073] In addition, the all-optical wavelength conversion unit 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, so that the detectors 11Aa to 11An can detect transmission quality data at the node positions of the optical transmission device 53.

[0074] Therefore, the network controller 20 can acquire transmission quality data of relay nodes such as the optical transmission device 53 that does not perform electrical termination. For example, if a failure occurs, the network controller 20 can determine whether or not a failure has occurred for each section based on the transmission quality data at the position of each relay node. The optical transmission device 53 can also interchange the transmission signal and the extracted signal. In this case, the optical transmission device 53 transmits each optical component with wavelengths λ11 to λ1n and detects each optical component with wavelengths λ21 to λ2n as an extracted signal to obtain transmission quality data. This allows the optical transmission device 53 to obtain transmission quality data even without wavelength conversion.

[0075] -<First example of the configuration of the all-optical wavelength conversion unit> FIG. 10 shows a first configuration example of the all-optical wavelength converter 13A included in the optical transmission system 200 of FIG.

[0076] The all-optical wavelength converter 13A shown in FIG. 10 includes a pumping 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.

[0077] The pumping light source 14 generates pumping light Oe having a predetermined wavelength λe. The pumping light Oe generated by the pumping light source 14 passes through an optical fiber 15A and enters the optical multiplexer 16. The wavelength λe of the pumping light Oe is different from each of the wavelengths λ1 to λn contained in the WDM input optical signal Oin. Furthermore, the optical intensity of the pumping light Oe is sufficiently greater than that of the WDM input optical signal Oin.

[0078] The optical multiplexer 16 multiplexes the WDM input optical signal Oin input from the optical fiber cable 15 and the pumping light Oe input from the optical fiber 15 A to generate light, which is then sent to the input end of the nonlinear optical medium 17 .

[0079] The output light Oout emitted from the output end of the nonlinear optical medium 17 is input to the optical demultiplexer 18. This output light Oout includes a WDM optical signal after wavelength conversion. The optical demultiplexer 18 demultiplexes the incident light using its wavelength selection characteristics, and extracts an outgoing optical signal Oo2, which is the WDM optical main signal to be relayed, and output light Oo11 to Oo1n other than the WDM optical main signal.

[0080] The wavelength of the outgoing optical signal Oo2, which is a WDM optical signal, is generated by each wavelength included in the WDM input optical signal Oin, the wavelength λe of the pumping light Oe, and the nonlinear optical characteristics of the nonlinear optical medium 17. That is, the input optical signal Oin, which includes multiple wavelengths λ1 to λn, passes through the nonlinear optical medium 17 together with the pumping light Oe, thereby generating an outgoing optical signal Oo2 that has been wavelength-converted for each WDM wavelength. Furthermore, the light output from the nonlinear optical medium 17 also contains optical components with the multiple wavelengths λ1 to λn that are the same as those before the wavelength conversion.

[0081] The wavelength-converted outgoing optical signal Oo2 output from the optical demultiplexer 18 is transmitted as a relay output from the output of the optical transmission device 53 to the downstream optical fiber cable 15. Furthermore, the WDM outgoing light Oo1 containing the same multiple wavelengths λ1 to λn as before the wavelength conversion output from the optical demultiplexer 18 is input via the optical fiber 15B to multiple detectors 11Aa to 11An in the optical transmission device 53 as outgoing light Oo11 to Oo1n separated by wavelength, respectively.

[0082] 10, it is possible to prevent an increase in delay by converting the wavelength of the WDM optical main signal relayed by the optical transmission device 53 without electrically terminating the signal, and to input the output light Oo11 to Oo1n having the same wavelengths λ1 to λn as before wavelength conversion from the all-optical wavelength converter 13A to the plurality of detectors 11Aa to 11An for each wavelength.

[0083] Each of the detectors 11Aa to 11An converts one of the wavelength-separated output beams Oo11 to Oo1n into an electrical signal and performs various processes on the electrical signal, thereby obtaining transmission quality data for each wavelength at the relay node position of the optical transmission device 53.

[0084] -<Wavelength distribution of optical signals at each part in Figure 10> Fig. 11 shows a list of optical signal wavelength distributions at each part of the all-optical wavelength conversion unit 13A in Fig. 10. In Fig. 11, the horizontal axis represents wavelength, and the vertical axis represents optical intensity.

[0085] 11, the input optical signal Oin input to the optical transmission device 53 from the upstream optical fiber cable 15 contains multiplexed components of wavelengths λ11 to λ1n. Also, as shown in the second graph, the pumping light Oe generated by the pumping light source 14 contains only a component of a single wavelength λe. Also, the optical intensity of the pumping light Oe is sufficiently greater than that of the input optical signal Oin.

[0086] On the other hand, the output light Oout output from the nonlinear optical medium 17 contains optical components of wavelengths λ11 to λ1n, λe, and λ21 to λ2n as shown in the third graph of FIG.

[0087] The optical components of 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 optical intensities of the components of wavelengths λ21 to λ2n contained in the output light Oout are equivalent to those of the input optical signal Oin. In other words, wavelength conversion can be performed without attenuating the optical intensity.

[0088] Furthermore, the optical intensities of the components of wavelengths λ11 to λ1n included in the output light Oout are equivalent to those of the input optical signal Oin. That is, optical signals other than the main signal and having the same wavelengths λ11 to λ1n as those before wavelength conversion can be extracted from the output of the nonlinear optical medium 17 with sufficiently high optical intensity.

[0089] As a result of the demultiplexing in the optical demultiplexer 18, an outgoing optical signal Oo2 containing optical components of wavelengths λ21 to λ2n is extracted at one output of the optical demultiplexer 18, and this outgoing optical signal Oo2 is sent out as a relay output WDM optical main signal to the downstream optical fiber cable 15. The fourth graph shows the outgoing optical signal Oo2.

[0090] Furthermore, due to the demultiplexing by optical demultiplexer 18, output light Oo11 to Oo1n containing optical components with wavelengths λ11 to λ1n that are the same as those before wavelength conversion is extracted at the other output of optical demultiplexer 18, and this output light Oo11 to Oo1n is input to multiple detectors 11Aa to 11An for each wavelength via optical fiber 15B. The fifth graph shows output light Oo11. The sixth graph shows output light Oo1n. Here, since the emitted light Oo11-Oo1n with a sufficiently high optical intensity is input to the detectors 11Aa-11An, the detectors 11Aa-11An can easily detect the transmission quality data for each wavelength at the position of the corresponding relay node. Of course, each detector 11Aa-11An internally converts the input optical signal into an electrical signal and detects the transmission quality data by processing the electrical signal.

[0091] -<Second example of the all-optical wavelength conversion unit> FIG. 12 shows a second configuration example of the all-optical wavelength converter 13B that can be implemented in the optical transmission system 200 of FIG.

[0092] In the all-optical wavelength conversion unit 13B shown in FIG. 12, a wavelength filter 19 is connected to the downstream side of an optical fiber 15B, and a single detector 11A is connected to the output side of the wavelength filter 19.

[0093] The wavelength filter 19 can selectively extract a component of an 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.

[0094] As a representative example of the wavelength filter 19, it is assumed that any one of the following (1) to (3) is adopted. (1) A 1xn wavelength selective switch (WSS) is used, which allows electrical control of the wavelength of the optical signal passing through each port. (2) A coupler splits the optical signal into multiple ports, and a tunable filter is installed 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 in the detector 11A. In this case, the wavelength filter 19 is omitted, and the output light Oo1 is made incident on the detector 11A as a WDM signal, and the wavelength to be processed is selected inside the detector 11A. Other than the above, the configuration of the all-optical wavelength conversion unit 13B is the same as that of the all-optical wavelength conversion unit 13A.

[0095] -<Wavelength distribution of optical signals at each part in Figure 12> Fig. 13 shows a list of optical signal wavelength distributions at each part of all-optical wavelength conversion unit 13B in Fig. 12. In Fig. 13, the horizontal axis represents wavelength, and the vertical axis represents optical intensity.

[0096] 13, the input optical signal Oin input to the optical transmission device 53 from the upstream optical fiber cable 15 contains multiplexed components of wavelengths λ11 to λ1n. The pumping light Oe generated by the pumping light source 14 contains only a component of a single wavelength λe. The optical intensity of the pumping light Oe is sufficiently greater than that of the input optical signal Oin.

[0097] On the other hand, the output light Oout output from the nonlinear optical medium 17 contains the optical components of wavelengths λ11 to λ1n, λe, and λ21 to λ2n as shown in FIG.

[0098] The optical components of 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 optical intensities of the components of wavelengths λ21 to λ2n contained in the output light Oout are equivalent to those of the input optical signal Oin. In other words, wavelength conversion can be performed without attenuating the optical intensity.

[0099] Furthermore, the optical intensities of the components of wavelengths λ11 to λ1n included in the output light Oout are equivalent to those of the input optical signal Oin. That is, optical signals other than the main signal and having the same wavelengths λ11 to λ1n as those before wavelength conversion can be extracted from the output of the nonlinear optical medium 17 with sufficiently high optical intensity.

[0100] By the demultiplexing in the optical demultiplexer 18, an outgoing optical signal Oo2 containing optical components of wavelengths λ21 to λ2n is extracted at one output of the optical demultiplexer 18, and this outgoing optical signal Oo2 is sent to the downstream optical fiber cable 15 as a relay output WDM optical main signal.

[0101] Furthermore, due to the demultiplexing by the optical demultiplexer 18, output light Oo1 containing optical components with wavelengths λ11 to λ1n that are the same as those before the wavelength conversion is extracted at the other output of the optical demultiplexer 18, and this output light Oo1 is input to the wavelength filter 19. The wavelength filter 19 selectively extracts an optical component with one wavelength λ1a from the wavelengths λ11 to λ1n, and inputs it to the detector 11A.

[0102] 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 output light Oo1, converts each wavelength into an electrical signal in turn, and processes the electrical signal, thereby making it possible to detect transmission quality data for each wavelength at the position of the relay node.

[0103] <Optical transmission management method processing procedure> An example of the processing procedure of the optical transmission management method of the present invention is shown in Fig. 14. The processing procedure of Fig. 14 will be explained below.

[0104] This processing procedure can be used to manage, for example, an optical transmission system 100 as shown in Fig. 6. In this optical transmission system 100, at the node position of the optical transmission device 43 that relays communications, the optical transmission device 43 receives the input optical signal Oin from the upstream optical fiber cable 15 in step S11, and the all-optical wavelength converter 13 performs wavelength conversion of the input optical signal Oin in step S12.

[0105] In step S13, the optical demultiplexer 18 in the all-optical wavelength converter 13 sends the wavelength-converted outgoing optical signal Oo2 as a relay output to the downstream optical fiber cable 15. In step S14, the optical demultiplexer 18 in the all-optical wavelength converter 13 also extracts the outgoing light Oo1 having the same wavelength as before the wavelength conversion, i.e., unnecessary light that is not used for relaying communications.

[0106] In step S15, the detector 11A in the optical transmission device 43 receives the unwanted light extracted by the optical demultiplexer 18 and converts it into an electrical signal. The detector 11A may be a device equivalent to the receiver of a transponder, a spectrum analyzer, a polarization monitor, a power meter, or the like. In a device equivalent to the receiver of a transponder, transmission quality data is acquired in step S16 by converting unwanted light into an electrical signal and processing it. In the case of a spectrum analyzer, the signal-to-noise ratio is acquired. In the case of a polarization monitor, the polarization state of the optical signal is acquired, and in the case of a power meter, the optical intensity is acquired.

[0107] 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 of FIG. 14, the network controller 20 can obtain transmission quality data even for relay nodes that omit electrical termination processing of the optical signal to be transmitted.

[0108] <Description of Modifications> The configuration of the all-optical wavelength conversion unit 13C is shown in Fig. 15. This all-optical wavelength conversion unit 13C is a modified example of the all-optical wavelength conversion unit 13 shown in Fig. 7 .

[0109] 15, outgoing light Oo1 of wavelength λ1, out of the optical components of wavelengths λ1 and λ2 contained in outgoing light Oout from nonlinear optical medium 17, is extracted by optical demultiplexer 18 and sent as a relay output to optical fiber cable 15. In addition, outgoing optical signal Oo2 of wavelength λ2, out of the optical components of wavelengths λ1 and λ2 contained in outgoing light Oout from nonlinear optical medium 17, is extracted by optical demultiplexer 18 and input to detector 11A via optical fiber 15B. 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 in FIG.

[0110] 15, the relay node using the all-optical wavelength converter 13C does not convert the wavelength of the optical signal to be relayed. However, by using the all-optical wavelength converter 13C, it is possible to extract unnecessary light other than the optical main signal and input it to the detector 11A without attenuating the optical intensity of the optical main signal to be relayed.

[0111] 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 determined in advance. Then, the transmission quality data detected by the detector 11A is converted into transmission quality data for 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 on the network controller 20 side.

[0112] Furthermore, a realistic configuration of the optical transmission device 43 is one in which the optical demultiplexer 18 can selectively control the wavelength of light output to each output port. This allows switching between 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 as needed. This allows the network controller 20 to dynamically switch between the presence and absence of wavelength conversion at each relay node depending on the situation.

[0113] <Possibility of deformation other than those mentioned above> In the all-optical wavelength converter 13 shown in FIG. 7, unwanted optical components other than the optical main signal that has passed through the nonlinear optical medium 17 are extracted from the output light Oout appearing on the optical output side of the nonlinear optical medium 17, i.e., the output light Oo1 having the same wavelength λ1 as the input optical signal Oin, 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 optical input side of the nonlinear optical medium 17, it may be possible to extract the reflected light or scattered light on the input side of the nonlinear optical medium 17. In this case, an optical demultiplexer (unwanted light extraction unit) may be connected to the optical input side of the nonlinear optical medium 17 to extract, as unwanted light, optical components having the same wavelength as the main optical signal to be relayed before wavelength conversion, and input the extracted unwanted light to the detector 11A. This improves the degree of freedom in connecting optical demultiplexers.

[0114] Furthermore, an optical demultiplexer (unwanted light extraction unit) is connected to the light output side of the nonlinear optical medium 17, and the wave of the optical main signal to be relayed is extracted from the light output from this nonlinear optical medium 17. long Transformed wave long The light component may be extracted as unnecessary light.

[0115] In the network controller 20 of the optical transmission system 100, it is generally assumed that the "Pre-FEC BER" ​​detected by the transponder 11 of each optical relay node is used as transmission quality data. Meanwhile, the detector 11A and the transponder 11 can acquire data such as the chromatic dispersion compensation amount, polarization mode dispersion, and polarization dependent loss in addition to the "Pre-FEC BER" ​​through electrical signal processing of the communication data. Therefore, the network controller 20 can also collect data such as the chromatic dispersion compensation amount, polarization mode dispersion, and polarization dependent loss from each optical relay node equipped with the detector 11A or the transponder 11 and use it as learning data for machine learning. This helps realize failure prediction in optical networks without electrical termination processing.

[0116] <Features of optical transmission equipment> The following items [1] to [8] are characteristic features of the optical transmission device and the optical transmission management method of the present invention. [1] An optical transmission device that can be installed in at least one optical relay node of an optical transmission system (100) in which an optical transmitting node capable of transmitting an optical signal and an optical receiving node capable of receiving an optical signal are connected via an optical transmission path, and one or more optical relay nodes are connected to intermediate positions of the optical transmission path, 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 unnecessary light components (output light Oo1) other than the optical main signal that have the same wavelength as the optical main signal to be relayed before wavelength conversion; an optical-electrical signal conversion unit (detector 11A) that converts the light of the unnecessary light component extracted by the unnecessary light extraction unit into an electrical signal; An optical transmission device (43) comprising:

[0117] According to the optical transmission device having the configuration described in [1] above, the optical relay node extracts unnecessary optical components other than the optical main signal relayed and converts them into an electrical signal, eliminating the need for electrical termination of the optical main signal. This allows the unnecessary optical components to be extracted and converted into an electrical signal without affecting the delay, optical intensity, transmission quality, and other degradation of the optical main signal. This makes it possible to detect transmission quality data at the location of each relay node, facilitating the identification of faulty sections. Furthermore, by providing an optical signal wavelength conversion function within the optical relay node, it becomes possible to effectively utilize limited wavelength resources, thereby increasing the amount of traffic accommodated.

[0118] [2] The unwanted light extraction unit is connected to the light output side of the all-optical wavelength conversion device and extracts, from the light output from the all-optical wavelength conversion device, an optical component having the same wavelength as the wavelength of the optical main signal to be relayed before wavelength conversion.

[0119] According to the optical transmission device having the configuration described in [2] above, unnecessary optical components contained in the light that has passed through the all-optical wavelength conversion device are extracted and utilized, so that unnecessary optical components with sufficiently high optical intensity can be extracted, and therefore the optical-electrical signal conversion unit can easily convert the unnecessary optical components into an electrical signal with little degradation.

[0120] [3] The optical transmission device includes a pumping light source (pumping light source 14) that emits pumping light of a wavelength different 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 pumping light emitted from the pumping light source can be simultaneously incident, The unnecessary light extraction section 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.

[0121] 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 main optical signal being relayed. Furthermore, an optical signal with sufficiently high optical intensity can be obtained for the unwanted light components extracted by the unwanted light extractor.

[0122] [4] The optical transmission device includes, as the nonlinear optical medium, at least one of a highly nonlinear fiber, a periodically poled lithium niobate, and a semiconductor optical amplifier.

[0123] According to the optical transmission device having the configuration [4] above, it is possible to efficiently convert the wavelength of an optical signal by utilizing the nonlinear optical medium.

[0124] [5] The optical transmission device includes a transmission quality detection unit (detector 11A) that generates transmission quality data based on the electrical signal output from the optical-electrical signal conversion unit.

[0125] According to the optical transmission device configured as described above in [5], the transmission quality data generated by the transmission quality detector can be used to detect degradation of transmission quality due to differences in the location of relay nodes. This makes it possible to determine whether a fault exists in each section when a fault occurs, and to predict failures.

[0126] [6] In an optical transmission device, an optical multiplexer that multiplexes WDM signal light including optical main signals of multiple wavelengths (λ11 to λ1n) different from each other and pump light used for wavelength conversion is connected to the light input side of the all-optical wavelength conversion device; an optical demultiplexer that extracts unnecessary optical components divided into wavelengths identical to the wavelengths of the plurality of optical main signals included in the WDM signal light before wavelength conversion is connected to the light output side of the all-optical wavelength conversion device; A plurality of the optical-electrical signal conversion units (a plurality of detectors 11Aa to 11An) are connected to the output of the optical demultiplexer, and the plurality of the optical-electrical signal conversion units individually convert the plurality of unnecessary light components (emitted light Oo11 to Oo1n) having different wavelengths into electrical signals.

[0127] According to the optical transmission device having the configuration described in [6] above, when WDM signal light is relayed at each optical relay node, transmission quality data at the position of the corresponding relay node can be constantly detected for each wavelength of the optical main signal contained in the WDM signal light.

[0128] [7] In an optical transmission device, an optical multiplexer that multiplexes WDM signal light including optical main signals of multiple wavelengths (λ11 to λ1n) different from each other and pump light used for wavelength conversion is connected to the light input side of the all-optical wavelength conversion device; the unnecessary light extraction unit is connected to the light output side of the all-optical wavelength conversion device, and the unnecessary light extraction unit has a function of extracting unnecessary light components of wavelengths (λ11 to λ1n) that are the same as the wavelengths of the plurality of optical main signals included in the WDM signal light before wavelength conversion, An optical wavelength selection section (wavelength filter 19) is disposed between the output of the unnecessary light extraction section and the input of one of the optical-electrical signal conversion sections (detector 11A).

[0129] According to the optical transmission device having the configuration described in [7] above, when a WDM signal light is relayed at each optical relay node, transmission quality data for each wavelength of the optical main signal contained in the WDM signal light can be detected sequentially. Also, the number of optical-electrical signal converters implemented in each optical relay node can be reduced. This allows for reduced power consumption and cost.

[0130] [8] In the optical transmission device, the unnecessary light extractor is connected to the light output side of the all-optical wavelength conversion device, and extracts a wave of an optical main signal to be relayed from the light output from the all-optical wavelength conversion device. long Transformed wave long The light component is extracted as unnecessary light.

[0131] [9] An optical transmission management method for managing an optical transmission system (100) in which an optical transmitting node capable of transmitting an optical signal and an optical receiving node capable of receiving an optical signal are connected via an optical transmission path, and one or more optical repeater nodes are connected to intermediate positions of the optical transmission path, comprising: In at least one of the optical repeater nodes (optical transmission device 43 or 53) of the optical transmission system, A step (step S13) of converting the wavelength of the received optical signal and transmitting the optical signal after the wavelength conversion as a relay output; A step (step S14) of extracting unnecessary optical components other than the main optical signal, which have the same wavelength as the main optical signal to be relayed before wavelength conversion, from the received optical signal; A step of converting the extracted unnecessary light components into an electrical signal (step S15); generating transmission quality data based on the electrical signal (step S16); An optical transmission management method that implements the above.

[0132] According to the optical transmission management method described in [9] above, the optical relay node extracts unnecessary optical components other than the optical main signal relayed and converts them into electrical signals, eliminating the need for electrical termination of the optical main signal. This allows the unnecessary optical components to be extracted and converted into electrical signals without affecting the delay, optical intensity, transmission quality, and other degradation of the optical main signal. This makes it possible to detect transmission quality data at the location of each relay node, facilitating the identification of faulty sections. Furthermore, wavelength conversion of optical signals within the optical relay node makes it possible to effectively utilize limited wavelength resources, thereby increasing the amount of traffic accommodated. [Explanation of symbols]

[0133] 10-1, 10-2, 10-3, 10-4, 10-5 Optical transmission equipment 11 Transponder 11A, 11Aa-11An detectors 12 Optical Splitter 12a,12b Optical output end 13, 13A, 13B, 13C All-optical wavelength conversion unit (all-optical wavelength conversion device) 14 Excitation light source 15 Fiber optic cable 15A, 15B optical fiber 16 Optical multiplexer 17 Nonlinear Optical Media 18 Optical demultiplexer (unnecessary light extraction section) 19 Wavelength Filter 20 Network Controller 31,32 Optical communication links 41, 42, 43, 44, 45 Optical transmission equipment 51, 52, 53, 54, 55 Optical transmission equipment 100, 100A, 100B, 100C, 100D, 200 Optical Transmission System Oe excitation 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

1. An optical transmission device that can be installed in at least one optical repeater node of an optical transmission system in which an optical transmitting node capable of transmitting an optical signal and an optical receiving node capable of receiving an optical signal are connected via an optical transmission line, and one or more optical repeater nodes are connected to intermediate positions of the optical transmission line, an all-optical wavelength conversion device that converts the wavelength of an optical signal relayed by at least one of the optical repeating nodes, the all-optical wavelength conversion device comprising an unwanted light extraction unit that splits an optical main signal relayed by at least one of the optical repeating nodes into a wavelength after wavelength conversion and the same wavelength as the optical main signal before wavelength conversion, and extracts the same wavelength as the optical main signal before wavelength conversion as an unwanted light component; an optical-electrical signal conversion unit that converts the light of the unnecessary light component extracted by the unnecessary light extraction unit into an electrical signal; An optical transmission device comprising:

2. a pumping light source that emits pumping light of a wavelength different 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 pumping light emitted from the pumping light source can be simultaneously incident, the unnecessary light extraction unit included in the all-optical wavelength conversion device separates the output light from the nonlinear optical medium into an optical component having a wavelength after wavelength conversion and an optical component having a wavelength before wavelength conversion.

2. The optical transmission device according to claim 1.

3. The nonlinear optical medium includes at least one of a highly nonlinear fiber, a periodically poled lithium niobate, and a semiconductor optical amplifier.

3. The optical transmission device according to claim 2.

4. a transmission quality detection unit that generates transmission quality data based on the electrical signal output from the optical-electrical signal conversion unit; 2. The optical transmission device according to claim 1.

5. an optical multiplexer for multiplexing WDM signal light including optical main signals having a plurality of wavelengths different from each other and pump light used for wavelength conversion on a light input side of the all-optical wavelength conversion device; an optical demultiplexer configured to extract unnecessary optical components divided into a plurality of wavelengths identical to wavelengths of the optical main signals included in the WDM signal light before wavelength conversion, on a light output side of the all-optical wavelength conversion device; a plurality of the optical-electrical signal conversion units are connected to the output of the optical demultiplexer, and the plurality of the optical-electrical signal conversion units convert the plurality of unnecessary optical components having different wavelengths into individual electrical signals; 2. The optical transmission device according to claim 1.

6. an optical multiplexer for multiplexing WDM signal light including optical main signals having a plurality of wavelengths different from each other and pump light used for wavelength conversion on a light input side of the all-optical wavelength conversion device; the unnecessary light extraction unit is provided on the light output side of the all-optical wavelength conversion device, and the unnecessary light extraction unit has a function of extracting unnecessary light components having wavelengths identical to wavelengths of a plurality of optical main signals included in the WDM signal light before wavelength conversion, an optical wavelength selection unit is disposed between an output of the unnecessary light extraction unit and an input of one of the optical-electrical signal conversion units; 2. The optical transmission device according to claim 1.

7. the unnecessary light extraction unit is provided on the light output side of the all-optical wavelength conversion device, and extracts, as unnecessary light, an optical component of a wavelength after wavelength conversion of the optical main signal to be relayed from the light output from the all-optical wavelength conversion device.

2. The optical transmission device according to claim 1.

8. An optical transmission management method for managing an optical transmission system in which an optical transmitting node capable of transmitting an optical signal and an optical receiving node capable of receiving the optical signal are connected via an optical transmission path, and one or more optical repeater nodes are connected to an intermediate position of the optical transmission path, comprising: a step of performing wavelength conversion of a received optical signal in at least one of the optical repeater nodes of the optical transmission system and transmitting the optical signal after wavelength conversion as a repeater output; a step of splitting the optical main signal to be relayed into a wavelength after wavelength conversion and the same wavelength as that of the optical main signal before wavelength conversion, and extracting the same wavelength as that of the optical main signal before wavelength conversion as an unnecessary optical component; converting the extracted unnecessary light component into an electrical signal; generating transmission quality data based on the electrical signal; An optical transmission management method that implements the above.

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