WO2023098232A1 - 光信号发送的方法、导频接收机和发射机 - Google Patents

光信号发送的方法、导频接收机和发射机 Download PDF

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Publication number
WO2023098232A1
WO2023098232A1 PCT/CN2022/119627 CN2022119627W WO2023098232A1 WO 2023098232 A1 WO2023098232 A1 WO 2023098232A1 CN 2022119627 W CN2022119627 W CN 2022119627W WO 2023098232 A1 WO2023098232 A1 WO 2023098232A1
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signal
optical signal
polarization
pilot
electrical signal
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PCT/CN2022/119627
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English (en)
French (fr)
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甘霖
郭强
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华为技术有限公司
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Publication of WO2023098232A1 publication Critical patent/WO2023098232A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/06—Polarisation multiplex systems

Definitions

  • the present application relates to the field of optical communication, in particular to a method for transmitting an optical signal, a pilot receiver and a transmitter.
  • the wavelength division multiplexing (WDM) system can realize the coupling of multiple optical signals of different wavelengths into the same optical fiber for transmission.
  • the WDM system has been widely used in optical communication. In order to make the WDM system work stably and reliably, it is necessary to effectively monitor the power of the optical signal transmitted in each wavelength channel of the WDM system, so as to analyze the performance of each wavelength channel.
  • the more commonly used monitoring method is the pilot tone method.
  • the transmitter sends out optical signals of different wavelengths, modulates a pilot signal for each optical signal of wavelength, and modulates the pilot frequency of the pilot signal for optical signals of different wavelengths.
  • the modulated optical signal is transmitted in the optical fiber, amplified by an amplifier at intervals, and a part of the amplified optical signal (such as 5% to 10% optical signal) is input to the pilot receiver through an optical coupler.
  • the pilot receiver calculates the power of the pilot frequency, and then can obtain the power of the corresponding optical signal, so as to realize the performance analysis of each wavelength channel in the WDM system.
  • the optical power of the short-wavelength optical signal will be transferred to the optical power of the long-wavelength optical signal. If an optical signal of wavelength f is dropped at a node, no optical signal of this wavelength should be transmitted in the optical fiber behind the node.
  • the power of the pilot frequency corresponding to the wavelength f is transferred to the long-wavelength optical signal.
  • the subsequent pilot receiver can still obtain the power of the pilot frequency corresponding to the wavelength f, and then calculate the power of the optical signal of the wavelength f.
  • the optical signal of wavelength f is not transmitted in this section of optical fiber, so a monitoring error occurs. Therefore, there is an urgent need for a method that can reduce the interference of the pilot signal transferred to other wavelength optical signals in the above-mentioned Raman power transfer effect.
  • Embodiments of the present application provide a method for transmitting an optical signal and a pilot receiver, which can reduce the interference of pilot signals transferred to other wavelength optical signals in the aforementioned Raman power transfer effect. Described technical scheme is as follows:
  • a method for transmitting an optical signal is provided.
  • the method can be implemented by a transmitter in a wavelength division multiplexing system, and the method includes: modulating a first pilot signal on a first polarization state of the optical signal.
  • a second pilot signal is modulated on a second polarization state of the optical signal.
  • the phase of the first pilot signal is different from the phase of the second pilot signal. Output the modulated optical signal.
  • the optical signal of the first wavelength modulates the pilot signal of the first frequency and the optical signal of the second wavelength modulates the pilot signal of the second frequency.
  • Raman power transfer occurs between the optical signal of the first wavelength and the optical signal of the second wavelength, and part of the power of the optical signal of the first wavelength will be transferred to the power of the optical signal of the second wavelength.
  • the pilot signal of the first frequency will also be transferred to the optical signal of the second wavelength.
  • the two polarization-modulated pilot signals of the optical signal are in-phase, then when the two in-phase pilot signals of the first frequency are transferred to the second optical signal, it will appear as shown in the left figure of Figure 1
  • the superposition situation that is, the peak and the peak superposition.
  • the two polarization-modulated pilot signals of the optical signal are out of phase.
  • the phases of the first pilot signal and the second pilot signal are reversed.
  • Inversion means that the phase is opposite, or the phase difference is 180° (expressed as ⁇ in radian system).
  • the pilot signal of the first frequency will also be transferred to the optical signal of the second wavelength. If according to the related technology, the two polarization-modulated pilot signals of the optical signal are in-phase, then when the two in-phase pilot signals of the first frequency are transferred to the second optical signal, it will appear as shown in the left figure of Figure 2 The superposition situation, that is, the peak and the peak superposition.
  • the phases of the pilot signals modulated on the same sub-band of the first polarization state and the second polarization state are reversed.
  • the phases of the pilot signals modulated on each sub-band of the first polarization state and the pilot signals modulated on each sub-band of the second polarization state are reversed.
  • the pilot signal modulated on the first sub-band of the first polarization state on the Nth sub-band is the same as the pilot signal modulated on the first sub-band of the second polarization state on the Nth sub-band
  • the second pilot signal is inverted, and the pilot signal modulated on the N+1th sub-band of the first polarization state to the last sub-band is the same as the pilot signal modulated on the N+1th sub-band of the second polarization state to the last sub-band
  • the up-modulated pilot signal is inverted, where N is a positive integer.
  • the pilot signal modulated on the A-th sub-band of the first polarization state is in the opposite phase to the pilot signal modulated on the A-th sub-band of the second polarization state, and in the first polarization state
  • the pilot signal modulated on the B-th sub-band of the second polarization state is the reverse phase of the pilot signal modulated on the B-th sub-band, where A is odd and B is even, or A is even and B is odd.
  • a pilot receiver in a second aspect, includes a polarization maintaining power divider, a first polarizer, a second polarizer, a first photodetector, a second photodetector and a processor ,in:
  • the polarization maintaining power divider is used to receive the input optical signal, output the first optical signal to the first polarizer, and output the second optical signal to the second analyzer.
  • the polarization states of the first optical signal, the second optical signal and the input optical signal are the same, and the powers of the first optical signal and the second optical signal are the same.
  • the first polarizer is used to filter the polarization state of the first optical signal, and output the third optical signal obtained by polarization state filtering to the first photodetector.
  • the second polarizer is used to filter the polarization state of the second optical signal, and output the fourth optical signal obtained by polarization state filtering to the second photodetector, the polarization direction of the first polarizer and the polarization direction of the second polarizer.
  • the polarization directions are not orthogonal.
  • the first photodetector is used to convert the third light signal into the first electrical signal, and output the first electrical signal to the processor.
  • the second photodetector is used for converting the four optical signals into a second electrical signal, and outputting the second electrical signal to the processor.
  • the processor is configured to process the first electrical signal and the second electrical signal to obtain the power corresponding to the pilot frequency of the optical signal of each wavelength in the input optical signal.
  • the angle between the polarization direction of the first analyzer and the polarization direction of the second analyzer ranges from 40° to 50°. For example, 45°.
  • the first polarizer is a 0° polarizer
  • the second polarizer is a 45° polarizer
  • the processor is further configured to determine RSOP information of the input optical signal according to the first electrical signal and the second electrical signal.
  • the processor is further configured to determine the polarization-dependent loss PDL of the input optical signal according to the first electrical signal and the second electrical signal.
  • the pilot receiver further includes a third polarizer and a third photodetector, and the angle of the third polarizer is larger than the angle of the polarizer and smaller than the second Deviating angle.
  • the polarization maintaining power divider is also used to output the fifth optical signal to the third polarization analyzer.
  • the fifth optical signal, the first optical signal, the second optical signal and the input optical signal have the same polarization state, and the fifth optical signal, the first optical signal and the second optical signal have the same power.
  • the third polarizer is used to filter the polarization state of the fifth optical signal, and output the sixth optical signal obtained by filtering the polarization state to the third photodetector.
  • the third photodetector is used for converting the sixth light signal into a third electrical signal, and outputting the third electrical signal to the processor.
  • the processor is used to process the first electrical signal, the second electrical signal and the third electrical signal to obtain the power of the pilot signal corresponding to the optical signal of each wavelength in the input optical signal.
  • the analysis angle of the third polarizer is half of the included angle between the polarization direction of the first polarizer and the polarization direction of the second analyzer.
  • the pilot receiver further includes a circular polarization linear polarization converter, a fourth polarizer, and a fourth photodetector.
  • the polarization maintaining power splitter is also used to output the seventh optical signal to the circular polarization linear polarization converter, wherein the polarization states of the seventh optical signal, the first optical signal, the second optical signal and the input optical signal are the same, and the seventh optical signal , the power of the first optical signal and the second optical signal are the same.
  • the circular polarization linear polarization converter is used to convert the elliptical polarization state in the seventh optical signal into a linear polarization state, and output the converted eighth optical signal to the fourth polarizer.
  • the fourth polarizer is configured to convert the eighth optical signal into a fourth electrical signal, and output the fourth electrical signal to the processor.
  • the processor is configured to process the first electrical signal, the second electrical signal and the fourth electrical signal to obtain the power corresponding to the pilot frequency of the optical signal of each wavelength in the input optical signal.
  • the circular polarization linear polarization converter is a quarter wave plate.
  • the polarization analysis angle of the fourth polarization analyzer is the same as the polarization analysis angle of the first polarization analyzer or the polarization analysis angle of the second polarization analyzer.
  • the processor is configured to perform Fourier transform on the first electrical signal to obtain the first sub-power corresponding to the pilot frequency of the optical signal of each wavelength in the input optical signal. Perform Fourier transform on the second electrical signal to obtain the second sub-power corresponding to the pilot frequency of the optical signal of each wavelength in the input optical signal. For each pilot frequency, the actual power corresponding to the pilot frequency is obtained according to the first sub-power and the second sub-power corresponding to the pilot frequency.
  • a pilot receiver includes a polarization controller, a polarization beam splitter, a first photodetector, a second photodetector, and a processor, wherein:
  • the polarization controller is configured to receive an optical signal, scramble the optical signal, and output the scrambled optical signal to the polarization beam splitter;
  • the polarization beam splitter is used to polarize and split the scrambled optical signal to obtain a first optical signal and a second optical signal, output the first optical signal to the first photodetector, and send the first optical signal to the
  • the second photodetector outputs the second optical signal, wherein the first optical signal and the second optical signal are orthogonal;
  • the first photodetector is configured to convert the first optical signal into a first electrical signal, and output the first electrical signal to the processor;
  • the second photodetector is configured to convert the second optical signal into a second electrical signal, and output the second electrical signal to the processor;
  • the processor is configured to process the first electrical signal and the second electrical signal to obtain the power of the pilot signal corresponding to the optical signal of each wavelength in the input optical signal.
  • the processor is further configured to:
  • the processor is further configured to:
  • a pilot receiver in a fourth aspect, includes a polarization maintaining power splitter, a polarization rotator, a first polarization beam splitter, a second polarization beam splitter, a first photodetector, A second photodetector, a third photodetector, a fourth photodetector and a processor, wherein:
  • the polarization maintaining power splitter is configured to receive an input optical signal, output a first optical signal to the polarization rotator, and output a second optical signal to the first polarization beam splitter, wherein the first optical signal signal, the second optical signal, and the input optical signal have the same polarization state, and the first optical signal and the second optical signal have the same power;
  • the polarization rotator is configured to rotate the polarization of the first optical signal to obtain a third optical signal, and send the third optical signal to the second polarization beam splitter;
  • the first polarization beam splitter is configured to perform polarization splitting on the second optical signal to obtain a fourth optical signal and a fifth optical signal, and output the fourth optical signal to the first photodetector , outputting the fifth optical signal to the second photodetector;
  • the second polarization beam splitter is configured to perform polarization splitting on the third optical signal to obtain a sixth optical signal and a seventh optical signal, and output the sixth optical signal to the third photodetector , outputting the seventh optical signal to the fourth photodetector;
  • the first photodetector is configured to convert the fourth optical signal into a first electrical signal, and output the first electrical signal to the processor;
  • the second photodetector configured to convert the fifth optical signal into a second electrical signal, and output the second electrical signal to the processor
  • the third photodetector is configured to convert the sixth optical signal into a third electrical signal, and output the third electrical signal to the processor;
  • the fourth photodetector is configured to convert the seventh optical signal into a fourth electrical signal, and output the fourth electrical signal to the processor;
  • the processor is configured to process the first electrical signal, the second electrical signal, the third electrical signal, and the fourth electrical signal to obtain optical signals of each wavelength in the input optical signal The power of the corresponding pilot signal.
  • the polarization rotator is a 45° polarization rotator.
  • the processor is configured to:
  • the actual power corresponding to the pilot frequency is obtained according to the first sub-power and the second sub-power corresponding to the pilot frequency.
  • the processor is further configured to:
  • the processor is further configured to:
  • a transmitter in the fifth aspect, includes a signal transmitter and a modulator, wherein:
  • the signal transmitter is used to send an optical signal
  • the modulator is configured to modulate a first pilot signal on a first polarization state of the optical signal, and modulate a second pilot signal on a second polarization state of the optical signal, wherein the first pilot signal The phase of the frequency signal is different from that of the second pilot signal, and a modulated optical signal is output.
  • FIG. 1 is a schematic diagram of a pilot signal provided by an embodiment of the present application
  • FIG. 2 is a schematic diagram of a pilot signal provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of a WDM system provided by an embodiment of the present application.
  • FIG. 4 is a schematic diagram of a Raman power transfer provided by an embodiment of the present application.
  • FIG. 5 is a flow chart of a method for sending an optical signal provided in an embodiment of the present application.
  • FIG. 6 is a schematic structural diagram of a transmitter provided by an embodiment of the present application.
  • FIG. 7 is a schematic structural diagram of a transmitter provided in an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a pilot signal inversion provided by an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a pilot signal inversion provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a pilot signal inversion provided by an embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of a pilot receiver provided in an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a pilot receiver provided in an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of a pilot receiver provided in an embodiment of the present application.
  • FIG. 14 is a schematic structural diagram of a pilot receiver provided by an embodiment of the present application.
  • FIG. 15 is a schematic structural diagram of a pilot receiver provided by an embodiment of the present application.
  • Fig. 16 is a schematic structural diagram of a pilot receiver provided by an embodiment of the present application.
  • An embodiment of the present application provides a method for sending an optical signal, and the method can be applied to a wavelength division multiplexing (wavelength division multiplexing, WDM) system.
  • WDM wavelength division multiplexing
  • the sending end may include multiple transmitters, such as Tx1, Tx2...TxN, and may also include a wavelength division multiplexer.
  • the receiving end may also include multiple receivers, such as Rx1, Rx2, Rx3...RxN, and may also include a wavelength division multiplexer.
  • the transmission link between the sending end and the receiving end may be an optical fiber, and amplifiers, power splitters, etc. may be provided on the transmission link.
  • the transmitter modulates the service signal and pilot signal on the optical signal, and sends the modulated optical signal.
  • the optical signal is combined into one beam by the wavelength division multiplexer and amplified by the amplifier. Then, it is transmitted by optical fiber.
  • optical signals can be amplified by amplifiers at intervals. For example, an amplifier can be set every 80 kilometers (km) on the optical fiber to amplify the optical signal.
  • the amplified optical signal can be split by a power divider to enter a part of the optical signal into the pilot receiver. For example, if the power splitter is a 10:90 power splitter, then the amplified optical signal can split 10% of the optical signal into the pilot receiver by the 10:90 power splitter.
  • the optical signal is transmitted to the receiving end, and the wavelength division multiplexer at the receiving end divides it into N optical signals that are output to the receiver, and the receiver processes the input optical signal.
  • the three transmitters at the sending end can respectively send optical signals with wavelengths ⁇ 1 , ⁇ 2 and ⁇ 3 .
  • the transmitter modulates a pilot signal with a frequency of f1 on an optical signal with a wavelength of ⁇ 1 , modulates a pilot signal with a frequency of f2 on an optical signal with a wavelength of ⁇ 2 , and modulates a pilot signal with a frequency of f2 on an optical signal with a wavelength of ⁇ 3.
  • Modulate the pilot signal at frequency f3 When stimulated Raman scattering exists in the fiber, the optical signal will appear Raman power shift.
  • the power of the optical signal with a wavelength of ⁇ 1 will be partially transferred to the optical signals with a wavelength of ⁇ 2 and ⁇ 3
  • the power of an optical signal with a wavelength of ⁇ 2 will be partially transferred to the optical signals with a wavelength of ⁇ 1 and ⁇ 3
  • the power of the optical signal with wavelength ⁇ 3 will be partially transferred to the optical signals with wavelength ⁇ 1 and ⁇ 2 .
  • the power of the pilot signal with frequency f 1 will be partially transferred to the optical signals with wavelengths ⁇ 1 and ⁇ 2
  • the power of the pilot signal with frequency f 2 will be partially transferred
  • the power of the pilot signal whose frequency is f3 will be partially transferred to the optical signals whose wavelengths are ⁇ 1 and ⁇ 2 .
  • an embodiment of the present application proposes a method for transmitting optical signals, which can be implemented by a transmitter in a WDM system.
  • the method may include the following steps:
  • Step 501 Acquire a first polarization state and a second polarization state of an optical signal.
  • first polarization state and the second polarization state are orthogonal.
  • a laser in the transmitter emits an optical signal. Then, the optical signal is bidirectionally polarized by the device in the transmitter that can realize the bidirectional polarization function, so as to obtain the first polarization state and the second polarization state of the optical signal.
  • the devices that realize the bidirectional polarization function can also be different, and several transmitters are listed below for illustration.
  • the transmitter may include a laser and a dual polarization IQ modulator.
  • the laser emits an optical signal, which enters the dual-polarization IQ modulator.
  • a dual polarization IQ modulator splits an optical signal into orthogonal first and second polarization states.
  • the transmitter includes a laser, a polarization beam splitter, an IQ modulator, a variable optical attenuator (Variable Optical Attenuator, VOA) and a polarization beam combiner.
  • the laser emits an optical signal, which enters the polarizing beam splitter.
  • the polarization beam splitter divides the optical signal into a first polarization state and a second polarization state which are orthogonal to each other and output to two IQ modulators respectively.
  • Step 502 modulate the first pilot signal in the first polarization state, and modulate the second pilot signal in the second polarization state.
  • the phases of the first pilot signal and the second pilot signal are different.
  • the transmitter separately modulates the first pilot signal and the second pilot signal with the same frequency but different phases on two orthogonal polarization states of the optical signal.
  • the devices used to modulate the pilot signal can also be different.
  • the dual-polarized IQ modulator divides the input optical signal into the first polarization state and the second polarization state
  • quadrature amplitude modulation is performed, and in the first polarization state and the second polarization state
  • the pilot signals are respectively modulated, and the phases of the pilot signals modulated on the first polarization state and the second polarization state are different.
  • the pilot signal modulated on the first polarization state is as follows:
  • the pilot signal modulated on the second polarization state is as follows:
  • m is the modulation depth
  • f k is the modulation frequency
  • t is the time
  • ⁇ 0 is the initial phase
  • ⁇ is the phase difference
  • the value of ⁇ can be (0, 2 ⁇ ).
  • the values of the modulation frequency and the modulation depth of the pilot signal are exemplarily described below.
  • the adjustment frequency of the pilot signal may be between 30 megahertz (MHz) and 40 MHz, and the modulation depth of the pilot signal may be between 0.01 and 0.2.
  • the modulation depth is defined as: Among them, P max is the maximum power of the optical signal, P min is the minimum power of the optical signal, is the average power of the optical signal.
  • the dual-biased IQ modulator can also modulate the data to be sent in the first polarization state and the second polarization state.
  • the data to be sent may be service data that the user wants to send.
  • the IQ modulator modulates the data to be transmitted on the input polarization state, and outputs to the corresponding VOA.
  • a digital signal processor digital signal process, DSP
  • the pilot signals respectively modulated on the two polarization states of the optical signal can be expressed as Inverted signals, that is, the phases of the two pilot signals differ by 180° (ie, ⁇ in radians).
  • pilot signals modulated on the two polarization states may have multiple anti-phase forms, some of which are listed below for illustration.
  • the pilot signals modulated on each sub-band of the first polarization state are in phase
  • the pilot signals modulated on each sub-band of the second polarization state are in phase
  • the pilot signals modulated on each sub-band of the first polarization state are out of phase with the pilot signals modulated on each frequency sub-band of the first polarization state.
  • the pilot signals modulated on each sub-band of the first polarization state are m*sin(2 ⁇ f k t+ ⁇ 0 ), and the pilot signals modulated on each sub-band of the second polarization state are m* sin(2 ⁇ f k t+ ⁇ 0 + ⁇ ).
  • the pilot signal modulated on the A-th sub-band of the first polarization state is inverse to the second pilot signal modulated on the A-th sub-band of the second polarization state, and the first pilot signal modulated on the B-th sub-band of the first polarization state
  • the frequency signal and the modulated second pilot signal on the Bth sub-frequency band of the second polarization state are in reverse phase.
  • A is an odd number and B is an even number, or A is an even number and B is an odd number.
  • the polarization state has k+1 sub-bands, and k is an even number, then the value of A can be 1, 3, 5...k+1, and correspondingly, the value of B can be 2, 4, 6.. .k. Alternatively, the value of A may be 2, 4, 6...k, and correspondingly, the value of B may be 1, 3, 5...k+1.
  • the pilot signal modulated on the 1st, 3rd, 5...k+1 sub-bands of the first polarization state is m*sin(2 ⁇ f k t+ ⁇ 0 ), and the 2nd, 4th, The pilot signals modulated on 6...k sub-bands are m*sin(2 ⁇ f k t+ ⁇ 0 + ⁇ ).
  • the pilot signal modulated on the 1st, 3rd, 5...k+1 sub-bands of the second polarization state is m*sin(2 ⁇ f k t+ ⁇ 0 + ⁇ ), and in the second, 4.
  • the pilot signals modulated on the 6...k sub-frequency bands are all m*sin(2 ⁇ f k t+ ⁇ 0 ).
  • the polarization state has k+1 sub-frequency bands, which are respectively recorded as: f0, f0+df, f0+2df...f0+kdf.
  • the pilot signal modulated on the 1st, 3rd, 5...k+1 sub-bands of the first polarization state and the second pilot signal modulated on the 2nd, 4, 6...k sub-bands of the second polarization state invert.
  • the pilot signals modulated on the 2nd, 4th, 6th...k sub-bands of the first polarization state are inverted from the pilot signals modulated on the 1st, 3rd, 5th...k+1 sub-bands of the second polarization state Mutually.
  • the first sub-band of the first polarization state modulates the pilot signal on the Nth sub-band and the first sub-band of the second polarization state modulates the pilot signal on the Nth sub-band, and the first polarization state
  • the phase of the pilot signal modulated on the last sub-band of the N+1th sub-band of the second polarization state is opposite to that of the pilot signal modulated on the last sub-band of the N+1th sub-band of the second polarization state.
  • the pilot signals modulated on the Nth sub-band in the first sub-band of the first polarization state are all m*sin(2 ⁇ f k t+ ⁇ 0 ), and in the second
  • the pilot signals modulated on the first sub-frequency band of the polarization state and the Nth sub-frequency band are all m*sin(2 ⁇ f k t+ ⁇ 0 + ⁇ ).
  • the pilot signals modulated on the N+1th sub-band of the first polarization state to the k+1th sub-band are all m*sin(2 ⁇ f k t+ ⁇ 0 + ⁇ ), and in the N+1th sub-band of the second polarization state
  • the pilot signals modulated on the k+1th sub-band from one sub-frequency band are all m*sin(2 ⁇ f k t+ ⁇ 0 ).
  • the polarization state has k+1 sub-bands, which are respectively recorded as: f0, f0+df, f0+2df...f0+kdf.
  • the pilot signal modulated on the Nth sub-band in the first sub-band of the first polarization state is in reverse phase to the pilot signal modulated on the Nth sub-band in the first sub-band of the second polarization state.
  • the pilot signal modulated on the N+1th sub-band of the first polarization state on the k+1th sub-band is inverted from the pilot signal modulated on the N+1th sub-band of the second polarization state Mutually.
  • Step 503 sending the modulated optical signal.
  • the transmitter outputs the modulated optical signal to the wavelength division multiplexer after modulating the data to be transmitted and the pilot signal.
  • the embodiment of the present application also provides several pilot receivers correspondingly.
  • the pilot receiver includes a polarization maintaining power divider, a first polarization analyzer, a second polarization analyzer, a first photodetector, a second photodetector and a processor.
  • the polarization state can completely pass through the analyzer.
  • the polarization direction of the polarization state is orthogonal (perpendicular) to the polarization direction of the analyzer, the polarization state cannot pass through the analyzer.
  • the angle between the polarization direction of the polarization state and the polarization direction of the analyzer changes from 0° to 90°, the signal strength of the polarization state passing through the analyzer becomes weaker and weaker.
  • the included angle of the polarization direction is 45°, only half of the polarization state can pass through the analyzer.
  • the first polarization state and the second polarization state of the optical signal may undergo polarization rotation during transmission, and the following situation occurs: the included angle (acute angle) between the polarization direction of the polarization state and the polarization direction of the analyzer is 45°.
  • each polarizer will output half of the first polarization state and half of the first polarization state to the corresponding photodetector.
  • the photodetector corresponding to each polarizer will receive half of the first pilot signal and half of the second pilot signal.
  • the pilot signals modulated on the two polarization states are out of phase, the two pilot signals received by the photodetector will cancel each other out, and finally the pilot signal power obtained is 0.
  • the polarization direction of the first analyzer is not perpendicular to the polarization direction of the second analyzer.
  • the polarization maintaining power splitter needs to divide the input optical signal into two paths.
  • the polarization maintaining power splitter is 1:1 Polarization maintaining power splitter.
  • the polarization maintaining power divider receives the input optical signal, performs polarization maintaining power division on the input optical signal, outputs the first optical signal to the first polarization analyzer, and outputs the second optical signal to the second polarization analyzer.
  • the first optical signal and the second optical signal obtained after polarization-maintaining power division are the same, and the polarization state of the two optical signals is the same as that of the input optical signal, and the power of the two optical signals is half of the input optical signal.
  • the first polarizer performs polarization state filtering on the first optical signal, and outputs a third optical signal obtained by polarization state filtering to the first photodetector.
  • the second polarizer performs polarization state filtering on the second optical signal, and outputs a fourth optical signal obtained by polarization state filtering to the second photodetector.
  • the first photodetector converts the third light signal into a first electrical signal, and outputs the first electrical signal to the processor.
  • the second photodetector converts the four light signals into a second electrical signal, and outputs the second electrical signal to the processor.
  • the processor processes the first electrical signal and the second electrical signal to obtain the power of the pilot signal of each wavelength of the optical signal in the input optical signal.
  • the processing of the processor may be as follows:
  • the processor performs Fourier transform on s 1 (t) to obtain the first sub-power corresponding to each pilot frequency f k :
  • the first sub-power and the second sub-power are squared and summed first, and then the square root is taken to obtain the actual power corresponding to the pilot frequency f k :
  • the actual power corresponding to the pilot frequency f k is also the power of the pilot signal with the pilot frequency f k modulated on the optical signal with the wavelength ⁇ k in the input optical signal.
  • the polarization direction of the first polarizer and the polarization direction of the second analyzer can be 45°.
  • the angle between the polarization direction of the first analyzer and the polarization direction of the second analyzer can be 45°
  • ⁇ is the angle between the polarization direction after combining two orthogonal polarization states input to the analyzer and the polarization direction of the first analyzer.
  • the polarization analysis angle of the first polarizer is 0°
  • the polarization analysis angle of the second polarizer is 45°
  • An analyzer with an analysis angle of 0° can also be called a 0° analyzer, and an analyzer with an analysis angle of 45° can also be called a 45° analyzer.
  • ⁇ in the above cos(2 ⁇ ) and sin(2 ⁇ ) is the polarization angle after combining two orthogonal polarization states input to the polarizer.
  • both the first polarizer and the second polarizer are fiber-type polarizers.
  • the polarization maintaining power splitter is a polarization maintaining fiber coupler.
  • the pilot receiver provided in the embodiment of the present application may include N polarizers in addition to the above-mentioned first polarizer and second polarizer, corresponding , corresponding to the N analyzers may also include N photodetectors, and the N analyzers correspond to the N photodetectors one by one.
  • the polarization analysis angles of the N polarization analyzers are all different, and the polarization analysis angles of the N polarization analyzers are all larger than the polarization analysis angle of the first polarization analyzer and smaller than the polarization analysis angle of the second polarization analyzer.
  • the analysis angles of the above N analyzers can be respectively in, is the angle between the polarization direction of the first analyzer and the polarization direction of the second analyzer.
  • the polarization maintaining power divider needs to perform polarization maintaining power division on the input optical signal, and output N+2 optical signals, and the power of the N+2 optical signals is equal to is the power of the input optical signal Moreover, the polarization states of the N+2 optical signals are the same as the polarization states of the input optical signals.
  • the pilot receiver also includes a third polarizer besides the first polarizer and the second polarizer, and correspondingly, also includes a third photoelectric sensor corresponding to the third polarizer detector.
  • the analysis angle of the third analyzer is 22.5°.
  • the processor can receive electrical signals output from N+2 photodetectors, and for each electrical signal, the processor performs Fourier transform on the electrical signal to obtain each The subpower corresponding to the pilot frequency. Then, for each pilot frequency, the sub-powers corresponding to the pilot frequency obtained by Fourier transform are squared and summed, and then the square root is taken to obtain the actual power corresponding to the pilot frequency.
  • the application implements
  • the pilot receiver provided in this example may further include that the receiver further includes a circular polarization linear polarization converter, a fourth polarizer and a fourth photodetector.
  • the amplitude of the electrical signal output by the first photodetector is cos 2 ( ⁇ )-sin 2 ( ⁇ )
  • the amplitude of the electrical signal output by the second photodetector is The amplitude is
  • the amplitude of the electrical signal output by the fourth photodetector is [sin 2 ( ⁇ + ⁇ )-cos 2 ( ⁇ + ⁇ )] sin ⁇ .
  • ⁇ is the angle between the polarization direction of the fourth analyzer and the polarization direction of the first analyzer.
  • ⁇ is the ellipticity after synthesis of two orthogonal polarization states input to the analyzer.
  • the polarization maintaining power divider needs to perform polarization maintaining power division on the input optical signal, and output three optical signals , the three optical signals are respectively output to the first analyzer, the second analyzer and the circular polarization linear polarization converter.
  • the powers of the three optical signals are one-third of the power of the input optical signal, and the polarization states of the three optical signals are the same as the polarization states of the input optical signal.
  • the polarization maintaining power splitter converts the polarization state of the received optical signal. If the input polarization state is a linear polarization state, it will be converted to a circular polarization state for output. If the input polarization state is a circular polarization state, it will be converted to a linear polarization state. output.
  • the above-mentioned circular polarization linear polarization converter, the fourth polarizer and the fourth photodetector can also be set on the basis of the pilot receiver shown in FIG. 12 , see FIG. 14 .
  • the polarization analysis angle of the fourth polarizer is the same as the polarization analysis angle of the first polarization analyzer or the polarization analysis angle of the second polarization analyzer.
  • the circular polarization linear polarization converter is a quarter wave plate.
  • monitoring of polarization rotation and polarization-dependent loss can also be implemented.
  • the monitoring of polarization rotation (rotation of state of polarization, RSOP) and polarization dependent loss (polarization dependent loss, PDL) are described separately below.
  • the first photodetector outputs a first electrical signal to the processor, and the second photodetector outputs a second electrical signal to the processor.
  • the processor calculates a ratio of the first electrical signal to the second electrical signal. If the ratio of the first electrical signal to the second electrical signal changes over time, it is determined that the polarization state has undergone polarization rotation over time, that is, the polarization angle of the polarization state has changed over time.
  • the time derivative of the ratio of the first electrical signal to the second electrical signal may be calculated as the polarization rotation information, so as to characterize the time-domain change of the polarization angle of the polarization state.
  • the first photodetector outputs a first electrical signal to the processor
  • the second photodetector outputs a second electrical signal to the processor.
  • ⁇ is the angle between the polarization direction after the synthesis of two orthogonal polarization states and the polarization direction of the first analyzer
  • ⁇ is two positive Polarization angle after synthesis of cross-polarized states.
  • the processor compares the power of the first electrical signal with the power of the second electrical signal according to the monitoring period, so as to determine the polarization-dependent loss.
  • the processor obtains the maximum power of the first electrical signal in the monitoring period, and the first power of the second electrical signal when the first electrical signal is in the maximum power in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the first electrical signal is at the maximum power P max1 in the monitoring period, the first power is Then it can be confirmed that there is no polarization-dependent loss in the two polarization states.
  • the processor In each monitoring period, the processor also acquires the maximum power of the second electrical signal in the monitoring period, and the second power of the first electrical signal when the second electrical signal is in the maximum power in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the second electrical signal is at the maximum power P max2 in the monitoring period, the second power is Then it can be confirmed that there is no polarization-dependent loss in the two polarization states.
  • the first photodetector outputs a first electrical signal to the processor
  • the second photodetector outputs a second electrical signal to the processor
  • the third photodetector outputs a third electrical signal. Then, according to any two electrical signals of the first electrical signal, the second electrical signal and the third electrical signal, it is determined whether the polarization state has undergone polarization rotation with time.
  • the processor calculates a ratio of any two electrical signals among the first electrical signal, the second electrical signal and the third electrical signal. If the ratio changes over time, it is determined that the polarization state has undergone a polarization rotation over time.
  • the time derivative of the ratio of any two electrical signals can be calculated as the polarization rotation information to characterize the time-domain change of the polarization angle of the polarization state.
  • the processor calculates a ratio of the first electrical signal to the second electrical signal. If the ratio of the first electrical signal to the second electrical signal changes over time, it is determined that the polarization state has undergone polarization rotation over time.
  • the first photodetector outputs a first electrical signal to the processor
  • the second photodetector outputs a second electrical signal to the processor
  • the third photodetector outputs a third electrical signal to the processor.
  • the amplitude of the first electrical signal is cos 2 ( ⁇ )-sin 2 ( ⁇ )
  • the amplitude of the second electrical signal is
  • the amplitude of the third electrical signal is cos 2 ( ⁇ + ⁇ ) ⁇ sin 2 ( ⁇ + ⁇ ).
  • the processor compares the power of the first electrical signal, the power of the second electrical signal and the power of the third electrical signal according to the monitoring cycle to determine the polarization-dependent loss.
  • the processor acquires the maximum power of the first electrical signal in the monitoring period, the first power of the second electrical signal when the first electrical signal is at the maximum power in the monitoring period, and the first power of the second electrical signal.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the first electrical signal is at the maximum power P max1 in the monitoring period, the first power is And the third power is [cos 2 ( ⁇ )-sin 2 ( ⁇ )]*P max1 , then it can be determined that there is no polarization-dependent loss in the input optical signal.
  • the processor In each monitoring period, the processor also obtains the maximum power of the second electrical signal in the monitoring period, the second power of the first electrical signal when the second electrical signal is at the maximum power in the monitoring period, and the second electrical signal. A fourth power of the third electrical signal when the signal is at maximum power during the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the second electrical signal is at the maximum power P max2 in the monitoring period, the second power is and the fourth power is Then it can be determined that there is no polarization-dependent loss in the input optical signal.
  • the processor also obtains the maximum power of the third electrical signal in the monitoring period, the fifth power of the first electrical signal when the third electrical signal is at the maximum power in the monitoring period, and the third electrical signal.
  • monitoring of polarization rotation and polarization-dependent loss can also be implemented.
  • the processing of monitoring polarization rotation and polarization-dependent loss under the pilot receiver structure shown in Figure 13 is similar to the process of monitoring polarization rotation and polarization-dependent loss under the pilot receiver structure shown in Figure 14, and only Figure 13 is used below The monitoring of polarization rotation and polarization-dependent loss is realized under the shown pilot receiver structure.
  • the monitoring of polarization rotation is the same as or similar to the monitoring of polarization rotation under the receiver structure shown in FIG. 11 , and will not be repeated here.
  • the monitoring of polarization-dependent loss will be described below.
  • the first photodetector outputs a first electrical signal to the processor
  • the second photodetector outputs a second electrical signal to the processor
  • the fourth photodetector outputs a fourth electrical signal to the processor.
  • the amplitude of the first electrical signal is cos 2 ( ⁇ )-sin 2 ( ⁇ )
  • the amplitude of the second electrical signal is The amplitude of the fourth electrical signal is [sin 2 ( ⁇ + ⁇ )-cos 2 ( ⁇ + ⁇ )] sin ⁇ .
  • the processor compares the power of the first electrical signal, the power of the second electrical signal, and the power of the fourth electrical signal according to the monitoring period, so as to determine the polarization-dependent loss.
  • the processor acquires the maximum power of the first electrical signal in the monitoring period, the first power of the second electrical signal when the first electrical signal is at the maximum power in the monitoring period, and the first power of the second electrical signal.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the first electrical signal is at the maximum power P max1 in the monitoring period, the first power is And the seventh power is [sin 2 ( ⁇ )-cos 2 ( ⁇ )] sin ⁇ *P max1 , then it can be determined that there is no polarization-dependent loss in the input optical signal.
  • the processor also obtains the maximum power of the second electrical signal in the monitoring period, the second power of the first electrical signal when the second electrical signal is at the maximum power in the monitoring period, and the second electrical signal.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the second electrical signal is at the maximum power P max2 in the monitoring period, the second power is And the eighth power is 0, it can be determined that there is no polarization-dependent loss in the input optical signal.
  • the processor also acquires the maximum power of the fourth electrical signal in the monitoring period, the ninth power of the first electrical signal when the fourth electrical signal is at the maximum power in the monitoring period, and the fourth electrical signal The tenth power of the second electrical signal when the signal is at maximum power during the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the fourth electrical signal is at the maximum power P max4 in the monitoring period, the ninth power is [cos 2 (- ⁇ )-sin 2 (- ⁇ )]* If P max is 4 and the tenth power is 0, it can be determined that there is no polarization-dependent loss in the input optical signal.
  • the pilot receiver includes a polarization controller, a polarization beam splitter, a first photodetector, a second photodetector, and a processor.
  • the polarization controller receives an input optical signal, performs polarization scrambling or polarization locking on the input optical signal, and outputs the scrambled or polarization locked optical signal to the polarization beam splitter.
  • Depolarization scrambling means randomly disturbing the input optical signal to change the polarization direction of the polarization state of the input optical signal.
  • Polarization locking is to lock the polarization direction of the polarization state of the input optical signal, and output the polarization state with the fixed polarization direction.
  • polarization scrambling or polarization locking it is to avoid the polarization direction of the polarization state of the optical signal input into the polarization beam splitter to be 45°. Therefore, when the polarization controller is used for polarization locking, the polarization state output by the polarization controller must also be guaranteed.
  • the polarization angle is not 45°.
  • the polarization beam splitter is used to perform polarization splitting on the scrambled or locked optical signal to obtain orthogonal first and second optical signals, output the first optical signal to the first photodetector, and output the first optical signal to the second photodetector
  • the device outputs a second optical signal.
  • the first photodetector converts the first optical signal into a first electrical signal, and outputs the first electrical signal to the processor.
  • the second photodetector converts the second optical signal into a second electrical signal, and outputs the second electrical signal to the processor.
  • the processor processes the first electrical signal and the second electrical signal to obtain the power of the pilot signal of each wavelength of the optical signal in the input optical signal. It should be noted that the specific processing of the processor here is the same as that of the processor in the pilot receiver shown in FIG. 11 above, and will not be repeated here.
  • monitoring of polarization-dependent loss can be implemented.
  • the processor compares the power of the first electrical signal and the power of the second electrical signal according to the monitoring period to determine the polarization-dependent loss.
  • the processor obtains the maximum power of the first electrical signal within the monitoring period, and the power of the second electrical signal when the first electrical signal is at the maximum power within the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the first electrical signal is at the maximum power during the monitoring period, the second electrical signal is also at the maximum power during the monitoring period, and the two maximum powers are the same, then Verify that there is no polarization-dependent loss in the input optical signal.
  • the processor obtains the maximum power of the second electrical signal in the monitoring period, and the power of the first electrical signal when the second electrical signal is at the maximum power in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the second electrical signal is at the maximum power during the monitoring period, the first electrical signal is also at the maximum power during the monitoring period, and the two maximum powers are the same, then Verify that there is no polarization-dependent loss in the input optical signal.
  • the embodiment of the present application also provides a pilot receiver.
  • the pilot receiver includes a polarization maintaining power splitter, a polarization rotator, a first polarization beam splitter, a second polarization beam splitter, a first A photodetector, a second photodetector, a third photodetector, a fourth photodetector and a processor.
  • the optical signal undergoes polarization rotation, and the polarization angle of the first polarization state or the second polarization state after the polarization rotation is 45°.
  • each optical signal output by the polarization beam splitter contains half of the first polarization state and half of the second polarization state, so that each After the optical signal is input to the photodetector, the anti-phase pilot signals modulated on the two polarization states will cancel out, so that the processor cannot calculate the power of the pilot signal.
  • the input optical signal of the pilot receiver enters the polarization maintaining power divider first, and the polarization maintaining power divider maintains the input optical signal Partial power splitting, outputting the first optical signal to the polarization rotator, and outputting the second optical signal to the first polarization beam splitter.
  • the first optical signal and the second optical signal obtained after polarization-maintaining power division are the same, and the polarization state of the two optical signals is the same as that of the input optical signal, and the power of the two optical signals is half of the input optical signal.
  • the polarization rotator performs polarization rotation on the first optical signal to obtain a third optical signal, and sends the third optical signal to the second polarization beam splitter.
  • the first polarization beam splitter performs polarization splitting on the second optical signal to obtain a fourth optical signal and a fifth optical signal, and outputs the fourth optical signal to the first photodetector, and outputs the fifth light to the second photodetector. Signal.
  • the polarization rotator performs polarization rotation on the received optical signal, so that the output optical signal no longer has a polarization with a polarization angle of 45° In this way, the final processor can effectively calculate the power of the pilot signal.
  • the second polarization beam splitter performs polarization splitting on the third optical signal to obtain the sixth optical signal and the seventh optical signal, and outputs the sixth optical signal to the third photodetector, and outputs the seventh light to the fourth photodetector. Signal.
  • the first photodetector converts the fourth optical signal into a first electrical signal, and outputs the first electrical signal to the processor.
  • the second photodetector is used to convert the fifth light signal into a second electrical signal, and output the second electrical signal to the processor.
  • the third photodetector converts the sixth light signal into a third electrical signal, and outputs the third electrical signal to the processor.
  • the fourth photodetector converts the seventh light signal into a fourth electrical signal, and outputs the second electrical signal to the processor.
  • the processor processes the first electrical signal, the second electrical signal, the third electrical signal and the fourth electrical signal to obtain the power of the pilot signal of each wavelength optical signal in the input optical signal.
  • the processor sums the first electrical signal and the second electrical signal to obtain a fifth electrical signal, and sums the third electrical signal and the fourth electrical signal to obtain a sixth electrical signal. Then, the processor performs Fourier Fourier transform on the fifth electrical signal to obtain the first sub-power corresponding to each pilot frequency. And performing Fourier Fourier transform on the sixth electrical signal to obtain the second sub-power corresponding to each pilot frequency. Finally, for each pilot frequency, the first sub-power and the second sub-power corresponding to the pilot frequency are squared and summed, and the square root is taken to obtain the actual power corresponding to the pilot frequency.
  • the above polarization rotator is a 45° polarization rotator, that is, the polarization rotator can rotate the polarization state of the optical signal by 45° before outputting.
  • the polarization rotator can also be a polarization rotator with other angles, for example, between 40° and 50°.
  • monitoring of polarization rotation and polarization-dependent loss can be realized.
  • the monitoring of polarization rotation and polarization-dependent loss is described separately below.
  • the first electrical signal and the second electrical signal are monitored as a group, and the third electrical signal and the fourth electrical signal are monitored as a group.
  • the monitoring method for each group is the same as the polarization of the pilot receiver shown in Figure 11 above.
  • the rotation monitoring is the same, and will not be repeated here.
  • the processor compares the power of the first electrical signal, the power of the second electrical signal, the power of the third electrical signal and the power of the fourth electrical signal according to the monitoring period, so as to judge the polarization-dependent loss.
  • the processor acquires the maximum power of the first electrical signal in the monitoring period, the first power of the second electrical signal when the first electrical signal is at the maximum power in the monitoring period, and the first The second power of the third electrical signal when the electrical signal is at the maximum power in the monitoring period, and the third power of the fourth electrical signal when the first electrical signal is at the maximum power in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the first electrical signal is at the maximum power during the monitoring period, the second electrical signal is also at the maximum power during the monitoring period and the two maximum powers are the same, and the second electrical signal If the second power and the third power are 0, it is determined that there is no polarization-dependent loss in the input optical signal.
  • the processor also obtains the maximum power of the second electrical signal in the monitoring period, the fourth power of the first electrical signal when the second electrical signal is at the maximum power in the monitoring period, and the second electrical signal The fifth power of the third electrical signal when it is at the maximum power in the monitoring period, and the sixth power of the fourth electrical signal when the second electrical signal is at the maximum power in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the second electrical signal is at the maximum power during the monitoring period, the first electrical signal is also at the maximum power during the monitoring period and the two maximum powers are the same, and the second electrical signal If the fifth power and the sixth power are 0, it is determined that there is no polarization-dependent loss in the input optical signal.
  • the processor also acquires the maximum power of the third electrical signal in the monitoring period, the seventh power of the second electrical signal when the third electrical signal is at the maximum power in the monitoring period, and the third electrical signal The eighth power of the second electrical signal when the power is at the maximum in the monitoring period, and the ninth power of the fourth electrical signal when the third electrical signal is at the maximum power in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the third electrical signal is at the maximum power during the monitoring period, the fourth electrical signal is also at the maximum power during the monitoring period and the two maximum powers are the same, and the second If the eighth power and the ninth power are 0, it is determined that there is no polarization-dependent loss in the input optical signal.
  • the processor also acquires the maximum power of the fourth electrical signal in the monitoring period, the tenth power of the first electrical signal when the fourth electrical signal is at the maximum power in the monitoring period, and the second electrical signal
  • the eleventh power of the third electrical signal is at the maximum power in the monitoring period
  • the twelfth power of the fourth electrical signal is at the maximum power of the second electrical signal in the monitoring period.
  • the condition for judging that there is no polarization-dependent loss in the input optical signal is: if the fourth electrical signal is at the maximum power during the monitoring period, the third electrical signal is also at the maximum power during the monitoring period and the two maximum powers are the same, and the fourth electrical signal If the eleventh power and the twelfth power are 0, it is determined that there is no polarization-dependent loss in the input optical signal.
  • the program can be stored in a computer-readable storage medium.
  • the above-mentioned The storage medium mentioned may be a read-only memory, a magnetic disk or an optical disk, and the like.

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Abstract

本申请实施例公开了一种光信号发送的方法、导频接收机和发射机，属于光通信技术领域。方法包括：在光信号的第一偏振态上调制第一导频信号。在光信号的第二偏振态上调制第二导频信号。其中，第一导频信号的相位和第二导频信号的相位不同。输出调制后的光信号。采用本申请，可以减弱上述拉曼功率转移效应中转移到其他波长光信号上的导频信号的干扰。

Description

光信号发送的方法、导频接收机和发射机
本申请要求于2021年11月30日提交的申请号为202111446802.1、发明名称为“光信号发送的方法、导频接收机和发射机”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光通信领域，特别涉及一种光信号发送的方法、导频接收机和发射机。
背景技术
波分复用(wavelength division multiplexing，WDM)系统，可以实现将多种不同波长的光信号耦合在同一根光纤中传输，目前WDM系统在光通信中得到了广泛应用。为了使WDM系统可以稳定可靠的工作，需要有效监测WDM系统的各波长通道中传输的光信号的功率，以分析各波长通道的性能。
目前，较为常用的监测方法为导频音调法。在WDM系统中，发射机发出不同波长的光信号，对于每个波长的光信号调制一个导频信号，且对于不同波长的光信号调制的导频信号的导频频率。调制后的光信号在光纤中传输，每隔一段距离经放大器放大，并将放大后的部分光信号(如5％到10％的光信号)经过光耦合器输入到导频接收机。对于每个导频频率，导频接收机计算得到该导频频率的功率，进而可以得到相应光信号的功率，从而实现对WDM系统中各波长通道的性能分析。
然而，由于光纤存在拉曼功率转移效应，使得短波长光信号的光功率会向长波长光信号的光功率转移。如果波长f的光信号在一个节点处下波，则在该节点后的光纤中不应该再有该波长的光信号传输。但是，由于上述拉曼功率转移效应，使得波长f对应的导频频率的功率转移到了长波长光信号上。那么，后续导频接收机便仍可得到波长f对应的导频频率的功率，进而计算得到波长f的光信号的功率。但是，实际上波长f的光信号并未在这段光纤中传输，这样就出现了监测错误。因此，亟需一种能够减弱上述拉曼功率转移效应中转移到其他波长光信号上的导频信号的干扰。
发明内容
本申请实施例提供了一种光信号发送的方法和导频接收机，可以减弱上述拉曼功率转移效应中转移到其他波长光信号上的导频信号的干扰。所述技术方案如下：
第一方面，提供了一种光信号发送的方法，方法可以有波分复用系统中的发射机实现，方法包括：在光信号的第一偏振态上调制第一导频信号。在光信号的第二偏振态上调制第二导频信号。其中，第一导频信号的相位和第二导频信号的相位不同。输出调制后的光信号。
在本申请实施例所示的方案中，假设第一波长的光信号调制了第一频率的导频信号和第二波长的光信号调制了第二频率的导频信号。在光纤传输过程中，第一波长的光信号和第二波长的光信号之间发生了拉曼功率转移，部分第一波长的光信号的功率会向第二波长的光信 号的功率转移。相应的，第一频率的导频信号也会向第二波长的光信号转移。如果按照相关技术，光信号的两个偏振态调制的导频信号是同相的，那么，第一频率的两个同相导频信号转移到第二光信号时，会出现如图1左图所示的叠加情况，即波峰和波峰叠加。而采用本申请提供的方案，光信号的两个偏振态调制的导频信号是不同相的，那么，第一频率的两个不同相的导频信号转移到第二光信号时，会出现如图1右图所示的叠加情况，即波峰和波峰是错开的，通过比较图1中的两种情况，可以看出本申请提供的方案，在出现拉曼功率转移时，导频信号叠加后的功率是要小于相关技术中导频信号叠加后的功率的，也即是，通过本申请的方案可以在一定程度上减弱因为拉曼功率转移效应而转移到其他波长光信号上的导频信号的干扰。
在一种可能的实现方式中，第一导频信号和第二导频信号反相。
反相也即是相位相反，或者说相位差为180°(弧度制表示为π)。
假设在光纤传输过程中，第一波长的光信号和第二波长的光信号之间发生了拉曼功率转移，第一频率的导频信号也会向第二波长的光信号转移。如果按照相关技术，光信号的两个偏振态调制的导频信号是同相的，那么，第一频率的两个同相导频信号转移到第二光信号时，会出现如图2左图所示的叠加情况，即波峰和波峰叠加。而采用本申请提供的方案，在第一导频信号和第二导频信号反相的情况下，第一频率的两个不同相的导频信号转移到第二光信号时，会出现如图2右图所示的叠加情况，即波峰和波谷相遇，使得两个导频信号相互抵消，通过比较图2中的两种情况，可以看出本申请提供的方案，在出现拉曼功率转移时，相同频率的两个导频信号相互抵消，也即是，通过本申请的方案可以在一定程度上减弱甚至消除因为拉曼功率转移效应而转移到其他波长光信号上的导频信号的干扰。
在一种可能的实现方式中，在第一偏振态和第二偏振态的相同子频带上调制的导频信号反相。
在一种可能的实现方式中，在第一偏振态的各子频带上调制的导频信号与在第二偏振态的各子频带上调制的导频信号均反相。
在一种可能的实现方式中，在第一偏振态的第一个子频带到第N个子频带上调制的导频信号与在第二偏振态的第一个子频带到第N个子频带上调制的第二导频信号反相，在第一偏振态的第N+1个子频带到最后一个子频带上调制的导频信号与在第二偏振态的第N+1个子频带到最后一个子频带上调制的导频信号反相，其中，N为正整数。
在一种可能的实现方式中，在第一偏振态的第A个子频带上调制的导频信号与在第二偏振态的第A个子频带上调制的导频信号反相，在第一偏振态的第B个子频带上调制的导频信号与在第二偏振态的第B个子频带上调制导频信号反相，其中，A为奇数且B为偶数，或者，A为偶数且B为奇数。
第二方面，提供了一种导频接收机，导频接收机包括保偏功分器、第一检偏器、第二检偏器、第一光电探测器、第二光电探测器和处理器，其中：
保偏功分器用于接收输入光信号，并向第一检偏器输出第一光信号，向第二检偏器输出第二光信号。其中，第一光信号、第二光信号和输入光信号的偏振态相同，第一光信号和所述第二光信号的功率相同。
第一检偏器用于对第一光信号进行偏振态过滤，向第一光电探测器输出偏振态过滤得到 的第三光信号。第二检偏器，用于对第二光信号进行偏振态过滤，向第二光电探测器输出偏振态过滤得到的第四光信号，第一检偏器的偏振化方向和第二检偏器的偏振化方向不正交。
第一光电探测器用于将第三光信号转换为第一电信号，并向处理器输出第一电信号。第二光电探测器用于将四光信号转换为第二电信号，并向处理器输出第二电信号。
处理器用于对第一电信号和第二电信号进行处理，得到输入光信号中各波长的光信号的导频频率对应的功率。
在一种可能的实现方式中，第一检偏器的偏振化方向和第二检偏器的偏振化方向夹角的范围为40°到50°。例如，45°。
在一种可能的实现方式中，第一检偏器为0°检偏器，第二检偏器为45°检偏器。
在一种可能的实现方式中，处理器还用于根据第一电信号和所述第二电信号，确定输入光信号的RSOP信息。
在一种可能的实现方式中，处理器还用于根据第一电信号和第二电信号，确定输入光信号的偏振相关损耗PDL。
在一种可能的实现方式中，导频接收机还包括第三检偏器和第三光电探测器，第三检偏器的检偏角度大于检偏器的检偏角度且小于所述第二检偏角度。
保偏功分器还用于向第三检偏器输出第五光信号。其中，第五光信号、第一光信号、第二光信号和所述输入光信号的偏振态相同，第五光信号、第一光信号和第二光信号的功率相同。
第三检偏器用于对第五光信号进行偏振态过滤，向第三光电探测器输出偏振态过滤得到的第六光信号。第三光电探测器用于将第六光信号转换为第三电信号，并向处理器输出第三电信号。处理器用于对第一电信号、第二电信号和第三电信号进行处理，得到输入光信号中各波长的光信号对应的导频信号的功率。
在一种可能的实现方式中，第三检偏器的检偏角度为所述第一检偏器的偏振化方向和所述第二检偏器的偏振化方向夹角的二分之一。
在一种可能的实现方式中，导频接收机还包括圆偏振线偏振转换器、第四检偏器和第四光电探测器。
保偏功分器还用于向圆偏振线偏振转换器输出第七光信号，其中，第七光信号、第一光信号、第二光信号和输入光信号的偏振态相同，第七光信号、第一光信号和第二光信号的功率相同。
圆偏振线偏振转换器用于将第七光信号中的椭圆偏振态转换为线偏振态，并向第四检偏器输出转换得到的第八光信号。第四检偏器，用于将第八光信号转换为第四电信号，并向处理器输出所述第四电信号。
处理器用于对第一电信号、第二电信号和第四电信号进行处理，得到输入光信号中各波长的光信号的导频频率对应的功率。
在一种可能的实现方式中，圆偏振线偏振转换器为四分之一波片。
在一种可能的实现方式中，第四检偏器的检偏角度与所述第一检偏器的检偏角度或第二检偏器的检偏角度相同。
在一种可能的实现方式中，处理器，用于对第一电信号进行傅里叶变换，得到输入光信号中各波长的光信号的导频频率对应的第一子功率。对第二电信号进行傅里叶变换，得到输 入光信号中各波长的光信号的导频频率对应的第二子功率。对于每个导频频率，根据导频频率对应的第一子功率和第二子功率，得到导频频率对应的实际功率。
第三方面，提供了一种导频接收机，所述导频接收机包括偏振控制器、偏振分束器、第一光电探测器、第二光电探测器和处理器，其中：
所述偏振控制器，用于接收光信号，对所述光信号进行扰偏，并向所述偏振分束器输出扰偏后的光信号；
所述偏振分束器，用于对扰偏后的光信号进行偏振分光束，得到第一光信号和第二光信号，向所述第一光电探测器输出所述第一光信号，向所述第二光电探测器输出所述第二光信号，其中，所述第一光信号和所述第二光信号正交；
所述第一光电探测器，用于将所述第一光信号转换为第一电信号，并向所述处理器输出所述第一电信号；
所述第二光电探测器，用于将所述第二光信号转换为第二电信号，并向所述处理器输出所述第二电信号；
所述处理器，用于对所述第一电信号和所述第二电信号进行处理，得到所述输入光信号中各波长的光信号对应的导频信号的功率。
在一种可能的实现方式中，所述处理器还用于：
根据所述第一电信号和所述第二电信号，确定所述输入光信号的RSOP信息。
在一种可能的实现方式中，所述处理器还用于：
根据所述第一电信号和所述第二电信号，确定所述输入光信号的PDL。
第四方面，提供了一种导频接收机，所述导频接收机包括保偏功分器、偏振旋转器、第一偏振分束器、第二偏振分束器、第一光电探测器、第二光电探测器、第三光电探测器、第四光电探测器和处理器，其中：
所述保偏功分器，用于接收输入光信号，并向所述偏振旋转器输出第一光信号，向所述第一偏振分束器输出第二光信号，其中，所述第一光信号、所述第二光信号和所述输入光信号的偏振态相同，所述第一光信号和所述第二光信号的功率相同；
所述偏振旋转器，用于对所述第一光信号进行偏振旋转，得到第三光信号，向所述第二偏振分束器发送所述第三光信号；
所述第一偏振分束器，用于对所述第二光信号进行偏振分束，得到第四光信号和第五光信号，并向所述第一光电探测器输出所述第四光信号，向所述第二光电探测器输出所述第五光信号；
所述第二偏振分束器，用于对所述第三光信号进行偏振分束，得到第六光信号和第七光信号，并向所述第三光电探测器输出所述第六光信号，向所述第四光电探测器输出所述第七光信号；
所述第一光电探测器，用于将所述第四光信号转换为第一电信号，并向所述处理器输出所述第一电信号；
所述第二光电探测器，用于将所述第五光信号转换为第二电信号，并向所述处理器输出所述第二电信号；
所述第三光电探测器，用于将所述第六光信号转换为第三电信号，并向所述处理器输出所述第三电信号；
所述第四光电探测器，用于将所述第七光信号转换为第四电信号，并向所述处理器输出所述第四电信号；
所述处理器，用于对所述第一电信号、所述第二电信号、所述第三电信号和所述第四电信号进行处理，得到所述输入光信号中各波长的光信号对应的导频信号的功率。
在一种可能的实现方式中，所述偏振旋转器为45°偏振旋转器。
在一种可能的实现方式中，所述处理器，用于：
将所述第一电信号和所述第二电信号进行相加，得到第五电信号；
将所述第三电信号和所述第四电信号进行相加，得到第六电信号；
对所述第五电信号进行傅里叶变换，得到所述输入光信号中各波长的光信号的导频频率对应的第一子功率；
对所述第六电信号进行傅里叶变换，得到所述输入光信号中各波长的光信号的导频频率对应的第二子功率；
对于每个导频频率，根据所述导频频率对应的第一子功率和第二子功率，得到所述导频频率对应的实际功率。
在一种可能的实现方式中，所述处理器还用于：
根据所述第一电信号、所述第二电信号、所述第三电信号和所述第四电信号，确定所述输入光信号的RSOP信息。
在一种可能的实现方式中，所述处理器还用于：
根据所述第一电信号、所述第二电信号、所述第三电信号和所述第四电信号，确定所述输入光信号的PDL。
第五方面，提供了一种发射机，发射机包括信号发射器和调制器，其中：
所述信号发射器，用于发送光信号；
所述调制器，用于在所述光信号的第一偏振态上调制第一导频信号，在所述光信号的第二偏振态上调制第二导频信号，其中，所述第一导频信号的相位和所述第二导频信号的相位不同，输出调制后的光信号。
附图说明
图1是本申请实施例提供的一种导频信号的示意图；
图2是本申请实施例提供的一种导频信号的示意图；
图3是本申请实施例提供的一种WDM系统的示意图；
图4是本申请实施例提供的一种拉曼功率转移的示意图；
图5是本申请实施例提供的一种光信号发送的方法流程图；
图6是本申请实施例提供的一种发射机的结构示意图；
图7是本申请实施例提供的一种发射机的结构示意图；
图8是本申请实施例提供的一种导频信号反相的示意图；
图9是本申请实施例提供的一种导频信号反相的示意图；
图10是本申请实施例提供的一种导频信号反相的示意图；
图11是本申请实施例提供的一种导频接收机的结构示意图；
图12是本申请实施例提供的一种导频接收机的结构示意图；
图13是本申请实施例提供的一种导频接收机的结构示意图；
图14是本申请实施例提供的一种导频接收机的结构示意图；
图15是本申请实施例提供的一种导频接收机的结构示意图；
图16是本申请实施例提供的一种导频接收机的结构示意图。
具体实施方式
本申请实施例提供了一种光信号发送的方法，该方法可以应用于波分复用(wavelength division multiplexing，WDM)系统中。参见图3，在WDM系统中，发送端可以包括多个发射机，如Tx1、Tx2……TxN，还可以包括波分复用器。相应的，接收端也可以包括多个接收机，如Rx1、Rx2、Rx3……RxN，还可以包括波分复用器。在发送端和接收端之间的传输链路可以为光纤，在传输链路上可以设置有放大器、功分器等。
发射机在光信号上调制业务信号和导频信号，并发送调制后的光信号，光信号经过波分复用器合成一束，并经过放大器放大。然后，由光纤进行传输。光纤传输过程中光信号可以每隔一段距离经过放大器进行放大。例如，可以在光纤上每隔80千米(km)设置一个放大器，用于对光信号进行放大。经过放大后的光信号可以由功分器分出部分光信号进入导频接收机。例如，功分器为10:90功分器，则经过放大后的光信号可以由10:90功分器分出10％光信号进入导频接收机。最后，光信号传输到接收端，由接收端的波分复用器分开成N路光信号分别输出至接收机，接收机再对输入的光信号进行处理。
下面对导频信号及拉曼功率转移进行简要说明。
例如，发送端的三个发射机分别可以发送波长为λ 1、λ 2和λ 3的光信号。并且发射机在波长为λ 1的光信号上调制频率为f 1的导频信号，在波长为λ 2的光信号上调制频率为f 2的导频信号，在波长为λ 3的光信号上调制频率为f 3的导频信号。当光纤存在受激拉曼散射时，光信号会出现拉曼功率转移。波长为λ 1的光信号的功率会有部分转移到波长为λ 2和λ 3的光信号上，波长为λ 2的光信号的功率会有部分转移到波长为λ 1和λ 3的光信号上，波长为λ 3的光信号的功率会有部分转移到波长为λ 1和λ 2的光信号上。相应的，如图4所示，频率为f 1的导频信号的功率会有部分转移到波长为λ 1和λ 2的光信号上，频率为f 2的导频信号的功率会有部分转移到波长为λ 1和λ 3的光信号上，频率为f 3的导频信号的功率会有部分转移到波长为λ 1和λ 2的光信号上。
为了能减弱上述拉曼功率转移效应中转移到其他波长光信号上的导频信号的干扰，本申请实施例提出了一种光信号发送的方法，该方法可以由WDM系统中的发射机实现，参见图5，该方法可以包括如下步骤：
步骤501、获取光信号的第一偏振态和第二偏振态。
其中，第一偏振态和第二偏振态正交。
在实施中，发射机中的激光器发出光信号。然后，由发射机中可实现双向起偏功能的器件，对光信号进行双向起偏，得到该光信号的第一偏振态和第二偏振态。
在不同的发射机结构中，实现双向起偏功能的器件也可以不同，下面列举几种发射机进 行说明。
如图6所示，发射机可以包括激光器和双偏振IQ调制器。激光器发射光信号，光信号进入双偏振IQ调制器。双偏振IQ调制器将光信号分为正交的第一偏振态和第二偏振态。
如图7所示，发射机包括激光器、偏振分束器、IQ调制器、可变光衰减器(variable optical attenuator，VOA)和偏振合束器。激光器发射光信号，光信号进入偏振分束器。偏振分束器将光信号分为正交的第一偏振态和第二偏振态，并分别输出至两个IQ调制器。
步骤502、在第一偏振态调制第一导频信号，在第二偏振态调制第二导频信号。
其中，第一导频信号和第二导频信号的相位不同。
在实施中，发射器在光信号的两个正交的偏振态上分别调制频率相同而相位不同的第一导频信号和第二导频信号。
在不同的发射机结构中，用于调制导频信号的器件也可以不同。
在图6所示的发射机中，双偏IQ调制器将输入的光信号分为第一偏振态和第二偏振态后，进行正交幅度调制，在第一偏振态和第二偏振态上分别调制导频信号，且在第一偏振态和第二偏振态上调制的导频信号相位不同。例如，在第一偏振态上调制的导频信号如下：
m*sin(2πf kt+Φ 0)
在第二偏振态上调制的导频信号如下：
m*sin(2πf kt+Φ 0+α)
其中，m为调制深度，f k为调制频率，t为时间，Φ 0为初始相位，α为相位差，α取值可以为(0，2π)。
下面对导频信号的调制频率和调制深度的取值进行示例性说明。
导频信号的调整频率可以在30兆赫(MHz)到40MHz之间，导频信号的调制深度可以在0.01到0.2之间。
调制深度的定义为：
Figure PCTCN2022119627-appb-000001
其中，P max为光信号的最大功率，P min为光信号的最小功率，
Figure PCTCN2022119627-appb-000002
为光信号的平均功率。
此外，还需说明的是，双偏IQ调制器还可以在第一偏振态和第二偏振态上调制待发送数据。该待发送数据可以为用户想要发送的业务数据。
在如图7所示的发射机中，IQ调制器在输入的偏振态上调制待发送数据，并输出至对应的VOA。然后，数字信号处理器(digital signal process，DSP)控制两个VOA在输入的光信号上分别调制导频信号，且两个VOA调制的导频信号的相位不同。
在一种可能的实现方式中，为了使两个偏振态上分别调制的导频信号在转移到其他光信号上后可以进行抵消，光信号的两个偏振态上分别调制的导频信号可以为反相信号，即，两个导频信号的相位相差180°(也即是弧度制的π)。
在实施中，在两个偏振态上分别调制的导频信号，可以有多种反相的形式，下面列举其中几种进行说明。
形式一、
如图8所示，在第一偏振态的各子频带上调制的导频信号均同相，在第二偏振态的各子频带上调制的导频信号均同相，且在第一偏振态的各子频带上调制的导频信号与在第一偏振态的各子频带上调制的导频信号均反相。
例如，在第一偏振态的各子频带上调制的导频信号均为m*sin(2πf kt+Φ 0)，在第二偏振 态的各子频带上调制的导频信号均为m*sin(2πf kt+Φ 0+π)。
形式二、
第一偏振态的第A个子频带上调制的导频信号与第二偏振态的第A个子频带上调制第二导频信号反相，第一偏振态的第B个子频带上调制的第一导频信号与第二偏振态的第B个子频带上调制第二导频信号反相。其中，A为奇数且B为偶数，或者，A为偶数且B为奇数。
例如，偏振态有k+1个子频带，k为偶数，则A的取值可以为1、3、5...k+1，相应的，B的取值可以为2、4、6...k。或者，A的取值可以为2、4、6...k，相应的，B的取值可以为1、3、5...k+1。在第一偏振态的第1、3、5...k+1个子频带上调制的导频信号为m*sin(2πf kt+Φ 0)，在第一偏振态的第2、4、6...k个子频带上调制的导频信号为m*sin(2πf kt+Φ 0+π)。在第二偏振态的第1、3、5...k+1个子频带上调制的导频信号为m*sin(2πf kt+Φ 0+π)，在第二偏振态的第2、4、6...k个子频带上调制的导频信号均为m*sin(2πf kt+Φ 0)。
如图9所示，偏振态有k+1个子频带，分别记为：f0、f0+df、f0+2df...f0+kdf。第一偏振态的第1、3、5...k+1个子频带上调制的导频信号与第二偏振态的第2、4、6...k个子频带上调制第二导频信号反相。第一偏振态的第2、4、6...k个子频带上调制的导频信号与第二偏振态的第1、3、5...k+1个子频带上调制的导频信号反相。
形式三、
第一偏振态的第一个子频带到第N个子频带上调制的导频信号与第二偏振态的第一个子频带到第N个子频带上调制的导频信号反相，第一偏振态的第N+1个子频带到最后一个子频带上调制的导频信号与第二偏振态的第N+1个子频带到最后一个子频带上调制的导频信号反相。
例如，偏振态有k+1个子频带，在第一偏振态的第一个子频带到第N个子频带上调制的导频信号均为m*sin(2πf kt+Φ 0)，在第二偏振态的第一个子频带到第N个子频带上调制的导频信号均为m*sin(2πf kt+Φ 0+π)。在第一偏振态的第N+1个子频带到第k+1个子频带上调制的导频信号均为m*sin(2πf kt+Φ 0+π)，在第二偏振态的第N+1个子频带到第k+1个子频带上调制的导频信号均为m*sin(2πf kt+Φ 0)。
如图10所示，偏振态有k+1个子频带，分别记为：f0、f0+df、f0+2df...f0+kdf。第一偏振态的第一个子频带到第N个子频带上调制的导频信号与第二偏振态的第一个子频带到第N个子频带上调制的导频信号反相。第一偏振态的第N+1个子频带到第k+1个子频带上调制的导频信号与第二偏振态的第N+1个子频带到第k+1个子频带上调制的导频信号反相。
步骤503、发送调制后的光信号。
在实施中，发射机在调制完待发送数据和导频信号后，向波分复用器输出调制后的光信号。
为了配合本申请实施例提供的光信号发送的方法，使得反相的导频信号可以被检测到，本申请实施例还相应提供了几种导频接收机。
参见图11，导频接收机包括保偏功分器、第一检偏器、第二检偏器、第一光电探测器、第二光电探测器和处理器。
下面先对检偏器的偏振化方向和光信号的偏振方向之间的关系进行简要说明。
在偏振态的偏振方向与检偏器的偏振化方向平行时，偏振态可以完全通过检偏器。在偏振态的偏振方向与检偏器的偏振化方向正交(垂直)时，偏振态无法通过检偏器。随着偏振态的偏振方向与检偏器的偏振化方向的夹角从0°向90°变化，偏振态通过检偏器的信号强度越来越弱，当偏振态的偏振方向与检偏器的偏振化方向的夹角为45°时，该偏振态仅有一半可以通过检偏器。
在实施中，光信号的第一偏振态和第二偏振态在传输过程中可能发生偏振旋转，而出现以下情况：偏振态的偏振方向和检偏器的偏振化方向的夹角(锐角)为45°。在此情况下，如果采用传统的偏振化方向为正交关系的两检偏器进行偏振过滤的话，每个检偏器均会输出向对应的光电探测器输出一半的第一偏振态和一半的第二偏振态，相应的，每个检偏器对应的光电探测器均会接收到一半的第一导频信号和一半的第二导频信号。在两个偏振态上调制的导频信号为反相的情况下，会导致光电探测器接收到的两个导频信号相互抵消，最终得到的导频信号功率为0。
为了避免上述问题的发生，使光电探测器可以检测到导频信号，在本申请实施例中第一检偏器的偏振化方向和第二检偏器的偏振化方向不正交。
在本申请实施例中，参见图11，因为设置了两个检偏器，所以保偏功分器需要将输入光信号分为两路，在此情况下，保偏功分器为1∶1保偏功分器。
保偏功分器接收输入光信号，并对输入光信号进行保偏功分，向第一检偏器输出第一光信号，向第二检偏器输出第二光信号。保偏功分后得到的第一光信号和第二光信号相同，且两个光信号的偏振态与输入光信号的偏振态相同，两个光信号的功率均为输入光信号的一半。
第一检偏器对第一光信号进行偏振态过滤，向第一光电探测器输出偏振态过滤得到的第三光信号。第二检偏器对第二光信号进行偏振态过滤，向第二光电探测器输出偏振态过滤得到的第四光信号。
第一光电探测器将第三光信号转换为第一电信号，并向处理器输出第一电信号。第二光电探测器将四光信号转换为第二电信号，并向处理器输出第二电信号。
处理器对第一电信号和第二电信号进行处理，得到输入光信号中各波长光信号的导频信号的功率。
具体的，处理器的处理可以如下：
假设第一电信号为s 1(t)，第二电信号为s 2(t)。
首先，处理器对s 1(t)进行傅里叶变换，得到各导频频率f k对应的第一子功率：
Figure PCTCN2022119627-appb-000003
并对s 2(t)进行傅里叶变换，得到各导频频率f k对应的第二子功率：
Figure PCTCN2022119627-appb-000004
然后，对于每个导频频率f k，将第一子功率和第二子功率先平方求和，再开平方，即可得到该导频频率f k对应的实际功率：
Figure PCTCN2022119627-appb-000005
此处，导频频率f k对应的实际功率也即是输入光信号中波长为λ k的光信号上调制的导频频率为f k的导频信号的功率。
在一种可能的实现方式中，为了使第一光电探测器和第二光电探测器输出的电信号成正交关系，第一检偏器的偏振化方向和第二检偏器的偏振化方向的夹角可以为45°。
在第一检偏器偏振化方向和第二检偏器的偏振化方向的夹角可以为45°的情况下，假设第一光电探测器输出的电信号的振幅为cos 2(θ)-sin 2(θ)＝cos(2θ)，则第二光电探测器输出的电信号的振幅为cos 2(θ+45°)-sin 2(θ+45°)＝cos(2θ+90°)＝sin(2θ)。其中，θ为输入检偏器的两个正交偏振态合成后的偏振方向和第一检偏器的偏振化方向的夹角。
在一种可能的实现方式中，第一检偏器的检偏角度为0°，第二检偏器的检偏角度为45°。
检偏角度为0°的检偏器也可称为0°检偏器，检偏角度为45°的检偏器也可称之为45°检偏器。
在第一检偏器为0°检偏器的情况下，上述cos(2θ)和sin(2θ)中的θ即为输入检偏器的两个正交偏振态合成后的偏振角。
在一种可能的实现方式中，第一检偏器和第二检偏器均为光纤型起检偏器。
在一种可能的实现方式中，保偏功分器为保偏光纤耦合器。
在一种可能的实现方式中，参见图12，本申请实施例提供的导频接收机中除上述第一检偏器和第二检偏器外，还可以包括N个检偏器，相应的，对应N个检偏器还可以包括N个光电探测器，N个检偏器和N个光电探测器一一对应。
N个检偏器的检偏角度均不同，N个检偏器的检偏角度均大于第一检偏器的检偏角度且小于第二检偏器的检偏角度。
在一种可能的实现方式中，上述N个检偏器的检偏角度可以分别为
Figure PCTCN2022119627-appb-000006
Figure PCTCN2022119627-appb-000007
其中，
Figure PCTCN2022119627-appb-000008
为第一检偏器的偏振化方向和第二检偏器的偏振化方向的夹角。
在导频接收机还包括上述N个检偏器的情况下，保偏功分器需要对输入光信号进行保偏功分，输出N+2路光信号，N+2路光信号的功率均为输入光信号的功率的
Figure PCTCN2022119627-appb-000009
且，N+2路光信号的偏振态与输入光信号的偏振态相同。
例如，N＝1，则导频接收机除第一检偏器和第二检偏器以外，还包括一个第三检偏器，相应的，还包括和第三检偏器对应的第三光电探测器。其中，第三检偏器的检偏角度为22.5°。
在图12所示的导频接收机中，处理器可以接收来自N+2个光电探测器输出的电信号，对于每一个电信号，处理器对该路电信号进行傅里叶变换，得到各导频频率对应的子功率。然后，对于每个导频频率，将傅里叶变换得到的该导频频率对应的各子功率进行平方求和，再开平方，即可得到该导频频率对应的实际功率。
在一种可能的实现方式中，参见图13，为了在偏振态在传输过程中旋转为特殊的偏振态时，导频接收机仍然可以对偏振态上调制的导频信号进行接收，本申请实施例提供的导频接收机还可以包括接收机还包括圆偏振线偏振转换器、第四检偏器和第四光电探测器。
下面先对上述特殊的偏振态进行简要说明。
在考虑偏振态由线偏振变为原偏振的情况下，假设第一光电探测器输出的电信号的振幅为cos 2(θ)-sin 2(θ)，第二光电探测器输出的电信号的振幅为
Figure PCTCN2022119627-appb-000010
第四光电探测器输出的电信号的振幅为[sin 2(θ+φ)-cos 2(θ+φ)]sinδ。其中，φ为第四检偏器的偏振化方向和第一检偏器的偏 振化方向的夹角。δ为输入检偏器的两个正交偏振态合成后的椭圆度。当θ＝45°，δ＝90°时，第一光电探测器输出的电信号的振幅为cos 2(θ)-sin 2(θ)和第二光电探测器输出的电信号的振幅为
Figure PCTCN2022119627-appb-000011
均为0，只有第四光电探测器输出的电信号的振幅为[sin 2(θ+φ)-cos 2(θ+φ)]sinδ不为0，此情况即为上述特殊的偏振态，可见，在此情况下，第一光电探测器和第二探测器均无电信号输出。
在导频接收机还包括圆偏振线偏振转换器、第四检偏器和第四光电探测器的情况下，保偏功分器需要对输入光信号进行保偏功分，输出三路光信号，三路光信号分别输出至第一检偏器、第二检偏器和圆偏振线偏振转换器。三路光信号的功率均为输入光信号的功率的三分之一，且三路光信号的偏振态与输入光信号的偏振态相同。
保偏功分器对接收到的光信号进行偏振态转换，如果输入的偏振态为线偏振态，则转换为圆偏振态输出，如果输入的偏振态为圆偏振态，则转换为线偏振态输出。
此外，上述圆偏振线偏振转换器、第四检偏器和第四光电探测器还可以在图12所示的导频接收机的基础上设置，参见图14。
在一种可能的实现方式中，第四检偏器的检偏角度与第一检偏器的检偏角度或第二检偏器的检偏角度相同。
在一种可能的实现方式中，圆偏振线偏振转换器为四分之一波片。
在一种可能的实现方式中，在图11所示的接收机结构下，还可以实现对偏振旋转、偏振相关损耗的监测。下面对监测偏振旋转(rotation of state of polarization，RSOP)和偏振相关损耗(polarization dependent loss，PDL)分别进行说明。
一、监测偏振旋转
第一光电探测器向处理器输出第一电信号，第二光电探测器向处理器输出第二电信号。处理器计算第一电信号和第二电信号的比值。如果第一电信号和第二电信号的比值随时间发生变化，则确定偏振态随时间变化发生了偏振旋转，即偏振态的偏振角随时间发生了改变。
具体的，可以计算第一电信号和第二电信号的比值对时间的导数，作为偏振旋转信息，以表征偏振态的偏振角的时域变化。
二、监测偏振相关损耗
第一光电探测器向处理器输出第一电信号，第二光电探测器向处理器输出第二电信号。假设第一电信号的振幅为cos 2(θ)-sin 2(θ)，第二电信号的振幅为
Figure PCTCN2022119627-appb-000012
其中，θ为两个正交偏振态合成后的偏振方向和第一检偏器的偏振化方向的夹角，在第一检偏器为0°检偏器的情况下，θ为两个正交偏振态合成后的偏振角。
Figure PCTCN2022119627-appb-000013
为第一检偏器的偏振化方向和第二检偏器的偏振化方向的夹角，在第二检偏器为45°检偏器的情况下，
Figure PCTCN2022119627-appb-000014
处理器按照监测周期对第一电信号的功率和第二电信号的功率进行比较，以判断偏振相关损耗。
具体的，在每个监测周期内，处理器获取第一电信号在该监测周期内的最大功率，以及当第一电信号在该监测周期内处于最大功率时第二电信号的第一功率。判断输入光信号不存在偏振相关损耗的条件为：如果第一电信号在该监测周期内处于最大功率P max1时，第一功率为
Figure PCTCN2022119627-appb-000015
则可以确定两个偏振态不存在偏振相关损耗。
在每个监测周期内，处理器还获取第二电信号在该监测周期内的最大功率，以及当第二电信号在该监测周期内处于最大功率时第一电信号的第二功率。判断输入光信号不存在偏振相关损耗的条件为：如果第二电信号在该监测周期内处于最大功率P max2时，第二功率为
Figure PCTCN2022119627-appb-000016
则可以确定两个偏振态不存在偏振相关损耗。
当以上两个判断输入光信号不存在偏振相关损耗的条件中，有任一条件满足时，则确定输入光信号不存在偏振相关损耗，当以上两个判断输入光信号不存在偏振相关损耗的条件均不满足时，则确实输入光信号存在偏振相关损耗。
在一种可能的实现方式中，在图12所示的接收机结构下，也可以实现对偏振旋转、偏振相关损耗的监测。下面以N＝1为例，对图12所示的接收机结构下监测偏振旋转和偏振相关损耗分别进行说明。
一、监测偏振旋转
第一光电探测器向处理器输出第一电信号，第二光电探测器向处理器输出第二电信号，第三光电探测器输出第三电信号。然后，根据第一电信号、第二电信号和第三电信号中的任意两个电信号，确定偏振态是否随时间变化发生了偏振旋转。
具体的，处理器计算第一电信号、第二电信号和第三电信号中的任意两个电信号的比值。如果比值随时间发生变化，则确定偏振态随时间变化发生了偏振旋转。
具体的，可以计算任意两个电信号的比值对时间的导数，作为偏振旋转信息，以表征偏振态的偏振角的时域变化。
例如，处理器计算第一电信号和第二电信号的比值。如果第一电信号和第二电信号的比值随时间发生变化，则确定偏振态随时间变化发生了偏振旋转。
二、监测偏振相关损耗
第一光电探测器向处理器输出第一电信号，第二光电探测器向处理器输出第二电信号，第三光电探测器向处理器输出第三电信号。假设第一电信号的振幅为cos 2(θ)-sin 2(θ)，第二电信号的振幅为
Figure PCTCN2022119627-appb-000017
第三电信号的振幅为cos 2(θ+σ)-sin 2(θ+σ)。其中，σ为第三检偏器的偏振化方向和第一检偏器的偏振化方向的夹角，σ取值范围为(0°，45°)。在第三检偏器为22.5°检偏器的情况下，σ＝22.5°。
处理器按照监测周期对第一电信号的功率、第二电信号的功率和第三电信号的功率进行比较，以判断偏振相关损耗。
具体的，在每个监测周期内，处理器获取第一电信号在该监测周期内的最大功率、第一电信号在该监测周期内处于最大功率时第二电信号的第一功率，以及第一电信号在该监测周期内处于最大功率时第三电信号的第三功率。判断输入光信号不存在偏振相关损耗的条件为：如果第一电信号在该监测周期内处于最大功率P max1时，第一功率为
Figure PCTCN2022119627-appb-000018
且第三功率为[cos 2(σ)-sin 2(σ)]*P max1，则可以确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第二电信号在该监测周期内的最大功率、第二电信号在该监测周期内处于最大功率时第一电信号的第二功率，以及第二电信号在该监测周期内处于最大功率时第三电信号的第四功率。判断输入光信号不存在偏振相关损耗的条件为：如果第二电信号在该监测周期内处于最大功率P max2时，第二功率为
Figure PCTCN2022119627-appb-000019
且第四功率为
Figure PCTCN2022119627-appb-000020
则可以确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第三电信号在该监测周期内的最大功率、第三电信号在该监测周期内处于最大功率时第一电信号的第五功率，以及第三电信号在该监测周期内处于最大功率时第二电信号的第六功率。判断输入光信号不存在偏振相关损耗的条件为：如果第二电信号在该监测周期内处于最大功率P max3时，第五功率为[cos 2(-σ)-sin 2(-σ)]*P max3且第六功率为
Figure PCTCN2022119627-appb-000021
则可以确定输入光信号不存在偏振相关损耗。
当以上三个判断输入光信号不存在偏振相关损耗的条件中，有任一条件满足时，则确定输入光信号不存在偏振相关损耗，当以上三个判断输入光信号不存在偏振相关损耗的条件均不满足时，则确实输入光信号存在偏振相关损耗。
在一种可能的实现方式中，在图13和图14所示的导频接收机结构下，也可以实现对偏振旋转、偏振相关损耗的监测。在图13所示的导频接收机结构下监测偏振旋转和偏振相关损耗的处理与在图14所示的导频接收机结构下监测偏振旋转和偏振相关损耗的处理相似，下面仅以图13所示的导频接收机结构下实现对偏振旋转和偏振相关损耗的监测进行说明。
对于偏振旋转的监测与图11所示的接收机结构下的偏振旋转监测相同或相似，在此不再赘述。下面对偏振相关损耗的监测进行说明。
第一光电探测器向处理器输出第一电信号，第二光电探测器向处理器输出第二电信号，第四光电探测器向处理器输出第四电信号。在考虑特殊的偏振态的情况下，假设第一电信号的振幅为cos 2(θ)-sin 2(θ)，第二电信号的振幅为
Figure PCTCN2022119627-appb-000022
第四电信号的振幅为[sin 2(θ+φ)-cos 2(θ+φ)]sinδ。
处理器按照监测周期对第一电信号的功率、第二电信号的功率和第四电信号的功率进行比较，以判断偏振相关损耗。
具体的，在每个监测周期内，处理器获取第一电信号在该监测周期内的最大功率、第一电信号在该监测周期内处于最大功率时第二电信号的第一功率，以及第一电信号在该监测周期内处于最大功率时第四电信号的第七功率。判断输入光信号不存在偏振相关损耗的条件为：如果第一电信号在该监测周期内处于最大功率P max1时，第一功率为
Figure PCTCN2022119627-appb-000023
且第七功率为[sin 2(φ)-cos 2(φ)]sinδ*P max1，则可以确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第二电信号在该监测周期内的最大功率、第二电信号在该监测周期内处于最大功率时第一电信号的第二功率，以及第二电信号在该监测周期内处于最大功率时第四电信号的第八功率。判断输入光信号不存在偏振相关损耗的条件为：如果第二电信号在该监测周期内处于最大功率P max2时，第二功率为
Figure PCTCN2022119627-appb-000024
且第八功率为0，则可以确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第四电信号在该监测周期内的最大功率、第四电信号在该监测周期内处于最大功率时第一电信号的第九功率，以及第四电信号在该监测周期内处于最大功率时第二电信号的第十功率。判断输入光信号不存在偏振相关损耗的条件为：如果第四电信号在该监测周期内处于最大功率P max4时，第九功率为[cos 2(-φ)-sin 2(-φ)]*P max4 且第十功率为0，则可以确定输入光信号不存在偏振相关损耗。
当以上三个判断输入光信号不存在偏振相关损耗的条件中，有任一条件满足时，则确定输入光信号不存在偏振相关损耗，当以上三个判断输入光信号不存在偏振相关损耗的条件均不满足时，则确实输入光信号存在偏振相关损耗。
本申请实施例还提供了一种导频接收机，参见图15，该导频接收机包括偏振控制器、偏振分束器、第一光电探测器、第二光电探测器和处理器。
在实施中，偏振控制器接收输入光信号，对输入光信号进行扰偏或锁偏，并向偏振分束器输出扰偏或锁偏后的光信号。
扰偏即对输入光信号进行随机扰动，改变输入光信号的偏振态的偏振方向。
锁偏即将输入光信号的偏振态的偏振方向进行锁定，输出固定偏振方向的偏振态。
无论扰偏还是锁偏均是为了避免输入偏振分束器的光信号的偏振态的偏振方向为45°，因此，偏振控制器用于锁偏的情况下，也要保证偏振控制器输出的偏振态的偏振角不是45°。
偏振分束器，对扰偏或锁偏的光信号进行偏振分束，得到正交的第一光信号和第二光信号，向第一光电探测器输出第一光信号，向第二光电探测器输出第二光信号。
第一光电探测器，将第一光信号转换为第一电信号，并向处理器输出第一电信号。第二光电探测器，将第二光信号转换为第二电信号，并向处理器输出第二电信号。
处理器，对第一电信号和第二电信号进行处理，得到输入光信号中各波长光信号的导频信号的功率。需要说明的是，此处处理器的具体处理和上述图11所示的导频接收机中处理器的具体处理相同，在此不再赘述。
在一种可能的实现方式中，在图15所示的接收机结构下，可以实现对偏振相关损耗的监测。
处理器按照监测周期对第一电信号的功率和第二电信号的功率，以判断偏振相关损耗。
具体的，在每个监测周期内，处理器获取第一电信号在该监测周期内的最大功率、第一电信号在该监测周期内处于最大功率时第二电信号的功率。判断输入光信号不存在偏振相关损耗的条件为：如果第一电信号在该监测周期内处于最大功率时，第二电信号也在该监测周期内处于最大功率，且两个最大功率相同，则确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器获取第二电信号在该监测周期内的最大功率、第二电信号在该监测周期内处于最大功率时第一电信号的功率。判断输入光信号不存在偏振相关损耗的条件为：如果第二电信号在该监测周期内处于最大功率时，第一电信号也在该监测周期内处于最大功率，且两个最大功率相同，则确定输入光信号不存在偏振相关损耗。
当以上两个判断输入光信号不存在偏振相关损耗的条件中，有任一条件满足时，则确定输入光信号不存在偏振相关损耗，当以上两个判断输入光信号不存在偏振相关损耗的条件均不满足时，则确定输入光信号存在偏振相关损耗。
本申请实施例还提供了一种导频接收机，参见图16，该导频接收机包括保偏功分器、偏振旋转器、第一偏振分束器、第二偏振分束器、第一光电探测器、第二光电探测器、第三光电探测器、第四光电探测器和处理器。
在实施中，光信号在光纤传输过程中可能出现如下情况：光信号发生偏振旋转，并且偏 振旋转后的第一偏振态或第二偏振态的偏振角为45°。在此情况下，该光信号如果直接经过偏振分束器偏振分束的话，偏振分束器输出的每路光信号中均包含一半的第一偏振态和一半的第二偏振态，这样，每路光信号输入到光电探测器后，两个偏振态上调制的反相导频信号便会抵消，以至于处理器无法计算出导频信号的功率。
为了弥补上述情况所导致的问题，在本申请实施例所提供的导频接收机中，导频接收机的输入光信号先进入保偏功分器，保偏功分器对输入光信号进行保偏功分，向偏振旋转器输出第一光信号，向第一偏振分束器输出第二光信号。保偏功分后得到的第一光信号和第二光信号相同，且两个光信号的偏振态与输入光信号的偏振态相同，两个光信号的功率均为输入光信号的一半。
偏振旋转器对第一光信号进行偏振旋转，得到第三光信号，向第二偏振分束器发送第三光信号。第一偏振分束器对第二光信号进行偏振分束，得到第四光信号和第五光信号，并向第一光电探测器输出第四光信号，向第二光电探测器输出第五光信号。
这样，即使出现第一偏振态或第二偏振态的偏振角为45°的情况，偏振旋转器对接收的光信号进行了偏振旋转，使得输出的光信号不再有偏振角为45°的偏振态，这样，最后处理器便可以有效计算出导频信号的功率。
第二偏振分束器对第三光信号进行偏振分束，得到第六光信号和第七光信号，并向第三光电探测器输出第六光信号，向第四光电探测器输出第七光信号。
第一光电探测器，将第四光信号转换为第一电信号，并向处理器输出第一电信号。第二光电探测器，用于将第五光信号转换为第二电信号，并向处理器输出第二电信号。第三光电探测器，将第六光信号转换为第三电信号，并向处理器输出第三电信号。第四光电探测器，将第七光信号转换为第四电信号，并向处理器输出第二电信号。
处理器对第一电信号、第二电信号、第三电信号和第四电信号进行处理，得到输入光信号中各波长光信号的导频信号的功率。
在实施中，处理器对第一电信号和第二电信号进行求和，得到第五电信号，并对第三电信号和第四电信号进行求和，得到第六电信号。然后，处理器对第五电信号进行傅里叶傅里叶变换，得到各导频频率对应的第一子功率。并对第六电信号进行傅里叶傅里叶变换，得到各导频频率对应的第二子功率。最后，对于每个导频频率，将该导频频率对应的第一子功率和第二子功率进行平方求和，再开平方，即可得到该导频频率对应的实际功率。
在一种可能的实现方式中，上述偏振旋转器为45°偏振旋转器，即该偏振旋转器可以将光信号的偏振态旋转45°再输出。
此外，偏振旋转器也可以为其他角度的偏振旋转器，例如，40°到50°之间。
在一种可能的实现方式中，在图16所示的接收机结构下，可以实现对偏振旋转、偏振相关损耗的监测。下面对监测偏振旋转和偏振相关损耗分别进行说明。
一、监测偏振旋转
将第一电信号和第二电信号作为一组进行监测，将第三电信号和第四电信号作为一组进行监测，对于每组的监测方法与上述图11所示导频接收机的偏振旋转监测相同，在此不做赘述。
二、监测偏振相关损耗
处理器按照监测周期对第一电信号的功率、第二电信号的功率、第三电信号的功率和第 四电信号的功率进行比较，以判断偏振相关损耗。
具体的，在每个监测周期内，处理器获取第一电信号在该监测周期内的最大功率、第一电信号在该监测周期内处于最大功率时第二电信号的第一功率，第一电信号在该监测周期内处于最大功率时第三电信号的第二功率，第一电信号在该监测周期内处于最大功率时第四电信号的第三功率。判断输入光信号不存在偏振相关损耗的条件为：如果第一电信号在该监测周期内处于最大功率时，第二电信号也在该监测周期内处于最大功率且两个最大功率相同，且第二功率和第三功率为0，则确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第二电信号在该监测周期内的最大功率、第二电信号在该监测周期内处于最大功率时第一电信号的第四功率，第二电信号在该监测周期内处于最大功率时第三电信号的第五功率，第二电信号在该监测周期内处于最大功率时第四电信号的第六功率。判断输入光信号不存在偏振相关损耗的条件为：如果第二电信号在该监测周期内处于最大功率时，第一电信号也在该监测周期内处于最大功率且两个最大功率相同，且第五功率和第六功率为0，则确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第三电信号在该监测周期内的最大功率、第三电信号在该监测周期内处于最大功率时第二电信号的第七功率，第三电信号在该监测周期内处于最大功率时第二电信号的第八功率，第三电信号在该监测周期内处于最大功率时第四电信号的第九功率。判断输入光信号不存在偏振相关损耗的条件为：如果第三电信号在该监测周期内处于最大功率时，第四电信号也在该监测周期内处于最大功率且两个最大功率相同，且第八功率和第九功率为0，则确定输入光信号不存在偏振相关损耗。
在每个监测周期内，处理器还获取第四电信号在该监测周期内的最大功率、第四电信号在该监测周期内处于最大功率时第一电信号的第十功率，第二电信号在该监测周期内处于最大功率时第三电信号的第十一功率，第二电信号在该监测周期内处于最大功率时第四电信号的第十二功率。判断输入光信号不存在偏振相关损耗的条件为：如果第四电信号在该监测周期内处于最大功率时，第三电信号也在该监测周期内处于最大功率且两个最大功率相同，且第十一功率和第十二功率为0，则确定输入光信号不存在偏振相关损耗。
当以上四个判断输入光信号不存在偏振相关损耗的条件中，有任一条件满足时，则确定输入光信号不存在偏振相关损耗，当以上四个判断输入光信号不存在偏振相关损耗的条件均不满足时，则确实输入光信号存在偏振相关损耗。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以通过硬件来完成，也可以通过程序来指令相关的硬件完成，所述的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，磁盘或光盘等。
以上所述仅为本申请一个实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (22)

  1. 一种光信号发送的方法，其特征在于，所述方法包括：
    在光信号的第一偏振态上调制第一导频信号；
    在所述光信号的第二偏振态上调制第二导频信号，其中，所述第一导频信号的相位和所述第二导频信号的相位不同；
    输出调制后的光信号，其中，所述调制后的光信号承载有所述第一导频信号和所述第二导频信号。
  2. 根据权利要求1所述的方法，其特征在于，所述第一导频信号的相位和所述第二导频信号的相位不同，包括：
    第一导频信号和所述第二导频信号反相。
  3. 根据权利要求2所述的方法，其特征在于，所述第一导频信号和所述第二导频信号反相，包括：
    在所述第一偏振态和所述第二偏振态的相同子频带上调制的导频信号反相。
  4. 根据权利要求3所述的方法，其特征在于，所述在所述第一偏振态和所述第二偏振态的相同子频带上调制的导频信号反相，包括：
    在所述第一偏振态的各子频带上调制的导频信号与在所述第二偏振态的各子频带上调制的导频信号均反相。
  5. 根据权利要求3所述的方法，其特征在于，所述在所述第一偏振态和所述第二偏振态的相同子频带上调制的导频信号反相，包括：
    在所述第一偏振态的第一个子频带到第N个子频带上调制的导频信号与在所述第二偏振态的第一个子频带到第N个子频带上调制的第二导频信号反相，在所述第一偏振态的第N+1个子频带到最后一个子频带上调制的导频信号与在第二偏振态的第N+1个子频带到最后一个子频带上调制的导频信号反相，其中，N为正整数。
  6. 根据权利要求3所述的方法，其特征在于，所述在所述第一偏振态和所述第二偏振态的相同子频带上调制的导频信号反相，包括：
    在所述第一偏振态的第A个子频带上调制的导频信号与在所述第二偏振态的第A个子频带上调制的导频信号反相，在所述第一偏振态的第B个子频带上调制的导频信号与在所述第二偏振态的第B个子频带上调制导频信号反相，其中，A为奇数且B为偶数，或者，A为偶数且B为奇数。
  7. 一种导频接收机，其特征在于，所述导频接收机包括保偏功分器、第一检偏器、第二检偏器、第一光电探测器、第二光电探测器和处理器，其中：
    所述保偏功分器，用于接收输入光信号，并向所述第一检偏器输出第一光信号，向所述 第二检偏器输出第二光信号，其中，所述第一光信号、所述第二光信号和所述输入光信号的偏振态相同，所述第一光信号和所述第二光信号的功率相同；
    所述第一检偏器，用于对所述第一光信号进行偏振态过滤，向所述第一光电探测器输出偏振态过滤得到的第三光信号；
    所述第二检偏器，用于对所述第二光信号进行偏振态过滤，向所述第二光电探测器输出偏振态过滤得到的第四光信号，所述第一检偏器的偏振化方向和所述第二检偏器的偏振化方向不正交；
    所述第一光电探测器，用于将所述第三光信号转换为第一电信号，并向所述处理器输出所述第一电信号；
    所述第二光电探测器，用于将所述第四光信号转换为第二电信号，并向所述处理器输出所述第二电信号；
    所述处理器，用于对所述第一电信号和所述第二电信号进行处理，得到所述输入光信号中各波长的光信号的导频频率对应的功率。
  8. 根据权利要求7所述的导频接收机，其特征在于，所述第一检偏器的偏振化方向和所述第二检偏器的偏振化方向的夹角范围为45°±5°。
  9. 根据权利要求7-8中任一项所述的导频接收机，其特征在于，所述处理器还用于：
    根据所述第一电信号和所述第二电信号，确定所述输入光信号的偏振态旋转RSOP信息。
  10. 根据权利要求7-9中任一项所述的导频接收机，其特征在于，所述处理器还用于：
    根据所述第一电信号和所述第二电信号，确定所述输入光信号的偏振相关损耗PDL。
  11. 根据权利要求7-10中任一项所述的导频接收机，其特征在于，所述导频接收机还包括第三检偏器和第三光电探测器，所述第三检偏器的检偏角度大于所述检偏器的检偏角度且小于所述第二检偏角度；
    所述保偏功分器，还用于向所述第三检偏器输出第五光信号，其中，所述第五光信号、所述第一光信号、所述第二光信号和所述输入光信号的偏振态相同，所述第五光信号、所述第一光信号和所述第二光信号的功率相同；
    所述第三检偏器，用于对所述第五光信号进行偏振态过滤，向所述第三光电探测器输出偏振态过滤得到的第六光信号；
    所述第三光电探测器，用于将所述第六光信号转换为第三电信号，并向所述处理器输出所述第三电信号；
    所述处理器，用于对所述第一电信号、所述第二电信号和所述第三电信号进行处理，得到所述输入光信号中各波长的光信号的导频频率对应的功率。
  12. 根据权利要求7-11中任一项所述的导频接收机，其特征在于，所述导频接收机还包括圆偏振线偏振转换器、第四检偏器和第四光电探测器；
    所述保偏功分器，还用于向所述圆偏振线偏振转换器输出第七光信号，其中，所述第七 光信号、所述第一光信号、所述第二光信号和所述输入光信号的偏振态相同，所述第七光信号、所述第一光信号和所述第二光信号的功率相同；
    所述圆偏振线偏振转换器，用于将所述第七光信号中的椭圆偏振态转换为线偏振态，并向所述第四检偏器输出转换得到的第八光信号；
    所述第四检偏器，用于将所述第八光信号转换为第四电信号，并向所述处理器输出所述第四电信号；
    所述处理器，用于对所述第一电信号、所述第二电信号和所述第四电信号进行处理，得到所述输入光信号中各波长的光信号对应的导频信号的功率。
  13. 根据权利要求12所述的导频接收机，其特征在于，所述圆偏振线偏振转换器为四分之一波片。
  14. 根据权利要求12或13所述的导频接收机，其特征在于，所述第四检偏器的检偏角度与所述第一检偏器的检偏角度或所述第二检偏器的检偏角度相同。
  15. 根据权利要求7-10中任一项所述的导频接收机，其特征在于，所述处理器，用于：
    对所述第一电信号进行傅里叶变换，得到所述输入光信号中各波长的光信号的导频频率对应的第一子功率；
    对所述第二电信号进行傅里叶变换，得到所述输入光信号中各波长的光信号的导频频率对应的第二子功率；
    对于每个导频频率，根据所述导频频率对应的第一子功率和第二子功率，得到所述导频频率对应的实际功率。
  16. 一种导频接收机，其特征在于，所述导频接收机包括保偏功分器、偏振旋转器、第一偏振分束器、第二偏振分束器、第一光电探测器、第二光电探测器、第三光电探测器、第四光电探测器和处理器，其中：
    所述保偏功分器，用于接收输入光信号，并向所述偏振旋转器输出第一光信号，向所述第一偏振分束器输出第二光信号，其中，所述第一光信号、所述第二光信号和所述输入光信号的偏振态相同，所述第一光信号和所述第二光信号的功率相同；
    所述偏振旋转器，用于对所述第一光信号进行偏振旋转，得到第三光信号，向所述第二偏振分束器发送所述第三光信号；
    所述第一偏振分束器，用于对所述第二光信号进行偏振分束，得到第四光信号和第五光信号，并向所述第一光电探测器输出所述第四光信号，向所述第二光电探测器输出所述第五光信号；
    所述第二偏振分束器，用于对所述第三光信号进行偏振分束，得到第六光信号和第七光信号，并向所述第三光电探测器输出所述第六光信号，向所述第四光电探测器输出所述第七光信号；
    所述第一光电探测器，用于将所述第四光信号转换为第一电信号，并向所述处理器输出所述第一电信号；
    所述第二光电探测器，用于将所述第五光信号转换为第二电信号，并向所述处理器输出所述第二电信号；
    所述第三光电探测器，用于将所述第六光信号转换为第三电信号，并向所述处理器输出所述第三电信号；
    所述第四光电探测器，用于将所述第七光信号转换为第四电信号，并向所述处理器输出所述第四电信号；
    所述处理器，用于对所述第一电信号、所述第二电信号、所述第三电信号和所述第四电信号进行处理，得到所述输入光信号中各波长的光信号对应的导频信号的功率。
  17. 根据权利要求16中任一项所述的导频接收机，其特征在于，所述处理器还用于：
    根据所述第一电信号、所述第二电信号、所述第三电信号和所述第四电信号，确定所述输入光信号的RSOP信息。
  18. 根据权利要求16或17所述的导频接收机，其特征在于，所述处理器还用于：
    根据所述第一电信号、所述第二电信号、所述第三电信号和所述第四电信号，确定所述输入光信号的PDL。
  19. 一种导频接收机，其特征在于，所述导频接收机包括偏振控制器、偏振分束器、第一光电探测器、第二光电探测器和处理器，其中：
    所述偏振控制器，用于接收输入光信号，对所述光信号进行扰偏，并向所述偏振分束器输出扰偏后的光信号；
    所述偏振分束器，用于对扰偏后的光信号进行偏振分光束，得到第一光信号和第二光信号，向所述第一光电探测器输出所述第一光信号，向所述第二光电探测器输出所述第二光信号，其中，所述第一光信号和所述第二光信号正交；
    所述第一光电探测器，用于将所述第一光信号转换为第一电信号，并向所述处理器输出所述第一电信号；
    所述第二光电探测器，用于将所述第二光信号转换为第二电信号，并向所述处理器输出所述第二电信号；
    所述处理器，用于对所述第一电信号和所述第二电信号进行处理，得到所述输入光信号中各波长的光信号对应的导频信号的功率。
  20. 根据权利要求19所述的导频接收机，其特征在于，所述处理器还用于：
    根据所述第一电信号和所述第二电信号，确定所述输入光信号的RSOP信息。
  21. 根据权利要求19或20所述的导频接收机，其特征在于，所述处理器还用于：
    根据所述第一电信号和所述第二电信号，确定所述输入光信号的PDL。
  22. 一种发射机，其特征在于，所述发射机包括信号发射器和调制器，其中：
    所述信号发射器，用于发送光信号；
    所述调制器，用于在所述光信号的第一偏振态上调制第一导频信号，在所述光信号的第二偏振态上调制第二导频信号，其中，所述第一导频信号的相位和所述第二导频信号的相位不同，输出调制后的光信号，其中，所述调制后的光信号承载有所述第一导频信号和所述第二导频信号。
PCT/CN2022/119627 2021-11-30 2022-09-19 光信号发送的方法、导频接收机和发射机 WO2023098232A1 (zh)

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