Optical waveform control device, optical transmission system, and optical waveform control method

Abstract

As control becomes complicated when the terminal point of an optical signal propagating through an optical submarine cable is extended in an optical transmission system, this optical waveform control device is provided with: a communication means for communicating with each of a plurality of optical devices including at least a first optical device and a second optical device located at a post-stage of the first optical device; an optical signal noise ratio acquisition means for receiving, via the communication means, an individual optical signal noise ratio that is an optical signal noise ratio per wavelength channel of a wavelength multiplexed optical signal propagating through the plurality of optical devices and an average optical signal noise ratio that is the average of the individual optical signal noise ratios; a first control means for controlling the optical output power of the first optical device via the communication means so that the optical input power of an optical amplifier that the second optical device includes becomes a prescribed value; and a second control means for controlling at least one of the plurality of optical devices via the communication means so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio.

Description

Technical Field

[0001] The present invention relates to an optical waveform control device, an optical transmission system, and an optical waveform control method, and particularly to an optical waveform control device, an optical transmission system, and an optical waveform control method used together with an optical submarine cable system.

Background Art

[0002] An optical submarine cable system that connects continents with optical fibers plays an important role as infrastructure that supports international communication networks. The optical submarine cable system is composed of a submarine cable that houses optical fibers, a submarine repeater equipped with an optical amplifier, a submarine branching device that branches optical signals, and a terminal device installed at a cable landing station. An example of such an optical submarine cable system is described in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0006] However, the characteristics of optical fibers laid on land vary greatly depending on the type of fiber used and the degree of degradation over time. Therefore, in order to keep the optical signal-to-noise ratio (OSNR) constant for each wavelength channel, it is necessary to adjust the settings of the optical amplifiers and wavelength selectable switches (WSS) in the landing station (CLS), inline amplifier (ILA), and POP equipment. In this case, adjustments must be made in all landing stations (CLS), inline amplifiers (ILA), and POP equipment, requiring complex control.

[0007] Thus, in optical transmission systems, extending the termination point of optical signals propagating through optical submarine cables presents a problem of increased control complexity.

[0008] The object of the present invention is to provide an optical waveform control device, an optical transmission system, and an optical waveform control method that solve the above-mentioned problem of increased control complexity when the termination point of an optical signal propagating through an optical submarine cable is extended in an optical transmission system. [Means for solving the problem]

[0009] The optical waveform control device of the present invention includes: communication means for communicating with a plurality of optical devices, each including at least a first optical device and a second optical device located downstream of the first optical device; optical signal noise ratio acquisition means for receiving, via the communication means, an individual optical signal noise ratio, which is the optical signal noise ratio for each wavelength channel of a wavelength-division multiplexed optical signal propagating through the plurality of optical devices, and an average optical signal noise ratio, which is the average of the individual optical signal noise ratios; a first control means for controlling the optical output power of the first optical device via the communication means so that the optical input power of the optical amplifier provided in the second optical device becomes a predetermined value; and a second control means for controlling at least one of the plurality of optical devices via the communication means so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio.

[0010] The optical transmission system of the present invention comprises a plurality of optical devices, each including a first optical device and a second optical device located downstream of the first optical device, and an optical waveform control device, wherein the second optical device includes an optical amplifier, and the optical waveform control device comprises communication means for communicating with each of the plurality of optical devices, optical signal noise ratio acquisition means for receiving, via the communication means, an individual optical signal noise ratio which is the optical signal noise ratio for each wavelength channel of the wavelength-division multiplexed optical signal propagated through the plurality of optical devices, and an average optical signal noise ratio which is the average of the individual optical signal noise ratios, a first control means for controlling the optical output power of the first optical device via the communication means so that the optical input power of the optical amplifier becomes a predetermined value, and a second control means for controlling at least one of the plurality of optical devices via the communication means so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio.

[0011] The optical waveform control method of the present invention receives the individual optical signal noise ratio, which is the optical signal noise ratio for each wavelength channel, and the average optical signal noise ratio, which is the average of the individual optical signal noise ratios, of a wavelength-division multiplexed optical signal propagating through a plurality of optical devices, which include at least a first optical device and a second optical device located downstream of the first optical device. The method controls the optical output power of the first optical device so that the optical input power of the optical amplifier in the second optical device becomes a predetermined value, and controls at least one of the plurality of optical devices so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio. [Effects of the Invention]

[0012] According to the optical waveform control device, optical transmission system, and optical waveform control method of the present invention, control can be simplified even when the termination point of an optical signal propagating through an optical submarine cable is extended in an optical transmission system. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing the configuration of an optical waveform control device according to a first embodiment of the present invention. [Figure 2] This is a block diagram showing the configuration of an optical transmission system equipped with an optical waveform control device according to the first embodiment of the present invention. [Figure 3] This is a flowchart illustrating the optical waveform control method according to the first embodiment of the present invention. [Figure 4] This is a block diagram showing the configuration of an optical transmission system equipped with an optical waveform control device according to a second embodiment of the present invention. [Figure 5A] This figure shows the optical spectrum of a wavelength-division multiplexed optical signal transmitted by a first optical device constituting an optical transmission system according to a second embodiment of the present invention. [Figure 5B] This figure shows the optical spectrum of a wavelength-division multiplexed optical signal in a third optical device constituting an optical transmission system according to a second embodiment of the present invention. [Figure 6] This is a flowchart illustrating the optical waveform control method according to a second embodiment of the present invention. [Figure 7] This is a block diagram showing the configuration of an optical transmission system equipped with an optical waveform control device according to a third embodiment of the present invention. [Figure 8A] This figure shows the optical spectrum of a wavelength-division multiplexed optical signal transmitted by a first optical device constituting an optical transmission system according to a third embodiment of the present invention. [Figure 8B] This figure shows the optical spectrum of a wavelength-division multiplexed optical signal in a third optical device constituting an optical transmission system according to a third embodiment of the present invention. [Figure 9]It is a block diagram showing another configuration of an optical transmission system including an optical waveform control device according to a third embodiment of the present invention. [Figure 10] It is a flowchart for explaining an optical waveform control method according to a third embodiment of the present invention. [Figure 11] It is a flowchart for explaining an optical waveform control method according to a third embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0015] 〔First Embodiment〕 FIG. 1 is a block diagram showing the configuration of an optical waveform control device 100 according to a first embodiment of the present invention. The optical waveform control device 100 includes a communication unit (communication means) 110, an optical signal-to-noise ratio acquisition unit (optical signal-to-noise ratio acquisition means) 120, a first control unit (first control means) 130, and a second control unit (second control means) 140. The optical waveform control device 100 is preferably used together with an optical submarine cable system.

[0016] The communication unit 110 communicates with a plurality of optical devices including at least a first optical device and a second optical device located downstream of the first optical device. The optical signal-to-noise ratio acquisition unit 120 receives an individual optical signal-to-noise ratio and an average optical signal-to-noise ratio via the communication unit 110. Here, the individual optical signal-to-noise ratio is the optical signal-to-noise ratio (Optical Signal to Noise Ratio: OSNR) for each wavelength channel of a wavelength division multiplexed optical signal propagated through a plurality of optical devices. The average optical signal-to-noise ratio is the average of the individual optical signal-to-noise ratios.

[0017] The first control unit 130 controls the optical output power of the first optical device via the communication unit 110 so that the optical input power of the optical amplifier in the second optical device is at a predetermined value. The second control unit 140 then controls at least one of the multiple optical devices via the communication unit 110 so that the individual optical signal noise ratio is equal to the average optical signal noise ratio. This makes it possible to optimize and keep the optical signal noise ratio (OSNR) of each wavelength channel in a wavelength-division multiplexed optical signal constant.

[0018] As described above, the optical waveform control device 100 of this embodiment is configured such that the optical signal noise ratio acquisition unit 120 receives individual optical signal noise ratios and average optical signal noise ratios, and the first control unit 130 and the second control unit 140 control multiple optical devices. Therefore, it is not necessary to individually adjust the equipment of multiple optical devices such as landing stations (CLS), inline amplifiers (ILA), and pop-up devices. As a result, control in the optical transmission system can be simplified.

[0019] Figure 2 shows the configuration of an optical transmission system 1000 equipped with an optical waveform control device according to this embodiment. The optical transmission system 1000 includes a plurality of optical devices, including at least a first optical device 1100 and a second optical device 1200 located downstream of the first optical device 1100, and an optical waveform control device 1400. The configuration of the optical waveform control device 1400 is the same as that of the optical waveform control device 100 described above. Figure 2 also shows a third optical device 1300 located at the last stage among the plurality of optical devices.

[0020] Here, multiple optical devices, including the first optical device 1100, the second optical device 1200, and the third optical device 1300, are connected to each other via optical fibers installed on land.

[0021] The first optical device 1100 is typically installed at a point of presence (POP) with a data center or backbone network. The second optical device 1200 can be configured to include an optical amplifier 1210 such as an in-line amplifier (ILA). The third optical device 1300 is typically installed at a cable landing station (CLS) of a submarine optical cable system and can be configured to connect to a submarine optical cable laid on the seabed. This configuration allows the termination point of the optical signal propagating through the submarine optical cable to be extended to a data center or POP.

[0022] The communication unit 1410 (110 in Figure 1) of the optical waveform control device 1400 communicates with multiple optical devices using an in-band communication signal 20 transmitted via an optical transmission path through which the wavelength-division multiplexed optical signal 10 propagates. This allows the optical waveform control device 1400 to acquire optical signal information of the wavelength-division multiplexed optical signal 10 from multiple optical devices and configure equipment such as optical amplifiers and wavelength-selective switches (WSS) in each optical device based on this information. Specifically, for example, an optical transceiver can be attached to the ports of a switching hub (Layer 2 switch) connected to each of the first optical device 1100, the second optical device 1200, and the third optical device 1300. Using these optical transceivers, optical signal information can be acquired via the optical transmission path using the in-band communication signal 20, and equipment settings can be configured.

[0023] The third optical device 1300 can be configured to include an Optical Channel Monitor (OCM) or an Optical Spectrum Analyzer (OSA). The optical signal noise ratio acquisition unit 120 (see Figure 1) of the optical waveform control device 1400 can acquire the individual optical signal noise ratio and the average optical signal noise ratio from the optical channel monitor (OCM) or optical spectrum analyzer (OSA) via the communication unit 110.

[0024] As described above, the first control unit 130 (see Figure 1) of the optical waveform control device 1400 controls the optical output power of the first optical device 1100 via the communication unit 1410 so that the optical input power of the optical amplifier 1210 of the second optical device 1200 becomes a predetermined value. The optical amplifier 1210 is typically an erbium-doped fiber amplifier (EDFA).

[0025] A predetermined value for the optical input power of the optical amplifier 1210 can be an optical input power value optimized to maximize the average optical signal-to-noise ratio. Here, the average optical signal-to-noise ratio is the average of the individual optical signal-to-noise ratios in the wavelength band of the wavelength-division multiplexed optical signal 10, as described above. When the optical input power of the optical amplifier 1210 changes, the wavelength dependence of the gain profile of the optical amplifier 1210 also changes. Therefore, depending on the gain characteristics of the optical amplifier 1210, there exists an optical input power value optimized to maximize the average optical signal-to-noise ratio.

[0026] As described above, the second control unit 140 of the optical waveform control device 1400 controls at least one of the multiple optical devices via the communication unit 110 so that the individual optical signal noise ratio is equal to the average optical signal noise ratio. This makes it possible to optimize and keep the optical signal noise ratio (OSNR) of each wavelength channel in the wavelength-division multiplexed optical signal 10 constant.

[0027] Next, the optical waveform control method according to this embodiment will be explained using the flowchart shown in Figure 3.

[0028] In the optical waveform control method according to this embodiment, first, the individual optical signal noise ratio and the average optical signal noise ratio of the wavelength-division multiplexed optical signal propagating through a plurality of optical devices are received (step S110). Here, the plurality of optical devices include at least a first optical device and a second optical device located downstream of the first optical device. The individual optical signal noise ratio is the optical signal noise ratio for each wavelength channel of the wavelength-division multiplexed optical signal. The average optical signal noise ratio is the average of the individual optical signal noise ratios.

[0029] Furthermore, the optical output power of the first optical device (the preceding optical device) is controlled so that the optical input power of the optical amplifier in the second optical device becomes a predetermined value (step S120). Then, at least one of the multiple optical devices is controlled so that the individual optical signal noise ratio is equal to the average optical signal noise ratio (step S130).

[0030] For step S110, for example, the optical signal noise ratio acquisition means is the main operator. For step S120, for example, the first control means is the main operator. And for step S130, for example, the second control means is the main operator.

[0031] As described above, the optical waveform control method of this embodiment accepts the individual optical signal noise ratio and the average optical signal noise ratio, and is configured to control multiple optical devices. Therefore, it is not necessary to individually adjust the equipment of multiple optical devices such as the landing station (CLS), inline amplifier (ILA), and POP device. As a result, control can be simplified in the optical transmission system.

[0032] The predetermined value of the optical input power of the optical amplifier described above is an optical input power value optimized to maximize the average optical signal-to-noise ratio.

[0033] Furthermore, the system may also be configured to communicate with multiple optical devices using an in-band method via an optical transmission path through which wavelength-division multiplexed optical signals propagate.

[0034] As described above, according to the optical waveform control device 100, optical transmission system 1000, and optical waveform control method of this embodiment, control can be simplified even when the termination point of the optical signal propagating through the optical submarine cable is extended in the optical transmission system.

[0035] [Second Embodiment] Next, a second embodiment of the present invention will be described. The configuration of the optical waveform control device according to this embodiment is the same as the configuration of the optical waveform control device 100 according to the first embodiment shown in Figure 1. That is, the optical waveform control device 100 has a communication unit (communication means) 110, an optical signal noise ratio acquisition unit (optical signal noise ratio acquisition means) 120, a first control unit (first control means) 130, and a second control unit (second control means) 140. The optical waveform control device 100 is preferably used in conjunction with an optical submarine cable system.

[0036] The communication unit 110 communicates with a plurality of optical devices, each including at least a first optical device and a second optical device located downstream of the first optical device. The optical signal-to-noise ratio acquisition unit 120 receives the individual optical signal-to-noise ratio and the average optical signal-to-noise ratio via the communication unit 110. Here, the individual optical signal-to-noise ratio is the optical signal-to-noise ratio (OSNR) for each wavelength channel of the wavelength-division multiplexed optical signal propagating through the plurality of optical devices. The average optical signal-to-noise ratio is the average of the individual optical signal-to-noise ratios.

[0037] The first control unit 130 controls the optical output power of the first optical device via the communication unit 110 so that the optical input power of the optical amplifier in the second optical device is at a predetermined value. The second control unit 140 controls at least one of the multiple optical devices via the communication unit 110 so that the individual optical signal noise ratio is equal to the average optical signal noise ratio.

[0038] In the optical waveform control device according to this embodiment, the first control unit (first control means) 130 controls the optical output power of the first optical device by controlling the optical attenuator provided in the first optical device.

[0039] Figure 4 shows the configuration of an optical transmission system 2000 equipped with an optical waveform control device according to this embodiment. The optical transmission system 2000 includes a plurality of optical devices, including at least a first optical device 1100 and a second optical device 1200 located downstream of the first optical device 1100, and an optical waveform control device 1400. The configuration of the optical waveform control device 1400 is the same as that of the optical waveform control device 100 described above. Figure 4 also shows the second optical device 2200 included in the plurality of optical devices and the third optical device 1300 located at the last stage of the plurality of optical devices. Since the second optical device 2200 is located downstream of the second optical device 1200, the second optical device 1200 functions as the first optical device 2100 in relation to the second optical device 2200.

[0040] Here, the first optical device 1100 is typically installed at a point of connection (POP) with a data center or backbone network. The third optical device 1300 is typically installed at a landing station (CLS) of an optical submarine cable system and can be configured to be connected to an optical submarine cable laid on the seabed. This configuration allows the termination point of optical signals propagating through the optical submarine cable to be extended to a data center or POP.

[0041] The optical transmission system 2000 is configured such that the first optical devices 1100 and 2100 are equipped with optical attenuators 1110 and 2110, and the second optical devices 1200 and 2200 are equipped with optical amplifiers 1210 and 2210. The second optical device 2200 is located before the third optical device 1300, which is the last stage. Therefore, the second optical device 2200 functions as the first optical device with respect to the third optical device 1300, and thus a configuration equipped with an optical attenuator 2111 is shown.

[0042] Optical attenuators 1110, 2110, and 2111 are typically variable optical attenuators (VOAs). Wavelength selective switches (WSSs) may also be used as optical attenuators 1110, 2110, and 2111.

[0043] As described above, the first control unit 130 (see Figure 1) of the optical waveform control device 1400 controls the optical output power of the first optical devices 1100 and 2100 so that the optical input power of the optical amplifiers 1210 and 2210 of the second optical devices 1200 and 2200 is set to a predetermined value. At this time, the first control unit 130 controls the optical output power of the first optical devices 1100 and 2100 by controlling the optical attenuators 1110 and 2110 of the first optical devices 1100 and 2100. Here, the predetermined value of the optical input power of the optical amplifiers 1210 and 2210 is an optical input power value optimized to maximize the average optical signal-to-noise ratio.

[0044] The optical input power of the optical amplifiers 1210 and 2210 is adjusted by the first control unit 130, which starts with the optical device on the transmitting side of the wavelength-division multiplexed optical signal 10 and then sequentially controls the subsequent optical devices. This optimizes all optical amplifiers 1210 and 2210 and maximizes the average optical signal-to-noise ratio.

[0045] Figure 5A shows an example of the optical spectrum of the wavelength-division multiplexed optical signal 10 transmitted by the first optical device 1100, which is located in the first stage of a group of optical devices. As the wavelength-division multiplexed optical signal 10, dummy light can be used, which is shaped into a comb-like waveform by controlling the bandwidth of amplified spontaneous emission (ASE) to either an odd or even channel, as shown in Figure 5A. Figure 5B shows an example of the optical spectrum of the wavelength-division multiplexed optical signal 10 in the third optical device 1300, which is in the final stage. Here, the wavelength-division multiplexed optical signal 10 has the maximum average optical signal-to-noise ratio.

[0046] As described above, the second control unit 140 of the optical waveform control device 1400 controls at least one of the multiple optical devices via the communication unit 110 so that the individual optical signal noise ratio is equal to the average optical signal noise ratio. This makes it possible to optimize and keep the optical signal noise ratio (OSNR) of each wavelength channel in the wavelength-division multiplexed optical signal 10 constant.

[0047] Next, the optical waveform control method according to this embodiment will be explained using the flowchart shown in Figure 6.

[0048] In the optical waveform control method according to this embodiment, first, the individual optical signal noise ratio and the average optical signal noise ratio of the wavelength-division multiplexed optical signal propagating through a plurality of optical devices are received (step S110). Here, the plurality of optical devices include at least a first optical device and a second optical device located downstream of the first optical device. The individual optical signal noise ratio is the optical signal noise ratio for each wavelength channel of the wavelength-division multiplexed optical signal. The average optical signal noise ratio is the average of the individual optical signal noise ratios.

[0049] Furthermore, the optical output power of the first optical device is controlled so that the optical input power of the optical amplifier in the second optical device becomes a predetermined value. In this case, the optical waveform control method according to this embodiment is configured to control the optical attenuator in the first optical device (preceding optical device) (step S220).

[0050] Then, at least one of the multiple optical devices is controlled so that the individual optical signal noise ratio is equal to the average optical signal noise ratio (step S130).

[0051] For step S110, for example, the optical signal noise ratio acquisition means is the main operator. For step SS220, for example, the first control means is the main operator. And for step S130, for example, the second control means is the main operator.

[0052] As described above, the optical waveform control method of this embodiment accepts the individual optical signal noise ratio and the average optical signal noise ratio, and is configured to control multiple optical devices. Therefore, it is not necessary to individually adjust the equipment of multiple optical devices such as the landing station (CLS), inline amplifier (ILA), and POP device. As a result, control can be simplified in the optical transmission system.

[0053] As described above, according to the optical waveform control device, optical transmission system 2000, and optical waveform control method of this embodiment, control can be simplified even when the termination point of an optical signal propagating through an optical submarine cable is extended in the optical transmission system.

[0054] [Third Embodiment] Next, a third embodiment of the present invention will be described. The configuration of the optical waveform control device according to this embodiment is the same as the configuration of the optical waveform control device 100 according to the first embodiment shown in Figure 1. That is, the optical waveform control device 100 has a communication unit (communication means) 110, an optical signal noise ratio acquisition unit (optical signal noise ratio acquisition means) 120, a first control unit (first control means) 130, and a second control unit (second control means) 140. The optical waveform control device 100 is preferably used in conjunction with an optical submarine cable system.

[0055] The communication unit 110 communicates with a plurality of optical devices, each including at least a first optical device and a second optical device located downstream of the first optical device. The optical signal noise ratio acquisition unit 120 receives the individual optical signal noise ratio and the average optical signal noise ratio via the communication unit 110. Here, the individual optical signal noise ratio is the optical signal noise ratio (OSNR) for each wavelength channel of the wavelength-division multiplexed optical signal propagating through the plurality of optical devices. The average optical signal noise ratio is the average of the individual optical signal noise ratios.

[0056] The first control unit 130 controls the optical output power of the first optical device via the communication unit 110 so that the optical input power of the optical amplifier in the second optical device is at a predetermined value. The second control unit 140 controls at least one of the multiple optical devices via the communication unit 110 so that the individual optical signal noise ratio is equal to the average optical signal noise ratio.

[0057] In the optical waveform control device according to this embodiment, the second control unit (second control means) 140 controls a dummy light generator provided in at least one of the multiple optical devices and adjusts the light intensity of the dummy light emitted by the dummy light generator.

[0058] Figure 7 shows the configuration of an optical transmission system 3000 equipped with an optical waveform control device according to this embodiment. The optical transmission system 3000 includes a plurality of optical devices, including at least a first optical device 1100 and a second optical device 1200 located downstream of the first optical device 1100, and an optical waveform control device 1400. At least one of the plurality of optical devices is configured to be equipped with a dummy light generator. In Figure 7, the first optical device 1100, located in the first stage of the plurality of optical devices, is shown to be equipped with a dummy light generator 3110. The other configurations are the same as those of the optical transmission system 2000 according to the second embodiment.

[0059] Here, the first optical device 1100 is typically installed at a point of connection (POP) with a data center or backbone network. The third optical device 1300 is typically installed at a landing station (CLS) of an optical submarine cable system and can be configured to be connected to an optical submarine cable laid on the seabed. This configuration allows the termination point of optical signals propagating through the optical submarine cable to be extended to a data center or POP.

[0060] The dummy light generator 3110 generates dummy light. As the dummy light generator 3110, for example, an ASE (Amplified Spontaneous Emission) light source can be used, which is an erbium-doped fiber amplifier (EDFA) in a state of no input signal.

[0061] As described above, the second control unit 140 (see Figure 1) of the optical waveform control device 1400 controls at least one of the multiple optical devices via the communication unit 1410 so that the individual optical signal noise ratio is equal to the average optical signal noise ratio. At this time, the second control unit 140 controls the dummy light generator 3110 and adjusts the light intensity of the dummy light emitted by the dummy light generator 3110.

[0062] In other words, the second control unit 140 controls the dummy light generator 3110 to adjust the peak levels of the wavelength-division multiplexed optical signal 10 so that the individual optical signal noise ratio values ​​are equal across the wavelength band of the wavelength-division multiplexed optical signal 10. At this point, the optical signal noise ratio acquisition unit 120 of the optical waveform control device 1400 receives the individual optical signal noise ratio and the average optical signal noise ratio via the communication unit 110.

[0063] The second control unit 140 adjusts the peak levels of the wavelength-division multiplexed optical signals 10 as follows: If the individual optical signal noise ratio of the target optical signal peak is higher than the average optical signal noise ratio, the dummy light generator 3110 is controlled to reduce the peak level by the difference. On the other hand, if the individual optical signal noise ratio of the target optical signal peak is lower than the average optical signal noise ratio, the dummy light generator 3110 is controlled to increase the peak level by the difference.

[0064] Figure 8A shows an example of the optical spectrum of the wavelength-division multiplexed optical signal 10 transmitted by the dummy light generator 3110 after the second control unit 140 has adjusted each peak level. Figure 8B shows an example of the optical spectrum of the wavelength-division multiplexed optical signal 10 at the third optical device 1300, the final stage, after it has propagated through the optical fiber connecting the multiple optical devices. As can be seen from the figures, the optical waveform control device and optical transmission system 3000 of this embodiment make it possible to keep the optical signal-to-noise ratio (OSNR) of each wavelength channel of the wavelength-division multiplexed optical signal 10 constant.

[0065] In the above description, the optical waveform control device 1400 is configured such that the second control unit 140 controls a dummy light generator provided in at least one of the multiple optical devices and adjusts the light intensity of the dummy light emitted by this dummy light generator. However, the second control unit 140 may also be configured to control a Wavelength Selectable Switch (WSS) provided in at least one of the multiple optical devices and adjust the light intensity of the wavelength-division multiplexed optical signal 10 emitted by this wavelength selectable switch.

[0066] Figure 9 shows the configuration of an optical transmission system 3001 equipped with an optical waveform control device configured as described above. In the optical transmission system 3001, at least one of the multiple optical devices is equipped with a wavelength selective switch (WSS). Figure 9 shows a configuration in which the second optical device 3200 is equipped with a wavelength selective switch 3210. Even with a configuration using the wavelength selective switch 3210, the optical signal-to-noise ratio (OSNR) of each wavelength channel of the wavelength-division multiplexed optical signal 10 can be kept constant.

[0067] Next, the optical waveform control method according to this embodiment will be explained using the flowchart shown in Figure 10.

[0068] In the optical waveform control method according to this embodiment, first, the individual optical signal noise ratio and the average optical signal noise ratio of the wavelength-division multiplexed optical signal propagating through a plurality of optical devices are received (step S110). Here, the plurality of optical devices include at least a first optical device and a second optical device located downstream of the first optical device. The individual optical signal noise ratio is the optical signal noise ratio for each wavelength channel of the wavelength-division multiplexed optical signal. The average optical signal noise ratio is the average of the individual optical signal noise ratios.

[0069] Furthermore, the optical output power of the first optical device (the preceding optical device) is controlled so that the optical input power of the optical amplifier in the second optical device reaches a predetermined value (step S120).

[0070] Then, at least one of the multiple optical devices is controlled so that the individual optical signal noise ratio is equal to the average optical signal noise ratio. In this case, the optical waveform control method according to this embodiment is configured to adjust the light intensity of the dummy light emitted by a dummy light generator provided in at least one of the multiple optical devices (step S331). However, it is also possible to adjust the light intensity of the wavelength-division multiplexed optical signal emitted by a wavelength-selective switch provided in at least one of the multiple optical devices (step S332).

[0071] For step S110, for example, the optical signal noise ratio acquisition means is the main operator. For step SS120, for example, the first control means is the main operator. Furthermore, for steps S331 and S332, for example, the second control means is the main operator.

[0072] As described above, the optical waveform control method of this embodiment accepts the individual optical signal noise ratio and the average optical signal noise ratio, and is configured to control multiple optical devices. Therefore, it is not necessary to individually adjust the equipment of multiple optical devices such as the landing station (CLS), inline amplifier (ILA), and POP device. As a result, control can be simplified in the optical transmission system.

[0073] Furthermore, in the optical waveform control method of this embodiment, controlling the optical output power may include controlling the optical output power before and after the step of controlling at least one of a plurality of optical devices. Figure 11 shows a flowchart of the optical waveform control method with such a configuration. The step of controlling the optical output power (S120) may also involve controlling the optical output power before and after the step of controlling optical devices such as a dummy light generator or a wavelength selective switch (S330).

[0074] Specifically, after the step of controlling optical devices such as a dummy light generator and a wavelength selective switch (S330), it is determined whether a predetermined condition is met (step S340). Here, the predetermined condition can be, for example, that the difference between the individual optical signal noise ratio and the average optical signal noise ratio is less than or equal to a predetermined amount across the entire wavelength band of the wavelength-division multiplexed optical signal. Alternatively, the predetermined condition may be that the number of times steps S120 and S330 have been performed has reached a predetermined number of times. If the predetermined condition is met (step S340 / YES), the process ends. If the predetermined condition is not met (step S340 / NO), the process returns to the step of controlling the optical output power (S120).

[0075] The step (S330) of controlling the optical device so that the individual optical signal noise ratio is equal to the average optical signal noise ratio may cause the optical input power of the optical amplifier to deviate from a predetermined value. However, even in such cases, according to the optical waveform control method shown in Figure 11, the optical input power can be optimized by repeating the step (S120) of controlling the optical output power of the preceding optical device.

[0076] As described above, according to the optical waveform control device, optical transmission system 3000, and optical waveform control method of this embodiment, control can be simplified even when the termination point of the optical signal propagating through the optical submarine cable is extended in the optical transmission system.

[0077] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0078] (Note 1) An optical waveform control device comprising: communication means for communicating with a plurality of optical devices, each including at least a first optical device and a second optical device located downstream of the first optical device; optical signal noise ratio acquisition means for receiving, via the communication means, an individual optical signal noise ratio which is the optical signal noise ratio for each wavelength channel of a wavelength-division multiplexed optical signal propagated through the plurality of optical devices, and an average optical signal noise ratio which is the average of the individual optical signal noise ratios; a first control means for controlling the optical output power of the first optical device via the communication means so that the optical input power of the optical amplifier provided in the second optical device becomes a predetermined value; and a second control means for controlling at least one of the plurality of optical devices via the communication means so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio.

[0079] (Note 2) The first control means is an optical waveform control device as described in Note 1, which controls the optical output power of the first optical device by controlling the optical attenuator provided in the first optical device.

[0080] (Note 3) The second control means is an optical waveform control device as described in Note 1 or 2, which controls a dummy light generator provided in at least one of the plurality of optical devices and adjusts the light intensity of the dummy light emitted by the dummy light generator.

[0081] (Note 4) The optical waveform control device described in Note 1 or 2, wherein the second control means controls a wavelength selection switch provided in at least one of the plurality of optical devices and adjusts the optical intensity of the wavelength division multiplexed optical signal transmitted by the wavelength selection switch.

[0082] (Note 5) The communication means is an optical waveform control device described in any one of Notes 1 to 4, which communicates with the plurality of optical devices by an in-band method via an optical transmission path through which the wavelength-division multiplexed optical signal propagates.

[0083] (Note 6) The optical waveform control device described in any one of Notes 1 to 5, wherein the predetermined value is an optical input power value optimized to maximize the average optical signal noise ratio.

[0084] (Note 7) An optical transmission system comprising: a plurality of optical devices, each comprising a first optical device and a second optical device located downstream of the first optical device; and an optical waveform control device, wherein the second optical device comprises an optical amplifier; the optical waveform control device comprises: communication means for communicating with each of the plurality of optical devices; optical signal noise ratio acquisition means for receiving, via the communication means, an individual optical signal noise ratio which is the optical signal noise ratio for each wavelength channel of a wavelength-division multiplexed optical signal propagated through the plurality of optical devices, and an average optical signal noise ratio which is the average of the individual optical signal noise ratios; first control means for controlling the optical output power of the first optical device via the communication means so that the optical input power of the optical amplifier becomes a predetermined value; and second control means for controlling at least one of the plurality of optical devices via the communication means so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio.

[0085] (Note 8) The optical transmission system described in Note 7, wherein the first optical device comprises an optical attenuator, and the first control means controls the optical output power of the first optical device by controlling the optical attenuator.

[0086] (Note 9) An optical transmission system as described in Note 7 or 8, wherein at least one of the plurality of optical devices comprises a dummy light generator, and the second control means controls the dummy light generator and adjusts the light intensity of the dummy light emitted by the dummy light generator.

[0087] (Note 10) An optical transmission system as described in Note 7 or 8, wherein at least one of the plurality of optical devices is equipped with a wavelength selector switch, and the second control means controls the wavelength selector switch and adjusts the light intensity of the wavelength division multiplexed optical signal transmitted by the wavelength selector switch.

[0088] (Note 11) The communication means is an optical transmission system described in any one of Notes 7 to 10, which communicates with the plurality of optical devices by an in-band method via an optical transmission path through which the wavelength-division multiplexed optical signal propagates.

[0089] (Note 12) The optical transmission system described in any one of Notes 7 to 11, wherein the predetermined value is an optical input power value optimized to maximize the average optical signal noise ratio.

[0090] (Note 13) The optical transmission system described in any one of Notes 7 to 12, wherein the plurality of optical devices are connected to each other via optical fibers installed on land, and the third optical device located at the rear of the plurality of optical devices is connected to an optical submarine cable installed on the seabed.

[0091] (Note 14) An optical waveform control method that receives the individual optical signal noise ratio, which is the optical signal noise ratio for each wavelength channel, and the average optical signal noise ratio, which is the average of the individual optical signal noise ratios, of a wavelength-division multiplexed optical signal propagating through a plurality of optical devices, which include at least a first optical device and a second optical device located downstream of the first optical device, and controls the optical output power of the first optical device so that the optical input power of the optical amplifier provided in the second optical device becomes a predetermined value, and controls at least one of the plurality of optical devices so that the individual optical signal noise ratio becomes equal to the average optical signal noise ratio.

[0092] (Note 15) The optical waveform control method described in Note 14, wherein controlling the optical output power includes controlling the optical attenuator provided in the first optical device.

[0093] (Appendix 16) The optical waveform control method described in Appendix 14 or 15, wherein controlling at least one of the plurality of optical devices includes adjusting the light intensity of dummy light emitted by a dummy light generator provided in at least one of the plurality of optical devices.

[0094] (Appendix 17) The optical waveform control method described in Appendix 14 or 15, wherein controlling at least one of the plurality of optical devices includes adjusting the light intensity of the wavelength-division multiplexed optical signal transmitted by a wavelength-selective switch provided in at least one of the plurality of optical devices.

[0095] (Note 18) An optical waveform control method described in any one of Notes 14 to 17, further comprising communicating with the plurality of optical devices in an in-band manner via an optical transmission path through which the wavelength-division multiplexed optical signal propagates.

[0096] (Note 19) The optical waveform control method described in any one of Notes 14 to 18, wherein the predetermined value is an optical input power value optimized to maximize the average optical signal noise ratio.

[0097] (Note 20) The optical waveform control method described in any one of Notes 14 to 19, wherein controlling the optical output power includes controlling the optical output power in a step before and after the step of controlling at least one of the plurality of optical devices.

[0098] Although the present invention has been described above with reference to embodiments, the present invention is not limited to the above embodiments. Various modifications to the structure and details of the present invention can be made, which can be understood by those skilled in the art within the scope of the present invention. [Explanation of Symbols]

[0099] 100, 1400 Optical Waveform Control Device 110, 1410 Communications Department 120 Optical signal noise ratio acquisition unit 130 First control unit 140 Second control unit 1000, 2000, 3000, 3001 Optical Transmission Systems 1100, 2100 First optical device 1110, 2110, 2111 Optical attenuators 1200, 2200 Second optical device 1210, 2210 Optical Amplifiers 1300 Third Optical Device 3110 Dummy Light Generator 3210 Wavelength Selective Switch 10 wavelength multiplexed optical signal 20 In-band communication signals

Claims

1. A communication means for communicating with each of a plurality of optical devices, each including a first optical device and a second optical device located downstream of the first optical device, An optical signal noise ratio acquisition means that receives, via the communication means, the individual optical signal noise ratio, which is the optical signal noise ratio for each wavelength channel of the wavelength-division multiplexed optical signal propagating through the plurality of optical devices, and the average optical signal noise ratio, which is the average of the individual optical signal noise ratios. A first control means controls the optical output power of the first optical device via the communication means so that the optical input power of the optical amplifier of the second optical device becomes a predetermined value, The system includes a second control means that controls at least one of the plurality of optical devices via the communication means based on the individual optical signal noise ratio and the average optical signal noise ratio, controls a dummy light generator provided in at least one of the plurality of optical devices, and adjusts the light intensity of the dummy light emitted by the dummy light generator. Optical waveform control device.

2. The optical waveform control device according to claim 1, wherein the second control means controls at least one of the plurality of optical devices such that the individual optical signal noise ratio is equal to the average optical signal noise ratio.

3. The first control means controls the optical output power of the first optical device by controlling the optical attenuator provided in the first optical device. An optical waveform control device according to claim 1 or 2.

4. The second control means controls a wavelength selection switch provided in at least one of the plurality of optical devices and adjusts the light intensity of the wavelength-division multiplexed optical signal transmitted by the wavelength selection switch. An optical waveform control device according to claim 1 or 2.

5. The communication means communicates with the plurality of optical devices in an in-band manner via an optical transmission path through which the wavelength-division multiplexed optical signal propagates. An optical waveform control device according to claim 1 or 2.

6. The predetermined value is an optical input power value optimized to maximize the average optical signal-to-noise ratio. An optical waveform control device according to claim 1 or 2.

7. A plurality of optical devices, including at least a first optical device and a second optical device located downstream of the first optical device, It has an optical waveform control device, The second optical device includes an optical amplifier, The optical waveform control device is A communication means for communicating with each of the aforementioned multiple optical devices, An optical signal noise ratio acquisition means that receives, via the communication means, the individual optical signal noise ratio, which is the optical signal noise ratio for each wavelength channel of the wavelength-division multiplexed optical signal propagating through the plurality of optical devices, and the average optical signal noise ratio, which is the average of the individual optical signal noise ratios. A first control means controls the optical output power of the first optical device via the communication means so that the optical input power of the optical amplifier becomes a predetermined value, The system includes a second control means that controls at least one of the plurality of optical devices via the communication means based on the individual optical signal noise ratio and the average optical signal noise ratio, controls a dummy light generator provided in at least one of the plurality of optical devices, and adjusts the light intensity of the dummy light emitted by the dummy light generator. Optical transmission system.

8. The optical transmission system according to claim 7, wherein the second control means controls at least one of the plurality of optical devices such that the individual optical signal noise ratio is equal to the average optical signal noise ratio.

9. The first optical device includes an optical attenuator, The first control means controls the optical output power of the first optical device by controlling the optical attenuator. The optical transmission system according to claim 7 or 8.

10. An optical waveform control method used in an optical waveform control device comprising an optical signal noise ratio acquisition means, a first control means and a second control means, The optical signal noise ratio acquisition means, The optical device receives the individual optical signal noise ratio, which is the optical signal noise ratio for each wavelength channel, and the average optical signal noise ratio, which is the average of the individual optical signal noise ratios, of a wavelength-division multiplexed optical signal propagating through a plurality of optical devices, which include at least a first optical device and a second optical device located downstream of the first optical device. The first control means, The optical output power of the first optical device is controlled so that the optical input power of the optical amplifier in the second optical device becomes a predetermined value. The second control means, Based on the individual optical signal noise ratio and the average optical signal noise ratio, at least one of the plurality of optical devices is controlled. Controlling a dummy light generator provided in at least one of the aforementioned multiple optical devices, Adjusting the light intensity of the dummy light emitted by the dummy light generator. A method for controlling optical waveforms.

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