Wavelength band conversion device

Abstract

Provided is a wavelength band conversion device that can be applied to an optical transmission device having a basic node structure which is premised on the use of a plurality of wavelength bands, and that achieves a lower cost and lower power consumption as compared with the prior art. A wavelength band conversion device (200) according to the present disclosure comprises: a first optical switch (201) that has M inputs and N outputs (where M and N are each an integer of 1 or more, and M>N) and that is configured to be capable of selecting, from among M ports, input ports to which optical signals of a wavelength group are input; N wavelength band conversion units (202) that convert optical signals of the wavelength group which have been output from the first optical switch (201) into optical signals of another wavelength group and that output the optical signals of the other wavelength group; and a second optical switch (203) that is connected to the outputs of the wavelength band conversion units, that has N inputs and M outputs, and that is configured to be capable of selecting, from among M ports, output ports from which optical signals of the wavelength group output from the respective wavelength band conversion units are output.

Description

Wavelength band conversion device

[0001] The present disclosure relates to a wavelength band conversion device.

[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, optical transmission devices using optical switches can be used in optical communication networks, which enable flexible setting of paths between any number of points in the optical communication network.

[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 (e.g., C-band and L-band) for the purpose of transmitting more information through a single optical fiber has begun to be put into practical use (see, for example, non-patent document 1).

[0005] FIG. 1 is a diagram schematically illustrating the basic configuration of a conventional optical transmission device 100. Note that FIG. 1 illustrates, as an example, a case in which there is one input port for wavelength-multiplexed signals input from an external device and one output port for wavelength-multiplexed signals output to an external device. However, this is intended for illustrative purposes only, and the number of input ports and output ports (number of directions) of the optical transmission device 100 may be M (M is an integer equal to or greater than 1). Furthermore, in the optical transmission device 100 having such a configuration, as will be described later, the first optical switch is configured to output the direction of an optical signal of a wavelength group to one of M directions in accordance with a user selection. Note that in FIG. 1, the traveling direction of the optical signal is depicted by an arrow.

[0006] As shown in FIG. 1, optical transmission device 100 capable of connecting optical fibers with up to M directions includes a wavelength group demultiplexer 101 that demultiplexes an externally input wavelength-multiplexed signal into optical signals of N wavelength groups (N is an integer of 2 or more), N optical amplifiers 102a-c that amplify each of the optical signals of the N wavelength groups output from wavelength group demultiplexer 101, N 1-input M-output first optical switches 103a-c connected to the output ports of each of optical amplifiers 102a-c, N M-input 1-output second optical switches 104a-c connected to the output ports of each of first optical switches 103a-c, and a wavelength group multiplexer 105 connected to the output port of second optical switches 104a-c and multiplexing the input N wavelength groups. In addition, in Figure 1, the number N of optical signals of wavelength groups that are demultiplexed by the wavelength group demultiplexer 101 is depicted as 3, but this is intended as an example, and the number N can be set arbitrarily depending on the number of wavelength groups that the wavelength multiplexed signal has.

[0007] When a wavelength-multiplexed signal is input from outside the optical transmission device 100, the externally input wavelength-multiplexed signal is demultiplexed into N wavelength groups (three wavelength groups in the example of FIG. 1 ) by the wavelength group demultiplexer 101 (for example, demultiplexed into S-band, C-band, and L-band). Each of the demultiplexed optical signals of the N wavelength groups is input to a respective optical amplifier 102 a-c configured to be able to amplify the optical signal of that wavelength group. For example, the optical amplifier 102 a is configured to be able to amplify an optical signal of the S-band, the optical amplifier 102 b is configured to be able to amplify an optical signal of the C-band, and the optical amplifier 102 a is configured to be able to amplify an optical signal of the L-band.

[0008] The output ports of the optical amplifiers 102a-c are input to respective 1-input, M-output first optical switches 103a-c for selecting an output route. In the above example, an amplified S-band optical signal is input to the first optical switch 103a, an amplified C-band optical signal is input to the first optical switch 103b, and an amplified L-band optical signal is input to the first optical switch 103c. The optical signals of each wavelength group input to each of the first optical switches 103a-c are output to any of the M routes selected by the user and input to the corresponding second optical switches 104a-c. However, the output ports of each of the first optical switches 103a-c are all connected to respective input ports of different second optical switches 104a-c.

[0009] The second optical switches 104a-c are provided at each of the M output ports of the optical transmission device 100. As described above, the optical transmission device 100 is configured so that a user can select which of the M second optical switches 104a-c an optical signal of each wavelength group transmitted from each of the first optical switches 103a-c is input to. The output port of each of the second optical switches 104a-c is connected to an input port of a wavelength group multiplexer 105 provided at each of the M output ports. The wavelength group multiplexer 105 has the function of multiplexing and outputting optical signals of N wavelength groups.

[0010] The optical transmission device 100 having such a configuration has a function of routing wavelength-multiplexed signals bundled as wavelength groups as control units. Furthermore, the optical transmission device 100 can also be equipped with other functions, such as routing control functions on a wavelength-by-wavelength basis, a signal insertion / removal function, and a function for reducing the signal level deviation between wavelength-multiplexed signals. However, the optical transmission device 100 can be said to be the most basic node configuration when multiple wavelength bands are used.

[0011] In a basic node configuration that assumes the use of multiple wavelength bands, such as the optical transmission device 100, the unit of route control is a coarse unit called a wavelength group, as described above. In such a network, if a failure occurs and signals need to be transferred to a detour route, it is necessary to prepare a wideband, free route for detour. However, since the free detour routes that must be prepared increase the cost of the system, there is a desire to minimize the number of such routes.

[0012] In order to minimize such empty detour paths, it is effective to convert the wavelength group to which the optical signal belongs to another wavelength group, thereby increasing the flexibility of detour route selection. One method for converting the wavelength group of an optical signal is to receive the optical signal of one wavelength group using a receiver and then retransmit the received optical signal of the wavelength group as it is using another wavelength group. However, this method requires the same number of receivers and transmitters as the number of signal wavelengths in the wavelength group, which results in high costs and high power consumption.

[0013] 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)

[0014] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a wavelength band conversion device that can be applied to optical transmission devices having a basic node configuration that assumes the use of multiple wavelength bands, and that is lower cost and consumes less power than conventional technology.

[0015] In response to the above-described problems, the present disclosure provides a wavelength band conversion device comprising: a first optical switch with M inputs and N outputs (M and N are integers equal to or greater than 1, provided that M>N) configured to be able to select to which of the M input ports an optical signal of a wavelength group to be input to and converted in a wavelength band conversion unit described below is to be input; N wavelength band conversion units that convert the optical signal of the wavelength group output from the first optical switch into an optical signal of another wavelength group and output the converted optical signal; and a second optical switch with N inputs and M outputs connected to the outputs of the wavelength band conversion units, configured to be able to select from which of the M output ports the optical signal of the wavelength group output from each of the wavelength band conversion units is to be output.

[0016] 1 is a diagram illustrating a schematic diagram of a basic configuration of a conventional optical transmission device 100. FIG. 2 is a diagram illustrating a conceptual diagram of a configuration of a wavelength band conversion device 200 according to the present invention.

[0017] 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 disclosure.

[0018] FIG. 2 is a diagram conceptually illustrating the configuration of a wavelength band converter 200 of the present invention. As shown in FIG. 2, the wavelength band converter 200 includes a first optical switch 201 with M inputs and N outputs (M and N are integers equal to or greater than 1, where M>N), N wavelength band converters 202a-c that convert optical signals of an input wavelength group into optical signals of another wavelength group and output the converted optical signals, and an N-input, M-output second optical switch 203 connected to the outputs of the N wavelength band converters 202a-c. Here, M may correspond to the number of connectable optical fibers (number of input directions) through which externally input wavelength-multiplexed signals are transmitted in an optical transmission device (not shown) to which the wavelength band converter 200 is applied. Meanwhile, N may be set to any number depending on the user's selection and design, but as described above, the relationship M>N must be satisfied.

[0019] 2, as an example, the number of input ports of the first optical switch 201 and the number of output ports of the second optical switch 203 (both corresponding to M) are depicted as seven, but this is intended as an example. Also, in FIG. 2, as an example, the number of wavelength band conversion units 202a-c installed (corresponding to N) is depicted as three, but this is also intended as an example.

[0020] In the wavelength band converter 200 according to the present disclosure having such a configuration, optical signals of a wavelength group are input from any combination of N paths (corresponding to three paths in the example of FIG. 1 ) in an optical transmission device to which it is applied. The M input paths of the wavelength band converter 200 correspond one-to-one to the M input ports of the first optical switch 201, and the optical signals of the wavelength group input from the any combination of N paths in the first optical switch 201 are input to corresponding N ports out of the M input ports of the first optical switch 201 (seven in the example of FIG. 1 ). That is, the input port to which the optical signals of the wavelength group input to the first optical switch 201 are input is determined by specifying which input port of the wavelength band converter 200 the optical signals of the wavelength group input to are to be converted.

[0021] Optical signals of a wavelength group input to N ports out of the M input ports of the first optical switch 201 are input to each of the wavelength band conversion units 202 a-c via the first optical switch 201. Each of the wavelength band conversion units 202 a-c converts the optical signal of the input wavelength band into an optical signal of another wavelength band. The optical signal converted into another wavelength band by the wavelength band conversion units 202 a-c is output from one of the M output ports via the second optical switch 203. The M output ports of the second optical switch 203 correspond to output routes of the optical transmission device to which the wavelength band conversion device 200 is applied, and are configured so that the optical signal of the converted wavelength group can be sent from an output route selected by the user.

[0022] Each of the wavelength band converters 202a-c may be any known device that performs wavelength band conversion on an input optical signal of a wavelength group. For example, each of the wavelength band converters 204a-f may be a wavelength conversion element configured to perform wavelength conversion based on second-order nonlinear optical effects (sum frequency generation (SFG), difference frequency generation (DFG), and second harmonic generation (SFG)) using periodically poled lithium niobate (PPLN). In another example, each of the wavelength band converters 202a-c may be a highly nonlinear fiber.

[0023] As described above, the wavelength band converter 200 is configured so that M>N, and therefore the number of wavelength band converters 202a-c is fewer than the number of input routes of the optical transmission device to which the wavelength band converter 200 is applied. This makes it possible to reduce the number of wavelength band converters 202a-c that are installed, which is a factor in high costs. Furthermore, the wavelength band converter 200 can convert optical signals of wavelength groups input from any route (three routes in the example of FIG. 2) up to the number of wavelength band converters 202a-c installed, into another wavelength group and output the converted signals from any route.

[0024] Furthermore, in most optical transmission devices, the paths of optical signals of wavelength groups are actually operated as a set of two, an outbound path and a return path. From this perspective, it is desirable that the wavelength band converter according to the present disclosure be configured in another form to include two wavelength band converter elements, in which the wavelength bands before and after conversion of the optical signal to be converted are paired. For example, a wavelength band converter according to another form has two wavelength band converter elements having the same configuration as the wavelength band converter 200, and if the wavelength band converters 202a-c in one wavelength band converter element are configured to convert optical signals in the S band to optical signals in the C band, it is preferable that the wavelength band converters 202a-c in the other wavelength band converter element are configured to convert optical signals in the C band to optical signals in the S band.

[0025] More generally, it is desirable that the wavelength band converter according to the present disclosure include wavelength band converter elements that have the function of converting optical signals of all wavelength groups used in the optical transmission device to optical signals of other wavelength groups and outputting the converted optical signals, for all combinations of wavelength groups. That is, if there are L wavelength groups used in the optical transmission device to which the wavelength band converter according to the present disclosure applies, the number of wavelength band conversion combinations is L×(L−1), and therefore it is desirable that the wavelength band converter according to the present disclosure include L×(L−1) types of wavelength band converter elements.

[0026] As described above, the wavelength band converter according to the present disclosure includes a number of wavelength band conversion units that is less than the number of input directions of the optical transmission device to which it is applied, and therefore is a wavelength band converter that is lower in cost and consumes less power than conventional techniques. Such wavelength band converters are expected to be applied to optical transmission devices that can transmit much larger amounts of data than conventional techniques.

Claims

1. A wavelength band conversion device comprising: a first optical switch with M inputs and N outputs (M and N are integers equal to or greater than 1, provided that M>N) configured to be able to select which of M input ports an optical signal of a wavelength group to input to and converted in a wavelength band conversion unit described below will be input to; N wavelength band conversion units that convert the optical signal of the wavelength group output from the first optical switch into an optical signal of another wavelength group and output the converted optical signal; and a second optical switch with N inputs and M outputs connected to the outputs of the wavelength band conversion units, configured to be able to select which of M output ports an optical signal of the wavelength group output from each of the wavelength band conversion units will be output from.

2. A wavelength band converter comprising L x (L-1) (L is an integer of 2 or more) wavelength band converter elements, comprising: a first optical switch with M inputs and N outputs (M and N are integers of 1 or more, provided that M>N) configured to be able to select which of the M input ports an optical signal of an input wavelength group will be input to; N wavelength band converters that convert the input optical signal of the wavelength group into an optical signal of another wavelength group and output the converted optical signal; and a second optical switch with N inputs and M outputs connected to the outputs of the wavelength band converters, configured to be able to select which of the M output ports an optical signal of the wavelength group output from each of the wavelength band converters will be output from; and the wavelength band converters are configured to include pairs of wavelength groups before and after conversion.

3. The wavelength band conversion device according to claim 1 or 2, wherein the wavelength band conversion unit is either a wavelength conversion element configured to perform wavelength conversion based on the second-order nonlinear optical effect using periodically poled lithium niobate, or a highly nonlinear fiber.

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