Optical transmission device and optical transmission system

Abstract

An optical transmission device according to the present invention comprises: a multiplexer for multiplexing optical signals of a plurality of channels having different wavelengths to generate a wavelength multiplexed signal, wherein channels corresponding to each of input ports can be set; a demultiplexer for demultiplexing and outputting an optical signal generated by multiplexing the optical signals of the plurality of channels having different wavelengths, wherein channels corresponding to each of output ports can be set; and one or more optical transceivers for transmitting and receiving an optical signal of a designated channel among the optical signals of the plurality of channels.　The optical transmission device is configured so that the channels corresponding to each of the input ports in the multiplexer, the channels corresponding to each of the output ports in the demultiplexer, and the channels of optical signals transmitted and received by each of the optical transceivers are set according to the number of times a wavelength band conversion device is passed through on the path to another optical transmission device for transmitting and receiving optical signals.

Description

Optical transmission device and optical transmission system

[0001] The present disclosure relates to an optical transmission device and an optical transmission system for optical information communication.

[0002] With the spread of the Internet, the demand for data communication networks is rapidly increasing. To meet this rapidly increasing demand, optical communication networks that can transmit large amounts of data with low power consumption are being widely constructed.

[0003] In addition to the function of directly connecting two points, such an optical communication network can also flexibly set routes by using optical transmission equipment that employs optical switches.

[0004] In recent years, as an example of an optical transmission device that applies such an optical switch, a transmission device that uses multiple wavelength bands (for example, C-band and L-band) has begun to be put into practical use in order to transmit more information over a single optical fiber (Non-Patent Document 1). In addition, by using a wavelength band converter, the routing function can be made more flexible by applying the function of changing the signal wavelength between multiple wavelength bands (Non-Patent Document 2).

[0005] Figure 1 shows the conversion function obtained by a typical wavelength band converter. As shown in Figure 1, a typical wavelength converter converts optical signals into ones with wavelengths that are mirror images of each other, with the midpoint between the band before and after wavelength band conversion as the axis of symmetry. In other words, optical signals arranged in order from shortest wavelength to longest wavelength in the band before wavelength band conversion are converted into optical signals arranged in order from longest wavelength to longest wavelength in the band after wavelength band conversion.

[0006] As described above, in a typical wavelength band converter, optical signals of each wavelength before conversion are converted into optical signals of wavelengths that are mirror images of each other with respect to the axis of symmetry. Therefore, when an optical signal passes through a wavelength band converter an even number of times before being transmitted from an optical transceiver and received by another optical transceiver, each optical signal transmitted from a transmitter arranged in order from shortest wavelength to shortest wavelength is received by a receiver arranged in order from shortest wavelength to shortest wavelength. In contrast, when an optical signal passes through a wavelength band converter an odd number of times before being transmitted from an optical transceiver and received by another optical transceiver, each optical signal transmitted from a transmitter arranged in order from shortest wavelength to shortest wavelength is received by a different receiver arranged in order from longest wavelength to longest wavelength.

[0007] Therefore, when attempting to communicate using a detour route in the event of a failure or other problem within the network, if the number of wavelength band converters passed through changes from an odd number to an even number, or from an even number to an odd number, the receiver that receives the transmitted optical signal will be a different receiver from the one before the change, and there is a problem that communication cannot be maintained between the same transmitter and receiver before and after the failure.

[0008] S. Yamamoto, H. Taniguchi, Y. Kisaka, S. Camatel, Y. Ma, D. Ogawa, K. Hadama, M. Fukutoku, T. Goh, and K. Suzuki: “First demonstration of a C+L band CDC-ROADM with a simple node configuration using multiband switching devices,” Optics Express, Vol. 29, No. 22, pp. 36353-36365, 2021. H. Minami et al., "Experimental Demonstration of Cascadable PPLN-Based Inter-Band Wavelength Converters for Band-Switchable Multi-Band Optical Cross-Connect," 2023 Optical Fiber Communications Conference and Exhibition (OFC), San Diego, CA, USA, 2023, pp. 1-3, doi: 10.1364 / OFC.2023.M4G.1.

[0009] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide an optical transmission device in which the receiver that receives a transmitted optical signal does not change even if the number of wavelength band converters that pass through changes from odd to even or from even to odd.

[0010] In order to achieve this objective, the present disclosure provides an optical transmission device that includes a multiplexer that generates a wavelength-multiplexed signal by multiplexing optical signals of multiple channels, each having a different wavelength for each channel, and in which a channel corresponding to each input port can be set; a demultiplexer that demultiplexes and outputs an optical signal in which optical signals of multiple channels, each having a different wavelength for each channel, and in which a channel corresponding to each output port can be set; and one or more optical transceivers that transmit and receive optical signals of specified channels from the optical signals of the multiple channels.

[0011] The optical transmission device according to the present disclosure is configured to set channels corresponding to each input port in the multiplexer, channels corresponding to each output port in the demultiplexer, and channels of optical signals transmitted and received by each of one or more optical transmitters and receivers, depending on the number of times the optical signal passes through a wavelength band conversion device on its way to another optical transmission device that transmits or receives the optical signal.

[0012] The optical transmission device according to the present disclosure may be configured such that when the number of times passing through the wavelength band conversion device is an odd number, the channels corresponding to each input port in the multiplexer, the channels corresponding to each output port in the demultiplexer, and the channels of the optical signals transmitted and received by each of the one or more optical transceivers are set to a channel number of N+1-M, where N is the number of channels (N is a natural number) and M is the channel number set when the number of times passing through the wavelength band conversion device is an even number (N is a natural number less than or equal to M), thereby enabling optical signals to be transmitted and received using the same optical transceiver when the number of times passing through the wavelength band conversion device is an even number and when the number of times passing through the wavelength band conversion device is an odd number.

[0013] FIG. 1 is a diagram illustrating a conversion function obtained by a general wavelength band converter. FIG. 2 is a diagram conceptually illustrating a configuration of an optical transmission device 100 according to the present disclosure. FIG. 3 is a diagram conceptually illustrating a configuration of an optical transmission system including a network using an optical transmission device according to the present disclosure. FIG. 4 is a diagram illustrating a state in which an optical wavelength band converter is not passed through on a path between two optical transmission devices constituting the optical transmission system of the present disclosure, and a state in which an optical wavelength band converter is passed through on an even number of times. FIG. 5 is a diagram illustrating a state in which an optical wavelength band converter is passed through on an odd number of times on a path between two optical transmission devices constituting the optical transmission system of the present disclosure.

[0014] Various embodiments of the present disclosure will be described in detail below with reference to the drawings. The same or similar reference numerals indicate the same or similar elements, and redundant description may be omitted. Materials and numerical values ​​are for illustrative purposes only and are not intended to limit the technical scope of the present disclosure. The following description is an example, and some configurations may be omitted or modified, or additional configurations may be added, as long as they do not deviate from the gist of one embodiment of the present invention.

[0015] 2 is a diagram conceptually illustrating the configuration of an optical transmission device 100 according to the present disclosure. As illustrated in FIG. 2, the optical transmission device 100 includes a wavelength multiplexer 101, a wavelength demultiplexer 102, one or more optical transceivers 103, and a controller 104.

[0016] The wavelength multiplexer 101 is a device that multiplexes optical signals of multiple channels, each with a different wavelength, to generate a wavelength multiplexed signal, and is capable of setting a corresponding channel for each input port. The wavelength multiplexer 101 illustrated in FIG. 2 has input ports 105 corresponding to the number of channels. １ ~105 ７ and an input port 105 １ ~105 ７ The wavelength demultiplexer 102 is a device that demultiplexes and outputs an optical signal in which optical signals of multiple channels, each with a different wavelength, are wavelength-multiplexed, and is capable of setting a corresponding channel for each output port. The wavelength demultiplexer 102 shown in FIG. 2 has output ports 106 corresponding to the number of channels. １ ~106 ７ and an output port 106 １ ~106 ７ The wavelength multiplexer 101 and the wavelength demultiplexer 102 can be configured to have the channel of the optical signal output from the wavelength multiplexer 101. For example, wavelength selective switches (WSS) can be used to achieve this function.

[0017] The optical transceiver 103 has a function of transmitting and receiving an optical signal of a specified channel among optical signals of multiple channels. The controller 104 controls the input port 105 of the wavelength multiplexer 101 based on information from a central controller such as a maintenance management operation system (information on the number of wavelength band conversions to be described later). １ ~105 ７ , the output port 106 of the wavelength demultiplexer 102 １ ~106 ７and can control the channel setting of the optical transceiver 103. Note that, although the controller 104 is described here as being provided in the optical transmission device, the controller 104 may be an external controller connected to the optical transmission device.

[0018] In the example shown in FIG. 2 (including the examples shown in FIGS. 3 to 5 described later), the number of channels N is 7, but the number of channels may be any number other than 7.

[0019] Furthermore, in the example shown in Figure 2 (including the examples shown in Figures 3 to 5 described below), for ease of explanation, the channels of optical signals transmitted and received by each input port of the wavelength multiplexer, each output port of the wavelength demultiplexer, and each optical transmitter / receiver are assigned in channel number order (i.e., in order of the wavelength size of the channel) from top to bottom of the figure, but the channel numbers set to each may not be in numerical order.

[0020] In the example shown in FIG. 2 (including the examples shown in FIGS. 3 to 5 described later), the optical transmission device 100 １ and 100 ２ In the above, the input ports of the wavelength multiplexer, the output ports of the wavelength demultiplexer, and the channels of the optical signals transmitted and received by each optical transmitter / receiver are all in the same order, but the order of the channels set in each may be different.

[0021] Furthermore, the optical transmission device shown in Figure 2 (including the examples shown in Figures 3 to 5 described below) is exemplified as having optical transceivers 103 equal to the number of channels (seven in Figure 2), but the number of optical transceivers 103 provided in the optical transmission device may be less than the number of channels, as long as it is one or more.

[0022] 3 is a conceptual diagram of a network using the optical transmission device 100 of the present disclosure, and is a diagram illustrating an optical transmission system using the optical transmission device 100 of the present disclosure. The optical transmission system 300 according to the present disclosure shown in FIG. 3 includes two opposing optical transmission devices 100. １ , 100 ２ This allows them to send and receive information to each other.

[0023] The optical transmission system according to the present disclosure includes two optical transmission devices 100 １ , 100 ２ and two optical transmission devices 100 １ , 100 ２ The optical transmission system includes a path 108 on which a wavelength band converter 107 may exist, which connects the optical transmission devices, and a central controller such as a maintenance and operation management system (not shown) that sets the connection path of the optical transmission system. The path 108 is a network that can connect two optical transmission devices via multiple paths.

[0024] When converting a wavelength band as described above, the wavelength band converter 107 converts the wavelengths into optical signals with wavelengths that are mirror images of each other with respect to the axis of symmetry on the wavelength axis. That is, wavelength multiplexed signals arranged in order from the shortest wavelength side are converted into wavelength multiplexed signals arranged in order from the longest wavelength side, and the channel numbers in the converted wavelength band are set to "the maximum channel number + 1 minus the channel number before conversion."

[0025] Here, if the number of channels of multiple channels with different wavelengths is N and the channel number of each channel before conversion is M, an optical signal with channel number M of the optical signal before conversion becomes an optical signal with channel number N+1-M in the converted wavelength band after conversion, where N and M are natural numbers and M is equal to or less than N.

[0026] In this specification, "channel number" refers to a number assigned to multiple channels with different wavelengths within each wavelength band in the order of wavelength magnitude. For example, if multiple channels with different wavelengths are assigned numbers in order from the smallest wavelength, the channel with the smallest wavelength will have a channel number of 1, and the numbers will increase sequentially in order of wavelength magnitude until the channel with the largest wavelength has a channel number of N. Conversely, multiple channels with different wavelengths may be assigned numbers in order from the largest wavelength.

[0027] The optical transmission device according to the present disclosure includes two optical transmission devices 100 １ , 100 ２The configuration of the wavelength multiplexer 101, wavelength demultiplexer 102, and optical transmitter / receiver 103 is changed depending on the number of times that the optical signal transmitted and received passes through the wavelength band converter 107 within the network.

[0028] A specific example of the setting is shown below. １ , 100 ２ Among the optical transmission devices 100, only one optical transmission device 100 needs to have its settings changed. Therefore, for convenience, the optical transmission device 100 whose settings are not changed is ２ the optical transmission device (parent), and the optical transmission device 100 for which the setting is to be changed. １ will be explained separately from the optical transmission device (child).

[0029] As shown in FIG. 4, two optical transmission devices 100 １ , 100 ２ When the optical transmission devices 101 and 102 are connected without passing through the wavelength band converter 107, the input port of the wavelength multiplexer 101 and the output port of the wavelength demultiplexer 102 input and output channels in ascending order of number. Also, the optical transceiver 103 is connected to the input port of the wavelength multiplexer 101 and the output port of the wavelength demultiplexer 102 with the same channel number, and the channel of the optical signal to be transmitted and received is a channel set so that it can be input and output at the connected port. Figure 4 illustrates a case where the number of channels is 7, as in Figure 3. Optical transmission device (child) 100 １ In FIG. 1, the input port 105 of the wavelength multiplexer 101 １ ~105 ７、 Output port 106 of wavelength demultiplexer 102 １ ~106 ７ are set to correspond to the channel numbers 1 to 7 in order, and the optical transceiver 103 １ ~103 ７ At this time, each optical transceiver 103 １ ~103 ７ The channel numbers of the optical signals transmitted and received by the optical transmission device (parent) 100 are set to 1 to 7. ２ In the wavelength multiplexer 101, the input port 105 １ ~105 ７、 Output port 106 of wavelength demultiplexer 102 １ ~106 ７are set to correspond to the channel numbers 1 to 7 in order, and the optical transceiver 103 １ ~103 ７ At this time, each optical transceiver 103 １ ~103 ７ The channel numbers of the optical signals transmitted and received by the two optical transmission devices 100 are set to 1 to 7. Therefore, in the state shown in FIG. １ and 100 ２ In this case, communication is possible between optical transceivers (with the same branch number) that transmit and receive optical signals of the same channel.

[0030] In addition, two optical transmission devices 100 １ and 100 ２ When the optical transceivers are connected via the wavelength band converter 107 an even number of times, the order of the wavelength multiplexed signals is restored from the mirror image position, so communication is possible between optical transceivers (with the same branch number) that transmit and receive optical signals of the same channel, just as when the optical transceivers are connected without passing through the wavelength band converter 107 in Figure 4.

[0031] In contrast, two optical transmission devices 100 １ and 100 ２ However, when the optical transmission device (child) 100 is connected via the wavelength band converter 107 an odd number of times, the wavelength multiplexed signals arranged in order from the shortest wavelength side are converted into wavelength multiplexed signals arranged in order from the longest wavelength side. １ The optical transceiver 103 to which the channel number 1 is set １ The optical signal transmitted from the optical transmission device (parent) 101 ２ In the example, the optical transceiver 103 to which the channel number 7 is set is ７ Therefore, the optical transmitter / receiver 103 of the optical transmission device (child) １ In this case, an optical signal transmitted from the optical transceiver 100 is received by an optical transceiver that transmits and receives an optical signal of a channel different from that in the case where the optical signal is connected via an even number of wavelength band converters.

[0032] Therefore, in the present disclosure, as shown in FIG. 5, an optical transmission device (child) 100 １The settings are changed so that each input port of the wavelength multiplexer 101 and each output port of the wavelength demultiplexer 102 inputs and outputs channels numbered N+1-M. The optical transceiver 103 is also set to transmit and receive optical signals on channels numbered N+1-N.

[0033] Here, as described above, N is the number of channels with different wavelengths, M is the channel number assigned to each input channel of the wavelength multiplexer, each output channel of the wavelength demultiplexer, and each optical transmitter / receiver when connected via an even number of wavelength band converters, M is a natural number less than or equal to N, and N is a natural number.

[0034] Therefore, in the example shown in the figure, the optical transmission device (child) 100 １ In FIG. 1, the input port 105 of the wavelength multiplexer 101 １ ~105 ７、 Output port 106 of wavelength demultiplexer 102 １ ~106 ７ are set to correspond to the channel numbers 7 to 1, respectively.

[0035] Also, the input port 105 of the wavelength multiplexer 101 １ ~105 ７、 Output port 106 of wavelength demultiplexer 102 １ ~106 ７ are optical transceivers 103 １ ~103 ７ Therefore, the optical transceiver 103 １ ~103 ７ As shown in the figure, the channel numbers of the optical signals transmitted and received in the optical network 100 are set to CH7 to CH1, respectively.

[0036] Since the optical transmission device of the present disclosure is configured in this manner, it is possible to change the channel of an optical signal transmitted and received by an optical transmitter / receiver without physically switching the connection path between the optical transmitter / receiver and the wavelength multiplexer or wavelength demultiplexer. ２ is 101 in FIG. ２ This is the same setting as above.

[0037] In this way, the optical transmission device (child) 100 １When the setting is changed, the two optical transmission devices 100 １ , 100 ２ In this case, optical signals can be transmitted and received between the same combination of optical transceivers 103, regardless of whether the connection is made without passing through the wavelength band conversion device 107, whether it is made by passing through the wavelength band conversion device 107 an even number of times, or whether it is made by passing through the wavelength band conversion device 107 an odd number of times.

[0038] In other words, even if the number of wavelength band converters passing through changes during operation from an odd number to an even number or from an even number to an odd number, it is not necessary to change the receiver that receives the transmitted optical signal, and an optical transmission device and optical transmission system that are easy to operate can be provided.

[0039] In the optical transmission system according to the present disclosure shown in FIG. 3, an optical transmission device (child) 100 １ , and the optical transmission device (parent) 100 ２ In each of the above, the channel corresponding to each input port in the multiplexer, the channel corresponding to each output port in the demultiplexer, and the channel of the optical signal transmitted and received by each optical transmitter / receiver can be set according to the number of times the signal passes through the wavelength band conversion device, but the same can be applied even if only one of them is settable.

[0040] The wavelength band converter 107 used in the present disclosure may be one that uses periodically poled lithium niobate (PPLN) as a medium. Alternatively, a highly nonlinear fiber may be used as the medium of the wavelength band converter 107. Using PPLN as the medium of the wavelength converter 107 has the advantage of reducing noise carried on the optical signal after wavelength conversion compared to using a highly nonlinear fiber as the medium.

[0041] The number of wavelength band conversions performed on the optical transmission and reception path between optical transmission devices can be grasped by a central controller (e.g., a maintenance operation monitoring system) during the process of setting up a path from the transmitting side to the receiving side, and information on the number of wavelength band conversions performed to the optical transmission device can be transmitted by the maintenance operation monitoring system. The maintenance operation monitoring system can also directly control the controller of the optical transmission device to set up a channel. Alternatively, an external device that transmits and receives a main signal to and from the optical transceiver 103 can detect a change in the party with which the signal is transmitted and received, thereby grasping that the number of wavelength band conversions has changed from an even number to an odd number or from an odd number to an even number, and thus the external device can transmit information on the number of wavelength band conversions performed to the optical transmission device.

[0042] As described above, the optical transmission device and optical transmission system according to the present invention can provide an optical transmission device and optical transmission system in which the receiver that receives the transmitted optical signal does not change even if the number of wavelength band converters through which the signal passes changes from odd to even or from even to odd.

[0043] Therefore, it is possible to facilitate operation of an optical transmission device and an optical transmission system that employ wavelength band conversion, which is capable of transmitting a much larger amount of data than conventional techniques.

[0044] 100 Optical transmission device 101 Wavelength multiplexer 102 Wavelength demultiplexer 103 Optical transmitter / receiver 104 Controller 105 Input port 106 Output port 107 Wavelength band converter 108 Path

Claims

1. An optical transmission device comprising: a multiplexer that generates a wavelength-multiplexed signal by multiplexing optical signals of multiple channels, each with a different wavelength for each channel, and in which a channel corresponding to each input port can be set; a demultiplexer that demultiplexes and outputs an optical signal in which optical signals of multiple channels, each with a different wavelength for each channel, and in which a channel corresponding to each output port can be set; and one or more optical transceivers that transmit and receive optical signals of specified channels among the optical signals of the multiple channels, wherein the optical transmission device is configured to set the channels corresponding to each input port in the multiplexer, the channels corresponding to each output port in the demultiplexer, and the channels of the optical signals transmitted and received by each of the one or more optical transceivers, depending on the number of times the optical signals pass through a wavelength band conversion device on their way to another optical transmission device that transmits and receives the optical signals.

2. The optical transmission device according to claim 1, wherein when the number of times passing through the wavelength band converter is an odd number, the channels corresponding to the input ports of the multiplexer, the channels corresponding to the output ports of the demultiplexer, and the channels of the optical signals transmitted and received by each of the one or more optical transceivers are set to N+1-M channel numbers, where N is the number of channels of the multiple channels (N is a natural number) and M is the channel number set when the number of times passing through the wavelength band converter is an even number (M is a natural number equal to or less than N), thereby enabling optical signals to be transmitted and received using the same optical transceiver when the number of times passing through the wavelength band converter is an even number and when the number of times passing through the wavelength band converter is an odd number.

3. The optical transmission device according to claim 1 or 2, wherein the multiplexer and the demultiplexer are wavelength selective switches.

4. An optical transmission system including two optical transmission devices and a path connecting the two optical transmission devices, transmitting and receiving optical signals of channels consisting of a plurality of different wavelengths via the path, wherein at least one of the two optical transmission devices is equipped with: a multiplexer that multiplexes optical signals of a plurality of channels, each with a different wavelength, to generate a wavelength-multiplexed signal, the multiplexer being capable of setting a channel corresponding to each input port; a demultiplexer that demultiplexes and outputs an optical signal in which optical signals of a plurality of channels, each with a different wavelength, are wavelength-multiplexed, the demultiplexer being capable of setting a channel corresponding to each output port; and one or more optical transceivers that transmit and receive optical signals of specified channels from among the optical signals of the plurality of channels, wherein a wavelength band conversion device may be present on the path, an optical transmission system characterized in that one of the optical transmission devices is configured to set channels corresponding to each input port in the multiplexer of the one of the optical transmission devices, channels corresponding to each output port in the demultiplexer, and channels of optical signals transmitted and received by each of the one or more optical transceivers, depending on the number of times the path from the one of the optical transmission devices to the other of the optical transmission devices passes through the wavelength band conversion device.

5. The optical transmission system according to claim 4, wherein when the number of times passing through the wavelength band converter is an odd number, the one of the optical transmission devices is configured to transmit and receive optical signals using the same optical transceiver when the number of times passing through the wavelength band converter is an even number and when the number of times passing through the wavelength band converter is an odd number by setting the channels corresponding to the input ports of the multiplexer, the channels corresponding to the output ports of the demultiplexer, and the channels of the optical signals transmitted and received by each of the one or more optical transceivers to N+1-M channel numbers, where N is the number of channels of the multiple channels (N is a natural number) and M is the channel number set when the number of times passing through the wavelength band converter is an even number (N is a natural number equal to or less than M).

6. The optical transmission system according to claim 4 or 5, wherein the wavelength band converter uses periodically poled lithium niobate (PPLN) as a medium.

7. An optical transmission system according to claim 4 or 5, wherein said wavelength band converter uses a highly nonlinear fiber as a medium.

Images