Apparatus, method and reconfigurable optical add-drop multiplexer for generating a false optical signal

Abstract

The embodiment of the application discloses a device for generating a false light signal, which is applied to the field of communication and comprises: a light source module for generating a first wavelength signal and a second wavelength signal, the first wavelength signal having N first channels, and the second wavelength signal having M second channels; and a polarization light combiner for polarization combining the first wavelength signal and the second wavelength signal and outputting a false light signal, the false light signal having N+M channels. Wherein, the polarization state of the wavelength signal in any one first channel and the polarization state of the wavelength signal in the second channel are orthogonal. The application can make the polarization states of the wavelength signals in the first channel and the second channel of the false light signal orthogonal, so that the wavelength signal of one channel forms the false light signal of one channel, thereby reducing the cost.

Description

Technical Field

[0001] This application relates to the field of communications, and more particularly to an apparatus, method for generating spurious optical signals, and a reconfigurable optical add-drop multiplexer. Background Technology

[0002] Submarine cable communication systems have high requirements for transmission stability. The coefficients must always operate according to the designed number of channels to ensure the long-term stable operation of optical devices in the system, such as optical amplifier repeaters.

[0003] However, in the initial stages of system deployment, the number of operational optical signals may not be sufficient to meet the capacity of the designed number of channels. Therefore, dummy light signals are needed to fill channels without operational optical signals. Specifically, to reduce the nonlinear overhead of the dummy light signal on the operational optical signal, the wavelength signal in a dummy light channel is a combination of two wavelength signals with orthogonal polarization states. When a channel is not filled with operational optical signals, this wavelength signal is combined and added to that channel.

[0004] Forming a wavelength signal bundle (i.e., a pseudo-optical signal from one channel) requires two wavelength signals from the same channel, which is costly. Summary of the Invention

[0005] This application provides an apparatus, method, and reconfigurable optical add-drop multiplexer for generating dummy optical signals, which allows the wavelength signals of the dummy optical signals in the first and second channels to be orthogonal, thereby forming a dummy optical signal for one channel from the wavelength signals of one channel, thus reducing costs.

[0006] This application provides an apparatus for generating a dummy optical signal. The apparatus includes: a light source module for generating a first wavelength signal and a second wavelength signal. The first wavelength signal has N first channels, and the second wavelength signal has M second channels, where N and M are integers greater than 0. The channels represent the frequency distribution of signal transmission in a wavelength division multiplexing (WDM) system as defined by the International Telecommunication Union (ITU-T). The frequency distribution range of the first wavelength signal can be equal to the frequency distribution range of the N first channels. A polarization beam combiner is used to polarize and combine the first wavelength signal and the second wavelength signal to output a dummy optical signal. The dummy optical signal has N+M channels, which include the N first channels and the M second channels; that is, the frequency distribution range of the dummy optical signal includes the frequency distribution range of the first wavelength signal and the frequency distribution range of the second wavelength signal. In the N+M channels of the dummy optical signal, the polarization state of the wavelength signal in any first channel is orthogonal to the polarization state of the wavelength signal in any second channel.

[0007] In this application, when the polarization states of the wavelength signals in any of the first and second channels are orthogonal, the nonlinear cost of the dummy optical signal to the service optical signal can be reduced. Furthermore, by forming a dummy optical signal from one channel's wavelength signal, the cost is reduced.

[0008] In one alternative approach of the first aspect, the first channel is an odd-numbered channel, and the second channel is an even-numbered channel. Specifically, when the N+M channels are arranged in order of wavelength, the first and second channels alternate. In practical applications, wavelength signals on lower-frequency channels generally exhibit better performance, such as a higher signal-to-noise ratio, thus providing better quality of service. Therefore, the service optical signal typically replaces the dummy optical signal starting with the lower-frequency channels out of the N+M channels. For example, if N+M is 120, and the service optical signal has 60 channels, the service optical signal will first replace the 60 lower-frequency channels out of the 120 channels. Therefore, after replacement by the service optical signal, the number of channels in the remaining dummy optical signal is similar for both the first and second channels. This minimizes the nonlinear cost of the remaining dummy optical signal to the service optical signal. Therefore, by limiting the first channel to an odd number and the second channel to an even number, nonlinear costs can be minimized while providing better quality of service.

[0009] In one alternative embodiment of the first aspect, the light source module includes a first light source, a second light source, a first combiner, and a second combiner. The first light source generates multiple first light beams, and the first combiner combines the multiple first light beams into a first wavelength signal. The second light source generates multiple second light beams, and the second combiner combines the multiple second light beams into a second wavelength signal. By adding more combiners, the number of polarization beam combiners can be reduced, thereby lowering costs.

[0010] In an alternative embodiment of the first aspect, the device further includes a polarization controller. The polarization controller adjusts the polarization states of the plurality of first beams or the plurality of second beams generated by the light source module, such that the polarization states of the plurality of first beams and the plurality of second beams are orthogonal. The laser beams generated by the light source module are linearly polarized. When the linear polarization directions of the laser beams generated by the first and second light sources are the same, adding a polarization controller can make the polarization states of the laser beams generated by the first and second light sources orthogonal. Therefore, the device can use the same first and second light sources, thereby reducing subsequent maintenance costs for the light sources.

[0011] In one alternative embodiment of the first aspect, the polarization controller is specifically used to adjust the polarization state of the first wavelength signal or the second wavelength signal such that the polarization states of the first wavelength signal and the second wavelength signal are orthogonal. Wherein, by placing the polarization controller after the combiner, the number of polarization controllers can be reduced, thereby lowering the cost.

[0012] In one alternative approach of the first aspect, the N+M channels encompass the same wavelength range as the C-band.

[0013] In one alternative approach of the first aspect, N equals M. In practical applications, there may be situations where no service optical signal replaces the dummy optical signal. When N equals M, the dummy optical signal itself has orthogonal polarization states, thereby reducing the nonlinear cost of the dummy optical signal itself.

[0014] In an alternative embodiment of the first aspect, the apparatus further includes: a wavelength selective switch for receiving a dummy optical signal and a service optical signal, and outputting a target optical signal based on the dummy optical signal and the service optical signal. The target optical signal has N+M channels, and the dummy optical signal in the target optical signal is used to fill the channels among the N+M channels that do not transmit service optical signals. Filling the channels that do not transmit service optical signals with dummy optical signals can also be understood as the service optical signal replacing the dummy optical signal in certain channels.

[0015] In one alternative of the first aspect, the target optical signal includes a first service optical signal, which is used to replace a dummy optical signal having the same channel as the first service optical signal, and the optical power of the first service optical signal is equal to the optical power of the dummy optical signal having the same channel.

[0016] In one alternative embodiment of the first aspect, the difference between the number of first channels and the number of second channels in the channels of the service optical signal is equal to 0 or 1. Wherein, when N equals M, the difference between the number of first channels and the number of second channels in the channels of the remaining dummy optical signal after being replaced by the service optical signal is equal to 1 or 0. Therefore, the nonlinear cost of the remaining dummy optical signal to the service optical signal can be minimized as much as possible.

[0017] A second aspect of this application provides a method for generating a dummy optical signal. The method includes: generating a first wavelength signal and a second wavelength signal through a light source module, wherein the first wavelength signal has N first channels and the second wavelength signal has M second channels, where N and M are integers greater than 0; and combining the first wavelength signal and the second wavelength signal using a polarization beam combiner to output a dummy optical signal. The dummy optical signal has N+M channels, including N first channels and M second channels. In the N+M channels of the dummy optical signal, the polarization state of the wavelength signal in any first channel is orthogonal to the polarization state of the wavelength signal in any second channel.

[0018] In one alternative approach of the second aspect, the first channel is an odd-numbered channel and the second channel is an even-numbered channel.

[0019] In one alternative embodiment of the second aspect, the light source module includes a first light source, a second light source, a first multiplexer, and a second multiplexer.

[0020] The method further includes: generating N first beams through the first light source, and combining the N first beams into a first wavelength signal through the first combiner; generating M second beams through the second light source, and combining the M second beams into a second wavelength signal through the second combiner.

[0021] In an alternative embodiment of the second aspect, the method further includes: adjusting the polarization states of the N first beams or M second beams generated by the light source module using a polarization controller, such that the polarization states of the N first beams and the polarization states of the N second beams are orthogonal.

[0022] In one alternative approach of the second aspect, the polarization state of the first wavelength signal or the second wavelength signal is adjusted by the polarization controller such that the polarization state of the first wavelength signal and the polarization state of the second wavelength signal are orthogonal.

[0023] In one alternative approach of the second aspect, the N+M channels encompass the same wavelength range as the C-band.

[0024] In one alternative approach to the second aspect, N equals M.

[0025] In an alternative embodiment of the second aspect, the method further includes: outputting a target optical signal via a wavelength selective switch, the target optical signal having N+M channels, and using dummy optical signals to fill the channels in the target optical signal that do not transmit service optical signals.

[0026] In one alternative embodiment of the second aspect, the target optical signal includes a first service optical signal, which is used to replace a dummy optical signal having the same channel as the first service optical signal, and the optical power of the first service optical signal is equal to the optical power of the dummy optical signal having the same channel.

[0027] In one alternative of the second aspect, the difference between the number of the first channel and the number of the second channel in the channels of the service optical signal is equal to 0 or 1.

[0028] A third aspect of this application provides a reconfigurable optical add-drop multiplexer (ROADM). The ROADM includes: a multiplexing module, an uplink module, and a device for generating dummy optical signals as described in the first aspect or any optional embodiment of the first aspect. The multiplexing module is used to acquire the dummy optical signals generated by the device, receive the dummy optical signals generated by the device, receive service optical signals from the uplink module, and output a target optical signal based on the dummy optical signals and the service optical signals. The target optical signal has N+M channels, and the dummy optical signals in the target optical signal are used to fill the channels among the N+M channels that do not transmit service optical signals. The target optical signal is then sent to the demultiplexing module.

[0029] In one alternative of the third aspect, the target optical signal includes a first service optical signal, which is used to replace a dummy optical signal having the same channel as the first service optical signal, and the optical power of the first service optical signal is equal to the optical power of the dummy optical signal having the same channel.

[0030] In one alternative approach of the third aspect, the difference between the number of the first channel and the number of the second channel in the channels of the service optical signal is equal to 0 or 1. Specifically, when N equals M, the difference between the number of the first channel and the number of the second channel in the channels of the remaining dummy optical signal after being replaced by the service optical signal is equal to 1 or 0. Therefore, the nonlinear cost of the remaining dummy optical signal to the service optical signal can be minimized as much as possible. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a submarine optical fiber transmission system; Figure 2 A schematic diagram of a device for generating spurious optical signals; Figure 3a Another schematic diagram of a device for generating spurious optical signals; Figure 3b This is a schematic diagram showing the distribution of spurious optical signals in two channels; Figure 4a This is a schematic diagram of the device for generating spurious optical signals provided in this application; Figure 4b This is a schematic diagram showing the distribution of spurious optical signals in the two channels provided in this application; Figure 5 This is a schematic diagram of the distribution of the spurious optical signal in the channel provided in the embodiments of this application; Figure 6 This is another schematic diagram of the device for generating spurious optical signals provided in this application; Figure 7 This is a schematic diagram of the output spectrum of the mode-locked laser provided in this application; Figure 8 This is another schematic diagram of the device for generating spurious optical signals provided in this application; Figure 9 This is another schematic diagram of the device for generating spurious optical signals provided in this application; Figure 10 This is another schematic diagram of the device for generating spurious optical signals provided in this application; Figure 11 This is another schematic diagram of the device for generating spurious optical signals provided in this application; Figure 12 This is a schematic diagram showing the distribution of dummy optical signals and service optical signals provided in this application; Figure 13 This is a schematic diagram of the structure of the ROADM provided in this application. Detailed Implementation

[0032] This application provides an apparatus, method, and reconfigurable optical add-drop multiplexer for generating dummy optical signals. This application allows the wavelength signal polarization states of the dummy optical signal to be orthogonal in the first and second channels, thereby forming a single-channel dummy optical signal from the wavelength signal of one channel, reducing costs. It should be understood that features or contents marked with dashed lines in the accompanying drawings of the embodiments of this application can be interpreted as optional operations or optional structures of the embodiments of this application. In the description of the embodiments of this application, terms such as "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance, nor as indicating or implying order.

[0033] The apparatus and method for generating dummy optical signals provided in this application are applicable to the field of communications, specifically, to the field of optical fiber communication (including terrestrial optical fiber transmission systems and submarine optical fiber transmission systems). The application scenario of the apparatus and method provided in this application will be described below using a submarine optical fiber transmission system as an example. Submarine optical fiber transmission systems have high requirements for transmission stability; the system must always operate at the designed wavenumber to ensure the long-term stable operation of units such as optical amplifiers in the line. However, in the initial stage of system deployment, the operating service optical signal may not necessarily meet the system's design capacity. Therefore, it is necessary to configure dummy optical signals to fill the remaining channels.

[0034] like Figure 1 As shown, Figure 1This is a schematic diagram of a submarine optical fiber transmission system. The system includes a transmitter and a receiver, which are connected by an optical fiber on the submarine. The transmitter includes a wavelength selective switch (WSS) 101 and an optical amplifier 102. WSS 101 receives dummy optical signals and service optical signals, and outputs the target optical signal based on these signals. Specifically, WSS 101 fills the channels without service optical signals with dummy optical signals, ensuring all channels have wavelength signals. When a new channel of service optical signal is added, WSS 101 reduces the wavelength signal of the dummy optical signal on the corresponding channel. For example, assuming WSS 101 has 120 channels, with 40 channels for service optical signals and the remaining 80 channels for dummy optical signals, when a new channel of service optical signal is added, WSS 1 reduces the number of channels for dummy optical signals. In this case, the target optical signal output by WSS 101 has 41 channels for service optical signals and 79 channels for dummy optical signals. Optical amplifier 102 receives the target optical signal output from WSS101 and amplifies the power of the target optical signal. Then, the target optical signal is transmitted to the receiving end via submarine optical fiber. Optical amplifier 103 in the receiving end amplifies the target optical signal again, and then inputs the target optical signal into WSS104.

[0035] Therefore, a device capable of generating dummy optical signals is needed to provide dummy optical signals to the WSS101. For example... Figure 2 As shown, Figure 2 This is a schematic diagram of a device for generating a dummy optical signal. The device includes an optical fiber amplifier 201, a filter 202, and an optical fiber amplifier 203. Optical fiber amplifiers 201 and 203 are erbium-doped fiber application amplifiers (EDFAs). Optical fiber amplifier 201 outputs a broadband amplified spontaneous emission (ASE) source through spontaneous emission. The ASE source is filtered by filter 202 to become the desired seed dummy optical signal. Optical fiber amplifier 203 uses a pump source to excite erbium ions in the baseband to a high-energy state, causing population inversion. This generates stimulated emission, amplifying the seed dummy optical signal and outputting the dummy optical signal.

[0036] However, this device requires multiple components, and the low integration of fiber optic amplifiers results in a large device size. Therefore, a laser light source based on semiconductor materials can be used to generate a dummy light signal. Figure 3a This is another schematic diagram of a device for generating spurious optical signals. (See diagram below.) Figure 3aAs shown, the device includes two semiconductor-based lasers 301. The two lasers 301 generate two wavelength signals with single polarization states (also called linear polarization states). A polarization beam combiner 302 combines the two wavelength signals to output a single channel of dummy light signal. Figure 3b This is a schematic diagram showing the distribution of spurious optical signals in two channels. (For example...) Figure 3b As shown, since the two wavelength signals generated by laser 301 share the same channel, the dummy optical signal formed by the two wavelength signals also shares a channel. One channel (ch40) of the dummy optical signal is the combined beam of wavelength signals 303 and 304. To reduce the polarization dependency cost of the dummy optical signal on the service optical signal, the polarization states of wavelength signals 303 and 304 are orthogonal. However, if the frequency difference between wavelength signals 303 and 304 is less than 5 GHz, the dummy optical signal will introduce additional nonlinear costs to the service optical signal. Therefore, the frequencies of wavelength signals 303 and 304 need to be offset by 5–20 GHz. Similarly, the combined beam of wavelength signals 305 and 306 generates another channel (ch41) of the dummy optical signal. Figure 3b It is known that forming a dummy optical signal in one channel requires two wavelength signals from the same channel (e.g., wavelength signal 303 and wavelength signal 304, or wavelength signal 305 and wavelength signal 306). Therefore, the cost of this device is relatively high. Here, "same channel" means that the channel of the required wavelength signal and the channel of the formed dummy optical signal are the same.

[0037] To address this, this application provides an apparatus for generating a dummy optical signal. By orthogonalizing the polarization states of the wavelength signals in the first channel and the second channel, the polarization dependency cost of the dummy optical signal on the service optical signal is reduced. Therefore, a dummy optical signal for one channel can be generated from the wavelength signal of one channel, thereby reducing costs. Figure 4a This is a schematic diagram of the device for generating spurious optical signals provided in this application. Figure 4a As shown, the device includes a light source module 401. The light source module 401 generates a first wavelength signal and a second wavelength signal, which belong to different light source beams, such as different laser beams. The first wavelength signal has N first channels, and the second wavelength signal has M second channels, where N and M are integers greater than 0. The following description assumes N and M equal to 1. Assume the first channel is ch40 and the second channel is ch41. A polarization combiner 402 performs polarization combining on the first and second wavelength signals, outputting dummy light signals for both channels. The dummy light signals have N+M channels, including N first channels and M second channels. Figure 4b This is a schematic diagram showing the distribution of spurious optical signals in the two channels provided in this application. For example... Figure 4bAs shown, the dummy optical signals of the two channels have ch40 and ch41, which are two adjacent channels. Since the first wavelength signal and the second wavelength signal each have two channels, the resulting dummy optical signal also has two channels. The dummy optical signals of the two channels are the combined beams of wavelength signals 403 and 404. The polarization states of wavelength signals 403 and 404 are orthogonal, meaning that the polarization state of the wavelength signal in any one of the first channels and the polarization state of the wavelength signal in any one of the second channels are orthogonal. Therefore, two channels of dummy optical signals can be formed using the first wavelength signal and the second wavelength signal respectively; that is, the wavelength signal of one channel forms the dummy optical signal of one channel. Specifically, the dummy optical signal ch40 is formed using the first wavelength signal, and the dummy optical signal ch41 is formed using the second wavelength signal. It should be noted that ch40 and ch41 here are only illustrative examples. In practical applications, the first and second channels may not be adjacent.

[0038] The relationship between the first wavelength signal and wavelength signal 403 is described in detail below. The light source module 401 can generate either a circularly polarized laser beam or a linearly polarized laser beam. If the first wavelength signal is a circularly polarized laser beam, the polarizing beam combiner 402 acts as a polarizer, meaning wavelength signal 403 is the wavelength signal after the first wavelength signal has passed through the polarizer. If the first wavelength signal is a linearly polarized laser beam, the polarizing beam combiner 402 acts as an analyzer, meaning wavelength signal 403 is the wavelength signal after the first wavelength signal has passed through the analyzer. Similarly, the relationship between the second wavelength signal and wavelength signal 404 can be referenced to the relationship between the first wavelength signal and wavelength signal 403.

[0039] The above describes the scenario where N and M equal 1, resulting in two channels of spurious optical signal. In practical applications, spurious optical signals can form more channels. The following describes the apparatus for generating spurious optical signals in this application, using N equal to M as an example. Figure 5 As shown, Figure 5 This is a schematic diagram showing the distribution of the spurious optical signal in the channel according to an embodiment of this application. Figure 5 In this diagram, ch1, ch2, ch3…ch2N are ordered according to wavelength. The first channel is an odd-numbered channel, including ch1, ch3, ch5…ch2N-1. The second channel is an even-numbered channel, including ch2, ch4, ch6…ch2N. The wavelength signals in ch1 and ch2 are orthogonal in polarization state, and the wavelength signals in ch2 and ch3 are orthogonal in polarization state. To achieve… Figure 5 The distribution of the spurious light signal shown indicates that the device for generating the spurious light signal requires two light sources.

[0040] Figure 6This is another schematic diagram of the device for generating spurious optical signals provided in this application. Figure 6 As shown, a first light source 601 generates a first wavelength signal, which has N first channels. A second light source 602 generates a second wavelength signal, which has N second channels. A polarization beam combiner 603 combines the first and second wavelength signals to output a dummy light signal.

[0041] The first light source 601 and the second light source 602 can be semiconductor lasers, such as distributed feedback (DFB) lasers or mode-locked lasers. In practical applications, the output bandwidth of the laser is limited, or in other words, the output wavelength range is limited. For example, ... Figure 7 As shown, Figure 7 This is a schematic diagram of the output spectrum of the mode-locked laser provided in this application. The effective output wavelength range of the mode-locked laser shown in the diagram is approximately 1556.5~1572.5nm, and the effective wavelength range is approximately 16nm. When a dummy optical signal is needed to cover the C-band channel, the wavelength range of the dummy optical signal is 1524.5~1572.5nm. Based on a 50GHz channel spacing for Dense Wavelength Division Multiplexing (DWDM), the channels are divided into ch1, ch2, ch3…ch120. That is, N and M equal 60. Since the first and second channels are arranged alternately... Figure 7 The mode-locked laser shown serves as the first light source 601. The wavelength signal output interval of the mode-locked laser is 100 GHz, meaning it can output one wavelength signal every other channel. A single mode-locked laser effectively outputs 20 wavelength signals. Since N equals 60, three mode-locked lasers are needed as the first light source 601.

[0042] Figure 8 This is another schematic diagram of the device for generating spurious optical signals provided in this application. Figure 8The illustrated device includes a first light source 801 and a second light source 802. The first light source 801 includes laser 1, laser 2, and laser 3. Laser 1 generates wavelength signals in 20 channels (ch1, ch3…ch39). Laser 2 generates wavelength signals in 20 channels (ch41, ch43…ch79). Laser 3 generates wavelength signals in 20 channels (ch81, ch83…ch119). The second light source 802 includes laser 4, laser 5, and laser 6. Laser 4 generates wavelength signals in 20 channels (ch2, ch4…ch40). Laser 5 generates wavelength signals in 20 channels (ch42, ch44…ch80). Laser 6 generates wavelength signals in 20 channels (ch82, ch84…ch120).

[0043] like Figure 8 As shown, the device also includes a first combiner 803 and a second combiner 804. The first combiner 803 receives three beams output from the first light source 801 and combines them into one beam to obtain a first wavelength signal. The second combiner 804 receives three beams output from the second light source 802 and combines them into one beam to obtain a second wavelength signal. The first wavelength signal has 60 channels (ch1, ch3…ch119), and the second wavelength signal has 60 channels (ch2, ch4…ch120). A polarization beam combiner 805 receives the first and second wavelength signals, performs polarization beam combining, and outputs a pseudo-light signal. The pseudo-light signal has 120 channels with continuous spectral distribution (ch1 to ch120). The polarization states of the first and second wavelength signals can be orthogonal or non-orthogonal. When the polarization states of the first and second wavelength signals are orthogonal, they are linearly polarized laser beams. At this point, the polarization beam combiner 805 acts as an analyzer, and it does not change the polarization states of the first and second wavelength signals. Therefore, the polarization states of the wavelength signals in the first channel (odd-numbered channels) and the wavelength signals in the second channel (even-numbered channels) contained in the dummy light signal are orthogonal. When the polarization states of the first and second wavelength signals are not orthogonal, the first and second wavelength signals can be circularly polarized laser beams. In this case, the polarization beam combiner 805 acts as a polarizer. The polarization beam combiner 805 converts the circularly polarized first wavelength signal into a linearly polarized first wavelength signal, and the circularly polarized second wavelength signal into a linearly polarized second wavelength signal. Therefore, the polarization states of the wavelength signals in the first channel (linearly polarized first wavelength signal) and the wavelength signals in the second channel (linearly polarized second wavelength signal) of the dummy light signal are orthogonal.

[0044] It should be noted that alternating the arrangement of the first and second channels is an optional approach in this application. In practical applications, other implementation schemes are also possible. For example, ... Figure 9 As shown, Figure 9 This is another schematic diagram of the device for generating spurious optical signals provided in this application. Figure 8 The assumptions remain unchanged, for example, N and M equal 60. The device includes a first light source 901 and a second light source 902. The first light source 901 includes laser 1 and laser 2. Laser 1 is used to generate wavelength signals of 30 channels (ch1, ch2...ch30). Laser 2 is used to generate wavelength signals of 30 channels (ch61, ch62...ch90). The second light source 902 includes laser 4 and laser 5. Laser 4 is used to generate wavelength signals of 30 channels (ch31, ch32...ch60). Laser 5 is used to generate wavelength signals of 30 channels (ch91, ch92...ch120).

[0045] Laser 1 is still Figure 7 The mode-locked laser shown. Figure 7 The mode-locked laser shown has an effective wavelength range of approximately 16 nm. When the wavelength signal output interval of the mode-locked laser is 100 GHz, a single mode-locked laser effectively outputs 20 channels of wavelength signal; when the wavelength signal output interval of the mode-locked laser is 50 GHz, a single mode-locked laser effectively outputs 40 channels of wavelength signal. Therefore, Figure 9 Laser 1 still has surplus output capability; that is, laser 1 is capable of outputting wavelength signals through 40 channels, but only outputs 30 of them. Figure 9 In the first channel, there are ch1, ch2…ch30, ch61, ch62…ch90; the second channel includes ch31, ch32…ch60, ch91, ch92…ch120.

[0046] like Figure 9 As shown, the device also includes a first combiner 903, a second combiner 904, and a polarization beam combiner 905. The first combiner 903 receives two wavelength signals generated by laser 1 and laser 2, combines the two wavelength signals, and outputs a first wavelength signal. The second combiner 904 receives two wavelength signals generated by laser 4 and laser 5, combines the two wavelength signals, and outputs a second wavelength signal. The polarization beam combiner 905 receives the first wavelength signal and the second wavelength signal, performs polarization beam combining on the first wavelength signal and the second wavelength signal, and outputs a dummy light signal.

[0047] Compared to Figure 8 The device in Figure 9The device reduces the number of lasers by changing the distribution of the first and second channels. Furthermore, it reduces the influence of the transition band.

[0048] Specifically, such as Figure 7 As shown, the effective output wavelength range of a mode-locked laser is 1556.5~1572.5nm. However, in the wavelength range below 1556.5nm (also known as the transition band) and in the wavelength range above 1572.5nm (also known as the transition band), the mode-locked laser still outputs wavelength signals. It's just that the spurious light signal doesn't need these wavelengths, or the power of these wavelengths doesn't meet the power requirements. Figure 8 For example, the wavelength range output by laser 1 corresponds to wavelengths ch1, ch3…ch39. Based on the description of the transition bands above, it can be seen that in some channels above ch39, such as ch41, laser 1 will also output a wavelength signal on ch41. For ease of description, the wavelength signal output by laser 1 on ch41 is called wavelength signal 1, and the wavelength signal output by laser 2 on the ch41 channel is called wavelength signal 2. When the first combiner 803 combines the three beams output by the first light source 801, wavelength signal 1 will affect wavelength signal 2. Specifically, wavelength signal 1 will reduce the power of wavelength signal 2, resulting in power loss. Conversely, the wavelength signal generated by laser 2 on ch39 will also affect the wavelength signal of laser 1 on ch39. And… Figure 9 In this example, laser 1 outputs wavelengths corresponding to ch1, ch2…ch30, while laser 2 outputs wavelengths corresponding to ch61, ch62…ch90. The number of channels between ch61 and ch30 is greater than the number of channels between ch41 and ch39. Specifically, the number of channels between ch61 and ch30 is 30, and the number of channels between ch41 and ch39 is 1. Therefore, ch61 may not be within the transition band of laser 1, thus reducing the influence of the transition band and lowering power loss. Similarly, in… Figure 3b In this context, the number of channels between ch40 and ch41 is 0.

[0049] Based on the above Figure 3a As described in the device description, the frequencies of the two wavelength signals within a channel need to be offset by 5–20 GHz. For example, wavelength signals 303 and 304. When the channel is in the laser's transition band, in addition to the two wavelength signals within the channel itself, the channel will also include a wavelength signal generated by the laser. For example, Figure 3bCh40 includes wavelength signals 303 and 304. Assume wavelength signal 303 is generated by laser 1, wavelength signal 304 by laser 2, wavelength signal 305 by laser 3, and wavelength signal 306 by laser 4. Based on the above description of the transition bands, Ch40 is located within the transition band between lasers 3 and 4. Therefore, laser 3 outputs wavelength signal 3 on Ch40, and laser 4 outputs wavelength signal 4 on Ch40. Thus, Ch40 includes wavelength signals 303, 304, 3, and 4. Wavelength signal 3 can be considered to correspond to wavelength signal 303, and wavelength signal 304 to wavelength signal 4. Specifically, wavelength signals 3 and 305 are both generated by laser 3; therefore, the linear polarization direction of wavelength signal 3 is the same as that of wavelength signal 5. Figure 3b It is known that wavelength signals 303 and 305 have the same linear polarization direction. Therefore, wavelength signal 303 and wavelength signal 3 have the same linear polarization direction, meaning wavelength signal 3 corresponds to wavelength signal 303. Similarly, it can be seen that wavelength signals 304 and 4 have the same linear polarization direction, meaning wavelength signal 4 corresponds to wavelength signal 304. Furthermore, since the output frequency of semiconductor lasers is easily affected by temperature, it is particularly difficult to stagger the four wavelength signals by more than 5 GHz within 50 GHz. Below 5 GHz, dummy optical signals will introduce additional nonlinear costs to the service optical signal. In this application, a dummy optical signal is formed from the wavelength signal of one channel. Therefore, even if the channel is in a transition band, the channel will only add one wavelength signal. Therefore, compared to... Figure 3a The device described in this application, within the 50 GHz range, can relatively easily stagger two wavelength signals by more than 5 GHz. Therefore, it can reduce the nonlinear cost of spurious optical signals to service optical signals.

[0050] It should be understood that the above Figure 8 and Figure 9 This is merely an example from this application. In practical applications, there are many more alternative approaches.

[0051] For example, a polarization beam combiner is placed between a laser and a beam combiner. Figure 8 Based on, Figure 10This is another schematic diagram of the apparatus for generating dummy optical signals provided in this application. Polarization beam combiner 1001 receives two wavelength signals generated by lasers 1 and 4, and performs polarization beam combining on the two wavelength signals. Similarly, polarization beam combiner 1002 receives two wavelength signals generated by lasers 2 and 5. Polarization beam combiner 1003 receives two wavelength signals generated by lasers 4 and 6. A beam combiner 1004 receives the wavelength signals output from polarization beam combiners 1001, 1002, and 1003 to obtain a dummy optical signal. Figure 8 The device requires two multiplexers. Figure 10 The device requires one multiplexer. Therefore, with Figure 8 Compared to the device in the middle, Figure 10 The device in the middle can reduce the number of multiplexers.

[0052] For example, in Figure 8 In this configuration, the device may not include lasers 2 and 5. That is, the generated spurious optical signal has 80 channels with discontinuous spectral distributions, namely channels ch1 to ch40 and ch81 to ch120. Therefore, the device for generating spurious optical signals can produce spurious optical signals with discontinuous channels.

[0053] For example, in Figure 9 In this design, laser 3 is added to the first light source 901, and laser 6 is added to the second light source 902. Laser 1 generates wavelength signals through 20 channels (ch1, ch2...ch20). Laser 2 generates wavelength signals through 20 channels (ch61, ch62...ch80). Laser 3 generates wavelength signals through 20 channels (ch101, ch102...ch120). A first combiner receives the three wavelength signals generated by lasers 1, 2, and 3, and combines them to generate the first wavelength signal. Similarly, lasers 4-6 each generate the remaining 20 wavelength signals. A second combiner receives the three wavelength signals generated by lasers 4, 5, and 6, and combines them to generate the second wavelength signal. Generally, the more channels a laser outputs, the more expensive it is. Figure 9 In the previous embodiment, the laser needed to output wavelength signals with 30 channels; in this embodiment, the laser needs to output wavelength signals with 20 channels. Therefore, by reducing the number of laser output channels, this embodiment can reduce the output capability requirements of the device generating spurious optical signals.

[0054] For example, in Figure 9Based on this, laser 1 generates wavelength signals with 15 channels (ch1, ch3...ch29), and laser 2 generates wavelength signals with 15 channels (ch61, ch63...ch89). A first combiner receives the two wavelength signals generated by lasers 1 and 2, and combines them to generate the first wavelength signal. Laser 4 generates wavelength signals with 15 channels (ch32, ch34...ch60), and laser 5 generates wavelength signals with 15 channels (ch92, ch94...ch120). A second combiner receives the two wavelength signals generated by lasers 4 and 5, and combines them to generate the second wavelength signal. At this point, the number of channels between ch61 and ch29 is 30. Figure 8 In comparison, this can further reduce the impact of the transition band.

[0055] The following is based on Figure 8 Taking the device shown as an example, the technical solution provided in this application will be further expanded. For example... Figure 11 As shown, Figure 11 This is another schematic diagram of the device for generating spurious optical signals provided in this application.

[0056] The device includes a first light source 1101, a second light source 1102, a first multiplexer 1103, and a second multiplexer 1104. For a description of this part, please refer to the foregoing description of the first light source 801, the second light source 802, the first multiplexer 803, and the second multiplexer 804.

[0057] As described above, if the first light source 1101 generates a circularly polarized laser beam (first wavelength signal), then the polarization beam combiner 1105 acts as a polarizer. In this case, the polarization beam combiner 1105 will attenuate the first wavelength signal, resulting in power waste. Therefore, the first light source 1101, which generates a linearly polarized laser beam, can be used instead. Furthermore, using the same light source simplifies later operation and maintenance compared to using different light sources. For better later operation and maintenance, it is desirable that the first light source 1101 and the second light source 1102 are identical, meaning that the linear polarization directions generated by the first light source 1101 and the second light source 1102 are the same. In this case, if the first wavelength signal and the second wavelength signal are directly input into the polarization beam combiner 1105, then the polarization beam combiner 1105 acts as an analyzer. Since the first wavelength signal and the second wavelength signal have the same linear polarization direction, one of the wavelength signals will be attenuated to the maximum extent by the polarization beam combiner 1105, resulting in power waste. Therefore, in this embodiment of the application, a polarization controller 1106 is provided between the second combiner 1104 and the polarization beam combiner 1105. The polarization controller 1106 is used to change the linear polarization direction of the second wavelength signal, so that the polarization state of the first wavelength signal and the polarization state of the second wavelength signal are orthogonal, thereby reducing the power attenuation of the first wavelength signal or the second wavelength signal by the polarization beam combiner 1105.

[0058] It should be understood that Figure 11 The location of the polarization controller 1106 is merely an example. In practical applications, the polarization controller 1106 can also be positioned between the second light source 1102 and the second combiner 1104. Specifically, the polarization controller includes polarization controller 1, polarization controller 2, and polarization controller 3. Polarization controller 1 is used to change the linear polarization direction of the wavelength signal output by laser 4. Polarization controller 2 is used to change the linear polarization direction of the wavelength signal output by laser 5. Polarization controller 3 is used to change the linear polarization direction of the wavelength signal output by laser 6.

[0059] The device also includes a WSS1108 and an Optical Transform Unit (OTU) 1107. The OTU1107 transmits service optical signals to the WSS1108. The WSS1108 receives dummy optical signals and service optical signals, and outputs a target optical signal based on these signals. The target optical signal has N+M channels, and the dummy optical signals in the target optical signal are used to fill the N+M channels that do not transmit service optical signals. Figure 12 For example. Figure 12 This is a schematic diagram showing the distribution of dummy optical signals and service optical signals provided in this application. (Regarding...) Figure 12 For a description of the spurious optical signal, please refer to [link / reference]. Figure 5 The corresponding description. In Figure 12In the target optical signal, the service optical signal has ch1, ch2, ch3, and ch6, or the service optical signal has ch1, ch2, ch3, and ch6. Therefore, dummy optical signals are used to fill the target optical signal on ch4, ch5, ch7~ch2N where no service optical signal is transmitted, or the service optical signal is used to replace the dummy optical signal that has the same channels (ch1, ch2, ch3, and ch6) as the service optical signal.

[0060] In other embodiments, the difference between the number of the first channel and the number of the second channel in the channels of the service optical signal is equal to 0 or 1. For example, as Figure 12 As shown, ch1 and ch3 are the first channels, and ch2 and ch6 are the second channels. The difference between the number of first channels and the number of second channels is 0. At this point, in the remaining spurious optical signals (wavelength signals on ch4, ch5, ch7~ch2N), the number of first channels and the number of second channels are the same, meaning the wavelength signals of the first channels and the wavelength signals of the second channels form orthogonal polarization states in a one-to-one correspondence. Therefore, the nonlinear cost of the remaining spurious optical signals to the service optical signal can be minimized as much as possible.

[0061] In other embodiments, the target optical signal includes a first service optical signal, which is used to replace a dummy optical signal having the same channel as the first service optical signal. The optical power of the first service optical signal is equal to the optical power of the dummy optical signal having the same channel. For example, such as Figure 12 As shown, the first service optical signal is the wavelength signal on ch1. The power of the wavelength signal on ch1 is equal to the power of the dummy optical signal on ch1 that is being replaced.

[0062] This application also provides a method for generating spurious optical signals. Specifically, this method is based on the above... Figure 4a , Figure 6 , Figure 8 , Figure 9 , Figure 10 or Figure 11 The described apparatus generates spurious optical signals. The corresponding functions are performed through modules or components within the apparatus.

[0063] The apparatus for generating spurious optical signals in this application has been described above; the ROADM in this application will be described below. Figure 13 As shown, Figure 13 This is a schematic diagram of the structure of the ROADM provided in this application.

[0064] The ROADM includes: a multiplexing module 1301, a demultiplexing module 1302, an uplink module 1303, and the aforementioned... Figure 4a , Figure 6 , Figure 8 , Figure 9 , Figure 10or Figure 11 The device 1305 described for generating spurious optical signals, and the multiplexing module 1301 can be a wavelength selection switch.

[0065] The multiplexing module 1301 acquires the dummy optical signal generated by the dummy optical signal generating device 1305, receives the service optical signal from the uplink module 1303, and outputs a target optical signal based on the dummy optical signal and the service optical signal. The target optical signal has N+M channels, and the dummy optical signals in the target optical signal are used to fill the channels among the N+M channels that do not transmit service optical signals. The target optical signal is then sent to the demultiplexing module 1302. For example, the multiplexing module 1301 selects to output the service optical signal in the channels with service optical signals and selects to output the dummy optical signal in the channels without service optical signals. Therefore, the output target optical signal can contain both service optical signals and dummy optical signals. The spectral range of the service optical signal is usually within the spectral range of the dummy optical signal. Of course, the spectral range of the service optical signal can also completely overlap with the spectral range of the dummy optical signal. Specifically, the dummy optical signal has M+N channels, the service optical signal has X channels (the spectral range of these X channels is within the spectral range of the M+N channels), and the target optical signal contains X service optical signals and (M+NX) dummy optical signals. The multiplexing module 1301 can also send the target optical signal to the demultiplexing module 1302.

[0066] In other embodiments, the ROADM also includes a transmitter 1304 for transmitting service optical signals to an uplink module 1303, which amplifies the power of the service optical signals.

[0067] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A device for generating spurious optical signals, characterized in that, include: A light source module is used to generate a first wavelength signal and a second wavelength signal. The first wavelength signal has N first channels, and the second wavelength signal has M second channels, where N and M are integers greater than 0. A polarization beam combiner is used to polarize and combine the first wavelength signal and the second wavelength signal to output a pseudo-optical signal. The pseudo-optical signal has N+M channels, including the N first channels and the M second channels. In the N+M channels of the dummy optical signal, the polarization state of the wavelength signal of any first channel and the polarization state of the wavelength signal of any second channel are orthogonal, N is equal to M, and the dummy optical signal is used to fill the channels in the N+M channels that do not transmit service optical signals. The difference between the number of first channels and the number of second channels in the channels with service optical signals is equal to 0 or 1.

2. The apparatus according to claim 1, characterized in that, The first channel is an odd-numbered channel, and the second channel is an even-numbered channel.

3. The apparatus according to any one of claims 1 or 2, characterized in that, The light source module includes a first light source, a second light source, a first combiner, and a second combiner. Wherein, the first light source is used to generate a plurality of first beams, and the first combiner is used to combine the plurality of first beams into a first wavelength signal; The second light source is used to generate multiple second beams, and the second combiner is used to combine the multiple second beams into a second wavelength signal.

4. The apparatus according to any one of claims 1 or 2, characterized in that, The device also includes a polarization controller; The polarization controller is used to adjust the polarization state of the plurality of first beams or the plurality of second beams generated by the light source module, so that the polarization states of the plurality of first beams and the polarization states of the plurality of second beams are orthogonal.

5. The apparatus according to claim 4, characterized in that, The polarization controller is specifically used to adjust the polarization state of the first wavelength signal or the second wavelength signal so that the polarization state of the first wavelength signal and the polarization state of the second wavelength signal are orthogonal.

6. The apparatus according to any one of claims 1 or 2, characterized in that, The N+M channels include the same wavelength range as the C-band.

7. A method for generating a false optical signal, characterized in that, include: A first wavelength signal and a second wavelength signal are generated by a light source module. The first wavelength signal has N first channels, and the second wavelength signal has M second channels, where N and M are integers greater than 0. The first wavelength signal and the second wavelength signal are combined by a polarization beam combiner to output a pseudo light signal. The pseudo light signal has N+M channels, including the N first channels and the M second channels. In the N+M channels of the dummy optical signal, the polarization state of the wavelength signal of any first channel and the polarization state of the wavelength signal of any second channel are orthogonal, N is equal to M, and the dummy optical signal is used to fill the channels in the N+M channels that do not transmit service optical signals. The difference between the number of first channels and the number of second channels in the channels with service optical signals is equal to 0 or 1.

8. The method according to claim 7, characterized in that, The first channel is an odd-numbered channel, and the second channel is an even-numbered channel.

9. The method according to claim 7 or 8, characterized in that, The light source module includes a first light source, a second light source, a first combiner, and a second combiner. The method further includes: Multiple first beams are generated by the first light source; The first beam combiner combines the plurality of first beams into the first wavelength signal. Multiple second beams are generated by the second light source; The second beam combiner combines the plurality of second beams into the second wavelength signal.

10. The method according to any one of claims 7 or 8, characterized in that, The method further includes: The polarization state of the multiple first beams or multiple second beams generated by the light source module is adjusted by the polarization controller so that the polarization states of the multiple first beams and the multiple second beams are orthogonal.

11. The method according to claim 10, characterized in that, Specifically, the polarization state of the first wavelength signal or the second wavelength signal is adjusted by the polarization controller so that the polarization state of the first wavelength signal and the polarization state of the second wavelength signal are orthogonal.

12. The method according to any one of claims 7 or 8, characterized in that, The N+M channels include the same wavelength range as the C-band.

13. The method according to any one of claims 7 or 8, characterized in that, The method further includes: The dummy optical signal and the service optical signal are received by a wavelength selective switch, and a target optical signal is output according to the dummy optical signal and the service optical signal. The target optical signal has N+M channels, and the dummy optical signal in the target optical signal is used to fill the channels in the N+M channels that do not transmit the service optical signal.

14. The method according to claim 13, characterized in that, The target optical signal includes a first service optical signal, which is used to replace a fake optical signal that has the same channel as the first service optical signal. The optical power of the first service optical signal is equal to the optical power of the fake optical signal that has the same channel.

15. A reconfigurable optical add-drop multiplexer, characterized in that, include: A beam combiner module, an uplink module, and the apparatus for generating spurious optical signals as described in any one of claims 1 to 6; The wavelength division multiplexing module is used to acquire the dummy optical signal generated by the device, receive the service optical signal from the uplink module, and output a target optical signal based on the dummy optical signal and the service optical signal. The target optical signal has the N+M channels. The dummy optical signal in the target optical signal is used to fill the channels in the N+M channels that do not transmit the service optical signal, and to send the target optical signal to the wavelength division multiplexing module.

16. The reconfigurable optical add-drop multiplexer according to claim 15, characterized in that, The target optical signal includes a first service optical signal, which is used to replace a fake optical signal that has the same channel as the first service optical signal. The optical power of the first service optical signal is equal to the optical power of the fake optical signal that has the same channel.

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