Optical test device, optical transmitter, test method, and communication method

Abstract

The embodiments of the present application are applied to the technical field of optical communications. Provided are an optical test device, an optical transmitter, a test method, and a communication method. The optical test device is used for receiving a first optical signal. The first optical signal comprises an optical signal of at least one channel. At least one pilot signal is carried on an optical signal of each channel, and different pilot signals are carried on optical signals of the corresponding channel having different spectral ranges. The pilot signals have different phases, and the same pilot signal having different phases is carried on different spectral partitions of a corresponding spectral range of an optical signal. The sum of the powers of at least one pilot signal of the same channel is less than a certain threshold. The optical power of an optical signal within a spectral range in which the at least one pilot signal is located is obtained on the basis of the first optical signal. In the present embodiment, the problem of SRS crosstalk in transmission of the pilot signal is avoided when an optical communication performance test is performed on the basis of the pilot signal.

Description

Optical detection device, optical transmitter, detection method and communication method

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 22, 2023, with application number 202311796311.9 and application name “A light detection device, light transmitter, detection method and communication method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of optical communication technology, and in particular to an optical detection device, an optical transmitter, a detection method, and a communication method. Background Art

[0003] In the field of optical communications, multiple network nodes are constructed, forming an optical communication system based on optical fibers for optical communication. During optical communication, one or more network nodes can use corresponding optical transmitters to modulate service information onto service optical signals on different channels, and then transmit and transmit these service optical signals through optical fibers. Similarly, network nodes can also receive corresponding service optical signals from optical fibers and parse them to obtain the corresponding service information, completing the reception of service information. Typically, to ensure normal optical communication between multiple network nodes, it is necessary to test the optical communication performance of each channel.

[0004] An existing detection method is to divide the optical signal into different channels according to the spectrum range, and the transmitter can communicate based on one or more channels. Each channel is divided into different spectrum ranges. Pilot signals corresponding to different frequencies are modulated on the optical signals in different spectrum ranges. One or more optical detection devices are set up in the optical communication system. Each optical detection device can obtain pilot signals in different spectrum ranges from the optical fiber to detect the optical communication performance of each channel. However, in actual applications, due to the stimulated Raman scattering (SRS) effect during optical fiber transmission, crosstalk will occur between pilot signals of different frequencies between multiple channels, thereby affecting the detection accuracy of optical communication performance.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide an optical detection device, an optical transmitter, a detection method, and a communication method, which improve the detection accuracy of optical communication performance.

[0007] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0008] In a first aspect, an optical detection device is provided, comprising a filter and a signal processing structure. The filter is configured to receive a first optical signal, the first optical signal comprising an optical signal of at least one channel, the optical signal of each channel carrying at least one pilot signal, different pilot signals corresponding to different spectrum ranges within the channel, pilot signals having different phases, and the same pilot signal with different phases corresponding to different spectrum partitions of the spectrum range. The sum of the powers of at least one pilot signal of the same channel is less than a certain threshold. The first optical signal is filtered to obtain at least one filtered optical signal, the at least one filtered optical signal carrying at least one pilot signal. The signal processing structure is configured to obtain, based on the at least one filtered optical signal, the optical power of the optical signal within the spectrum range where the at least one pilot signal resides.

[0009] In an embodiment of the present application, by partitioning the optical signal of a channel into different spectral regions corresponding to the same pilot signal in different phases, power cancellation can be performed between the same pilot signals of different phases during transmission, so that the sum of the powers of the same pilot signals of multiple phases satisfies a certain threshold, thereby ensuring that the sum of the powers of at least one pilot signal of the same channel is less than a certain threshold. Ideally, power cancellation can be achieved between the same pilot signals of different phases during transmission, so that the sum of the powers of the same pilot signal is zero. However, due to processing errors on the transmitting side, transmission errors in optical fiber transmission, and detection errors during detection, the actual detected value of the sum of the powers of the same pilot signal may not be zero. Therefore, in practical applications, as long as the sum of the powers of at least one pilot signal of the same channel is ensured to be less than a certain threshold, the problem of SRS power crosstalk between pilot signals of different channels carried on the optical signal can be avoided, thereby improving the transmission accuracy of the pilot signal. This threshold can be a detection threshold affected by the above-mentioned processing errors, transmission errors, and detection errors, or a preset certain threshold. At the optical detection device, a filter can be used to separate the pilot signals of different phases within the corresponding channel's optical signal, ensuring proper reception and processing of the pilot signals. This allows for optical power detection based on the pilot signals. Optical power is a fundamental parameter for optical communication performance testing, and therefore, this method enables accurate detection of optical communication performance.

[0010] In one possible embodiment, half the length of the filter's spectrum period is greater than or equal to the length of the spectrum partition. The signal processing structure includes a first photodetector, a second photodetector, and a data processor. The filter is configured to filter the first optical signal to obtain at least one filtered optical signal, the at least one filtered optical signal including a first filtered optical signal and a second filtered optical signal. The first filtered optical signal and the second filtered optical signal are consistent with the spectrum range of the optical signal of at least one channel. The first photodetector is configured to perform photoelectric conversion on the first filtered optical signal to obtain a first filtered electrical signal. The second photodetector is configured to perform photoelectric conversion on the second filtered optical signal to obtain a second filtered electrical signal. The data processor is specifically configured to determine, based on the first filtered electrical signal and the second filtered electrical signal, the optical power of an optical signal within the spectrum range of at least one pilot signal. In an embodiment of the present application, filtering processing can be performed based on the filter to separate the same pilot signal of different phases into different filtered optical signals (for example, separating pilot signals of different phases into a first filtered optical signal and a second filtered optical signal). By performing photoelectric processing on the at least one filtered optical signal, a corresponding filtered electrical signal is obtained. The data processor can detect optical communication performance, such as optical power, based on the filtered electrical signal.

[0011] In one possible embodiment, the at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; at least one pilot signal includes a first pilot signal, the first filtered optical signal carries a first pilot signal of a first phase, and the second filtered optical signal carries a first pilot signal of a second phase; the first phase and the second phase differ by 180°. In an embodiment of the present application, for the same pilot signal, two different phases can be set, and the two phases are inversely phased (i.e., a phase difference of 180°). Based on the two inversely phased phases, the power of the same pilot signal during transmission can be better adjusted (i.e., power cancellation can be achieved between the inversely phased phases during transmission), so that the sum of its powers remains zero within a threshold range over time during transmission, thereby avoiding the crosstalk problem of pilot signals between multiple channels.

[0012] In one possible implementation, depending on the application scenario and actual needs, filters with different cycle lengths can be selected to filter and separate the pilot signal to match channels with different code types. At the same time, the pilot signal can also be modulated in different ways. Several typical cases are illustrated below:

[0013] In some examples, the same pilot signal with different phases may correspond to a fixed spectrum partition.

[0014] In some examples, the same pilot signal of different phases corresponds to different spectrum partitions, and in different time slots, the same pilot signal of the same phase corresponds to different spectrum partitions. At this time, at least one pilot signal also includes a second pilot signal. In the first time slot, the first filtered optical signal carries the second pilot signal of the first phase, and the second filtered optical signal carries the second pilot signal of the second phase. In the second time slot, the first filtered optical signal carries the second pilot signal of the second phase, and the second filtered optical signal carries the second pilot signal of the first phase, and the first time slot and the second time slot alternate with each other. In an embodiment of the present application, pilot signals of different phases can also be modulated on the optical signal in different time slots to achieve a sum of the powers of at least one pilot signal of the same channel that is less than a certain threshold.

[0015] Exemplarily, the spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel. The length of one-quarter of the filter cycle is equal to the area length of the spectrum partition. On the optical signal of the corresponding channel, a second spectral partition is separated between the second pilot signal of the first phase and the second pilot signal of the second phase. In the first time slot, the second pilot signal of the first phase corresponds to the first spectral partition of the first filtered optical signal, and the second pilot signal of the second phase corresponds to the third spectral partition of the second filtered optical signal. The first spectral partition, the second spectral partition, and the third spectral partition are three adjacent spectral partitions. In the second time slot, the second pilot signal of the second phase corresponds to the first spectral partition of the first filtered optical signal, and the second pilot signal of the first phase corresponds to the third spectral partition of the second filtered optical signal. In this embodiment of the present application, depending on the code type, a second spectral partition with an interval can be set between the pilot signals of the two phases. The second spectral partition and the third spectral partition carrying the second pilot signal of the second phase can form an output signal spectrum with a length of half a filter cycle. This achieves the filtering and separation of the second pilot signal of the first phase and the pilot signal of the second phase into different filtered optical signals.

[0016] Exemplarily, the optical signal corresponding to the channel also carries a reference pilot signal, which corresponds to the second spectral partition of the second filtered optical signal and has a frequency different from that of at least one pilot signal. The data processor is further configured to determine a stimulated Raman scattering crosstalk level of the second pilot signal based on the first filtered electrical signal and the second filtered electrical signal. In this embodiment of the present application, signal processing can be performed based on the reference pilot signal and the second pilot signal to detect the stimulated Raman scattering crosstalk level of the second pilot signal.

[0017] Exemplarily, the spectrum range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectrum range division of the optical signal of the at least one channel. The quarter cycle length of the filter is equal to the partition length of the spectrum partition. In the first time slot, the second pilot signal of the first phase corresponds to the first spectrum partition of the first filtered optical signal, and the second pilot signal of the second phase corresponds to the second spectrum partition of the second filtered optical signal. In the second time slot, the second pilot signal of the second phase corresponds to the first spectrum partition of the first filtered optical signal, and the second pilot signal of the first phase corresponds to the second spectrum partition of the second filtered optical signal. There is no corresponding pilot signal on the third spectrum partition of the second filtered optical signal, and the first spectrum partition, the second spectrum partition and the third spectrum partition are three spectrum partitions adjacent in sequence. In an embodiment of the present application, the first spectrum partition and the second spectrum partition can be set on the output signal spectra of two different half-cycle lengths of the filter, so as to realize the filtering and separation of the second pilot signal of the first phase and the second pilot signal of the second phase to different filtered optical signals.

[0018] Exemplarily, the spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel. The length of one quarter of the filter cycle is equal to the partition length of the spectrum partition. In the first time slot, the second pilot signal of the first phase corresponds to the first spectral partition of the first filtered optical signal, and the second pilot signal of the second phase corresponds to the second and third spectral partitions of the second filtered optical signal; the first spectral partition, the second spectral partition, and the third spectral partition are three adjacent spectral partitions. In the second time slot, the second pilot signal of the second phase corresponds to the first spectral partition of the first filtered optical signal, and the second pilot signal of the first phase corresponds to the second and third spectral partitions of the second filtered optical signal. The modulation signal amplitude of the second pilot signal corresponding to the second and third spectral partitions is half the modulation signal amplitude of the second pilot signal corresponding to the first spectral partition. In this embodiment of the present application, the second and third spectral partitions can form an output signal spectrum with a length of half a filter cycle. This achieves the filtering and separation of the second pilot signal of the first phase and the pilot signal of the second phase into different filtered optical signals. However, since the second spectrum partition and the third spectrum partition both carry second pilot signals of the same phase, in order to ensure power cancellation between the second pilot signals on the second spectrum partition and the third spectrum partition and the second pilot signal on the first spectrum partition, the signal amplitude (i.e., the modulation signal amplitude) of the second pilot signals on the second spectrum partition and the third spectrum partition can be halved.

[0019] In some possible implementations, at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal. The spectrum range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectrum range division of the optical signal of the at least one channel. The length of one quarter cycle of the filter is equal to the partition length of the spectrum partition. At least one pilot signal includes a third pilot signal. In a first time slot, the third pilot signal with a third phase corresponds to the second spectrum partition of the first filtered optical signal, and the third pilot signal with a fourth phase corresponds to the third spectrum partition of the second filtered optical signal. There is a phase difference of 120° between the third phase and the fourth phase. In a second time slot, the third pilot signal with a third phase corresponds to the first spectrum partition of the first filtered optical signal, and the third pilot signal with a fourth phase corresponds to the second spectrum partition of the second filtered optical signal. The first spectrum partition, the second spectrum partition, and the third spectrum partition are three adjacent spectrum partitions. In an embodiment of the present application, under time division-based modulation, the third pilot signals of the third phase and the fourth phase with a phase difference of 120° are staggered and distributed within the spectrum range in different time slots, so that the sum of the powers of at least one pilot signal of the same channel is less than a certain threshold, thereby avoiding the SRS crosstalk problem.

[0020] In one possible implementation, the optical signal of at least one channel has different polarization states, and the optical signals of different polarization states carry different pilot signals. The signal processing structure is further configured to obtain polarization-dependent loss of the optical signal of at least one channel based on at least one filtered optical signal. In this embodiment of the present application, the optical signal can be an optical signal modulated based on different polarization states. In this case, different pilot signals can be set for optical signals of different polarization states. Polarization-dependent loss can be detected based on, for example, the optical power of the pilot signals corresponding to different polarization states.

[0021] In some possible implementations, the signal processing structure is further configured to determine a channel's filtering capability based on at least one filtered optical signal. In this embodiment of the present application, the filtering capability of the wavelength signal may also be determined based on an insertion loss ratio between pilot signals of different phases within each channel.

[0022] In some possible implementations, the filter is a comb filter. In some examples, depending on the actual number of outputs, the filter can be a comb filter with one output, two outputs, or more outputs. Exemplarily, the filter can use different device structures to form a comb filter, for example, based on a Mach-Zehnder interferometer, a Michelson interferometer, and an interferometer based on an arrayed waveguide grating. In addition, the center frequency points of the transmittance spectrum of the comb filter can be equally spaced or unequally spaced, and its transmittance spectrum width can also be different. In an embodiment of the present application, the filter can filter and separate optical signals in different spectral ranges, and correspond one separated part to a filtered optical signal. The filter can filter and output only the optical signals in a part of the spectral range of all spectral ranges, or it can filter and output the optical signals in multiple part of the spectral ranges of all spectral ranges separately. The optical signal of the filtered output spectral range can be used as a filtered optical signal for output, or the optical signals in multiple spectral ranges of the filtered output can be used as multiple filtered optical signals for output.

[0023] In some possible implementations, the filter's output duty cycle is at least one of the following: 12.5%, 25%, 50%, 75%, or 87.5%. In the embodiments of this application, the filter's output duty cycle is 50% as an example. However, in actual applications, other output duty cycles can be selected based on application requirements. For design considerations for selecting other output duty cycles, please refer to the relevant descriptions of the aforementioned embodiments and will not be repeated here.

[0024] In one possible implementation, the pilot signal frequency is in the range of several MHz. In this embodiment of the present application, after avoiding SRS crosstalk during transmission, the pilot signal frequency requirement is reduced. In commercial scenarios, the pilot signal frequency can be reduced to the range of several MHz. This reduction in the pilot signal frequency can reduce the impact of fiber dispersion and other issues on the pilot signal, improving the transmission and processing accuracy of the pilot signal.

[0025] In a second aspect, embodiments of the present application further provide an optical transmitter configured to modulate a carrier optical signal to obtain an optical signal comprising one or more channels, wherein the optical signal of each channel carries at least one pilot signal, wherein different pilot signals correspond to different spectral ranges of the channel, and the pilot signals have different phases, and the same pilot signal with different phases corresponds to different spectral partitions within the spectral range. The sum of the power of at least one pilot signal of the same channel is less than a certain threshold. The optical transmitter transmits the optical signal of one or more channels into an optical fiber.

[0026] In one possible implementation, modulating the carrier optical signal to obtain an optical signal including one or more channels includes generating at least one pilot signal, the at least one pilot signal including a first pilot signal, the first pilot signal having a first phase and a second phase, the first phase and the second phase differing by 180°. Modulating the first pilot signal onto the carrier optical signal to obtain an optical signal corresponding to the channel, the first pilot signal with the first phase and the first pilot signal with the second phase corresponding to different spectrum partitions within a spectrum range.

[0027] In one possible implementation, modulating the carrier optical signal to obtain an optical signal comprising one or more channels includes generating at least one pilot signal, the at least one pilot signal including a second pilot signal, the second pilot signal having a first phase and a second phase, the first phase and the second phase differing by 180°. The second pilot signal having a different phase is modulated onto the carrier optical signal to obtain an optical signal for the corresponding channel. During the first and second time slots, the second pilot signal having the same phase corresponds to different spectral partitions within the spectrum, and the first and second time slots alternate.

[0028] In one possible implementation, on an optical signal corresponding to a channel, a second pilot signal of a first phase and a second pilot signal of a second phase are separated by a second spectrum partition. Modulating the carrier optical signal to obtain an optical signal including one or more channels further includes: carrying a reference pilot signal on the optical signal corresponding to the channel, the reference pilot signal corresponding to the second spectrum partition, and the reference pilot signal having a different frequency from at least one pilot signal.

[0029] In one possible embodiment, modulating the carrier optical signal to obtain an optical signal comprising one or more channels includes generating at least one pilot signal, wherein the at least one pilot signal includes a third pilot signal, wherein the third pilot signal has a third phase and a fourth phase, and the third and fourth phases differ by 180°. The third pilot signals of different phases are modulated onto the carrier optical signal to obtain optical signals corresponding to the channels. In the first time slot, the third pilot signal of the third phase corresponds to the second spectrum partition, and the third pilot signal of the fourth phase corresponds to the third spectrum partition. In the second time slot, the third pilot signal of the third phase corresponds to the first spectrum partition, and the third pilot signal of the fourth phase corresponds to the second spectrum partition. The first time slot and the second time slot alternate with each other.

[0030] The first spectrum partition, the second spectrum partition and the third spectrum partition are three spectrum partitions that are adjacent in sequence.

[0031] In a possible implementation, the above-mentioned modulating the carrier optical signal to obtain an optical signal including one or more channels further includes: modulating the carrier optical signal in different polarization states, where the optical signals in different polarization states carry different pilot signals.

[0032] In some possible implementations, the frequency of the pilot signal is at the level of several MHz.

[0033] In a third aspect, an embodiment of the present application further provides a detection method, which is based on an optical detection device, and the optical detection device includes a filter. The method includes: receiving a first optical signal, the first optical signal includes an optical signal of at least one channel, the optical signal of each channel carries at least one pilot signal, different pilot signals correspond to optical signals of different spectrum ranges within the channel, the pilot signals have different phases, and the same pilot signal with different phases corresponds to different spectrum partitions within the spectrum range. The sum of the powers of at least one pilot signal of the same channel is less than a certain threshold. The first optical signal is filtered to obtain at least one filtered optical signal, and at least one filtered optical signal carries at least one pilot signal. The optical power of the optical signal within the spectrum range where the at least one pilot signal is located is obtained based on the at least one filtered optical signal.

[0034] In one possible embodiment, at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal. The above-mentioned filtering process of the first optical signal to obtain at least one filtered optical signal includes: filtering the first optical signal to obtain at least one filtered optical signal, the at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; the first filtered optical signal and the second filtered optical signal are consistent with the spectrum range division of the optical signal of at least one channel. The above-mentioned obtaining the optical power of the optical signal within the spectrum range where at least one pilot signal is located based on the at least one filtered optical signal includes: performing photoelectric conversion on the first filtered optical signal to obtain a first filtered electrical signal; performing photoelectric conversion on the second filtered optical signal to obtain a second filtered electrical signal; obtaining the optical power of the optical signal within the spectrum range where at least one pilot signal is located based on the first filtered electrical signal and the second filtered electrical signal.

[0035] In one possible embodiment, at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; the spectrum range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectrum range division of the optical signal of the at least one channel. At least one pilot signal also includes a second pilot signal. On the optical signal of the corresponding channel, the second pilot signal of the first phase and the second pilot signal of the second phase are separated by a second spectrum partition. The optical signal of the corresponding channel also carries a reference pilot signal, the reference pilot signal corresponds to the second spectrum partition, and the reference pilot signal has a different frequency from the at least one pilot signal. The method also includes: obtaining the stimulated Raman scattering crosstalk degree of the second pilot signal based on the first filtered electrical signal and the second filtered electrical signal.

[0036] In one possible implementation, the optical signal of at least one channel has different polarization states, and the optical signals of different polarization states carry different pilot signals. The method further includes: obtaining polarization-dependent loss of the optical signal of at least one channel according to the at least one filtered optical signal.

[0037] In some possible implementations, the method further includes: obtaining a filtering processing capability of the channel according to at least one filtered optical signal.

[0038] In some possible implementations, the output duty cycle of the filter is at least one of the following: 12.5%, 25%, 50%, 75%, and 87.5%.

[0039] In a possible implementation, the frequency of the pilot signal is at the level of several MHz.

[0040] Fourthly, embodiments of the present application further provide a communication method based on an optical transmitter. The method comprises: modulating a carrier optical signal to obtain an optical signal comprising one or more channels, wherein the optical signal of each channel carries at least one pilot signal, wherein different pilot signals correspond to different spectral ranges within the channel, the pilot signals have different phases, and the same pilot signal with different phases corresponds to different spectral partitions within the spectral range. The sum of the power of at least one pilot signal of the same channel is less than a certain threshold. The optical signal of one or more channels is transmitted into an optical fiber.

[0041] In one possible implementation, modulating the carrier optical signal to obtain an optical signal including one or more channels includes generating at least one pilot signal, the at least one pilot signal including a first pilot signal, the first pilot signal having a first phase and a second phase, the first phase and the second phase differing by 180°. Modulating the first pilot signal onto the carrier optical signal to obtain an optical signal corresponding to the channel, the first pilot signal with the first phase and the first pilot signal with the second phase corresponding to different spectrum partitions within a spectrum range.

[0042] In one possible implementation, modulating the carrier optical signal to obtain an optical signal including one or more channels includes generating at least one pilot signal, the at least one pilot signal including a second pilot signal, the second pilot signal having a first phase and a second phase, the first phase and the second phase differing by 180°. During a first time slot and a second time slot, the second pilot signal having the same phase is modulated into different spectral partitions corresponding to the carrier optical signal to obtain optical signals corresponding to the channels, with the first time slot and the second time slot alternating with each other.

[0043] In one possible implementation, on an optical signal corresponding to a channel, a second pilot signal of a first phase and a second pilot signal of a second phase are separated by a second spectrum partition. Modulating the carrier optical signal to obtain an optical signal including one or more channels further includes: carrying a reference pilot signal on the optical signal corresponding to the channel, the reference pilot signal corresponding to the second spectrum partition, and the reference pilot signal having a different frequency from at least one pilot signal.

[0044] In one possible embodiment, modulating the carrier optical signal to obtain an optical signal comprising one or more channels includes generating at least one pilot signal, wherein the at least one pilot signal includes a third pilot signal, wherein the third pilot signal has a third phase and a fourth phase, and the third and fourth phases differ by 180°. The third pilot signals of different phases are modulated onto the carrier optical signal to obtain optical signals corresponding to the channels. In the first time slot, the third pilot signal of the third phase corresponds to the second spectrum partition, and the third pilot signal of the fourth phase corresponds to the third spectrum partition. In the second time slot, the third pilot signal of the third phase corresponds to the first spectrum partition, and the third pilot signal of the fourth phase corresponds to the second spectrum partition. The first time slot and the second time slot alternate with each other.

[0045] The first spectrum partition, the second spectrum partition and the third spectrum partition are three spectrum partitions that are adjacent in sequence.

[0046] In a possible implementation, the above-mentioned modulating the carrier optical signal to obtain an optical signal including one or more channels further includes: modulating the carrier optical signal in different polarization states, where the optical signals in different polarization states carry different pilot signals.

[0047] In a fifth aspect, an embodiment of the present application further provides a computer-readable storage medium, which includes instructions. When the instructions are executed on a data processor, the data processor executes a detection method, which includes: obtaining the optical power of an optical signal within the spectrum range where at least one pilot signal is located based on at least one filtered electrical signal. The at least one filtered electrical signal is obtained by photoelectric conversion of at least one filtered optical signal. The at least one filtered optical signal is obtained by filtering the optical signal of at least one channel. The optical signal of the corresponding channel carries the above-mentioned at least one pilot signal, and the pilot signals have different phases; the same pilot signal with different phases corresponds to different spectrum partitions within the channel; and at least one filtered optical signal carries at least one pilot signal.

[0048] In a sixth aspect, an embodiment of the present application further provides an optical communication system, comprising at least one optical detection device as described in the first aspect and a plurality of optical transmitters as described in the second aspect. The optical transmitters and optical detection devices are respectively coupled to optical fibers.

[0049] Regarding the technical principles and beneficial effects of the second, third, fourth, fifth and sixth aspects mentioned above, please refer to the relevant description of the first aspect mentioned above, and no further details will be given here. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic structural diagram of an optical communication system provided in an embodiment of the present application;

[0051] FIG2 is a schematic diagram of a pilot-spectrum range distribution of a pilot signal carried on an optical signal of a corresponding channel in an existing embodiment;

[0052] FIG3 is a schematic diagram showing SRS crosstalk generated by different pilot signals;

[0053] FIG4 is a schematic structural diagram of another optical communication system provided in an embodiment of the present application;

[0054] FIG5 is a first structural diagram of a light detection device provided in an embodiment of the present application;

[0055] FIG6 is a second structural diagram of another optical detection device provided in an embodiment of the present application;

[0056] FIG7 is a third structural diagram of another optical detection device provided in an embodiment of the present application;

[0057] FIG8 is a fourth structural diagram of another optical detection device provided in an embodiment of the present application;

[0058] FIG9 is a flow chart of a communication method provided in an embodiment of the present application;

[0059] FIG10 is a schematic diagram of carrying first pilot signals of a first phase and a second phase on different spectrum partitions of an optical signal of a corresponding channel in a frequency division-based manner provided by an embodiment of the present application;

[0060] FIG11 is a schematic diagram of carrying second pilot signals of a first phase and a second phase on different spectrum partitions of an optical signal of a corresponding channel in a time division-based manner provided by an embodiment of the present application;

[0061] FIG12 is a schematic diagram of carrying third pilot signals of a third phase and a fourth phase on different spectrum partitions of an optical signal of a corresponding channel in a time division-based manner according to an embodiment of the present application;

[0062] FIG13 is a schematic diagram of a flow chart of a detection method provided in an embodiment of the present application;

[0063] FIG14 is a schematic diagram of the output principle of a comb filter provided in an embodiment of the present application;

[0064] FIG15 is a schematic diagram of a filtering process for an optical signal of a corresponding channel under the modulation mode shown in FIG10 , provided by an embodiment of the present application;

[0065] FIG16 is a schematic diagram of another filtering process for an optical signal of a corresponding channel under the modulation mode shown in FIG10 according to an embodiment of the present application;

[0066] FIG17 is a schematic diagram of modulation of optical signals of corresponding channels with a certain spectrum spacing between the same pilot signals of different phases provided by an embodiment of the present application;

[0067] FIG18 is a schematic diagram of filtering processing of an optical signal of a corresponding channel under the modulation mode shown in FIG11( a ) according to an embodiment of the present application. DETAILED DESCRIPTION

[0068] It should be noted that the terms "first", "second", etc. involved in the embodiments of the present application are only used to distinguish features of the same type and cannot be understood as indicating relative importance, quantity, order, etc.

[0069] The terms "exemplary" or "for example" in the embodiments of this application are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0070] The terms "coupling" and "connection" involved in the embodiments of this application should be understood in a broad sense. For example, they may refer to a physical direct connection, or an indirect connection achieved through electronic devices, such as a connection achieved through resistors, inductors, capacitors or other electronic devices.

[0071] First, some basic concepts involved in the embodiments of this application are explained:

[0072] Dense wavelength division multiplexing (DWDM) is a fiber-optic data transmission technology that uses laser wavelengths to transmit data within optical fibers, either in parallel or in series, using either bit-by-bit or string-by-string transmission. DWDM is a crucial component of fiber-optic networks, enabling communication data based on diverse protocols and technologies to be transmitted over a unified fiber layer. Driven by emerging services and the demand for high-speed transmission of massive amounts of data, optical networks are becoming increasingly complex and widespread, and optical connections are becoming increasingly dynamic and flexible. Therefore, there is an urgent need to implement appropriate testing methods to ensure the stable and efficient operation of optical networks. Especially with the large-scale application of DWDM systems, it is crucial to simultaneously test the optical channel performance of each DWDM wavelength channel using low-cost methods to ensure reliable operation and reduce network disruptions.

[0073] An embodiment of the present application provides an optical communication system that may include multiple network nodes coupled to each other via optical fibers. Each of the multiple network nodes may include optical receivers and / or optical transmitters. Optical communication is achieved based on optical receivers and optical transmitters. As shown in Figure 1, in an optical communication system 10000, multiple optical transmitters 1000 are coupled to an optical receiver 2000 via an optical fiber F. Each optical transmitter 1000 can modulate service information onto an optical signal of a different wavelength. The optical signals emitted by the different optical transmitters 1000 are combined to form a transmission optical signal on the optical fiber F for transmission. The optical receiver 2000 obtains an optical signal of a wavelength corresponding to the corresponding service from the optical fiber F and parses the relevant service information from the optical signal. To ensure orderly and normal signal communication, the optical signal is typically divided into frequency bands according to the spectrum range, and the optical signal is divided into multiple channels, each channel corresponding to an optical signal within a certain spectrum range. Different transmitters 1000 perform optical communication corresponding to different channels. A single transmitter 1000 can perform optical communication based on one or more channels.

[0074] In order to ensure the communication quality of optical communication between multiple network nodes, as shown in Figure 1, an optical detection device 3000 is also provided in the optical communication system 10000. Among them, the optical transmitter 1000 modulates pilot tone signals of different frequencies on the optical signal of the corresponding channel. The optical detection device 3000 is used to: obtain a first optical signal from the transmission optical signal on the optical fiber F, and filter to obtain the pilot signal carried by the first optical signal. The optical communication performance of each channel during optical communication is obtained through the pilot signal to realize the detection of the optical communication status. In an embodiment of the present application, as shown in Figure 1, a low-frequency pilot signal can be modulated on the envelope of the high-frequency optical signal. The optical detection device 3000 can obtain a portion of the transmission optical signal from the optical fiber F based on a smaller splitting ratio (for example, 5%) to obtain a first optical signal, and perform various signal processing (for example, filtering processing) on ​​the first optical signal to obtain the corresponding pilot optical signal.

[0075] For example, usually, the pilot signal refers to a modulated optical signal with a certain broadband spectrum range (such as a 50GHz bandwidth polarization multiplexing-16 order orthogonal amplitude modulation (PDM-16QAM) optical signal), which is modulated once more by a certain method to obtain an optical signal of at least one channel with an additional low-frequency intensity (for example, a frequency value of 30-60MHz and a modulation depth of 0.01-0.2) on its optical signal envelope. The modulation depth is defined as: (maximum power of the optical signal - minimum power of the optical signal) / average power of the optical signal. The high-frequency part of the frequency optical signal is the service optical signal carrying service information, and the low-frequency variation part on its envelope is the corresponding pilot signal. Usually, for a dense wavelength division multiplexing optical transmission system, multiple wavelength optical signals can be used, such as λ1, λ2, λ3, etc. In general, in a typical optical transmission system, 80 different wavelengths can be included, i.e., λ1 to λ 80). As shown in Figure 2, different wavelengths correspond to different spectrum ranges, and pilot signals of different frequencies can be carried on optical signals based on different spectrum ranges. For example, spectrum range 1 corresponds to a pilot signal carrying a frequency of f1, and spectrum range 2 corresponds to a pilot signal carrying a frequency of f2. The frequency value of the optical signal corresponding to each channel ch can be within the spectrum range corresponding to one or more pilot signals (for example, the frequency value of the frequency optical signal corresponding to channel ch1 can be within spectrum range 1 and spectrum range 2). Each channel ch can be modulated to obtain a high-speed optical signal, such as a PDM-16QAM or polarization division multiplexing-quadrature phase shift keying (PDM-QPSK) optical signal with a 50GHz-100GHz baud symbol transmission rate. In some examples, according to actual applications, the range value of the spectrum range corresponding to each pilot signal can be 25GHz, and the spectrum range of the frequency optical signal corresponding to each channel ch can be 25GHz and its multiples. During signal transmission, a small portion of the optical signal can be received by the optical detection device 3000 for optical communication performance detection of each wavelength signal, such as power detection. A photodetector (PD) can be provided in the optical detection device 3000 to convert the received pilot signal into an electrical signal.

[0076] Based on the pilot signals shown in Figures 1 and 2, the connection status of different channels (ch) can be detected. This technology is low-cost and offers a wide range of detection capabilities (capable of testing a variety of performance parameters). However, in practical applications, pilot signals between multiple channels (ch) are affected by stimulated Raman scattering (SRS) during fiber transmission. Crosstalk can occur between pilot signals of different frequencies, a particularly pronounced effect over long distances and in multi-channel transmission.

[0077] For example, Figure 3(a) shows an example of an optical signal obtained by optical transmitter 1000 after initial modulation. In the figure, optical fiber F can transmit optical signals within a certain spectrum. This optical signal is divided into multiple channels ch according to different spectral ranges. Multiple optical transmitters 1000 transmit optical signals based on one or more different channels ch. Each channel ch can include one or more optical signals of different wavelengths (corresponding to different spectral ranges), including optical signal λ1, optical signal λ2, and optical signal λ3. A pilot signal with a frequency of f1 is modulated onto optical signal λ1. A pilot signal with a frequency of f2 is modulated onto optical signal λ2. A pilot signal with a frequency of f3 is modulated onto optical signal λ3 (i.e., each spectral range can be modulated to carry a pilot signal of a corresponding frequency). The optical signal shown in Figure 3(a) is then transmitted over optical fiber F. Ideally, optical signals of different wavelengths will only carry pilot signals of corresponding frequencies. By detecting and analyzing the corresponding pilot signal based on the optical signal obtained from optical fiber F by optical detection device 3000, the optical transmission performance of the corresponding channel ch can be obtained. When an optical signal of a certain wavelength (for example, optical signal λ1) is dropped at a network node on optical fiber F, the pilot signal of the corresponding frequency will not be detected during subsequent optical fiber transmission. However, during actual transmission, due to the influence of stimulated Raman scattering (SRS) on optical fiber F, crosstalk will occur between pilot signals of different frequencies. As shown in Figure 3 (b), a portion of the optical power of the pilot signal with frequency f1 on optical signal λ1 is transferred to optical signals of other wavelengths (for example, optical signal λ2). Taking the example of optical detection device 3000 receiving an optical signal along the transmission path after optical signal λ1 is dropped, as shown in FIG3(c), if the photodetector based on optical detection device 3000 directly detects the received optical signal, pilot signals of multiple frequency values ​​will be detected on the optical signal of different wavelengths (for example, a pilot signal of the dropped frequency f1 will be detected). As shown in FIG3(d), after filtering the optical signal based on a bandpass filter (BPF), the photodetector performs photoelectric conversion, but pilot signals of frequencies related to crosstalk (for example, a pilot signal of the dropped frequency f1 will still be detected, resulting in erroneous detection of the optical communication performance related to optical signal λ1. The crosstalk problem caused by SRS makes it impossible for optical detection device 3000 to accurately detect various performance parameters of different channels ch, such as power, based on the pilot signals. Detection of the power of channel ch is the basis for detecting other performance parameters. Therefore, how to address the impact of SRS is a major issue.

[0078] In order to reduce the pilot signal crosstalk caused by SRS and to improve the accuracy of optical communication performance detection, in some possible implementations, the optical transmitter 1000 can modulate the pilot signal on the optical signal based on the multi-phase balanced transmission technology. The optical detection device 3000 can be an optical detection device that processes the pilot signal based on the multi-phase balanced transmission technology. In the multi-phase balanced transmission technology, two points need to be achieved: first, the optical transmitter 1000 modulates the pilot signal on the optical signal based on the multi-phase balanced transmission technology, so that when the optical signal carrying the pilot signal is transmitted on the optical fiber F, the power of the pilot signal of each channel remains zero to achieve transmission power balance between multiple channels, thereby avoiding the SRS crosstalk problem. Second, on the optical detection device 3000, the pilot signal with zero power in each channel can be accurately detected and acquired. The embodiment of the present application can achieve multi-phase balanced transmission based on the following scheme:

[0079] In some possible implementations, one or more of the multiple optical transmitters 1000 can modulate a carrier optical signal based on a multiphase balanced transmission technique. As shown in Figure 4 , the optical transmitter 1000 is configured to: modulate the carrier optical signal to obtain an optical signal comprising one or more channels ch, each of which carries at least one pilot signal f. The optical signal has multiple spectrum partitions p, each of which carries pilot signals f with different phases. The same pilot signal f with different phases is carried on different spectrum partitions p of the optical signal; the sum of the power of at least one pilot signal f on the same channel is less than a certain threshold. The optical signal is then transmitted into the optical fiber F.

[0080] Exemplarily, the sum of the powers of at least one pilot signal f being less than a certain threshold means that, under ideal conditions, power cancellation occurs between different phases of each pilot signal f, such that the sum of the powers of at least one pilot signal f remains zero over time. However, due to limitations in detection technology or the influence of actual transmission, the detected power value may have a measurable amount of power under certain detection errors and / or transmission errors. The measurable amount of power caused by such detection errors and / or transmission errors is extremely greater than the aforementioned certain threshold. Alternatively, in actual applications, a threshold may be preset. As long as the sum of the powers of the same pilot signal at different phases is less than the threshold, the sum of the powers of at least one pilot signal f on the same channel can be made less than the certain threshold. As long as a certain degree of power cancellation exists between the same pilot signals at different phases, interference caused by SRS crosstalk can be effectively reduced.

[0081] As shown in Figure 4 , optical transmitter 1000 includes a laser 10 and a signal modulator 20. Laser 10 can provide signal modulator 20 with a carrier optical signal, etc., for carrying service information. Signal modulator 20 modulates the service information onto the carrier optical signal to generate an optical signal. Furthermore, signal modulator 20 can modulate a pilot signal onto different spectrum partitions p of the optical signal.

[0082] Exemplarily, the signal modulator 20 may modulate the carrier optical signal based on different polarization states to obtain an optical signal.

[0083] In the embodiment of the present application shown in FIG4 , the carrier optical signal is an optical signal with a certain spectrum range, used to carry different service information. According to the provisions of relevant optical communication technical standards in the field of optical communications, the channels ch are divided, and the carrier optical signal corresponding to each channel ch can be within a certain spectrum range. One or more pilot signals f can be modulated on the carrier optical signal of a channel ch. According to the provisions of relevant optical communication technical standards, the spectrum range is divided, and pilot signals f of different frequencies can correspond to corresponding fixed-range spectrum regions. For example, the spectrum regions of different pilot signals can typically be divided using a width of 25 GHz. Based on this division, depending on the pilot signal f carried by each channel ch, when the pilot signal f is modulated onto the carrier optical signal to obtain an optical signal, the spectrum range of the optical signal corresponding to each channel ch also varies, but can be 25 GHz or integer multiples thereof. In the above-mentioned embodiments of the first optical detection device 3000A, the second optical detection device, and the third optical detection device 3000C, each pilot signal f corresponds to a spectrum range. Adjacent pilot signals f can experience crosstalk during transmission. In the embodiment of the present application as shown in Figure 4, each pilot signal f is set to multiple different phases. For each pilot signal f in the channel ch, the spectrum range corresponding to the pilot signal f is divided into different spectrum partitions p, and each spectrum partition p is used to carry the pilot signal f of one phase. Because there is mutual balance between the same pilot signals f of different phases, the same pilot signals f of multiple different phases satisfy the power of the pilot signal f to be zero during transmission. In this case, the pilot signal f in each channel ch maintains zero power during transmission, and the problem of power crosstalk caused by the SRS effect will not occur. At the same time, the implementation method shown in Figure 4 can be applied to scenarios with different code types.

[0084] In the embodiments of the present application, channels, spectrum ranges, and spectrum partitions are all divisions of the spectrum span of an optical signal. The descriptions of carrying a pilot signal on a certain channel, carrying a pilot signal of a certain frequency value on a certain spectrum range, or carrying a pilot signal of a certain phase on a certain spectrum partition in the embodiments of the present application all refer to carrying the pilot signal using a modulation technique on the optical signal corresponding to the spectrum span.

[0085] Taking a pilot signal carried on a channel as an example, the optical signal is divided into multiple channels according to different spectral spans. Each optical transmitter 1000 performs optical communication based on one or more channels. In this case, the optical transmitter can modulate pilot signals of different frequencies onto the optical signal of the corresponding channel. Specifically, the optical transmitter can modulate the optical signal based on the allocated spectral span and carry pilot signals of different frequencies onto the optical signal of the corresponding spectral span to assist in optical communication performance testing, for example. Depending on the size of the channel's spectral span, a single channel can modulate pilot signals of one or more frequencies.

[0086] Taking a pilot signal carrying a certain frequency value within a certain spectrum range as an example, each channel of optical transmitter 1000 can be divided into one or more spectrum ranges. Each spectrum range corresponds to a pilot signal with a spectrum value, and the pilot signals in different spectrum ranges have different frequency values. When optical transmitter 1000 is performing optical communication, the pilot signal with the corresponding frequency value is modulated according to the spectrum range of the optical signal within the corresponding channel.

[0087] Taking a pilot signal carrying a certain phase on a certain spectrum partition as an example, a spectrum partition in a channel corresponds to a pilot signal of a frequency value. When multiple different phases are set for a pilot signal of a frequency value, the spectrum range corresponding to the pilot signal of the frequency value can be divided into different spectrum partitions. Each spectrum partition may correspond to a pilot signal of the frequency value of a phase, or may not correspond to a pilot signal of the frequency value of a certain phase. When the optical transmitter 1000 is performing optical communication, for the optical signal it transmits, the pilot signal of the corresponding frequency value and the corresponding phase is modulated according to the spectrum partition in which the optical signal is located within the spectrum range of the corresponding channel.

[0088] In some possible implementations, multiple optical transmitters 1000 transmit corresponding optical signals to the optical fiber F, and different optical signals form a transmission optical signal transmitted on the optical fiber F. The optical detection device 3000 that follows the subsequent transmission path can obtain a first optical signal from the transmission optical signal, and the first optical signal includes an optical signal of at least one channel. After transmitting optical signals of different channels based on the embodiment shown in FIG4 , it is also necessary to achieve normal acquisition of pilot signals f of different phases based on the optical detection device 3000 to achieve normal detection of optical communication performance. At this time, as shown in FIG5 , the optical detection device 3000 includes a filter 110 and a subsequent signal processing structure X. Among them, the filter 110 is used to: receive the first optical signal. At least one filtered optical signal is obtained based on the first optical signal, and at least one filtered optical signal carries at least one pilot signal. The signal processing structure X is used to: obtain the optical power of the optical signal within the spectrum range where the at least one pilot signal is located based on the at least one filtered optical signal.

[0089] In the embodiment of the present application shown in FIG5 , in optical detection device 3000, the same pilot signal f with different phases can be separated based on filter 110 to obtain at least one filtered optical signal. Each filtered optical signal carries the obtained at least one pilot signal f, and the same pilot signal f with different phases is carried on different filtered optical signals. By performing certain signal processing on the obtained at least one filtered optical signal through the signal processing structure X after filter 110, the optical power of the optical signal corresponding to the at least one pilot signal can be obtained, thereby completing the performance test of the optical power.

[0090] In some possible implementations, the filter 110 may be a filter device that can output one, two, or more channels. Exemplarily, the filter 110 may be a comb filter. In some examples, depending on the actual number of outputs, the filter 110 may be a comb filter with one, two, or more outputs. The spectrum range division of at least one filtered optical signal output by the filter 110 is consistent with the spectrum range division of the optical signal of at least one channel. The filter 110 may filter and separate optical signals of different spectrum ranges, and carry each separated part on a corresponding filtered optical signal. The filter 110 may filter and output only optical signals of a portion of the spectrum range in all spectrum ranges, or may filter and output optical signals of multiple portion of the spectrum range in all spectrum ranges separately. The optical signals of the filtered output spectrum range may be output as a single filtered optical signal, or the optical signals of multiple filtered output spectrum ranges may be output as multiple filtered optical signals. Exemplarily, the filter 110 may form a comb filter using different device structures, for example, based on a Mach-Zehnder interferometer, a Michelson interferometer, and an interferometer based on an arrayed waveguide grating. Furthermore, the center frequency points of the transmittance spectrum of the comb filter may be equally spaced or unequally spaced, and the transmittance spectrum widths may also be different.

[0091] In the embodiment of the present application, filter 110 is a filter capable of filtering out and separating different phases of the same pilot signal f. Depending on how the optical transmitter 1000 sets the phase value and number of phases of the same pilot signal f during modulation, in one case, filters 110 with a corresponding number of separation functions can be provided at the optical detection device 3000. For example, when the same pilot signal f has two different phases, a filter 110 with a two-way phase separation function can be provided. When the same pilot signal f has three different phases, a filter with a three-way phase separation function can be provided. Similarly, when the same pilot signal f has more different phases, filters with more phase separation functions can be provided as filter 110. In another case, a slightly smaller number of filters 110 with separation functions can be provided at the optical detection device 3000. For example, when the same pilot signal f has N different phases, filters 110 with a multi-way phase separation function, less than N, can be provided.

[0092] The following text uses an example of carrying two different phases on the same pilot signal and separating the two phases of the pilot signal f at the optical detection device 3000 as an example:

[0093] When the optical detection device 3000 needs to separate signals of multiple phases from the pilot signal, as shown in Figure 6, taking the filter 110 as a comb filter as an example, half of the spectral period length of the comb filter is greater than or equal to the region length of the spectrum partition. The signal processing structure X includes a first photodetector 120, a second photodetector 130, and a data processor 200. The comb filter can filter the first optical signal to obtain at least one filtered optical signal. The following description will be given by taking the example of at least one filtered optical signal including two filtered optical signals, a first filtered optical signal and a second filtered optical signal: wherein: the first photodetector 120 is used to obtain a first filtered electrical signal based on the first filtered optical signal. The second photodetector 130 is used to obtain a second filtered electrical signal based on the second filtered optical signal. The data processor 200 is specifically used to obtain the optical power of an optical signal within the spectral range of at least one pilot signal based on the first filtered electrical signal and the second filtered electrical signal. In an embodiment of the present application, for the same pilot signal f, the first filtered optical signal and the second filtered optical signal respectively carry different phases of the pilot signal f. First photodetector 120 and second photodetector 130 perform photoelectric conversion on the two filtered optical signals, respectively, to generate a first filtered electrical signal and a second filtered electrical signal. Data processor 200 can detect the power of optical signals corresponding to the same pilot signal at multiple phases based on the first and second filtered electrical signals, and can also detect other optical communication performance characteristics based on the optical power.

[0094] In some examples, the output duty cycle of the filter is at least one of: 12.5%, 25%, 50%, 75%, 87.5%.

[0095] In some examples, as shown in FIG7 , the optical detection device 3000 may include an optical detection board. The optical detection board includes an optical processing structure 100 and a data processor 200. The optical processing structure 100 includes a filter 110, a first photodetector 120, and a second photodetector 130 as shown in FIG5 and FIG6 . In the embodiments of the present application, a single board is provided in many optical communication-related devices, and an independent optical processing structure and data processor are provided on the single board. Filters and photodetectors are provided in the optical processing structure to obtain relevant optical signals from the optical fiber F and obtain electrical signals through photoelectric conversion. The optical processing structure then transmits the electrical signals to the data processor on the single board so that the data processor can perform relevant signal processing in the digital domain.

[0096] In some examples, as shown in FIG8 , the optical detection device 3000 may include a detection light processing structure D, which includes the filter 110, the first photodetector 120, the second photodetector 130, and the data processor 200 shown in FIG5 and FIG6 . In some embodiments of the present application, a data processor may be integrated into some optical processing structure products. The optical processing structure may acquire an optical signal from an optical fiber F and obtain a related electrical signal after photoelectric conversion. The data processor within the optical processing structure may then perform related signal processing on the electrical signal in the digital domain and output the processing result.

[0097] Based on the optical transmitter 1000 of the structure shown in FIG4 , the following communication method including the operations of steps S110 to S120 shown in FIG9 may be performed:

[0098] S110 . Modulate the carrier optical signal to obtain an optical signal including one or more channels.

[0099] In some possible implementations, as shown in FIG4 , the carrier optical signal is modulated to obtain an optical signal including one or more channels ch. At least one pilot signal f is carried on the optical signal corresponding to each channel ch. In an embodiment of the present application, the pilot signal f has different phases, and the same pilot signal f with different phases can be carried on different spectrum partitions p of the optical signal, so that during the transmission of the optical signal on the optical fiber F, the sum of the powers of at least one pilot signal of the same channel is less than a certain threshold. In this case, the pilot signal f will not have a power leakage problem. When the sum of the powers of the pilot signals of multiple channels ch remains zero over time, there will be no SRS crosstalk problem between different channels ch.

[0100] In some possible implementations, the optical transmitter 1000 may carry pilot signals of different phases on a fixed spectrum partition p of the optical signal, or may carry pilot signals of different phases on a non-fixed spectrum partition p of the optical signal in a time division manner. Alternatively, pilot signals of different phases may be carried on the optical signal in a frequency division combined with a time division manner.

[0101] In some examples, taking the example of an optical transmitter 1000 carrying two first pilot signals of different phases on an optical signal in a frequency division manner, when the two different phases are a first phase and a second phase with a phase difference of 180° (i.e., mutually anti-phase), the above-mentioned modulation of the carrier optical signal includes: generating the at least one pilot signal, the at least one pilot signal including a first pilot signal, the first pilot signal having a first phase and a second phase, the first phase and the second phase differing by 180°. The first pilot signal is modulated onto the carrier optical signal to obtain an optical signal of the corresponding channel. As shown in Figure 10, for the first pilot signal f1 in the at least one pilot signal, the first pilot signal f1 of the first phase and the first pilot signal f1 of the second phase are carried on different spectrum partitions p of the optical signal. In an embodiment of the present application, when the optical transmitter 1000 carries two pilot signals of different phases on an optical signal in a frequency division manner. For the first pilot signal f1, its different phases correspond to fixed spectrum partitions p. The SRS crosstalk problem can be avoided by simply ensuring that the first pilot signals f1 of the two phases interact with each other during transmission so that the power of the first pilot signal f1 is zero.

[0102] In some examples, taking the example of an optical transmitter 1000 carrying two second pilot signals of different phases on a non-fixed spectrum partition p of an optical signal in a time-division manner, when the two different phases are a first phase and a second phase with a phase difference of 180° (i.e., mutually anti-phase), the above-mentioned modulation of the carrier optical signal includes: generating the at least one pilot signal, the at least one pilot signal including a second pilot signal, the second pilot signal having a first phase and a second phase, the first phase and the second phase differing by 180°. Modulating the second pilot signal of different phases onto the carrier optical signal to obtain an optical signal of the corresponding channel. As shown in (a), (b), and (c) of Figure 11, for the second pilot signal f2 in the at least one pilot signal, the phase on the optical signal in the first time slot differs by 180° from the phase on the optical signal in the second time slot. In an embodiment of the present application, the second pilot signal f2 is a pilot signal modulated based on a time-division manner. At optical transmitter 1000, time division is performed between the first and second time slots. In each time slot, second pilot signals f2 with different phases correspond to different spectrum partitions. Furthermore, for the two different time slots, the phases of the same pilot signal in the optical signals of the two time slots also differ by 180°. In this case, the power of second pilot signal f2 on the transmission path can be kept zero over time based on the time division scheme to avoid power leakage or SRS crosstalk.

[0103] In some possible implementations, when the optical transmitter 1000 modulates the second pilot signal f2 based on a time division method, a reference pilot signal may also be modulated on the spectrum. For example, as shown in FIG11 (a), on the optical signal, the second pilot signal f2 of the first phase and the second pilot signal f2 of the second phase are separated by a second spectrum partition. The second spectrum partition of the optical signal also carries a reference pilot signal, and the reference pilot signal has a different frequency from at least one pilot signal. In an embodiment of the present application, the reference pilot signal may be modulated between two pilot signals of different phases based on a traditional pilot signal modulation method. During actual transmission, when the reference pilot signal is affected by SRS crosstalk, corresponding changes will occur between the reference pilot signal and the second pilot signal f2. In subsequent optical detection, the intensity of the SRS crosstalk can be detected based on the reference pilot signal and the second pilot signal f2.

[0104] In some examples, taking the example of an optical transmitter 1000 carrying two third pilot signals of different phases on an optical signal in a time-division manner, when the two different phases are a third phase and a fourth phase with a phase difference of 120°, the above-mentioned modulation of the carrier optical signal includes: generating the at least one pilot signal, the at least one pilot signal including a third pilot signal, the third pilot signal having a third phase and a fourth phase, the third phase and the fourth phase differing by 180°. The third pilot signals of different phases are modulated onto the carrier optical signal to obtain an optical signal of the corresponding channel. As shown in FIG12 , for the third pilot signal f3 in the at least one pilot signal: in the first time slot, the third pilot signal f3 of the third phase is carried on the second spectrum partition p2 of the optical signal, and the third pilot signal f3 of the fourth phase is carried on the third spectrum partition p3 of the optical signal; there is a phase difference of 120° between the third phase and the fourth phase. In the second time slot, the third pilot signal f3 of the third phase is carried on the first spectrum partition p1 of the optical signal, and the third pilot signal f3 of the fourth phase is carried on the second spectrum partition p2 of the optical signal. The first spectrum partition p1, the second spectrum partition p2 and the third spectrum partition p3 are three spectrum partitions p that are adjacent in sequence. In the embodiments corresponding to Figures 10 and 11 of the present application, the two phases are mutually anti-phase. In the embodiment corresponding to Figure 12 of the present application, the angle of 2π is divided into two third phases and fourth phases (for example, 2π / 3 and 4π / 3) with a difference of 120°. In this way, when modulation is performed in a time division manner, if the spectrum partitions p corresponding to the two phases in different time slots are symmetrical, it is difficult to achieve that the sum of the powers of the third pilot signal f3 remains zero during transmission. In the embodiment corresponding to Figure 12, the spectrum partitions p corresponding to the two phases in different time slots are staggered and distributed (for example: in the first time slot, the third phase is in the second spectrum partition p2, and in the second time slot, the third phase is in the first spectrum partition p1. In the first time slot, the fourth phase is in the third spectrum partition p3, and in the second time slot, the fourth phase is in the second spectrum partition p2), so that the third pilot signal f3 of the third phase and the fourth phase can meet the purpose of keeping the sum of the power zero during transmission, thereby avoiding the SRS crosstalk problem.

[0105] In some possible implementations, the above-mentioned modulation of the carrier optical signal further includes: modulating the carrier optical signal with different polarization states, and different pilot signals are carried on the optical signals in different polarization states. In an embodiment of the present application, the optical transmitter 1000 can modulate optical communication based on different polarization states. For example, by modulating based on coherent optical communication with different polarization states, an optical signal including XI optical signal, XQ optical signal, YI optical signal and YQ optical signal can be modulated on the carrier optical signal, wherein X and Y represent two polarization states of the optical signal, respectively, and I and Q represent two optical signals orthogonal under coherent modulation, respectively. In this case, corresponding pilot signals can be assigned to optical signals in different polarization states. In the subsequent optical detection stage, polarization-dependent loss detection can be obtained based on pilot signals in different polarization states.

[0106] In some examples, optical signal modulation can be performed based on a pilot signal at a frequency of several MHz. In the embodiments of the present application, balanced transmission of the pilot signal is achieved based on multiple phases, thus avoiding interference from SRS crosstalk. In this case, the frequency requirement for the pilot signal can be reduced. In traditional commercial scenarios, a pilot signal of at least several tens of MHz is required for transmission. In the embodiments of the present application, pilot signal modulation in commercial scenarios can be achieved at a frequency of several MHz. By significantly reducing the frequency of the pilot signal, the impact of dispersion issues on optical fiber F during long-distance transmission can be further avoided.

[0107] S120 . Transmit an optical signal including one or more channels to the optical fiber F.

[0108] In the embodiment of the present application, each optical transmitter 1000 can modulate to obtain an optical signal including one or more channels ch. Multiple optical transmitters 1000 can each transmit corresponding optical signals to an optical fiber F. The optical signals corresponding to different optical transmitters 1000 are transmitted on the optical fiber F and can be combined to form a first optical signal.

[0109] In the optical communication scenarios of the embodiments shown in FIG. 4 , FIG. 9 , and FIG. 10 , the optical detection device 3000 described in the embodiments shown in FIG. 5 , FIG. 6 , FIG. 7 , and FIG. 8 may perform the following detection method including steps S210 to S230 as shown in FIG. 13 on the first optical signal transmitted on the optical fiber F:

[0110] S210: Receive a first optical signal.

[0111] In the application embodiment, the optical communication system 10000 may include one or more optical detection devices 3000 as shown in Figures 5, 6, 7, and 8. Based on the optical detection device 3000, it is possible to obtain a portion of the first optical signal from the optical fiber F with a smaller splitting ratio. The first optical signal is an optical signal obtained based on the embodiments shown in Figures 4, 9, and 10 above, which includes an optical signal of at least one channel ch, and the optical signal of channel ch carries at least one pilot signal f, and the pilot signal f has different phases. The same pilot signal f with different phases is carried on different spectrum partitions p of the optical signal. The sum of the power of at least one pilot signal f of the same channel is less than a certain threshold. On the optical detection device 3000 side, it is necessary to detect the power of the optical signals corresponding to different pilot signals f from the first optical signal.

[0112] Exemplarily, the optical detection device 3000 may obtain the first optical signal, etc. by filtering the optical signal transmitted by the optical fiber F based on a wavelength selection switch (WSS).

[0113] S220. Obtain at least one filtered optical signal according to the first optical signal.

[0114] In some possible implementations, as shown in Figures 5, 6, 7, and 8, different filters can be adaptively configured as filter 110 based on, for example, the number of phases of the same pilot signal on the first optical signal. The same pilot signal f with different phases is filtered and separated using filter 110. This allows the signal processing structure X at the subsequent stage of filter 110 to process the same pilot signal f with different phases to detect and obtain, for example, the optical power of the optical signal corresponding to the pilot signal f.

[0115] In some possible implementations, when the same pilot signal f has two phases, a comb filter can be used as filter 110 to achieve filtering and separation of the same pilot signal f with different phases. Figure 14 shows the filtering and separation principle of a comb filter. A comb filter is essentially an interferometer. The comb filter has a certain period length T. Within the spectral range of its period length T, it will separate input signals within different period lengths T into two different optical signals according to its output duty cycle. For example, if the duty cycle of both output signals is 50%, two filtered optical signals can be obtained. The division of the spectral ranges of the two filtered optical signals is consistent with the division of the spectral ranges of the optical signal input to filter 110. Filter 110 distributes the input optical signal according to duty cycles of 50% and 50%, and processes the input optical signal according to the spectral span of period length T. For each optical signal with a spectral span of period length T, two filtered optical signals with a spectral span of T / 2 can be filtered and separated. The spectrum range interval of the filtered optical signal within each T / 2 spectrum span is consistent with the spectrum range interval on the original input optical signal. In an embodiment of the present application, by designing the partition length of the spectrum partition p corresponding to the pilot signal f of each phase, and selecting a comb filter with a corresponding cycle length T, it is possible to filter and separate the same pilot signal f of two different phases into two different filtered optical signals, so as to achieve accurate reception and processing of the pilot signal. Under different pilot signal modulation modes (for example, frequency division, time division, and frequency division combined with time division, etc.), according to the different settings of the regional length of the spectrum partition p and the cycle length T of the comb filter, optical communication performance detection can be performed on optical signals of different code types. In practical applications, comb filters of different cycle lengths T can match channels of multiple code types. And this scheme can achieve filtering separation of pilot signals in channels of different code types without strict requirements on the cycle length T, and can maintain high processing accuracy. Since the cost of a comb filter increases with the cycle length T, it is possible to select a channel with the corresponding cycle length T and code type for pilot modulation and pilot reception processing based on actual application requirements, cost requirements, and code type requirements. The following are some typical application scenarios as examples:

[0116] The following description uses the example of the filter 110 filtering and separating the same pilot signal f of two phases. For the relevant content about the filter 110 filtering and separating the same pilot signal f of more than two phases, please refer to the relevant description of the two-phase embodiment, which will not be repeated later.

[0117] In some examples, the optical transmitter 1000 modulates a first phase and a second phase pilot signal f with a phase difference of 180° onto an optical signal using a frequency division method based on the embodiment shown in FIG10 . Taking the example of half the period length T of the comb filter being equal to the region length of the spectrum partition p, when a channel includes only one first pilot signal f1, taking the spectral range of channel ch as 25 GHz (i.e., the total spectral range of the first pilot signal f1 is 25 GHz), the period length of the comb filter is 25 GHz, and the output duty cycle is 12.5 GHz as an example, as shown in FIG15 , after the optical detection device 3000 acquires the corresponding optical signal and filters it through the comb filter, since the spectral range of the pilot signal is 25 GHz, the two phases of the first pilot signal f1 can each occupy the spectral partition p with a partition length of 12.5 GHz, and the output duty cycle of the comb filter is 50%. When the period length of the comb filter is 25 GHz, two 12.5 GHz filtered optical signals, i.e., the first filtered optical signal and the second filtered optical signal, can be output. By design, the first filtered optical signal (filtered and separated according to the 12.5 GHz spectrum range) can carry the first pilot signal f1 of the first phase (occupying the spectrum partition p of the partition length of 12.5 GHz), and the second filtered optical signal can carry the first pilot signal f1 of the second phase.

[0118] Similarly, when the channel ch shown in Figure 15 includes multiple first pilot signals f1, taking the spectrum range of the partition length of the spectrum partition p based on a comb filter with a period length of 25 GHz as an example, the first filtered optical signal can carry the first pilot signal f1 of the first phase, and the second filtered optical signal can carry the first pilot signal f1 of the second phase. In an embodiment of the present application, when the partition length of the spectrum partition p corresponding to the first pilot signal f1 of each phase is equal to half the period length T of the comb filter (25 GHz), for each first pilot signal f1, the first pilot signal f1 of the first phase can be divided into the first filtered optical signal, and the first pilot signal f1 of the second phase can be divided into the second filtered optical signal according to the description in the principle diagram shown in Figure 14. Regarding the description of the case where the area length of the spectrum partition p is equal to half the period length T of the comb filter, and more first pilot signals f1 are included in a channel, please refer to the relevant description of the embodiment of Figure 15, which will not be repeated here.

[0119] In some examples, the optical transmitter 1000 modulates the pilot signals f of the first phase and the second phase with a phase difference of 180° onto the optical signal in a frequency division manner based on the embodiment shown in FIG10 above. Taking as an example a quarter of the period length T of the comb filter being equal to the region length of the spectrum partition p (for example, the spectrum range of each pilot signal f is 25 GHz, the pilot signals of the two phases correspond to the spectrum partition p of the partition length of 12.5 GHz, the period length T of the comb filter is 50 GHz, and the output duty cycle of the comb filter is 50%), as shown in FIG16, when the channel ch1 includes two pilot signals f (for example, including the first pilot signal f 1a and the first pilot signal f 1b ), the first filtered optical signal carries a first pilot signal f of the first phase 1a and the first pilot signal f of the second phase 1b The second filtered optical signal carries the first pilot signal f of the second phase 1a and the first pilot signal f of the first phase 1b . Because the period length T of the comb filter is 50GHz and its output duty cycle is 50%, the comb filter performs filtering separation of the first filtered optical signal and the second filtered optical signal at a frequency interval of 25GHz. At this time, for two adjacent pilot signals f, it is necessary to ensure that the two phases of each pilot signal f are respectively carried on different filtered optical signals. Therefore, it can be designed so that the signals of different phases of two adjacent pilot signals f are located on the same output filtered optical signal side of the comb filter. That is, as shown in Figure 16, the first pilot signal f of the first phase in channel ch1 1a Located in the first half cycle of the first output cycle of the comb filter (for example, filtering and separating into the first filtered optical signal), the first pilot signal f of the second phase 1a and the first pilot signal f of the first phase 1b In the second half of the first output cycle of the comb filter (for example, filtering and separating into the second filtered optical signal), the first pilot signal f 1b Located in the first half cycle of the second output cycle of the comb filter (for example, filtered and separated onto the first filtered optical signal). When a channel ch includes more pilot signals, for example, three pilot signals f, any two adjacent pilot signals f among the multiple pilot signals f meet the relevant description of the first pilot signal in channel ch1. Therefore, reference can be made to the relevant description of channel ch1 in Figure 16, which is not repeated here.

[0120] In some examples, as shown in FIG17 , the region length of the spectrum partition p can also be less than half the period length T of the comb filter. In this case, it is sufficient to ensure that there is a certain spectral spacing between the same pilot signal f. The embodiment shown in FIG17 can be applied to the code pattern embodiments shown in FIG15 and FIG16 . In the embodiment of the present application, in actual applications, since the output transmittance spectrum of the comb filter is not a regular rectangular spectrum, when the optical transmitter 1000 modulates the pilot signal, pilot modulation can be performed only on the frequency points at some spectral positions. In the embodiment shown in FIG15 , the spectrum range of 0-12.5 GHz can be used as the spectrum partition p to modulate the first pilot signal f1 of the first phase. However, in the embodiment shown in FIG17 , the spectrum range of 0-10 GHz can be used as the spectrum partition p to modulate the first pilot signal f1 of the first phase, while the pilot signal is not modulated in the spectrum range of 10-12.5 GHz. Similarly, in the embodiment shown in FIG15 , the spectrum range of 12.5-25 GHz is used as the spectrum partition p to modulate the first pilot signal f1 of the second phase. However, in the embodiment shown in FIG17 , the spectrum range of 15-25 GHz may be used as the spectrum partition p to adjust the first pilot signal f1 of the second phase, while the spectrum range of 12.5-15 GHz is not modulated with the pilot signal.

[0121] In some examples, the optical transmitter 1000 modulates the pilot signal f of the first phase and the second phase, which differ by 180° in phase, onto the optical signal in a time-division manner based on the embodiment shown in FIG. 11 . In this case, in the structure shown in FIG. 6 , after the optical detection device 3000 acquires the corresponding optical signal and filters it through the comb filter, a time-division filtered optical signal is obtained: in the first time slot, the first filtered optical signal carries the second pilot signal of the first phase, and the second filtered optical signal carries the second pilot signal of the second phase. In the second time slot, the first filtered optical signal carries the second pilot signal of the second phase, and the second filtered optical signal carries the second pilot signal of the first phase. In the embodiment of the present application, on the optical detection device 3000 side, the separation and filtering of the second pilot signal of the first phase and the second pilot signal of the second phase can also be performed based on a time-division manner. For example, in the first time slot, the second pilot signal of the first phase is carried on the first filtered optical signal, and the second pilot signal of the second phase is carried on the second filtered optical signal. In the second time slot, the result of the filtering separation is opposite to that of the first time slot. In this way, the optical detection device 3000 can detect the second pilot signals with different phases in a time division manner, thereby realizing power detection of the optical signal corresponding to the second pilot signal.

[0122] In some examples, the optical transmitter 1000 modulates the second pilot signal f2, having a first phase and a second phase, with a phase difference of 180°, onto the optical signal in a time-division manner based on the embodiment shown in FIG11 . Taking the example of a comb filter where the length T of one-quarter of the period is equal to the length of the spectrum partition p (e.g., the length of the spectrum partition p is 25 GHz, the period length T of the comb filter is 100 GHz, and the output duty cycle of the comb filter is 50%), the following different time-division methods can be used to modulate the pilot signal:

[0123] Method 1: As shown in Figure 18, when the optical transmitter 1000 performs pilot signal modulation based on the embodiment of Figure 11 (a), on the optical signal, the second pilot signal f2 of the first phase and the second pilot signal f2 of the second phase are separated by a second spectrum partition p2. On the fourth optical signal detection device 3000, the comb filter performs different filtering separations on the second pilot signal f2 in different time slots: because the comb filter has a period length of 100 GHz and its output duty cycle is 50%, the comb filter can filter and separate the first filtered optical signal and the second filtered optical signal within an output spectrum range of 50 GHz. Because the partition length of the spectrum partition p occupied by the second pilot signal f2 of one phase is 25 GHz, the partition length of the two spectrum partitions p is equal to half the period length T of the comb filter. Therefore, for an optical signal with a 75 GHz interval pattern including a second pilot signal f2, during the first time slot, during the first half of the first cycle of the comb filter, duration T, the second pilot signal f2 with a first phase is carried on the first spectrum partition p1 of the first filtered optical signal and output. During the second half of the first cycle of the comb filter, duration T, the second pilot signal f2 with a second phase is carried on the third spectrum partition p3 of the second filtered optical signal and output. The first spectrum partition p1 and the third spectrum partition p3 are located in two adjacent output cycles of the comb filter. During the second time slot, the second pilot signal f2 with a second phase is carried on the first spectrum partition p1 of the first filtered optical signal, and the second pilot signal f2 with a first phase is carried on the third spectrum partition p3 of the second filtered optical signal.

[0124] For example, in the embodiment of FIG18 , if the optical transmitter 1000 is based on the embodiment of FIG11 (a), in the embodiment shown in FIG18 , a reference pilot signal is modulated in the second spectrum partition p2, then the reference pilot signal and the second pilot signal f2 within the same half-cycle spectrum range can be received together. For example, in the embodiment of FIG18 , for channel ch1, in the first time slot, the reference pilot signal on its second spectrum partition p2 and the second pilot signal f2 of the second phase are jointly carried on the second filtered optical signal. In the second time slot, the reference pilot signal on its second spectrum partition p2 and the second pilot signal f2 of the first phase are jointly carried on the second filtered optical signal. The power difference between the second pilot signal f2 and the reference pilot signal can then be calculated based on the first filtered optical signal and the second filtered optical signal to detect SRS crosstalk.

[0125] Method 2: When the optical transmitter 1000 performs pilot signal modulation based on the embodiment shown in Figure 11 (b), in the first time slot, the second pilot signal f2 of the first phase is carried on the first spectrum partition p1 of the first filtered optical signal, and the second pilot signal f2 of the second phase is carried on the second spectrum partition p2 of the second filtered optical signal; the first spectrum partition p1 and the second spectrum partition p2 are two adjacent spectrum partitions p. In the second time slot, the second pilot signal f2 of the second phase is carried on the first spectrum partition p1 of the first filtered optical signal, and the second pilot signal f2 of the first phase is carried on the second spectrum partition p2 of the second filtered optical signal. In the embodiment of the present application, the third spectrum partition p3 after the second spectrum partition p2 can be set as a spectrum partition p that does not carry a pilot signal, and the second pilot signal f2 of the first phase and the second pilot signal f2 of the second phase can be carried on different filtered optical signals by design. The specific implementation principle of Method 2 can refer to the specific implementation principle of Method 1 above, and will not be repeated here.

[0126] Method 3: When optical transmitter 1000 performs pilot signal modulation based on the embodiment shown in FIG11(c), in the first time slot, second pilot signal f2 of the first phase is carried on the first spectrum partition p1 of the first filtered optical signal, and second pilot signal f2 of the second phase is carried on the second spectrum partition p2 and the third spectrum partition p3 of the second filtered optical signal. The first spectrum partition p1, the second spectrum partition p2, and the third spectrum partition p3 are three adjacent spectrum partitions p. In the second time slot, second pilot signal f2 of the second phase is carried on the first spectrum partition p1 of the first filtered optical signal, and second pilot signal f2 of the first phase is carried on the second spectrum partition p2 and the third spectrum partition p3 of the second filtered optical signal. The modulation signal amplitudes of second pilot signal f2 corresponding to second spectrum partition p2 and third spectrum partition p3 are each half the modulation signal amplitude of second pilot signal f2 corresponding to first spectrum partition p1. In an embodiment of the present application, the spectrum range interval of the 75 GHz code type can be divided into three 25 GHz spectrum partitions: the first spectrum partition p1, the second spectrum partition p2, and the third spectrum partition p3. The first spectrum partition p1 can carry a second pilot signal f2 of a certain phase, and the second spectrum partition p2 and the third spectrum partition p3 can carry a second pilot signal f2 of another phase. Because the spectrum range of the second pilot signal f2 in the second spectrum partition p2 and the third spectrum partition p3 is twice the spectrum range of the second pilot signal f2 in the first spectrum partition p1, the modulation signal amplitude of the second pilot signal f2 corresponding to the second spectrum partition p2 and the third spectrum partition p3 can be set to half of the modulation signal amplitude of the second pilot signal f2 corresponding to the first spectrum partition p1, thereby achieving power balancing of the second pilot signal f2 of multiple phases in different time slots. On the optical detection device 3000 side, to accurately receive the second pilot signals f2 of two different phases, the second spectrum partition p2 and the third spectrum partition p3 can be used as an output spectrum of a comb filter. This allows the second pilot signals f2 of the same phase within the two spectrum partitions p to be carried simultaneously on the same filtered optical signal, while the second pilot signal f2 of a different phase within the first spectrum partition p1 can be carried on another filtered optical signal. The specific implementation of Method 3 can be referenced in the description of Method 1 above and will not be repeated here.

[0127] In the above-described method three, the duty cycle of the comb filter's two outputs is described as 50%. However, when the duty cycle of the comb filter's two outputs is other ratios, the second pilot signal f2 on the second filtered optical signal may be carried on more spectrum partitions p (e.g., N spectrum partitions p), and the modulation signal amplitude of each second pilot signal f2 on the second filtered optical signal is 1 / n of the modulation signal amplitude of the second pilot signal f2 on the first filtered optical signal. For example, when the duty cycles of the comb filter's two outputs are 25% (corresponding to the output duty cycle of the first filtered optical signal) and 75% (corresponding to the output duty cycle of the second filtered optical signal), the first filtered optical signal may have one second pilot signal f2 for spectrum partition p, and the second filtered optical signal may have three second pilot signals f2 for spectrum partitions p. In this case, the second pilot signal f2 of the second filtered optical signal is carried on three spectrum partitions p. Therefore, the modulation signal amplitude of the second pilot signal f2 in each spectrum partition p of the second filtered optical signal must be equal to 1 / 3 of the modulation signal amplitude of the second pilot signal f2 in the first spectrum partition p of the first filtered optical signal. This ensures that the optical powers of the two second pilot signals f2 with different phases are offset as much as possible. Similarly, for the case where the comb filter has more outputs, please refer to the description of the two outputs above and will not be repeated here.

[0128] The above examples illustrate implementations of a scheme for time-division of pilot signals of the first and second phases with a phase difference of 180° based on methods 1, 2, and 3. In some possible cases, the optical transmitter 1000 modulates the third pilot signal f3 of the third and fourth phases with a phase difference of 120° onto the optical signal in a time-division manner based on the embodiment shown in FIG. 12 . Taking the example of a comb filter where the length T of one-quarter of the cycle is equal to the length of the spectrum partition p (e.g., the length of the spectrum partition p is 25 GHz, the cycle length T of the comb filter is 100 GHz, and the output duty cycle of the comb filter is 50%), the following different time-division methods can be used to modulate the pilot signal: in the first time slot, the third pilot signal f3 of the third phase is carried on the second spectrum partition p2 of the first filtered optical signal, and the third pilot signal f3 of the fourth phase is carried on the third spectrum partition p3 of the second filtered optical signal. During the second time slot, the third pilot signal f3 of the third phase is carried on the first spectrum partition p1 of the first filtered optical signal, and the third pilot signal f3 of the fourth phase is carried on the second spectrum partition p2 of the second filtered optical signal. The first spectrum partition p1, the second spectrum partition p2, and the third spectrum partition p3 are three adjacent spectrum partitions p. In this embodiment of the present application, because the third phase and the fourth phase are not a pair of mutually anti-phase phases like the first phase and the second phase, in this embodiment of the present application, the optical transmitter 1000 staggers the third phase and the fourth phase on the three spectrum partitions p in different time slots to achieve balanced transmission of the third pilot signal f3. At the same time, on the optical detection device 3000 side, during the first and second time slots, the third pilot signal f3 on the first spectrum partition p1 is always carried on the first filtered optical signal, and the third pilot signals f3 on the second spectrum partition p2 and the third spectrum partition p3 are always carried on the second filtered optical signal, thereby achieving reception of third pilot signals f3 of different phases. However, in this manner, compared with the above-mentioned first-phase and second-phase solutions, the third-phase and fourth-phase solutions cannot achieve perfect reception and detection processing of the third pilot signal f3.

[0129] The above embodiments in step S220 are only examples of the application of several common scenarios of the comb filter when the duty cycle is 50%. In actual applications, the design can be adaptively adjusted according to the different values ​​of the duty cycle of the comb filter and the period length T, as well as the code type of the channel, the partition length of each spectrum partition p, etc. The specific design adjustment ideas can refer to the design ideas of the above embodiments, which will not be repeated here. In actual applications, as long as the same pilot signal of different phases is carried on different spectrum partitions p to achieve multi-phase transmission under power balance, and the same pilot signal of different phases is filtered and separated at the optical detection device, the multi-phase balanced pilot technology proposed in the embodiment of the present application is adopted.

[0130] In the above embodiment, the case where the same pilot signal has two phases and a filter is set to separate and output two filtered optical signals is used as an example. Regarding the case where N phases are set in the same pilot signal and N filtered optical signals are output based on the filter separation, reference can be made to the description of the above embodiment, which will not be repeated here. In addition, when N phases are set in the same pilot signal, less than N filtered optical signals can also be output based on the filter separation. For example, multiple phases (for example, two or three, etc.) can be set in the same pilot signal, and one filtered optical signal can be output based on the filter separation. The separated and output filtered optical signal can be any one of the filtered optical signals in the embodiment of N phase separation and output of N filtered optical signals. Taking the embodiment of Figure 11 as an example, in the embodiment of Figure 11, the same pilot signal can have a first phase and a second phase. By filtering and separating the two phases of the optical signal in Figure 11 (a), the first filtered optical signal and the second filtered optical signal shown in Figure 18 can be obtained. In actual applications, the filter can filter and separate the optical signal with two phases, or it can output only the first filtered optical signal or the second filtered optical signal. Optical communication performance testing can be achieved based on a single-phase pilot signal on the first or second filtered optical signal. Compared to scenarios based on multi-channel filtered optical signals, all pilot signals can be received and processed. However, not all pilot signals of all phases can be received, resulting in a certain reception loss in signal processing. Similarly, three different phases with a 120° phase difference can be set on the same pilot signal, and only two filtered optical signals are filtered and output at the optical detection device 3000, each of which carries the pilot signal at one of the three different phases.

[0131] S230: Perform optical communication performance detection according to at least one filtered optical signal.

[0132] In an embodiment of the present application, as shown in FIG5 , the signal processing structure X at the subsequent stage of the filter 110 can detect the optical communication performance based on at least one filtered optical signal. For example, the optical power of the optical signal containing at least one pilot signal is obtained based on the first filtered optical signal and the second filtered optical signal.

[0133] In some possible implementations, when the optical transmitter 1000 modulates a reference pilot signal in the second spectrum partition p between the second pilot signal f2 of the first phase and the second phase based on a time division scheme, as shown in FIG6 , FIG7 , and FIG8 , the data processor 200 is further configured to obtain a stimulated Raman scattering crosstalk level of the second pilot signal f2 based on the first filtered electrical signal and the second filtered electrical signal.

[0134] In some possible implementations, when the optical transmitter 1000 implements signal modulation of an optical signal based on optical signals of different polarization states, the optical signals of at least one channel have different polarization states, and the optical signals of different polarization states carry different pilot signals. At this time, as shown in FIG5 , the signal processing structure X is also used to obtain the polarization-dependent loss of the optical signal based on at least one filtered optical signal. For example, the data processor 200 shown in FIG6 , FIG7 and FIG8 can calculate the polarization-dependent loss of the optical signal based on at least one filtered optical signal. In an embodiment of the present application, when optical signals of different polarization states correspond to different pilot signals, the calculation of the polarization-dependent loss can be implemented based on the power of the pilot signals corresponding to the different polarization states, thereby realizing the detection of more optical communication performance parameters.

[0135] In some possible implementations, when a channel's optical signal carries multiple pilot signals, as shown in FIG5 , the signal processing structure X is also used to: obtain the filtering processing capability of the channel based on at least one filtered optical signal. Exemplarily, the filtering processing capability of the channel can be obtained based on the signal insertion loss ratio of at least one filtered electrical signal, where the signal insertion loss ratio is the ratio of a first insertion loss value to a second insertion loss value, wherein the first insertion loss value is the insertion loss value of the pilot signals of the two phases corresponding to the maximum frequency partition and the minimum frequency partition in the spectrum range corresponding to the channel, and the second insertion loss value is the insertion loss value of the pilot signals of all other phases except the pilot signals of the two phases corresponding to the maximum frequency partition and the minimum frequency partition in the spectrum partition corresponding to the channel. In an embodiment of the present application, the filtering performance of the WSS on different channels can also be detected based on at least one filtered optical signal.

[0136] Embodiments of the present application provide an optical detection device, an optical transmitter, a detection method, and a communication method. When modulating an optical signal carrying service information, the optical transmitter modulates the same pilot signal within a channel onto different spectral partitions of the optical signal at different phases, such that when the optical signal is transmitted over an optical fiber, the sum of the powers of at least one pilot signal within the same channel is less than a certain threshold. This pilot signal modulation method ensures that, when the optical signal is transmitted over an optical fiber, pilot signals within different channels are not affected by the SRS effect and thus do not generate power crosstalk. Furthermore, during optical signal transmission, the optical detection device can filter and separate the different phases of the same pilot signal within the channel using a filter, thereby ensuring normal reception of pilot signals with multiple phases, thereby enabling normal optical communication performance testing based on the pilot signal modulated by the optical transmitter. This optical detection device can achieve optical communication performance testing at low cost and with high precision, and is applicable to different code types. Furthermore, the optical detection device does not place strict requirements on filter accuracy. For example, using a comb filter as an example, comb filters with larger period lengths are more cost-effective. The embodiments of the present application can use comb filters of different costs and specifications to adapt to the reception and processing of pilot signals under channels with different code types.

[0137] An embodiment of the present application also proposes a computer-readable storage medium, which includes instructions. When the instructions are executed on a data processor, the data processor executes a detection method (for example, the detection method described in the above-mentioned embodiments of Figures 13, 15, 16 and 18).

[0138] The processor involved in the embodiments of the present application may be a chip. For example, it may be a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on chip (SoC), a central processor unit (CPU), a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), a programmable logic device (PLD), or other integrated chips.

[0139] The memory involved in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct RAM bus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0140] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0141] Those skilled in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0142] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0143] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the modules is merely a logical function division. In actual implementation, there may be other division methods, such as multiple modules or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0144] The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, that is, they may be located on a single device or distributed across multiple devices. Some or all of the modules may be selected to achieve the purpose of this embodiment based on actual needs.

[0145] In addition, the functional modules in the various embodiments of the present application may be integrated into one device, or each module may exist physically separately, or two or more modules may be integrated into one device.

[0146] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loading and executing computer program instructions on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website, computer, server or data center by wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode to another website, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that contains one or more media that can be integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

[0147] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A light detection device, characterized in that, It includes a filter and a signal processing structure; wherein: The filter is used for: Receiving a first optical signal, the first optical signal including optical signals of at least one channel, each optical signal of the channel carrying at least one pilot signal, different pilot signals corresponding to different spectral ranges within the channel, the pilot signals having different phases, and the same pilot signal with different phases corresponding to different spectral sub-regions within the spectral range; the sum of the powers of the at least one pilot signal in the same channel is less than a certain threshold; Filtering the first optical signal to obtain at least one filtered optical signal, the at least one filtered optical signal carrying the at least one pilot signal; The signal processing structure is used for: obtaining the optical power of the optical signal within the spectral range where the at least one pilot signal is located according to the at least one filtered optical signal.

2. The optical detection device according to claim 1, wherein Half of the spectral period length of the filter is greater than or equal to the region length of the spectral sub-region; the signal processing structure includes a first photodetector, a second photodetector, and a data processor; wherein: The filter is used for: filtering the first optical signal to obtain at least one filtered optical signal, the at least one filtered optical signal including a first filtered optical signal and a second filtered optical signal; The first photodetector is used for: performing photoelectric conversion on the first filtered optical signal to obtain a first filtered electrical signal; The second photodetector is used for: performing photoelectric conversion on the second filtered optical signal to obtain a second filtered electrical signal; The data processor is specifically used for: obtaining the optical power of the optical signal within the spectral range where the at least one pilot signal is located according to the first filtered electrical signal and the second filtered electrical signal.

3. The optical detection device according to claim 1 or 2, characterized in that, The at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; the at least one pilot signal includes a first pilot signal, the first filtered optical signal carrying the first pilot signal with a first phase, and the second filtered optical signal carrying the first pilot signal with a second phase; the first phase and the second phase differ by 180°.

4. The optical detection device according to any one of claims 1 to 3, characterized in that, The at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; the at least one pilot signal further includes a second pilot signal; At a first time slot, the first filtered optical signal carries the second pilot signal with a first phase, and the second filtered optical signal carries the second pilot signal with a second phase; the first phase and the second phase differ by 180°; At a second time slot, the first filtered optical signal carries the second pilot signal with a second phase, and the second filtered optical signal carries the second pilot signal with a first phase, and the first time slot and the second time slot alternate with each other.

5. The optical detection device according to claim 4, characterized in that, The spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel; a quarter of the period length of the filter is equal to the region length of the spectral sub-region; on the optical signal of the corresponding channel, there is a second spectral sub-region between the second pilot signal with a first phase and the second pilot signal with a second phase; In the first time slot, the second pilot signal of the first phase corresponds to the first spectral sub-division of the first filtered optical signal, and the second pilot signal of the second phase corresponds to the third spectral sub-division of the second filtered optical signal; the first spectral sub-division, the second spectral sub-division, and the third spectral sub-division are three adjacent spectral sub-divisions in sequence; In the second time slot, the second pilot signal of the second phase corresponds to the first spectral sub-division of the first filtered optical signal, and the second pilot signal of the first phase corresponds to the third spectral sub-division of the second filtered optical signal.

6. The optical detection device according to claim 4, characterized in that, The spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel; a reference pilot signal is further carried on the optical signal of the corresponding channel, the reference pilot signal corresponds to the second spectral sub-division of the second filtered optical signal, and the frequency of the reference pilot signal is different from that of the at least one pilot signal; the data processor is further configured to: Obtain the stimulated Raman scattering crosstalk degree of the second pilot signal according to the first filtered electrical signal and the second filtered electrical signal.

7. The optical detection device according to claim 4, characterized in that, The spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel; the quarter-period length of the filter is equal to the sub-division length of the spectral sub-division; In the first time slot, the second pilot signal of the first phase corresponds to the first spectral sub-division of the first filtered optical signal, and the second pilot signal of the second phase corresponds to the second spectral sub-division of the second filtered optical signal; In the second time slot, the second pilot signal of the second phase corresponds to the first spectral sub-division of the first filtered optical signal, and the second pilot signal of the first phase corresponds to the second spectral sub-division of the second filtered optical signal; There is no corresponding pilot signal in the third spectral sub-division of the second filtered optical signal, and the first spectral sub-division, the second spectral sub-division, and the third spectral sub-division are three adjacent spectral sub-divisions in sequence.

8. The optical detection device according to claim 4, characterized in that The spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel; the quarter-period length of the filter is equal to the sub-division length of the spectral sub-division; In the first time slot, the second pilot signal of the first phase corresponds to the first spectral sub-division of the first filtered optical signal, and the second pilot signal of the second phase corresponds to the second spectral sub-division and the third spectral sub-division of the second filtered optical signal; the first spectral sub-division, the second spectral sub-division, and the third spectral sub-division are three adjacent spectral sub-divisions in sequence; In the second time slot, the second pilot signal of the second phase corresponds to the first spectral sub-division of the first filtered optical signal, and the second pilot signal of the first phase corresponds to the second spectral sub-division and the third spectral sub-division of the second filtered optical signal; The modulation signal amplitudes of the second pilot signals corresponding to the second spectral sub-division and the third spectral sub-division are respectively half of the modulation signal amplitude of the second pilot signal corresponding to the first spectral sub-division.

9. The optical detection device according to claim 2, wherein The at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; the spectral range division of the first filtered optical signal and the second filtered optical signal is consistent with the spectral range division of the optical signal of the at least one channel; the quarter - period length of the filter is equal to the partition length of the spectral partition; the at least one pilot signal includes a third pilot signal; At a first time slot, the third pilot signal of a third phase corresponds to a second spectral partition of the first filtered optical signal, and the third pilot signal of a fourth phase corresponds to a third spectral partition of the second filtered optical signal; there is a 120° phase difference between the third phase and the fourth phase; At a second time slot, the third pilot signal of the third phase corresponds to a first spectral partition of the first filtered optical signal, and the third pilot signal of the fourth phase corresponds to the second spectral partition of the second filtered optical signal; The first spectral partition, the second spectral partition, and the third spectral partition are three sequentially adjacent spectral partitions.

10. The optical detection device according to any one of claims 1-9, characterized in that, The optical signals of the at least one channel have different polarization states, and different pilot signals are carried on the optical signals of different polarization states; the signal processing structure is further configured to: Obtain the polarization - dependent loss of the optical signals of the at least one channel according to the at least one filtered optical signal.

11. The optical detection device according to any one of claims 1-10, characterized in that, The filter is a comb - shaped filter.

12. An optical transmitter, characterized in that, The optical transmitter is configured to: Modulate a carrier optical signal to obtain an optical signal including one or more channels, at least one pilot signal is carried on the optical signal of each channel, different pilot signals correspond to different spectral ranges within the channel, the pilot signals have different phases, and the same pilot signal with different phases corresponds to different spectral partitions within the spectral range; the sum of the powers of the at least one pilot signal of the same channel is less than a certain threshold; Transmit the optical signal including one or more channels to an optical fiber.

13. The optical transmitter according to claim 12, characterized in that, The modulating the carrier optical signal to obtain an optical signal including one or more channels includes: Generating the at least one pilot signal, the at least one pilot signal includes a first pilot signal, the first pilot signal has a first phase and a second phase, and the first phase and the second phase differ by 180°; Modulating the first pilot signal onto the carrier optical signal to obtain an optical signal corresponding to a channel, the first pilot signal of the first phase and the first pilot signal of the second phase correspond to different spectral partitions within the spectral range.

14. The optical transmitter according to claim 12 or 13, characterized in that, The modulating the carrier optical signal to obtain an optical signal including one or more channels includes: Generating the at least one pilot signal, the at least one pilot signal includes a second pilot signal, the second pilot signal has a first phase and a second phase, and the first phase and the second phase differ by 180°; Modulating the second pilot signal with different phases onto the carrier optical signal to obtain an optical signal corresponding to a channel; at the first time slot and the second time slot, the second pilot signal of the same phase corresponds to different spectral partitions within the spectral range, and the first time slot and the second time slot alternate with each other.

15. The optical transmitter according to claim 14, characterized in that, On the optical signal of the corresponding channel, there is a second spectral partition between the second pilot signal of the first phase and the second pilot signal of the second phase; modulating the carrier optical signal to obtain an optical signal including one or more channels further includes: Modulating a reference pilot signal to correspond to the second spectral partition within the channel, the reference pilot signal having a different frequency from the at least one pilot signal.

16. The optical transmitter according to any one of claims 12-15, characterized in that, Modulating the carrier optical signal to obtain an optical signal including one or more channels includes: Generating the at least one pilot signal, the at least one pilot signal including a third pilot signal having a third phase and a fourth phase, the third phase and the fourth phase differing by 180°; Modulating the third pilot signals of different phases onto the carrier optical signal to obtain an optical signal corresponding to the channel; at the first time slot, the third pilot signal of the third phase corresponds to the second spectral partition within the channel, and the third pilot signal of the fourth phase corresponds to the third spectral partition within the channel; at The second time slot, the third pilot signal of the third phase corresponds to the first spectral partition within the channel, and the third pilot signal of the fourth phase corresponds to the second spectral partition within the channel; the first time slot and the second time slot alternate with each other; the first spectral partition, the second spectral partition, and the third spectral partition are three adjacent spectral partitions in sequence.

17. The optical transmitter according to any one of claims 12-16, characterized in that, Modulating the carrier optical signal to obtain an optical signal including one or more channels further includes: Modulating the carrier optical signal with different polarization states, and different pilot signals are carried on the optical signals with different polarization states.

18. A detection method, characterized in that, Based on an optical detection device, the optical detection device includes a filter; the method includes: Receiving a first optical signal, the first optical signal including an optical signal of at least one channel, each optical signal of the channel carrying at least one pilot signal, different pilot signals corresponding to different spectral ranges within the channel, the pilot signals having different phases, and different spectral partitions within the corresponding spectral range for the same pilot signal with different phases; the sum of the powers of the at least one pilot signal in the same channel is less than a certain threshold; Filtering the first optical signal to obtain at least one filtered optical signal, the at least one filtered optical signal carrying the at least one pilot signal; The signal processing structure is configured to: obtain the optical power of the optical signal within the spectral range where the at least one pilot signal is located according to the at least one filtered optical signal.

19. The detection method according to claim 18, wherein The at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; Filtering the first optical signal to obtain at least one filtered optical signal includes: filtering the first optical signal to obtain at least one filtered optical signal, the at least one filtered optical signal including a first filtered optical signal and a second filtered optical signal; Obtaining the optical power of the optical signal within the frequency spectrum range where the at least one pilot signal is located according to the at least one filtered optical signal includes: performing photoelectric conversion on the first filtered optical signal to obtain a first filtered electrical signal; performing photoelectric conversion on the second filtered optical signal to obtain a second filtered electrical signal; and obtaining the optical power of the optical signal within the frequency spectrum range where the at least one pilot signal is located according to the first filtered electrical signal and the second filtered electrical signal.

20. The detection method according to claim 18 or 19, characterized in that, The at least one filtered optical signal includes a first filtered optical signal and a second filtered optical signal; the division of the frequency spectrum ranges of the first filtered optical signal and the second filtered optical signal is consistent with the division of the frequency spectrum ranges of the optical signals of the at least one channel; the at least one pilot signal further includes a second pilot signal; on the optical signal of the corresponding channel, there is a second frequency spectrum partition between the second pilot signal of the first phase and the second pilot signal of the second phase; the optical signal of the corresponding channel further carries a reference pilot signal, the reference pilot signal corresponds to the second frequency spectrum partition, and the frequency of the reference pilot signal is different from that of the at least one pilot signal; the method further includes: Obtaining the stimulated Raman scattering crosstalk degree of the second pilot signal according to the first filtered electrical signal and the second filtered electrical signal.

21. The detection method according to any one of claims 18-20, characterized in that, The optical signals of the at least one channel have different polarization states, and different pilot signals are carried on the optical signals of different polarization states; the method further includes: Obtaining the polarization-dependent loss of the optical signals of the at least one channel according to the at least one filtered optical signal.

22. A communication method, characterized in that, Based on an optical transmitter; the method includes: Modulating a carrier optical signal to obtain an optical signal including one or more channels, at least one pilot signal is carried on the optical signal of each channel, different pilot signals correspond to different frequency spectrum ranges within the channel, the pilot signals have different phases, and different spectrum partitions within the corresponding frequency spectrum range correspond to the same pilot signal of different phases; the sum of the powers of the at least one pilot signal of the same channel is less than a certain threshold; Transmitting the optical signal of the one or more channels to an optical fiber.

23. The communication method according to claim 22, wherein The modulating the carrier optical signal to obtain an optical signal including one or more channels includes: Generating the at least one pilot signal, the at least one pilot signal includes a first pilot signal, the first pilot signal has a first phase and a second phase, and the first phase and the second phase differ by 180°; Modulating the first pilot signal onto the carrier optical signal to obtain the optical signal of the corresponding channel, and different spectrum partitions within the corresponding frequency spectrum range correspond to the first pilot signal of the first phase and the first pilot signal of the second phase.

24. The communication method according to claim 22 or 23, characterized in that, The modulating the carrier optical signal to obtain an optical signal including one or more channels includes: Generating the at least one pilot signal, the at least one pilot signal includes a second pilot signal, the second pilot signal has a first phase and a second phase, and the first phase and the second phase differ by 180°; In the first time slot and the second time slot, the second pilot signal with the same phase is modulated into optical signals corresponding to different spectral partitions of the carrier optical signal to obtain optical signals of corresponding channels, and the first time slot and the second time slot alternate with each other.

25. The communication method according to claim 24, wherein On the optical signals of the corresponding channels, there is a second spectral partition between the second pilot signal with the first phase and the second pilot signal with the second phase; modulating the carrier optical signal to obtain optical signals including one or more channels further includes: Modulating a reference pilot signal into the second spectral partition within the corresponding channel, where the frequency of the reference pilot signal is different from that of the at least one pilot signal.

26. The communication method according to any one of claims 22-25, characterized in that, Modulating the carrier optical signal to obtain optical signals including one or more channels includes: Generating the at least one pilot signal, where the at least one pilot signal includes a third pilot signal, and the third pilot signal has a third phase and a fourth phase, and the third phase and the fourth phase differ by 180°. Modulating the third pilot signals with different phases onto the carrier optical signal to obtain optical signals of corresponding channels; in the first time slot, the third pilot signal with the third phase corresponds to the second spectral partition, and the third pilot signal with the fourth phase corresponds to the third spectral partition; in the second time slot, the third pilot signal with the third phase corresponds to the first spectral partition, and the third pilot signal with the fourth phase corresponds to the second spectral partition; the first time slot and the second time slot alternate with each other; the first spectral partition, the second spectral partition, and the third spectral partition are three adjacent spectral partitions in sequence.

27. The communication method according to any one of claims 22-26, characterized in that, Modulating the carrier optical signal to obtain optical signals including one or more channels further includes: Modulating the carrier optical signal with different polarization states, and different pilot signals are carried on the optical signals with different polarization states.

28. An optical communication system, characterized in that, Including at least one optical detection device according to any one of claims 1-11 and a plurality of optical transmitters according to any one of claims 12-17; the optical transmitter and the optical detection device are respectively coupled to an optical fiber.

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