Power supply circuit, repeater, communication system, and power supply method in repeater

Abstract

To make it possible to increase the output of an optical amplifier in a repeater.SOLUTION: One or more optical amplifiers are connected in series to a cable including an optical fiber and a power line, and each amplifies a signal transmitted through the optical fiber. A power supply circuit supplies current to the one or more optical amplifiers. The power supply circuit has a DC / DC converter that amplifies the current supplied via the power line, and one or more Zener diodes that are connected in series with the output current of the DC / DC converter and each connected in parallel to the optical amplifier.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power supply circuit, a repeater, a communication system, and a power supply method in a repeater. [Background technology]

[0002] Dense Wavelength Division Multiplexing (DWDM) systems are often used in undersea communication networks. In such networks, multiple undersea optical repeaters are inserted into the transmission path. Generally, undersea optical repeaters include optical amplifiers using erbium-doped fibers. The optical amplifiers amplify attenuated optical signals to an appropriate level.

[0003] In the above-mentioned communication network, the cable laid on the seabed includes an optical fiber cable and a power supply line. The power supply line is also called a system cable. The system cable is connected to a power supply device such as a constant current source, and a constant current is supplied from the constant current source to the optical amplifiers of the optical repeater. The optical amplifiers have one or more pump laser modules connected in series to the system cable. A constant current (also called a system current) is supplied to each of the pump laser modules via the system cable.

[0004] As related art, Patent Document 1 discloses a power supply circuit and an optical submarine cable. The power supply circuit described in Patent Document 1 has a plurality of circuit elements connected in series with each other. A system current is supplied to the plurality of circuit elements from an external power supply. Each circuit element includes one or more Zener diodes and a current control circuit. In the power supply circuit, the one or more Zener diodes are connected in series with each other.

[0005] The current control circuit includes a DC (Direct Current) / DC converter and a feedback circuit. The DC / DC converter receives a predetermined voltage and outputs a voltage adjusted based on a feedback control signal to a load such as a laser diode. One or more Zener diodes are connected in parallel to a terminal that inputs the predetermined voltage to the DC / DC converter. The feedback circuit compares a reference voltage generated according to the output voltage of the DC / DC converter with a current detection voltage generated according to the current flowing through the load. The feedback circuit outputs a control signal indicating the comparison result to the DC / DC converter. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2022 / 158311 Summary of the Invention [Problem to be solved by the invention]

[0007] Currently, in order to expand the transmission capacity of submarine communication networks, it is necessary to increase the output power of submarine optical repeaters and the number of fiber pairs. This requires that the pump laser module in each submarine optical repeater have a high output power. However, with a typical submarine optical repeater, it is not possible to supply a current to the pump laser module that is greater than the current supplied from the system cable, and therefore the current required for the high output power of the pump laser module cannot be obtained.

[0008] To solve the above problems, it is possible to increase the power supply current of the power feeding equipment (PFE) installed on land or to increase the number of pump laser modules used in the optical amplifier (for example, from two to four). However, the upper limit current of commonly used power feeding equipment is 1.3 A, which is insufficient compared to the current (-1.8 A) allowed for high-power pump laser modules. Furthermore, increasing the number of pump laser modules complicates the control method for the pump laser modules in the optical amplifier. Furthermore, the number of couplers that combine the pump light increases, complicating the method of distributing the pump light to the erbium-doped fiber. As a result, the number of parts in the pump module increases, which leads to the problem of the submarine optical repeater becoming larger.

[0009] In the power supply circuit described in Patent Document 1, a Zener diode supplies a predetermined voltage to a DC / DC converter, and the DC / DC converter outputs a voltage adjusted so that the reference voltage and the current detection voltage are equal to each other to a load. In this way, the power supply circuit described in Patent Document 1 can supply a predetermined current to a load with high power efficiency when a constant current is supplied to a single power line.

[0010] However, in the power supply circuit described in Patent Document 1, a Zener diode is connected to the input side of the DC / DC converter. In other words, the DC / DC converter is connected after the Zener diode. In Patent Document 1, if multiple optical amplifiers are implemented in a repeater, a set of Zener diode and DC / DC converter is required for each optical amplifier load. In addition, the conversion efficiency of one DC / DC converter is approximately 80% to 90%. In the power supply circuit described in Patent Document 1, multiple DC / DC converters are connected in multiple stages, which creates the problem that the conversion efficiency decreases as the number of stages increases.

[0011] In view of the above circumstances, one object of the present disclosure is to provide a power supply circuit, a repeater, a communication system, and a power supply method for a repeater that can increase the output of an optical amplifier in the repeater. [Means for solving the problem]

[0012] A power supply circuit according to a first aspect of the present disclosure includes a DC / DC converter connected in series to a cable including an optical fiber and a power line, and amplifying a current supplied via the power line, and one or more Zener diodes connected in series to the output current of the DC / DC converter, each connected in parallel to an optical amplifier that amplifies a signal transmitted through the optical fiber.

[0013] A repeater according to a second aspect of the present disclosure includes one or more optical amplifiers connected in series to a cable including an optical fiber and a power line, each of which amplifies a signal transmitted through the optical fiber, and a power supply circuit which supplies current to the one or more optical amplifiers. The power supply circuit includes a DC / DC converter which amplifies the current supplied via the power supply line, and one or more Zener diodes which are connected in series with the output current of the DC / DC converter and each of which is connected in parallel to the optical amplifier.

[0014] A communication system according to a third aspect of the present disclosure includes first and second terminal devices disposed at one and the other ends of a cable including an optical fiber and a power line, and one or more repeaters inserted in series into the cable. Each of the one or more repeaters includes one or more optical amplifiers connected in series to the cable, each amplifying a signal transmitted through the optical fiber, and a power supply circuit supplying current to the one or more optical amplifiers. The power supply circuit includes a DC / DC converter that amplifies current supplied via the power line, and one or more Zener diodes connected in series to the output current of the DC / DC converter, each connected in parallel to the optical amplifier.

[0015] A power supply method in a repeater according to a fourth aspect of the present disclosure includes, in a repeater inserted in series in a cable including an optical fiber and a power line, inputting a first current supplied via the power line to a DC / DC converter, using the DC / DC converter to convert the first current into a second current greater than the first current, and supplying the second current from each of one or more Zener diodes connected in series to an output terminal of the DC / DC converter to an optical amplifier that amplifies a signal transmitted through the optical fiber. [Effects of the Invention]

[0016] The power supply circuit, repeater, communication system, and power supply method for a repeater according to the present disclosure can increase the output of an optical amplifier in a repeater without complicating the configuration. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a block diagram showing a schematic configuration of a communication system according to the present disclosure. [Figure 2] FIG. 2 is a block diagram showing a schematic configuration of a repeater. [Figure 3] 1 is a block diagram illustrating an example of a communication system according to the present disclosure. [Figure 4] FIG. 2 is a block diagram showing an example of the configuration of a repeater. [Figure 5] FIG. 2 is a block diagram showing a configuration example of an optical amplifier. [Figure 6] FIG. 2 is a block diagram showing a configuration example of a power supply circuit. DETAILED DESCRIPTION OF THE INVENTION

[0018] Prior to describing the embodiments of the present disclosure, an overview of the present disclosure will be provided. Fig. 1 shows a schematic configuration of a communication system according to the present disclosure. The communication system includes a first terminal device 11, a second terminal device 12, and one or more repeaters 13. The first terminal device 11 is disposed at one end of a cable (communication cable), and the second terminal device 12 is disposed at the other end of the cable. The cable includes an optical fiber and a power line. The one or more repeaters 13 are inserted in series into the cable.

[0019] 2 shows a schematic configuration of the repeater 13. The repeater 13 has a power supply circuit 15 and one or more optical amplifiers 16. Each of the one or more optical amplifiers 16 amplifies a signal transmitted through an optical fiber. The power supply circuit 15 supplies current to the one or more optical amplifiers.

[0020] The power supply circuit includes a DC / DC converter 21 and one or more Zener diodes 22. The DC / DC converter 21 amplifies the system current supplied via a power line included in the cable. The one or more Zener diodes 22 are connected in series with the output current of the DC / DC converter 21. Each Zener diode 22 is connected in parallel with the optical amplifier 16.

[0021] In the present disclosure, the power supply circuit 15 of the repeater 13 has a DC / DC converter 21 in a stage preceding the Zener diode 22. The DC / DC converter 21 outputs a current greater than the current supplied from the power supply line. In this case, the current increased by the DC / DC converter 21 is supplied to the optical amplifier 16. In this way, the output of the optical amplifier 16 can be increased compared to when the current supplied from the power supply line is directly supplied to the optical amplifier 16.

[0022] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the following description and drawings have been omitted and simplified as appropriate for clarity of explanation. In addition, in the following drawings, the same or similar elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary.

[0023] 3 shows an example of a communication system according to the present disclosure. The communication system 100 includes terminal devices 110A and 110B and one or more optical repeaters 120. In this embodiment, the communication system 100 constitutes, for example, an optical submarine optical fiber cable system. The terminal device 110A corresponds to the first terminal device 11 shown in FIG. 1. The terminal device 110B corresponds to the second terminal device 12 shown in FIG. 1. The optical repeater 120 corresponds to the repeater 13 shown in FIG. 1.

[0024] The terminal devices 110A and 110B are connected to each other via a cable 130, such as a submarine cable. One or more optical repeaters 120 are connected in series to the cable 130. The terminal devices 110A and 110B communicate with each other via the cable 130. The cable 130 includes one or more optical fibers for transmitting optical signals and a power line. The cable 130 may include a pair (fiber pair) of an optical fiber that transmits optical signals from the terminal device 110A to the terminal device 110B and an optical fiber that transmits optical signals from the terminal device 110B to the terminal device 110A.

[0025] For example, the terminal device 110A generates a wavelength multiplexed signal and transmits it to the opposing terminal device 110B via the cable 130. The terminal device 110B also generates a wavelength multiplexed signal and transmits it to the opposing terminal device 110A via the cable 130.

[0026] The terminal devices 110A and 110B include power supply devices 111A and 111B, respectively. The power supply devices 111A and 111B supply power to each of the one or more optical repeaters 120 via a power line (e.g., a system cable) included in the cable 130. The terminal devices 110A and 110B may monitor and control each optical repeater 120 using the system cable. The terminal devices 110A and 110B are also called land stations.

[0027] FIG. 4 shows a configuration example of an optical repeater 120. The optical repeater 120 has one or more optical amplifiers 121 and a power supply circuit 150. The optical repeater 120 has, for example, a cylindrical container having a space for accommodating one or more optical amplifiers 121 and a power supply circuit 150 therein. The container is made of a material that has pressure resistance, water resistance, corrosion resistance, etc., and that can be placed on the seabed for a long period of time. The optical amplifier 121 corresponds to the optical amplifier 16 shown in FIG. 2. The power supply circuit 150 corresponds to the power supply circuit 15 shown in FIG. 2.

[0028] Each of the one or more optical amplifiers 121 has an amplifier that amplifies the power of a signal transmitted through an optical fiber included in the cable 130. Each optical amplifier 121 is configured using, for example, an erbium-doped fiber amplifier (EDFA). Each optical amplifier 121 is arranged, for example, corresponding to a fiber pair included in the cable 130. Instead of arranging an optical amplifier 121 for each fiber pair, an optical amplifier 121 may be arranged for each optical fiber. The power supply circuit 150 is connected to the power supply devices 111A and 111B of the terminal devices 110A and 110B via a system cable included in the cable 130. The power supply circuit 150 supplies power to the pumping light sources of each optical amplifier 121.

[0029] 5 shows a configuration example of the optical amplifier 121. The optical amplifier 121 has EDFs (Erbium Doped Fibers) 132A and 132B, pumping light sources 135A and 135B, and an optical multiplexer / demultiplexer 136. In the optical amplifier 121, the EDF 132A is inserted into optical fiber 131A, which is one optical fiber of the fiber pair. The EDF 132B is inserted into optical fiber 131B, which is the other optical fiber of the fiber pair.

[0030] The pumping light sources 135A and 135B are light sources that output pumping light to be inserted into the fiber pair. The pumping light sources 135A and 135B are connected in series to each other. The pumping light sources 135A and 135B each output, for example, continuous light of a predetermined wavelength. The pumping light sources 135A and 135B include, for example, semiconductor lasers. The pumping light sources 135A and 135B constitute a pumping laser module.

[0031] The pumping lights output from the pumping light sources 135A and 135B are multiplexed in the optical multiplexer / demultiplexer 136, then demultiplexed into two, and then inserted into the optical fibers 131A and 131B. The optical amplifier 121 may have gain flattening filters corresponding to the optical fibers 131A and 131B, respectively.

[0032] 6 shows an example configuration of a power supply circuit 150. The power supply circuit 150 includes a diode bridge 151, a DC / DC converter 152, and one or more Zener diodes 153. The DC / DC converter 152 corresponds to the DC / DC converter 21 shown in FIG. 2. The Zener diode 153 corresponds to the Zener diode 22 shown in FIG. 2.

[0033] The diode bridge 151 has four diodes connected in a bridge configuration. The diode bridge 151 is connected in series to a system cable included in the cable 130. The diode bridge 151 outputs a first current (also called a system current) supplied from the terminal device 110A or 110B to the DC / DC converter 152. Note that if only one of the terminal devices 110A and 110B has a power supply device, i.e., if the system current is supplied to the optical repeater 120 from only one of the two terminal devices, the diode bridge 151 may be omitted from the power supply circuit 150.

[0034] The DC / DC converter 152 is a conversion device that converts the system current (direct current) input via the diode bridge 151 into a second current that is larger than the system current. For example, when a system current of 1.3 A is supplied from the system cable to each optical repeater 120, the DC / DC converter 152 outputs a current of 1.8 A.

[0035] One or more Zener diodes 153 are connected in series to the output terminal of the DC / DC converter 152. The Zener diodes 153 are arranged corresponding to the optical amplifiers 121 included in the optical repeater 120. Each Zener diode 153 is connected in parallel to the optical amplifier 121, particularly to the pumping light sources 135A and 135B of the optical amplifier 121. Each optical amplifier 121 operates using a constant DC voltage appearing across each Zener diode 153 as a power source.

[0036] In this embodiment, the system current supplied from the terminal device 110A or 110B, which is a land station, is supplied to each optical amplifier 121 via a DC / DC converter 152 installed in the subsequent stage of a diode bridge 151. The DC / DC converter 152 converts the system current into a current larger than the system current, so that each optical amplifier 121 can be supplied with a current sufficient to increase the output of the pump laser module.

[0037] Let us consider a case where the DC / DC converter 152 is omitted from the power supply circuit 150 shown in Fig. 6. In this case, the system current output from the diode bridge 151 is output directly to one or more Zener diodes 153. In this case, a current larger than the system current cannot be supplied to the optical amplifiers 121. In contrast, in this embodiment, by using the DC / DC converter 152, a current larger than the system current can be supplied to each optical amplifier 121, and a desired level of pump light can be obtained in the pump laser module.

[0038] In comparison with Patent Document 1, in Patent Document 1, a DC / DC converter is connected after a Zener diode. In contrast, in this embodiment, a Zener diode is arranged after a DC / DC converter. When multiple optical amplifiers are implemented in a repeater, Patent Document 1 requires multiple sets of Zener diodes and DC / DC converters. In contrast, in this embodiment, only one DC / DC converter is required. Therefore, the power supply circuit according to this embodiment can save space compared to the power supply circuit described in Patent Document 1. Furthermore, in the power supply circuit described in Patent Document 1, multiple DC / DC converters are connected in multiple stages, which reduces conversion efficiency. In contrast, the power supply circuit according to this embodiment does not require multiple DC / DC converters connected in multiple stages. Therefore, the power supply circuit according to this embodiment can suppress a reduction in conversion efficiency.

[0039] In this embodiment, the only change to the configuration of the optical repeater 120 is the addition of a DC / DC converter 152. This embodiment makes it possible to increase the output power of the pumping light without increasing the number of pumping laser modules in the optical repeater 120. If the number of pumping laser modules were to be increased, an optical coupler or the like would be required, and the configuration of the optical components that distribute the pumping light to the erbium-doped fibers would need to be changed. In this embodiment, the output power of the pumping light can be increased without changing the configuration of the optical components, and the structures of the optical repeater 120 and the optical amplifier 121 can be simplified compared to when the configuration of the optical components is changed. Therefore, this embodiment makes it possible to prevent the optical repeater 120 from becoming larger.

[0040] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.

[0041] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features described with reference to any one drawing can be combined with features shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features shown in any one drawing are necessary to describe an exemplary embodiment, and some features may be omitted.

[0042] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0043] [Appendix 1] a DC (Direct Current / DC) converter connected in series to a cable including an optical fiber and a power line, and amplifying a current supplied via the power line; a power supply circuit comprising one or more Zener diodes connected in series to the output current of the DC / DC converter and each connected in parallel to an optical amplifier that amplifies a signal transmitted through the optical fiber.

[0044] [Appendix 2] 2. The power supply circuit according to claim 1, further comprising a diode bridge on an input side of the DC / DC converter.

[0045] [Appendix 3] 3. The power supply circuit of claim 1, wherein the cable includes one or more fiber pairs, each pair consisting of a first optical fiber that transmits a signal in a first direction and a second optical fiber that transmits a signal in a second direction opposite to the first direction, and wherein the optical amplifier is disposed for each fiber pair.

[0046] [Appendix 4] 4. The power supply circuit according to claim 1, wherein the optical amplifier includes an erbium-doped fiber and a pumping light source that outputs pumping light to the erbium-doped fiber.

[0047] [Appendix 5] 5. The power supply circuit of claim 4, wherein the excitation light source includes two semiconductor lasers connected in series with each other.

[0048] [Appendix 6] 6. The power supply circuit according to claim 5, wherein the two semiconductor lasers are connected in parallel to the Zener diode.

[0049] [Appendix 7] one or more optical amplifiers connected in series to a cable including an optical fiber and a power line, each of which amplifies a signal transmitted through the optical fiber; a power supply circuit for supplying current to the one or more optical amplifiers; The power supply circuit includes: a DC (Direct Current / DC) converter that amplifies the current supplied via the power supply line; a repeater having one or more Zener diodes connected in series with the output current of the DC / DC converter and each connected in parallel with an optical amplifier.

[0050] [Appendix 8] 8. The repeater according to claim 7, wherein the power supply circuit further comprises a diode bridge on an input side of the DC / DC converter.

[0051] [Appendix 9] The repeater described in Appendix 7 or 8, wherein the cable includes one or more fiber pairs, each pair consisting of a first optical fiber that transmits a signal in a first direction and a second optical fiber that transmits a signal in a second direction opposite to the first direction, and the optical amplifier is disposed for each of the fiber pairs.

[0052] [Appendix 10] 10. The repeater according to any one of appendixes 7 to 9, wherein the optical amplifier includes an erbium-doped fiber and a pumping light source that outputs pumping light to the erbium-doped fiber.

[0053] [Appendix 11] 11. The repeater of claim 10, wherein the pumping light source includes two semiconductor lasers connected in series with each other.

[0054] [Appendix 12] 12. The repeater according to claim 11, wherein the two semiconductor lasers are connected in parallel to the Zener diode.

[0055] [Appendix 13] First and second terminal devices are arranged at one end and the other end of a cable including an optical fiber and a power line; one or more repeaters inserted in series into the cable; Each of the one or more repeaters one or more optical amplifiers connected in series to the cable, each of which amplifies a signal transmitted through the optical fiber; a power supply circuit for supplying current to the one or more optical amplifiers; The power supply circuit includes: a DC (Direct Current / DC) converter that amplifies the current supplied via the power supply line; and one or more Zener diodes connected in series with the output current of the DC / DC converter and each connected in parallel with an optical amplifier.

[0056] [Appendix 14] 14. The communication system according to claim 13, wherein at least one of the first terminal device and the second terminal device has a power supply device that supplies current to the power line.

[0057] [Appendix 15] In a repeater inserted in series into a cable including an optical fiber and a power line, a first current supplied via the power line is input to a DC (Direct Current) / DC converter; converting the first current to a second current greater than the first current using the DC / DC converter; A power supply method in a repeater, comprising supplying the second current from each of one or more Zener diodes connected in series to an output terminal of the DC / DC converter to an optical amplifier that amplifies a signal transmitted through the optical fiber.

[0058] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 6 that are dependent on Supplementary Note 1 (power supply circuit) may also be dependent on Supplementary Note 13 (communication system) and Supplementary Note 15 (power supply method in repeater) in the same dependency relationship as Supplementary Note 2 to Supplementary Note 6. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0059] 10:Communication Systems 11: First terminal device 12: Second terminal device 13: Repeater 15: Power supply circuit 16: Optical amplifier 21: DC / DC converter 22: Zener diode 100:Communication Systems 110A, 110B: Terminal equipment 111A, 111B: Power supply device 120: Optical repeater 121: Optical amplifier 130: Cable 131A, 131B: Optical fiber 132A, 132B:EDF 135A, 135B: Excitation light source 136: Optical multiplexer / demultiplexer 150: Power supply circuit 151: Diode bridge 152: DC / DC converter 153: Zener diode

Claims

1. a DC (Direct Current) / DC converter connected in series to a cable including an optical fiber and a power line, and amplifying a current supplied via the power line; a power supply circuit comprising one or more Zener diodes connected in series to the output current of the DC / DC converter and each connected in parallel to an optical amplifier that amplifies a signal transmitted through the optical fiber.

2. 2. The power supply circuit according to claim 1, further comprising a diode bridge on the input side of the DC / DC converter.

3. 3. The power supply circuit according to claim 1, wherein the cable includes one or more fiber pairs, each pair consisting of a first optical fiber that transmits a signal in a first direction and a second optical fiber that transmits a signal in a second direction opposite to the first direction, and the optical amplifier is disposed for each of the fiber pairs.

4. 3. The power supply circuit according to claim 1, wherein the optical amplifier includes an erbium-doped fiber and a pumping light source that outputs pumping light to the erbium-doped fiber.

5. 5. The power supply circuit according to claim 4, wherein the pump light source includes two semiconductor lasers connected in series with each other.

6. 6. The power supply circuit according to claim 5, wherein the two semiconductor lasers are connected in parallel to the Zener diode.

7. one or more optical amplifiers connected in series to a cable including an optical fiber and a power line, each of which amplifies a signal transmitted through the optical fiber; a power supply circuit for supplying current to the one or more optical amplifiers; The power supply circuit includes: a DC (Direct Current / DC) converter that amplifies the current supplied via the power supply line; a repeater having one or more Zener diodes connected in series with the output current of the DC / DC converter and each connected in parallel with an optical amplifier.

8. first and second terminal devices disposed at one end and the other end of a cable including an optical fiber and a power line; one or more repeaters inserted in series into the cable; Each of the one or more repeaters one or more optical amplifiers connected in series to the cable, each of which amplifies a signal transmitted through the optical fiber; a power supply circuit for supplying current to the one or more optical amplifiers; The power supply circuit includes: a DC (Direct Current / DC) converter that amplifies the current supplied via the power supply line; and one or more Zener diodes connected in series with the output current of the DC / DC converter and each connected in parallel with an optical amplifier.

9. 9. The communication system according to claim 8, wherein at least one of the first terminal device and the second terminal device includes a power supply device that supplies current to the power supply line.

10. In a repeater inserted in series into a cable including an optical fiber and a power line, a first current supplied via the power line is input to a DC (Direct Current) / DC converter; converting the first current to a second current greater than the first current using the DC / DC converter; A power supply method in a repeater, comprising supplying the second current from each of one or more Zener diodes connected in series to an output terminal of the DC / DC converter to an optical amplifier that amplifies a signal transmitted through the optical fiber.

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