Wavelength conversion device and wavelength conversion method

Abstract

A wavelength conversion device according to the present invention receives, as input, an optical signal having a first wavelength from among a plurality of types of wavelengths, outputs, from an output unit, an optical signal having a second wavelength, and comprises: a plurality of wavelength converters that handle conversion between two types of wavelengths each time; and a control unit that, in a case in which a first wavelength converter handles conversion from the first wavelength to the second wavelength, controls one or more switches for switching the path of each optical signal such that an optical signal of the first wavelength is input into the first wavelength converter and an optical signal having the second wavelength converted from the first wavelength is output from the output unit, or, in a case in which the first wavelength converter handles conversion from the first wavelength to a third wavelength, controls the one or more switches such that an optical signal of the first wavelength is input into the first wavelength converter, an optical signal having the third wavelength converted from the first wavelength is input into a second wavelength converter, and an optical signal having the second wavelength converted from the third wavelength by the second wavelength converter is output from the output unit.

Description

Wavelength conversion device and wavelength conversion method

[0001] The present invention relates to a wavelength conversion device and a wavelength conversion method.

[0002] Multiband transmission technology using multiple wavelength bands, such as the S-band (Short-wavelength band), the C-band (Conventional-band), the L-band (Long-wavelength band), and the U-band (Ultralong-wavelength band), is becoming increasingly important.

[0003] The wavelength bands used by communication systems vary from region to region depending on the degree of traffic congestion. For example, a communication system in one region may use the L band, while a communication system in another region may use the C band. In addition, multiple wavelength bands may be used in a communication system by providing a bypass for other wavelength bands within an existing wavelength band.

[0004] In such a situation, when communication systems in regions using different wavelength bands are connected, wavelength conversion of optical signals is required. Here, power consumption and costs increase depending on the number of opto-electrical converters required for converting optical signals to electrical signals. For this reason, technology that converts the wavelength of optical signals as they are without converting them to electrical signals (All Photonic Networking) becomes important. Patent Document 1 discloses a wavelength conversion device that converts the wavelength of an optical signal as it is.

[0005] Japanese Patent Application Laid-Open No. 2020-076834

[0006] The wavelength conversion device disclosed in Patent Document 1 includes one wavelength converter corresponding to one combination of wavelength bands to be converted. For example, if a wavelength conversion device includes one wavelength converter corresponding to wavelength conversion between the C band and the L band, that wavelength conversion device only supports wavelength conversion between the C band and the L band. Therefore, to perform wavelength conversion between the L band and the U band, for example, another wavelength conversion device including another wavelength converter corresponding to wavelength conversion between the L band and the U band is required. This makes it difficult to achieve wavelength conversion at low cost.

[0007] In addition, from the viewpoint of realizing wavelength conversion at low cost, it is desirable that a wavelength conversion device includes a plurality of wavelength converters. However, even if a wavelength conversion device simply includes a plurality of wavelength converters, there is a problem in that it is not possible to convert a first wavelength of an optical signal to a second wavelength while limiting the number of wavelength conversions by the wavelength conversion device to two or less for a combination of a first wavelength and a second wavelength selected from a plurality of predetermined wavelengths.

[0008] In view of the above circumstances, the present invention aims to provide a wavelength conversion device and a wavelength conversion method that are capable of converting a first wavelength of an optical signal to a second wavelength for a combination of a first wavelength and a second wavelength selected from a predetermined plurality of types of wavelengths, while limiting the number of wavelength conversions to two or less.

[0009] One aspect of the present invention is a wavelength conversion device that receives an input of an optical signal having a first wavelength from a plurality of predetermined types of wavelengths, converts the first wavelength to a second wavelength from the plurality of types of wavelengths, and outputs an optical signal having the second wavelength from an output unit, the wavelength conversion device comprising: a plurality of wavelength converters that are capable of converting between wavelengths for each of two types of wavelengths from the plurality of types; and a control unit that controls one or more switches that switch the paths of each optical signal so that, if a first wavelength converter from the plurality of wavelength converters is capable of converting from the first wavelength to the second wavelength, the optical signal of the first wavelength is input to the first wavelength converter, and an optical signal having the second wavelength converted from the first wavelength by the first wavelength converter is output from the output unit; or, if the first wavelength converter is capable of converting from the first wavelength to a third wavelength, the optical signal of the first wavelength is input to the first wavelength converter, and an optical signal having the third wavelength converted from the first wavelength by the first wavelength converter is input to a second wavelength converter from the plurality of wavelength converters, and an optical signal having the second wavelength converted from the third wavelength by the second wavelength converter is output from the output unit.

[0010] One aspect of the present invention is a wavelength conversion method performed by a wavelength conversion device that receives an input of an optical signal having a first wavelength among a plurality of predetermined types of wavelengths, converts the first wavelength to a second wavelength among the plurality of types of wavelengths, and outputs an optical signal having the second wavelength from an output unit, the wavelength conversion method including the steps of: controlling one or more switches that switch the paths of each optical signal so that, when a first wavelength converter among a plurality of wavelength converters that are compatible with conversion between wavelengths of two types among the plurality of types supports conversion from the first wavelength to the second wavelength, the optical signal of the first wavelength is input to the first wavelength converter, and the optical signal having the second wavelength converted from the first wavelength by the first wavelength converter is output from the output unit; or controlling the one or more switches so that, when the first wavelength converter supports conversion from the first wavelength to a third wavelength, the optical signal of the first wavelength is input to the first wavelength converter, the optical signal having the third wavelength converted from the first wavelength by the first wavelength converter is input to a second wavelength converter among the plurality of wavelength converters, and the optical signal having the second wavelength converted from the third wavelength by the second wavelength converter is output from the output unit.

[0011] According to the present invention, it is possible to convert the first wavelength of an optical signal to the second wavelength for a combination of a first wavelength and a second wavelength selected from a predetermined plurality of types of wavelengths, while limiting the number of wavelength conversions to two or less.

[0012] FIG. 1 is a diagram showing an example of the configuration of a wavelength conversion system in a first embodiment. FIG. 2 is a diagram showing an example of a conversion count table in the first embodiment. FIG. 3 is a flowchart showing an example of the operation of a wavelength conversion device in the first embodiment. FIG. 4 is a diagram showing an example of the configuration of a wavelength conversion system in a second embodiment. FIG. 5 is a diagram showing an example of a conversion count table in the second embodiment. FIG. 6 is a diagram showing an example of the configuration of a wavelength conversion system in a third embodiment. FIG. 7 is a diagram showing an example of a conversion count table in the third embodiment. FIG. 8 is a flowchart showing an example of the operation of a wavelength conversion device in the third embodiment. FIG. 9 is a diagram showing an example of the hardware configuration of a control unit in each embodiment.

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the term "wavelength" may be read as "wavelength band." The term "wavelength band" may be read as "wavelength."

[0014] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of a wavelength conversion system 1a in the first embodiment. The wavelength conversion system 1a is a system that converts the wavelength of an optical signal (main signal). An optical signal having a first wavelength among N predetermined wavelengths (N is an integer equal to or greater than 2) is input to the wavelength conversion system 1a. The wavelength conversion system 1a converts the input first wavelength into a second wavelength. The wavelength conversion system 1a outputs the optical signal having the second wavelength to, for example, an optical communication device (not shown).

[0015] The wavelength conversion system 1a includes a wavelength conversion device 2a and an external control device 3. The wavelength conversion device 2a includes a control unit 21, N switches 22, N couplers 23, and "N-1" wavelength converters. The external control device 3 is an information processing device, such as a personal computer, a smartphone terminal, or a tablet terminal.

[0016] In the following, the number "N" is 4, for example. The wavelength bands are not limited to specific wavelengths in the optical communication wavelength band. In the following, the four wavelength bands are, for example, S band, C band, L band, and U band. In the first embodiment, the three wavelength converters are wavelength converter 24, wavelength converter 25, and wavelength converter 26.

[0017] Each switch 22 is connected to four couplers 23 (four "N×1 couplers") via optical fibers. The path (output destination) of the optical signal output from each switch 22 (1×N switch) is determined under the control of the control unit 21.

[0018] The coupler 23-2 is connected to the wavelength converter 24 via an optical fiber. The coupler 23-3 is connected to the wavelength converter 25 via an optical fiber. The coupler 23-4 is connected to the wavelength converter 26 via an optical fiber.

[0019] Next, the wavelength conversion system 1a will be described in detail. The control unit 21 acquires information on the first wavelength of the optical signal input to the switch 22-1 and information on the second wavelength of the optical signal output from the coupler 23-1 from the external control device 3 using a control signal. The control unit 21 may pass through the control signal acquired from the external control device 3 and output it to the switch 22.

[0020] When a first wavelength converter among wavelength converters 24, 25, and 26 corresponds to conversion from a first wavelength to a second wavelength, control unit 21 uses switch 22-1 to input an optical signal of the first wavelength to a first wavelength converter among the "N-1" wavelength converters. Control unit 21 controls one or more switches 22 to output an optical signal having a second wavelength converted from the first wavelength by the first wavelength converter from coupler 23-1 (output unit).

[0021] When the first wavelength converter supports conversion from a first wavelength to a third wavelength, the control unit 21 uses the switch 22-1 to input an optical signal of the first wavelength to a first wavelength converter among the "N-1" wavelength converters. The control unit 21 inputs an optical signal having a third wavelength converted from the first wavelength by the first wavelength converter to a second wavelength converter among the "N-1" wavelength converters. The control unit 21 controls one or more switches 22 to output an optical signal having a second wavelength converted from the third wavelength by the second wavelength converter from the coupler 23-1 (output unit).

[0022] An optical signal of a first wavelength is input to the switch 22-1 from outside the wavelength conversion device 2a. Each switch 22 switches the path of the optical signal input to itself based on a control signal input from the control unit 21. That is, each switch 22 outputs the optical signal input to itself to one of the N couplers 23 based on the control signal.

[0023] The coupler 23 (optical fiber coupler) outputs the optical signal input thereto to a predetermined output destination. The coupler 23-1 outputs the input optical signal to the outside of the wavelength conversion device 2a. The coupler 23-2 outputs the input optical signal to the wavelength converter 24. The coupler 23-3 outputs the input optical signal to the wavelength converter 25. The coupler 23-4 outputs the input optical signal to the wavelength converter 26.

[0024] The wavelength converter inverts the wavelength of the optical signal input from the coupler 23 (previous stage) using the wavelength of the pump light as the inversion axis (center wavelength). The wavelength converter outputs the optical signal of the wavelength band converted by the inversion to the switch 22 (next stage). The wavelength converter is, for example, a wavelength converter using periodically poled lithium niobate (PPLN).

[0025] In the first embodiment, the base wavelength band is the L band, for example. That is, wavelength converters 24, 25, and 26 each support wavelength conversion between the L band and another wavelength band. Specifically, wavelength converter 24 supports wavelength conversion between the L band and the S band. Wavelength converter 25 supports wavelength conversion between the L band and the C band. Wavelength converter 26 supports wavelength conversion between the L band and the U band.

[0026] The wavelength converter 24 outputs the optical signal in the converted wavelength band to the switch 22-2. The wavelength converter 25 outputs the optical signal in the converted wavelength band to the switch 22-3. The wavelength converter 26 outputs the optical signal in the converted wavelength band to the switch 22-4.

[0027] 2 is a diagram showing an example of a table of the number of conversions in the first embodiment. In the first embodiment, the base wavelength band of the N types of wavelength bands is the L band, as an example. When the wavelength (first wavelength) of the optical signal input to the switch 22-1 is the base wavelength band, the number of conversions required to convert to a second wavelength (S band, C band, or U band) of the N types of wavelength bands is one. Furthermore, when the wavelength (first wavelength) of the optical signal input to the switch 22-1 is the S band, C band, or U band, the number of conversions required to convert to the base wavelength band (L band) of the N types of wavelength bands is one.

[0028] Even when the wavelength (first wavelength) of the optical signal input to switch 22-1 is other than the L band, the maximum number of conversions required to convert the optical signal to the second wavelength among the N wavelength bands is 2. For example, when a U-band optical signal is input to switch 22-1 and an S-band optical signal is output from coupler 23-1, wavelength converter 26 converts the U-band to the L-band, and wavelength converter 24 converts the L-band to the S-band.

[0029] In addition, a combination with "0" in the conversion count table indicates that wavelength conversion is not required (the switch 22-1 passes the optical signal input to itself through to the coupler 23-1).

[0030] Next, an example of operation of the wavelength conversion device 2a will be described. Fig. 3 is a flowchart showing an example of operation of the wavelength conversion device 2a in the first embodiment. The control unit 21 acquires information on the first wavelength of the optical signal input to the switch 22-1 and information on the second wavelength of the optical signal output from the coupler 23-1 from the external control device 3 using a control signal (step S101). The control unit 21 determines whether the first wavelength and the second wavelength are equal (step S102).

[0031] If it is determined that the first wavelength and the second wavelength are equal (step S102: YES), the control unit 21 switches the path of the switch 22-1 (first switch) and connects the switch 22-1 and the coupler 23-1 (first coupler) with an optical fiber (step S103).

[0032] If it is determined that the first wavelength and the second wavelength are different (step S102: NO), the control unit 21 connects the switch 22-1 to a wavelength converter corresponding to wavelength conversion between the first wavelength and the third wavelength via a second coupler based on the conversion number table.

[0033] For example, if the first wavelength is the L band and the second wavelength is the S band, the control unit 21 connects the switch 22-1 to a wavelength converter 24 that converts the L band (first wavelength) to the S band (third wavelength (= second wavelength)) via the coupler 23-2 (second coupler).

[0034] For example, if the first wavelength is the C band and the second wavelength is the S band, the control unit 21 connects the switch 22-1 to a wavelength converter 25 that converts the C band (first wavelength) to the L band (third wavelength (≠ second wavelength)) via the coupler 23-3 (second coupler).

[0035] For example, if the first wavelength is the C band and the second wavelength is the U band, the control unit 21 connects the switch 22-1 to a wavelength converter 25 that converts the C band (first wavelength) to the L band (third wavelength (≠ second wavelength)) via the coupler 23-3 (second coupler) (step S104).

[0036] The control unit 21 determines whether the third wavelength and the second wavelength are equal. For example, the control unit 21 may determine that the third wavelength and the second wavelength are equal for a combination that is marked "1" in the conversion number table. For example, the control unit 21 may determine that the third wavelength and the second wavelength are different for a combination that is marked "2" in the conversion number table (step S105).

[0037] If it is determined that the third wavelength and the second wavelength are equal (step S105: YES), the control unit 21 connects the wavelength converter that converts the first wavelength to the second wavelength to the first coupler via the second switch.

[0038] For example, if the first wavelength is the L band, the second wavelength is the S band, and the third wavelength (= second wavelength) is the S band, the control unit 21 connects a wavelength converter 24 that converts the L band (first wavelength) to the S band (second wavelength) to a coupler 23-1 (first coupler) via a switch 22-2 (second switch).

[0039] For example, if the first wavelength is the L band, the second wavelength is the C band, and the third wavelength (= second wavelength) is the C band, the control unit 21 connects a wavelength converter 25 that converts the L band (first wavelength) to the C band (second wavelength) to the coupler 23-1 (first coupler) via the switch 22-3 (second switch).

[0040] For example, if the first wavelength is the L band, the second wavelength is the U band, and the third wavelength (= second wavelength) is the U band, the control unit 21 connects a wavelength converter 26 that converts the L band (first wavelength) to the U band (second wavelength) to the coupler 23-1 (first coupler) via the switch 22-4 (second switch) (step S106).

[0041] If it is determined that the third wavelength and the second wavelength are different (step S105: NO), the control unit 21 connects a wavelength converter that converts the first wavelength to the third wavelength and a wavelength converter that converts the third wavelength to the second wavelength via the fourth switch and the third coupler.

[0042] For example, if the first wavelength is the C band, the second wavelength is the U band, and the third wavelength (≠ the second wavelength) is the L band, the control unit 21 connects a wavelength converter 25 that converts the C band (first wavelength) to the L band (third wavelength) and a wavelength converter 26 that converts the L band (third wavelength) to the U band (second wavelength) via switch 22-3 (fourth switch) and coupler 23-4 (third coupler).

[0043] For example, if the first wavelength is the C band, the second wavelength is the S band, and the third wavelength (≠ the second wavelength) is the L band, the control unit 21 connects the wavelength converter 25 that converts the C band (first wavelength) to the L band (third wavelength) and the wavelength converter 24 that converts the L band (third wavelength) to the S band (second wavelength) via the switch 22-3 (fourth switch) and the coupler 23-2 (third coupler) (step S107).

[0044] The control unit 21 connects the wavelength converter that converts the third wavelength to the second wavelength to the first coupler via the third switch.

[0045] For example, if the first wavelength is the C band, the second wavelength is the U band, and the third wavelength (≠ the second wavelength) is the L band, the control unit 21 connects a wavelength converter 26 that converts the L band (third wavelength) to the U band (second wavelength) to the coupler 23-1 (first coupler) via the switch 22-4 (third switch).

[0046] For example, if the first wavelength is the C band, the second wavelength is the S band, and the third wavelength (≠ the second wavelength) is the L band, the control unit 21 connects the wavelength converter 24 that converts the L band (third wavelength) to the S band (second wavelength) to the coupler 23-1 (first coupler) via the switch 22-2 (third switch) (step S108).

[0047] As described above, an optical signal having a first wavelength among a plurality of predetermined wavelengths (e.g., S band, C band, L band, and U band) is input to the wavelength conversion device 2a. The wavelength conversion device 2a converts the first wavelength into a second wavelength among the plurality of wavelengths. The wavelength conversion device 2a outputs the optical signal having the second wavelength from the coupler 23-1 (output unit).

[0048] When the number of wavelength conversions performed by the wavelength conversion device 2a is limited to two or less, the wavelength conversion device 2a includes a number of wavelength converters, "N-1" or more, which is one less than the number "N" of predetermined types of wavelength converters. The "N-1" wavelength converters correspond to wavelength conversion between every two types of wavelength converters among the plurality of types.

[0049] When a first wavelength converter among the plurality of wavelength converters supports conversion from a first wavelength to a second wavelength, the control unit 21 inputs an optical signal of the first wavelength to the first wavelength converter. The control unit 21 controls one or more switches 22 that switch the paths of each optical signal so that an optical signal having a second wavelength converted from the first wavelength by the first wavelength converter is output from a coupler 23-1 (output unit).

[0050] When the first wavelength converter supports conversion from a first wavelength to a third wavelength, the control unit 21 inputs an optical signal of the first wavelength to the first wavelength converter. The control unit 21 inputs an optical signal having a third wavelength converted from the first wavelength by the first wavelength converter to a second wavelength converter among the plurality of wavelength converters. The control unit 21 controls one or more switches 22 to output an optical signal having a second wavelength converted from the third wavelength by the second wavelength converter from coupler 23-1 (output unit).

[0051] This makes it possible to convert the first wavelength of an optical signal to the second wavelength for a combination of a first wavelength and a second wavelength selected from a predetermined plurality of types of wavelengths, while limiting the number of wavelength conversions to 2 or less. Furthermore, since the number of wavelength converters "N-1" is smaller than the number of combinations of selecting two types from N types, "N(N-1) / 2," wavelength conversion can be performed at low cost.

[0052] Second Embodiment In the second embodiment, the base wavelength band is, for example, the C band, which is a main difference from the first embodiment, in which the base wavelength band is, for example, the L band. In the second embodiment, the differences from the first embodiment will be mainly described.

[0053] 4 is a diagram showing an example of the configuration of a wavelength conversion system 1b in the second embodiment. The wavelength conversion system 1c is a system that converts the wavelength of an optical signal. The wavelength conversion system 1b includes a wavelength converter 2b and an external control device 3. The wavelength converter 2b includes a control unit 21, N switches 22, N couplers 23, and "N-1" wavelength converters. In the second embodiment, the three wavelength converters are a wavelength converter 27, a wavelength converter 28, and a wavelength converter 29.

[0054] Each switch 22 is connected via an optical fiber to each of the four couplers 23. The path (output destination) of the optical signal output from the switch 22 is determined under the control of the control unit 21.

[0055] The coupler 23-2 is connected to a wavelength converter 27 via an optical fiber. The coupler 23-3 is connected to a wavelength converter 28 via an optical fiber. The coupler 23-4 is connected to a wavelength converter 29 via an optical fiber.

[0056] An optical signal of a first wavelength is input to the switch 22-1 from outside the wavelength conversion device 2b. Each switch 22 switches the path of the optical signal input to itself based on a control signal input from the control unit 21. That is, each switch 22 outputs the optical signal input to itself to one of the N couplers 23 based on the control signal.

[0057] The coupler 23 (optical fiber coupler) outputs the optical signal input thereto to a predetermined output destination. The coupler 23-1 outputs the input optical signal to the outside of the wavelength conversion device 2b. The coupler 23-2 outputs the input optical signal to the wavelength converter 27. The coupler 23-3 outputs the input optical signal to the wavelength converter 28. The coupler 23-4 outputs the input optical signal to the wavelength converter 29.

[0058] The base wavelength band may be any wavelength band other than the L band (S band, C band, or U band). In the second embodiment, the base wavelength band is the C band, for example. That is, wavelength converter 27, wavelength converter 28, and wavelength converter 29 each support wavelength conversion between the C band and other wavelength bands. Specifically, wavelength converter 27 supports wavelength conversion between the C band and the S band. Wavelength converter 28 supports wavelength conversion between the C band and the L band. Wavelength converter 29 supports wavelength conversion between the C band and the U band.

[0059] The wavelength converter 27 outputs the optical signal in the converted wavelength band to the switch 22-2. The wavelength converter 28 outputs the optical signal in the converted wavelength band to the switch 22-3. The wavelength converter 29 outputs the optical signal in the converted wavelength band to the switch 22-4.

[0060] 5 is a diagram showing an example of a table of the number of conversions in the second embodiment. In the second embodiment, the base wavelength band of the N types of wavelength bands is the C band, as an example. When the wavelength (first wavelength) of the optical signal input to the switch 22-1 is the base wavelength band, the number of conversions required to convert to a second wavelength (S band, L band, or U band) of the N types of wavelength bands is one. Furthermore, when the wavelength (first wavelength) of the optical signal input to the switch 22-1 is the S band, L band, or U band, the number of conversions required to convert to the base wavelength band (C band) of the N types of wavelength bands is one.

[0061] Even when the wavelength (first wavelength) of the optical signal input to switch 22-1 is other than the C band, the maximum number of conversions required to convert the optical signal to the second wavelength among the N wavelength bands is 2. For example, when a U-band optical signal is input to switch 22-1 and an L-band optical signal is output from coupler 23-1, wavelength converter 26 converts the U-band to the C-band, and wavelength converter 25 converts the C-band to the L-band.

[0062] As described above, an optical signal having a first wavelength among a plurality of predetermined wavelengths (e.g., S band, C band, L band, and U band) is input to the wavelength conversion device 2b. The wavelength conversion device 2b converts the first wavelength into a second wavelength among the plurality of wavelengths. The wavelength conversion device 2b outputs the optical signal having the second wavelength from the coupler 23-1 (output unit).

[0063] When the number of wavelength conversions performed by the wavelength conversion device 2b is limited to two or less, the wavelength conversion device 2b includes a number of wavelength converters, "N-1" or more, which is one less than the number "N" of predetermined types of wavelength converters. The "N-1" wavelength converters correspond to wavelength conversion between every two types of wavelength converters among the predetermined types of wavelength converters.

[0064] This makes it possible to convert the first wavelength of an optical signal to the second wavelength for a combination of a first wavelength and a second wavelength selected from a predetermined number of types of wavelengths, while limiting the number of wavelength conversions to two or less.

[0065] (Third Embodiment) In the third embodiment, the main differences from the first and second embodiments are that the number of wavelength conversions by the wavelength conversion device is limited to one or less, and that the wavelength conversion device is provided with "N(N-1) / 2" or more wavelength converters. In the third embodiment, the differences from the first and second embodiments will be mainly described.

[0066] FIG. 6 is a diagram showing an example of the configuration of a wavelength conversion system 1c in the third embodiment. The wavelength conversion system 1c is a system that converts the wavelength of an optical signal. The wavelength conversion system 1c includes a wavelength conversion device 2c and an external control device 3. The wavelength conversion device 2c includes a control unit 21, a switch 11, a coupler 12, and "N(N-1) / 2" (= Ｎ C ２ ) wavelength converters.

[0067] In the third embodiment, the 6 (=4(4-1) / 2) wavelength converters are wavelength converter 24, wavelength converter 25, wavelength converter 26, wavelength converter 27, wavelength converter 28, and wavelength converter 29.

[0068] The switch 11 (1×M switch) is connected to the coupler 12 (M×1 coupler) via optical fiber, where "M" is "{N(N-1) / 2}+1." The switch 11 is connected to each of six wavelength converters via optical fiber. The path (output destination) of the optical signal output from the switch 11 is determined under the control of the control unit 21.

[0069] The control unit 21 obtains information on the first wavelength of the optical signal input to the switch 11 and information on the second wavelength of the optical signal output from the coupler 23-1 from the external control device 3 using a control signal.

[0070] The control unit 21 uses the switch 11 to input an optical signal of a first wavelength to a first wavelength converter among the "N(N-1) / 2" wavelength converters. The control unit 21 causes the coupler 12 (output unit) to output an optical signal having a second wavelength converted from the first wavelength by the first wavelength converter. The coupler 12 outputs the optical signal having the second wavelength to the outside of the wavelength conversion device 2c.

[0071] 7 is a diagram showing an example of a conversion count table in the third embodiment. In the third embodiment, for all combinations in which two types are selected from N types, the wavelength conversion device 2c is provided with a wavelength converter for each combination. Therefore, in the third embodiment, the number of conversions required to convert an optical signal input to the switch 22-1 from the first wavelength to the second wavelength is one.

[0072] Next, an example of the operation of the wavelength conversion device 2c will be described. Fig. 8 is a flowchart showing an example of the operation of the wavelength conversion device in the third embodiment. The control unit 21 acquires information on the first wavelength of the optical signal input to the switch 11 and information on the second wavelength of the optical signal output from the coupler 12 from the external control device 3 using a control signal (step S201). The control unit 21 determines whether the first wavelength and the second wavelength are equal (step S202).

[0073] If it is determined that the first wavelength and the second wavelength are equal (step S202: YES), the control unit 21 switches the path of the switch 11 (first switch) and connects the switch 11 and the coupler 12 (first coupler) with an optical fiber (step S203).

[0074] If it is determined that the first wavelength and the second wavelength are different (step S202: NO), the control unit 21 connects the switch 11 to a wavelength converter that corresponds to wavelength conversion between the first wavelength and the second wavelength based on the combination of the first wavelength and the second wavelength.

[0075] For example, if the first wavelength is the L band and the second wavelength is the S band, the control unit 21 connects the switch 11 to a wavelength converter 24 that converts the L band (first wavelength) to the S band (second wavelength).

[0076] For example, if the first wavelength is in the C band and the second wavelength is in the S band, the control unit 21 connects the switch 22-1 to a wavelength converter 27 that converts the C band (first wavelength) to the S band (second wavelength).

[0077] For example, if the first wavelength is the C band and the second wavelength is the U band, the control unit 21 connects the switch 22-1 to a wavelength converter 29 that converts the C band (first wavelength) to the U band (second wavelength) (step S204).

[0078] As described above, when the number of wavelength conversions performed by the wavelength conversion device 2c is limited to one or less, the plurality of wavelength converters included in the wavelength conversion device 2c are wavelength converters whose number of combinations of two types selected from a predetermined number "N" of types is equal to or greater than "N(N-1) / 2." The control unit 21 switches the output destination of the switch 11 based on the combination of the first wavelength and the second wavelength, thereby connecting a first wavelength converter among the plurality of wavelength converters to the switch 11 so that the optical signal is input to the first wavelength converter corresponding to the conversion from the first wavelength to the second wavelength. In other words, the control unit 21 controls the switch 11 to output, from the coupler 23-1 (output unit), an optical signal having the second wavelength converted from the first wavelength by the first wavelength converter.

[0079] This makes it possible to convert the first wavelength of an optical signal to the second wavelength while limiting the number of wavelength conversions to one or less for a combination of a first wavelength and a second wavelength selected from a predetermined number of types of wavelengths.

[0080] The control unit provided in the device of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0081] (Hardware Configuration) FIG. 9 is a diagram illustrating an example of the hardware configuration of the control unit 21 in each embodiment. The control unit 21 is realized as software by a processor 101, such as a CPU (Central Processing Unit), executing a program stored in a storage device 103 having a non-volatile recording medium (non-transitory recording medium) and a memory 102. The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), and a CD-ROM (Compact Disc Read Only Memory), and non-transitory recording media such as a hard disk or a solid-state drive (SSD) built into a computer system. The communication unit 104 executes predetermined communication processing.

[0082] The control unit 21 may be realized using hardware including an electronic circuit (electronic circuit or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0083] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0084] The present invention is applicable to optical communication systems.

[0085] 1a, 1b, 1c... wavelength conversion system, 2a, 2b, 2c... wavelength converter, 3... external control device, 11... switch, 12... coupler, 21... control unit, 22... switch, 23... coupler, 24... wavelength converter, 25... wavelength converter, 26... wavelength converter, 27... wavelength converter, 28... wavelength converter, 29... wavelength converter, 101... processor, 102... memory, 103... storage device, 104... communication unit

Claims

1. A wavelength conversion device that receives an optical signal having a first wavelength from a predetermined plurality of types of wavelengths, converts the first wavelength to a second wavelength from the plurality of types of wavelengths, and outputs an optical signal having the second wavelength from an output unit, comprising: a plurality of wavelength converters that support conversion between wavelengths for each two types of wavelengths from the plurality of types; and a control unit that controls one or more switches that switch the paths of each optical signal so that, when a first wavelength converter from the plurality of wavelength converters supports conversion from the first wavelength to the second wavelength, the optical signal of the first wavelength is input to the first wavelength converter, and an optical signal having the second wavelength converted from the first wavelength by the first wavelength converter is output from the output unit; or, when the first wavelength converter supports conversion from the first wavelength to a third wavelength, the optical signal of the first wavelength is input to the first wavelength converter, and an optical signal having the third wavelength converted from the first wavelength by the first wavelength converter is input to a second wavelength converter from the plurality of wavelength converters, and an optical signal having the second wavelength converted from the third wavelength by the second wavelength converter is output from the output unit.

2. A wavelength conversion device according to claim 1, wherein the number of said plurality of wavelength converters is at least one less than the number of said plurality of types of wavelength converters.

3. The wavelength conversion device according to claim 1, wherein the number of said plurality of wavelength converters is equal to or greater than the number of combinations of two types selected from said plurality of types.

4. A wavelength conversion device according to any one of claims 1 to 3, wherein the plurality of wavelength converters are wavelength converters using periodically poled lithium niobate.

5. A wavelength conversion method performed by a wavelength conversion device that receives an optical signal having a first wavelength among a predetermined plurality of types of wavelengths, converts the first wavelength to a second wavelength among the plurality of types of wavelengths, and outputs an optical signal having the second wavelength from an output unit, the wavelength conversion method comprising the steps of: when a first wavelength converter among a plurality of wavelength converters that are compatible with conversion between wavelengths of every two types of wavelengths among the plurality of types supports conversion from the first wavelength to the second wavelength, controlling one or more switches that switch the paths of each optical signal so that the optical signal of the first wavelength is input to the first wavelength converter and the optical signal having the second wavelength converted from the first wavelength by the first wavelength converter is output from the output unit; or when the first wavelength converter is compatible with conversion from the first wavelength to a third wavelength, controlling the one or more switches so that the optical signal of the first wavelength is input to the first wavelength converter, the optical signal having the third wavelength converted from the first wavelength by the first wavelength converter is input to a second wavelength converter among the plurality of wavelength converters, and the optical signal having the second wavelength converted from the third wavelength by the second wavelength converter is output from the output unit.

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