WO2020182202A1 - 一种相干检测方法及相干接收机 - Google Patents

一种相干检测方法及相干接收机 Download PDF

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WO2020182202A1
WO2020182202A1 PCT/CN2020/079179 CN2020079179W WO2020182202A1 WO 2020182202 A1 WO2020182202 A1 WO 2020182202A1 CN 2020079179 W CN2020079179 W CN 2020079179W WO 2020182202 A1 WO2020182202 A1 WO 2020182202A1
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light
signal
signal light
polarization
interference
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PCT/CN2020/079179
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English (en)
French (fr)
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钟一鸣
黄新刚
杨波
马壮
李明生
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中兴通讯股份有限公司
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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
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/616—Details of the electronic signal processing in coherent optical receivers
    • 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
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • 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
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/079—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using measurements of the data signal
    • H04B10/0795—Performance monitoring; Measurement of transmission parameters
    • 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
    • H04B10/61—Coherent receivers

Definitions

  • This application relates to the field of optical fiber communication, for example, to a coherent detection method and a coherent receiver.
  • both the amplitude and phase of the optical carrier can be modulated, and the use of higher-order amplitude/phase modulation formats can greatly improve the spectral efficiency of the system, thereby realizing high-speed optical fiber communication.
  • the detection method usually adopts multi-channel coherent detection.
  • a multi-channel coherent detection system based on phase diversity and polarization diversity needs to use a large number of optical devices, such as photoelectric detection modules, balanced receivers, etc., which increase the complexity and cost of the optical path.
  • the embodiments of the present application provide a coherent detection method and a coherent receiver.
  • the coherent detection method provided by the embodiment of the present application includes: receiving signal light, which is formed by loading a modulated signal on an optical carrier; and coherently interfering the signal light and intrinsic light to form at least one beam of interference signal light
  • the intrinsic light is circularly polarized light; photodetection is performed on the at least one interference signal light, and a photocurrent is output, and the photocurrent includes at least one of amplitude information and polarization information of the signal light.
  • the coherent receiver includes: a receiving module configured to receive signal light, which is formed by loading a modulated signal on an optical carrier; an intrinsic light source, configured to generate circularly polarized light as intrinsic light;
  • the optical coupling module is connected to the intrinsic light source and the receiving module, and is configured to coherently interfere the signal light and the intrinsic light to form at least one beam of interference signal light;
  • a photodetection module the photodetection The module is connected to the optical coupling module, and is configured to perform photoelectric detection of the at least one interference signal light and output a photocurrent, the photocurrent containing at least one of amplitude information and polarization information of the signal light.
  • Figure 1 shows a homodyne coherent detection system based on phase diversity and polarization diversity
  • FIG. 2 is a schematic flowchart of a coherent detection method provided by an embodiment of the application.
  • FIG. 3 is a system architecture diagram 1 of a heterodyne coherent receiver of application example 1 of this application;
  • FIG. 4 is a schematic diagram of demultiplexing polarization multiplexed signal light provided by an embodiment of the application.
  • FIG. 5 is a block diagram of generating a polarization multiplexed signal at a signal transmitting end provided by an embodiment of the application;
  • FIG. 6 is an architecture diagram of a subsequent DSP module of a receiver provided by an embodiment of the application.
  • FIG. 7 is a block diagram of a polarization modulation signal generation at a signal transmitting end provided by an embodiment of this application;
  • FIG. 8 is a second system architecture diagram of a heterodyne coherent receiver of application example two of this application.
  • FIG. 9 is a schematic diagram of the structural composition of a coherent receiver provided by an embodiment of the application.
  • FIG. 1 is a signal light based on a zero differential phase diversity and polarization diversity coherent detection system, wherein the signal light E S after the polarization beam splitter, forming the signal light two beams of linearly polarized bundle of polarized x-direction line , The other beam is linearly polarized signal light in the y direction; the intrinsic light is linearly polarized light. After the intrinsic light passes through the polarization beam splitter, two linearly polarized intrinsic lights are formed, one is the linearly polarized intrinsic light in the x direction.
  • the other beam is the intrinsic light linearly polarized in the y direction; then, the photoelectric detection is carried out by the balanced receiver, and the photocurrent is output.
  • the number of optical devices required in FIG. 1 is relatively large. If polarization diversity is not considered, the homodyne detection architecture based on phase diversity also requires at least half of the optical devices in FIG. 1. For the demodulation of polarization multiplexed signals, it is necessary to introduce polarization diversity, that is, as shown in Figure 1, the intrinsic light polarization is split into x and y directions for coherent detection, which further increases the complexity and complexity of the optical path. cost.
  • the embodiments of the present application provide a low-cost polarization-insensitive (that is, polarization-independent) coherent detection method, which realizes different polarization directions under the premise of minimizing optical devices such as photoelectric detection modules and balanced receivers. Coherent reception.
  • Fig. 2 is a schematic flowchart of a coherent detection method provided by an embodiment of the application. As shown in Fig. 2, the coherent detection method includes the following steps:
  • Step 201 Receive signal light, which is formed by loading a modulated signal on an optical carrier.
  • the modulation signal refers to a radio frequency (RF) signal
  • the modulation signal belongs to a digital signal.
  • the signal light is formed by loading the modulation signal on an optical carrier means: passing the digital signal through the amplitude of the optical carrier, At least one of phase and frequency is modulated.
  • Step 202 Perform coherent interference between the signal light and the intrinsic light to form at least one beam of interference signal light, and the intrinsic light is circularly polarized light.
  • the intrinsic light adopts circularly polarized light.
  • the circularly polarized light includes left-handed circularly polarized light or right-handed circularly polarized light.
  • the circularly polarized light can be generated by a quarter wave plate, where the quarter wave plate is a birefringent single crystal sheet with a certain thickness, when the linearly polarized light enters the quarter wave plate vertically And when the polarization direction of the linearly polarized light and the optical axis of the quarter wave plate are at an angle of 45°, the emitted light is circularly polarized.
  • the circularly polarized light can be generated by a polarization beam splitter, a phase shifter, and a polarization beam combiner. After the linearly polarized light is split by the polarization beam splitter, the linearly polarized light polarized in the x direction is formed.
  • the linear polarized light polarized in the y direction is delayed by 90° phase or advanced by 90° through the phase shifter, and then the linear polarized light polarized in the x direction and the phase-shifted light are polarized by the polarization beam combiner.
  • the linearly polarized light polarized in the y direction is combined to form circularly polarized light.
  • the signal light and the intrinsic light are coherently interfered by an optical coupling module (also called an optical coupler) to form at least one interference signal light, wherein the quantity of the interference signal light is equal to The number of output ports of the optical coupler is the same.
  • the optical coupling module is connected to an intrinsic light source that generates intrinsic light, and performs coherent interference (ie, multiplexing processing) between the received intrinsic light and signal light to form interference signal light.
  • the types of optical coupling modules include but are not limited to: 2 ⁇ 1 optical coupling modules and 2 ⁇ 2 optical coupling modules.
  • a 2 ⁇ 1 optical coupling module represents two input ports and one output port
  • a 2 ⁇ 2 optical coupling module represents two input ports and two output ports.
  • the output ports of the optical coupling module are not limited to one or two, and can also be other more numbers.
  • Step 203 Perform photoelectric detection on the at least one interference signal light, and output a photocurrent, where the photocurrent includes amplitude information and/or polarization information of the signal light.
  • the at least one beam of interference signal light is photoelectrically detected by a photodetection module, and a photocurrent is output, and the photocurrent includes amplitude information and/or polarization information of the signal light.
  • the photodetection module is connected to the optical coupling module, receives the interference signal light output by the optical coupling module, and converts the interference signal light into an electrical signal, that is, photocurrent output.
  • the photodetection module can convert the signal light The information of the polarization angle with the intrinsic light is converted into the phase information of the output signal (ie photocurrent), forming phase noise.
  • the number of photodetector modules is equal to the number of output ports of the optical coupling module. In one embodiment, when the number of photodetector modules is more than two, more than two photodetectors
  • the module is realized by a balanced receiver.
  • the optical coupling module includes at least one output port configured to output at least one beam of interference signal light.
  • the technical solution of the embodiment of the present application uses circularly polarized light as the intrinsic light, and uses an optical coupling module to coherently interfere the signal light and the circularly polarized light, so as to realize polarization demultiplexing and low-cost coherent detection that is polarization insensitive.
  • the low cost refers to the replacement of high-cost coherent receivers by means of optical coupling modules and photodetection modules.
  • Figure 3 uses an optical coupling module and a photodetection module to achieve coherent detection
  • Figure 1 uses multiple balanced receivers, and multiple polarization beam splitters and phase shifters to achieve coherent detection, obviously Compared with Figure 1, Figure 3 greatly saves costs.
  • Intrinsic light uses circularly polarized light to achieve polarization-insensitive reception of signal light.
  • the receiver can coherently detect the following three high-order modulation signals regardless of polarization.
  • the modulation signal is loaded on the optical carrier to form signal light, wherein the polarization state of the signal light remains unchanged, and the signal light is a linear polarization intensity modulation signal;
  • the signal light is coherent with the intrinsic light Interference to form a beam of interference signal light, the intrinsic light is left-handed circularly polarized light or right-handed circularly polarized light;
  • photoelectric detection is performed on the beam of interference signal light, and a photocurrent is output;
  • the photocurrent is amplified and / Or filter processing to form a heterodyne intermediate frequency signal, wherein the amplitude of the heterodyne intermediate frequency signal contains the amplitude information of the signal light; performing signal recovery on the heterodyne intermediate frequency signal to obtain the amplitude information of the signal light .
  • the receiver described in FIG. 3 includes an optical coupling module and The photodetection module, the optical coupling module coherently interferes with the circularly polarized light (left-handed/right-handed circularly polarized light) and the signal light to form interference signal light and send it to the photodetection module.
  • the photodetection module converts the interference signal light into amplitude information Photocurrent I PD .
  • the photocurrent I PD is sent to a digital signal processing (Digital Signal Processing, DSP) module for filtering, clock recovery, carrier recovery, amplitude and other electrical domain processing.
  • DSP Digital Signal Processing
  • the modulated signal is loaded on the linearly polarized optical carrier to form the following signal light:
  • E S represents the light field vector of the signal light
  • a S represents the amplitude of the signal light
  • j represents the imaginary unit
  • ⁇ S represents the frequency of the signal light.
  • ⁇ represents the angle between the polarization direction of the signal light and the x-axis direction
  • the signal light and the left-handed circularly polarized light are coherently interfered by the optical coupling module to form a beam of interference signal light; wherein, the left-handed circularly polarized light is: Among them, E LO represents the light field vector of left-handed circularly polarized light, A LO represents the amplitude of left-handed circularly polarized light, j represents the imaginary unit, and ⁇ LO represents the frequency of left-handed circularly polarized light. Represents the initial phase of left-handed circularly polarized light, Represents the unit vector in the x-axis direction, Represents the unit vector in the y-axis direction; or,
  • the signal light and the right-handed circularly polarized light are coherently interfered to form a beam of interference signal light; wherein, the right-handed circularly polarized light is:
  • E LO represents the light field vector of right-handed circularly polarized light
  • a LO represents the amplitude of right-handed circularly polarized light
  • j represents the imaginary unit
  • ⁇ LO represents the frequency of right-handed circularly polarized light.
  • Represents the initial phase of right-handed circularly polarized light Represents the unit vector in the x-axis direction
  • the generated signal light is sent to the photodetection module, through the photoelectric effect of the photodetection module, the interference signal light is converted into a photocurrent I PD containing amplitude information and polarization information, which can be expressed as:
  • I PD photocurrent
  • R coefficient
  • the angle ⁇ between the polarization direction of the signal light and the x-axis direction enters the trigonometric function and becomes phase noise.
  • the amplitude information can be extracted by the DSP module later.
  • the photocurrent amplifying and filtering processing to obtain an intermediate frequency heterodyne signal; the difference between the outer intermediate frequency signal waveform and the waveform restoration detection processing to obtain the amplitude information A S.
  • the embodiment of the present application uses circularly polarized light as the intrinsic light. According to the calculation of the above formula, finally, the angle information between the polarization direction of the signal light and the x-axis direction enters the trigonometric function, forming phase noise.
  • the optical carrier is polarized and split to form a first optical carrier polarized in a first direction and a second optical carrier polarized in a second direction.
  • the first direction is perpendicular to the second direction;
  • the modulated signals are respectively loaded on The first optical carrier and the second optical carrier are polarized and combined to form signal light, wherein the signal light is a polarization multiplexed intensity modulation signal;
  • the signal light is coherent with the intrinsic light Interference to form a beam of interference signal light, the intrinsic light is left-handed circularly polarized light or right-handed circularly polarized light;
  • photoelectric detection is performed on the beam of interference signal light, and a photocurrent is output;
  • the photocurrent is amplified and / Or filtering processing to form a heterodyne intermediate frequency signal, wherein the amplitude and phase of the heterodyne intermediate frequency signal contain the amplitude information and polarization information of the signal light;
  • signal recovery is performed on the heterodyne intermediate frequency signal to
  • the traditional linear polarization intensity modulation format is limited by its own characteristics, and cannot meet the requirements of higher-speed transmission systems with higher requirements.
  • the high-order modulation signal containing the information of the two dimensions of polarization and intensity has also been theoretically analyzed and studied in a sub-example in this embodiment.
  • the receiver described in Figure 3 can also do the corresponding Coherent reception demodulation.
  • the intrinsic light when the polarization state of circularly polarized light rotates to the x direction, the intrinsic light can coherently detect the x-polarized light signal in the signal light; and when the polarization state of circularly polarized light rotates to In the Y direction, the intrinsic light can coherently detect the light signal of the y polarization state of the signal light.
  • the two polarization state information in the scanning signal light is continuously detected in the 360° direction.
  • Fig. 5 is a structure diagram of the generation method of polarization multiplexed intensity modulation signal (such as DP-OOK signal or DP-PAM4 signal, etc.) at the transmitting end.
  • the linearly polarized optical carrier is polarized and split to form a first optical carrier polarized in the x-axis direction and a second optical carrier polarized in the y-axis direction; the modulation signals are respectively loaded on the first optical carrier And perform polarization combining on the second optical carrier to form the following signal light:
  • E S represents the light field vector of the signal light
  • a S1 represents the first amplitude of the signal light
  • a S2 represents the second amplitude of the signal light
  • j represents the imaginary unit
  • ⁇ S represents the frequency of the signal light.
  • the signal light and the left-handed circularly polarized light are coherently interfered by the optical coupling module to form a beam of interference signal light; wherein, the left-handed circularly polarized light is: Among them, E LO represents the light field vector of left-handed circularly polarized light, A LO represents the amplitude of left-handed circularly polarized light, j represents the imaginary unit, and ⁇ LO represents the frequency of left-handed circularly polarized light. Represents the initial phase of left-handed circularly polarized light, Represents the unit vector in the x-axis direction, Represents the unit vector in the y-axis direction; or,
  • the signal light and the right-handed circularly polarized light are coherently interfered to form a beam of interference signal light; wherein, the right-handed circularly polarized light is:
  • E LO represents the light field vector of right-handed circularly polarized light
  • a LO represents the amplitude of right-handed circularly polarized light
  • j represents the imaginary unit
  • ⁇ LO represents the frequency of right-handed circularly polarized light.
  • Represents the initial phase of right-handed circularly polarized light Represents the unit vector in the x-axis direction
  • the circularly polarized light and the signal light containing polarization multiplexing information are coherently interfered in the optical coupler, and then sent to the photodetection module.
  • the interference signal light is converted into light containing amplitude and polarization information.
  • the current I PD can be expressed as:
  • I PD photocurrent
  • R coefficient
  • the two multiplexed amplitude information becomes the fourth and fifth pre-trigonometric function amplitude information.
  • the photocurrent I PD is subsequently processed by the DSP module.
  • the photocurrent is amplified and filtered to obtain a heterodyne intermediate frequency signal; the heterodyne intermediate frequency signal is divided into two bundles Perform waveform detection and waveform recovery processing to obtain amplitude information A S1 and A S2 .
  • the photocurrent I PD detected by the photodetection module is first sent to the RF amplifier and filter to obtain the heterodyne intermediate frequency signal we need, and then divided into two channels for corresponding waveform detection and recovery, to obtain the sine sum in the formula The required amplitude information A S1 and A S2 before the amount of cosine.
  • the modulation signal is loaded on the optical carrier to form signal light, wherein the polarization state of the signal light changes with the change of the modulation signal, the signal light is a polarization modulation signal;
  • the characteristic light performs coherent interference to form a beam of interference signal light, the intrinsic light is left-handed circularly polarized light or right-handed circularly polarized light; photoelectric detection is performed on the one beam of interference signal light, and a photocurrent is output;
  • the current is amplified and/or filtered to form a heterodyne intermediate frequency signal, wherein the amplitude and phase of the heterodyne intermediate frequency signal include the polarization information of the signal light; signal recovery is performed on the heterodyne intermediate frequency signal to obtain the heterodyne intermediate frequency signal.
  • the polarization information of the signal light is a polarization modulation signal.
  • the polarization modulation technology widely used in optical fiber sensing can also be used as a new type of high-order modulation signal to increase the data transmission rate, and the different polarization states of linearly polarized light are used to characterize different data. Bits.
  • different polarization states correspond to different signal voltage amplitudes in the X polarization and Y polarization directions, which are used to map different linear polarizations.
  • the receiver described in FIG. 3 can also perform corresponding coherent reception demodulation.
  • the modulation signal is loaded on an optical carrier, and the linear polarization state of the optical carrier changes with the change of the modulation signal to form the following signal light:
  • E S represents the light field vector of the signal light
  • a S1 represents the first amplitude of the signal light
  • a S2 represents the second amplitude of the signal light
  • j represents the imaginary unit
  • ⁇ S represents the frequency of the signal light.
  • the polarization modulation signal and the polarization multiplexing signal are mainly different in the mapping in the electrical domain.
  • the use of a polarization modulator can generate signal light whose linear polarization state changes with the applied radio frequency signal at the transmitting end.
  • the signal light is essentially the same as the intensity of the signal light in each polarization state, but the polarization angle of the signal light changes, which is related to the added radio frequency signal.
  • the signal light and the left-handed circularly polarized light are coherently interfered by the optical coupling module to form a beam of interference signal light; wherein, the left-handed circularly polarized light is: Among them, E LO represents the light field vector of left-handed circularly polarized light, A LO represents the amplitude of left-handed circularly polarized light, j represents the imaginary unit, and ⁇ LO represents the frequency of left-handed circularly polarized light. Represents the initial phase of left-handed circularly polarized light, Represents the unit vector in the x-axis direction, Represents the unit vector in the y-axis direction; or,
  • the signal light and the right-handed circularly polarized light are coherently interfered to form a beam of interference signal light; wherein, the right-handed circularly polarized light is:
  • E LO represents the light field vector of right-handed circularly polarized light
  • a LO represents the amplitude of right-handed circularly polarized light
  • j represents the imaginary unit
  • ⁇ LO represents the frequency of right-handed circularly polarized light.
  • Represents the initial phase of right-handed circularly polarized light Represents the unit vector in the x-axis direction
  • the circularly polarized light and the signal light containing polarization multiplexing information are coherently interfered in the optical coupler, and then sent to the photodetection module.
  • the interference signal light is converted into light containing amplitude and polarization information.
  • the current I PD can be expressed as:
  • I PD photocurrent
  • R coefficient
  • the two multiplexed amplitude information becomes the fourth and fifth pre-trigonometric function amplitude information.
  • the photocurrent I PD is subsequently processed by the DSP module.
  • the photocurrent is amplified and filtered to obtain a heterodyne intermediate frequency signal; the heterodyne intermediate frequency signal is divided into two bundles Perform waveform detection and waveform recovery processing to obtain amplitude information A S1 and A S2 .
  • the photocurrent I PD detected by the photodetection module is first sent to the RF amplifier and filter to obtain the heterodyne intermediate frequency signal we need, and then divided into two channels for corresponding waveform detection and recovery, to obtain the sine sum in the formula The required amplitude information A S1 and A S2 before the amount of cosine.
  • the receiving principle of the receiver is shown in Fig. 8.
  • the intrinsic light uses circularly polarized light to realize polarization-insensitive reception of signal light.
  • This solution uses a balanced receiver to eliminate the DC component and common mode noise in the first embodiment, improve the signal-to-noise ratio of the received signal in the first embodiment, and improve the receiving sensitivity to a certain extent, but it will increase the cost of the optical path accordingly.
  • the receiver can coherently detect the following three high-order modulation signals regardless of polarization.
  • the modulation signal is loaded on the optical carrier to form signal light, wherein the polarization state of the signal light remains unchanged, and the signal light is a linear polarization intensity modulation signal; the signal light is coherent with the intrinsic light Interference to form two interfering signal lights, the intrinsic light being left-handed circularly polarized light or right-handed circularly polarized light; performing balanced photoelectric detection on the two interfering signal lights, and outputting photocurrent; amplifying the photocurrent And/or filtering processing to form a heterodyne intermediate frequency signal, wherein the amplitude of the heterodyne intermediate frequency signal contains the amplitude information of the signal light; performing signal recovery on the heterodyne intermediate frequency signal to obtain the amplitude of the signal light information.
  • the receiver described in FIG. 8 includes an optical coupling module and The photodetection module, the optical coupling module coherently interferes with the circularly polarized light (left-handed/right-handed circularly polarized light) and the signal light to form interference signal light and send it to the photodetection module.
  • the photodetection module converts the interference signal light into amplitude information Photocurrent I PD .
  • the photocurrent I PD is sent to a digital signal processing (Digital Signal Processing, DSP) module for filtering, clock recovery, carrier recovery, amplitude and other electrical domain processing.
  • DSP Digital Signal Processing
  • the modulated signal is loaded on the linearly polarized optical carrier to form the following signal light:
  • E S represents the light field vector of the signal light
  • a S represents the amplitude of the signal light
  • j represents the imaginary unit
  • ⁇ S represents the frequency of the signal light.
  • ⁇ represents the angle between the polarization direction of the signal light and the x-axis direction
  • the signal light and the left-handed circularly polarized light are coherently interfered by the optical coupling module to form two beams of interference signal light; wherein, the left-handed circularly polarized light is: Among them, E LO represents the light field vector of left-handed circularly polarized light, A LO represents the amplitude of left-handed circularly polarized light, j represents the imaginary unit, and ⁇ LO represents the frequency of left-handed circularly polarized light. Represents the initial phase of left-handed circularly polarized light, Represents the unit vector in the x-axis direction, Represents the unit vector in the y-axis direction; or,
  • the signal light and the right-handed circularly polarized light are coherently interfered to form two beams of interference signal light; wherein the right-handed circularly polarized light is:
  • E LO represents the light field vector of right-handed circularly polarized light
  • a LO represents the amplitude of right-handed circularly polarized light
  • j represents the imaginary unit
  • ⁇ LO represents the frequency of right-handed circularly polarized light.
  • Represents the initial phase of right-handed circularly polarized light Represents the unit vector in the x-axis direction
  • two beams of interference signal light can be expressed as:
  • E 1 represents the first interference signal light
  • E 2 represents the second interference signal light
  • the two beams of signal light generated are sent to the photodetection module, and through the photoelectric effect of the photodetection module, the interference signal light is converted into a photocurrent I PD containing amplitude information and polarization information, which can be expressed as:
  • I PD photocurrent
  • R coefficient
  • the angle ⁇ between the polarization direction of the signal light and the x-axis direction enters the trigonometric function and becomes phase noise.
  • the amplitude information can be extracted by the DSP module later.
  • the photocurrent amplifying and filtering processing to obtain an intermediate frequency heterodyne signal; the difference between the outer intermediate frequency signal waveform and the waveform restoration detection processing to obtain the amplitude information A S.
  • the optical carrier is polarized and split to form a first optical carrier polarized in a first direction and a second optical carrier polarized in a second direction.
  • the first direction is perpendicular to the second direction;
  • the modulated signals are respectively loaded on The first optical carrier and the second optical carrier are polarized and combined to form signal light, wherein the signal light is a polarization multiplexed intensity modulation signal;
  • the signal light is coherent with the intrinsic light Interference to form two interfering signal lights, the intrinsic light being left-handed circularly polarized light or right-handed circularly polarized light; performing balanced photoelectric detection on the two interfering signal lights, and outputting photocurrent; amplifying the photocurrent And/or filter processing to form a heterodyne intermediate frequency signal, wherein the amplitude and phase of the heterodyne intermediate frequency signal contain the amplitude information and polarization information of the signal light; the signal recovery is performed on the heterodyne intermediate frequency signal to obtain the Describe the amplitude information and
  • the input signal light is a polarization multiplexed intensity modulation signal (such as DP-OOK or DP-PAM4) containing intensity information and polarization information, as shown in FIG. 8
  • the receiver can also do corresponding coherent reception demodulation.
  • the intrinsic light when the polarization state of circularly polarized light rotates to the x direction, the intrinsic light can coherently detect the x-polarized light signal in the signal light; and when the polarization state of circularly polarized light rotates to In the Y direction, the intrinsic light can coherently detect the light signal of the y polarization state of the signal light.
  • the two polarization state information in the scanning signal light is continuously detected in the 360° direction.
  • Fig. 5 is a structure diagram of the generation method of polarization multiplexed intensity modulation signal (such as DP-OOK signal or DP-PAM4 signal, etc.) at the transmitting end.
  • the linearly polarized optical carrier is polarized and split to form a first optical carrier polarized in the x-axis direction and a second optical carrier polarized in the y-axis direction; the modulation signals are respectively loaded on the first optical carrier And perform polarization combining on the second optical carrier to form the following signal light:
  • E S represents the light field vector of the signal light
  • a S1 represents the first amplitude of the signal light
  • a S2 represents the second amplitude of the signal light
  • j represents the imaginary unit
  • ⁇ S represents the frequency of the signal light.
  • the signal light and the left-handed circularly polarized light are coherently interfered by the optical coupling module to form two beams of interference signal light; wherein, the left-handed circularly polarized light is: Among them, E LO represents the light field vector of left-handed circularly polarized light, A LO represents the amplitude of left-handed circularly polarized light, j represents the imaginary unit, and ⁇ LO represents the frequency of left-handed circularly polarized light. Represents the initial phase of left-handed circularly polarized light, Represents the unit vector in the x-axis direction, Represents the unit vector in the y-axis direction; or,
  • the signal light and the right-handed circularly polarized light are coherently interfered to form two beams of interference signal light; wherein the right-handed circularly polarized light is:
  • E LO represents the light field vector of right-handed circularly polarized light
  • a LO represents the amplitude of right-handed circularly polarized light
  • j represents the imaginary unit
  • ⁇ LO represents the frequency of right-handed circularly polarized light.
  • Represents the initial phase of right-handed circularly polarized light Represents the unit vector in the x-axis direction
  • two beams of interference signal light can be expressed as:
  • E 1 represents the first interference signal light
  • E 2 represents the second interference signal light
  • the circularly polarized light and the signal light containing polarization multiplexing information are coherently interfered in the optical coupler, and then sent to the photodetection module.
  • the interference signal light is converted into light containing amplitude and polarization information.
  • the current I PD can be expressed as:
  • I PD photocurrent
  • R coefficient
  • the two multiplexed amplitude information becomes the amplitude information before the trigonometric function.
  • the photocurrent I PD is subsequently processed by the DSP module.
  • the photocurrent is amplified and filtered to obtain a heterodyne intermediate frequency signal; the heterodyne intermediate frequency signal is divided into two bundles Perform waveform detection and waveform recovery processing to obtain amplitude information A S1 and A S2 .
  • the photocurrent I PD detected by the photodetection module is first sent to the RF amplifier and filter to obtain the heterodyne intermediate frequency signal we need, and then divided into two channels for corresponding waveform detection and recovery, to obtain the sine sum in the formula The required amplitude information A S1 and A S2 before the amount of cosine.
  • the modulation signal is loaded on the optical carrier to form signal light, wherein the polarization state of the signal light changes with the change of the modulation signal, the signal light is a polarization modulation signal;
  • the characteristic light performs coherent interference to form two interfering signal lights, where the intrinsic light is left-handed circularly polarized light or right-handed circularly polarized light; performing balanced photoelectric detection on the two interfering signal lights, and outputting photocurrent;
  • the photocurrent is amplified and/or filtered to form a heterodyne intermediate frequency signal, wherein the amplitude and phase of the heterodyne intermediate frequency signal contain the polarization information of the signal light; signal recovery is performed on the heterodyne intermediate frequency signal to obtain Polarization information of the signal light.
  • the receiver described in FIG. 8 can also perform corresponding coherent reception demodulation.
  • the modulation signal is loaded on an optical carrier, and the linear polarization state of the optical carrier changes with the change of the modulation signal to form the following signal light:
  • E S represents the light field vector of the signal light
  • a S1 represents the first amplitude of the signal light
  • a S2 represents the second amplitude of the signal light
  • j represents the imaginary unit
  • ⁇ S represents the frequency of the signal light.
  • the polarization modulation signal and the polarization multiplexing signal are mainly different in the mapping in the electrical domain.
  • the use of a polarization modulator can generate signal light whose linear polarization state changes with the applied radio frequency signal at the transmitting end.
  • the signal light is essentially the same as the intensity of the signal light in each polarization state, but the polarization angle of the signal light changes, which is related to the added radio frequency signal.
  • the signal light and the left-handed circularly polarized light are coherently interfered by the optical coupling module to form two beams of interference signal light; wherein, the left-handed circularly polarized light is: Among them, E LO represents the light field vector of left-handed circularly polarized light, A LO represents the amplitude of left-handed circularly polarized light, j represents the imaginary unit, and ⁇ LO represents the frequency of left-handed circularly polarized light. Represents the initial phase of left-handed circularly polarized light, Represents the unit vector in the x-axis direction, Represents the unit vector in the y-axis direction; or,
  • the signal light and the right-handed circularly polarized light are coherently interfered to form two beams of interference signal light; wherein the right-handed circularly polarized light is:
  • E LO represents the light field vector of right-handed circularly polarized light
  • a LO represents the amplitude of right-handed circularly polarized light
  • j represents the imaginary unit
  • ⁇ LO represents the frequency of right-handed circularly polarized light.
  • Represents the initial phase of right-handed circularly polarized light Represents the unit vector in the x-axis direction
  • two beams of interference signal light can be expressed as:
  • E 1 represents the first interference signal light
  • E 2 represents the second interference signal light
  • the circularly polarized light and the signal light containing polarization multiplexing information are coherently interfered in the optical coupler, and then sent to the photodetection module.
  • the interference signal light is converted into light containing amplitude and polarization information.
  • the current I PD can be expressed as:
  • I PD photocurrent
  • R coefficient
  • the two multiplexed amplitude information becomes the fourth and fifth pre-trigonometric function amplitude information.
  • the photocurrent I PD is subsequently processed by the DSP module.
  • the photocurrent is amplified and filtered to obtain a heterodyne intermediate frequency signal; the heterodyne intermediate frequency signal is divided into two bundles Perform waveform detection and waveform recovery processing to obtain amplitude information A S1 and A S2 .
  • the photocurrent I PD detected by the photodetection module is first sent to the RF amplifier and filter to obtain the heterodyne intermediate frequency signal we need, and then divided into two channels for corresponding waveform detection and recovery, to obtain the sine sum in the formula The required amplitude information A S1 and A S2 before the amount of cosine.
  • Application example 2 Compared with application example 1, the use of a balanced receiver eliminates the DC component and common mode noise in the photocurrent I PD in application example 1, and improves the signal-to-noise ratio of the received signal, and has a certain degree of receiving sensitivity. improve.
  • FIG. 9 is a schematic diagram of the structural composition of a coherent receiver provided by an embodiment of the application.
  • the coherent receiver includes: a receiving module 901 configured to receive signal light, and the signal light is loaded on the light by a modulated signal.
  • the intrinsic light source 902 is configured to generate circularly polarized light as intrinsic light
  • the optical coupling module 903 is connected to the intrinsic light source 902 and the receiving module 901 and is configured to connect the signal light to the The intrinsic light performs coherent interference to form at least one beam of interference signal light
  • a photodetection module 904 the photodetection module 904 is connected to the optical coupling module 903, and is configured to perform photoelectric detection on the at least one beam of interference signal light, A photocurrent is output, and the photocurrent includes amplitude information and/or polarization information of the signal light.
  • the optical coupling module 903 includes two input ports, the two input ports are respectively located on the transmission path of the signal light and the intrinsic light, and are configured to combine the modulated signal light and the intrinsic light.
  • the intrinsic light performs coherent interference to form at least one beam of interference signal light.
  • the number of the photodetection modules 904 is the same as the number of the output ports of the optical coupling module 903.
  • the two or more photodetection modules 904 are implemented by using a balanced receiver.
  • the optical coupling module 903 includes at least one output port configured to output at least one beam of interference signal light.
  • the circularly polarized light is left-handed circularly polarized light or right-handed circularly polarized light, wherein the wavelength of the circularly polarized light is different from the wavelength of the interference signal light.
  • each unit in the coherent receiver shown in FIG. 9 can be understood with reference to the relevant description of the aforementioned coherent detection method.
  • the optical coupling module and the photodetection module in the coherent receiver shown in FIG. 9 can be implemented by specific logic circuits.
  • the disclosed system, coherent receiver, and method may be implemented in other ways.
  • the above-described coherent receiver embodiments are only illustrative.
  • the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be Combined or can be integrated into another system, or some features can be ignored or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, the indirect coupling or communication connection of coherent receivers or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to implement the solution of the embodiment.

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Abstract

本申请公开了一种相干检测方法及相干接收机，该方法包括：接收信号光，所述信号光由调制信号加载在光载波上形成；将所述信号光与本征光进行相干干涉，形成至少一束干涉信号光，所述本征光为圆偏振光；对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和偏振信息中的至少一种。

Description

一种相干检测方法及相干接收机
本申请要求在2019年03月13日提交中国专利局、申请号为201910188811.1的中国专利申请的优先权，该申请的全部内容通过引用结合在本申请中。
技术领域
本申请涉及光纤通信领域，例如涉及一种相干检测方法及相干接收机。
背景技术
在相干光通信中，光载波的幅度和相位都可以被调制，高阶的幅度/相位调制格式的使用可以大大提高系统的频谱效率，从而实现高速率的光纤通信。对于高阶调制的信号光，其检测方式通常采用多路相干检测。为了实现不同偏振方向的相干接收，基于相位分集和偏振分集的多路相干检测系统需要采用大量的光学器件，如光电探测模块、平衡接收机等，增大了光路复杂度和成本。
发明内容
本申请实施例提供了一种相干检测方法及相干接收机。
本申请实施例提供的相干检测方法，包括：接收信号光，所述信号光由调制信号加载在光载波上形成；将所述信号光与本征光进行相干干涉，形成至少一束干涉信号光，所述本征光为圆偏振光；对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和偏振信息中的至少一种。
本申请实施例提供的相干接收机，包括：接收模块，设置为接收信号光，所述信号光由调制信号加载在光载波上形成；本征光源，设置为产生圆偏振光作为本征光；光耦合模块，与所述本征光源和所述接收模块相连，设置为将所述信号光与所述本征光进行相干干涉，形成至少一束干涉信号光；光电探测模块，所述光电探测模块与所述光耦合模块相连，设置为对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和偏振信息中的至少一种。
附图说明
附图以示例而非限制的方式大体示出了本文中所讨论的各个实施例。
图1为一种基于相位分集和偏振分集的零差相干检测系统；
图2为本申请实施例提供的相干检测方法的流程示意图；
图3为本申请应用示例一的外差相干的接收机的系统架构图一；
图4为本申请实施例提供的偏振复用信号光的解复用原理图；
图5为本申请实施例提供的信号发端偏振复用信号产生框图；
图6为本申请实施例提供的接收机后续DSP模块的架构图；
图7为本申请实施例提供的信号发端偏振调制信号发生框图；
图8为本申请应用实例二的外差相干的接收机的系统架构图二；
图9为本申请实施例提供的相干接收机的结构组成示意图。
具体实施方式
为了能够更加详尽地了解本申请实施例的特点与技术内容，下面结合附图对本申请实施例的实现进行详细阐述，所附附图仅供参考说明之用，并非用来限定本申请实施例。
在光纤通信领域，随着数据、语音业务的发展，特别是视频、多媒体业务的快速发展，对电信网络带宽的需求不断提高。对于有线传输业务，业界通常的方案为高阶调制格式加相干检测的接收方式。
但是，对于高阶调制的信号光，尤其是偏振复用信号，常规方式是采用多路相干检测，并分别检测多路信号。图1是一种基于相位分集和偏振分集的零差相干检测系统，其中，信号光E S经过偏振分束器后，形成两束线偏振的信号光，一束为x方向线偏振的信号光，另一束是y方向线偏振的信号光；本征光为线偏振光，本征光经过偏振分束器后，形成两束线偏振的本征光，一束为x方向线偏振的本征光，另一束是y方向线偏振的本征光；然后，通过平衡接收机进行光电检测，输出光电流。图1中需要的光学器件的数量较多，如果不考虑偏振分集情况下，基于相位分集的零差检测架构也需要图1中至少一半的光学器件。对于偏振复用信号的解调方式，需引入偏振分集的方式，即如图1所示，采用本征光偏振分束成x和y两个方向分别进行相干检测，进一步增大光路复杂度和成本。
基于此，本申请实施例提供了一种低成本的偏振不敏感(即偏振无关)的相干检测方法，该方法在尽量减少光电探测模块、平衡接收机等光学器件的前 提下，实现不同偏振方向的相干接收。
图2为本申请实施例提供的相干检测方法的流程示意图，如图2所示，所述相干检测方法包括以下步骤：
步骤201：接收信号光，所述信号光由调制信号加载在光载波上形成。
本申请实施例中，调制信号是指射频(Radio Frequency，RF)信号，调制信号属于数字信号，所述信号光由调制信号加载在光载波上形成是指：将数字信号通过光载波的幅度、相位、频率中的至少一种信息进行调制。
步骤202：将所述信号光与本征光进行相干干涉，形成至少一束干涉信号光，所述本征光为圆偏振光。
本申请实施例中，本征光采用圆偏振光，在一种实施方式中，圆偏振光包括左旋圆偏振光或右旋圆偏振光。
在一种实施方式中，所述圆偏振光可采用1/4波片产生，这里，1/4波片是具有一定厚度的双折射单晶薄片，当线偏振光垂直入射1/4波片,并且线偏振光的偏振方向和1/4波片的光轴面成45°角时，出射光为圆偏振光。在另一实施方式中，所述圆偏振光可采用偏振分束器、移相器和偏振合束器产生，将线偏振光经过偏振分束器分束后，形成x方向偏振的线偏振光和y方向偏振的线偏振光，将y方向偏振的线偏振光通过移相器延迟90°相位或提前90°相位，再通过偏振合束器对x方向偏振的线偏振光和移相后的y方向偏振的线偏振光进行合束，形成圆偏振光。
本申请实施例中，通过光耦合模块(也称为光耦合器)将所述信号光与本征光进行相干干涉，形成至少一束干涉信号光，其中，所述干涉信号光的数量与所述光耦合器输出端口的数量一致。在一种实施方式中，光耦合模块与产生本征光的本征光源相连，将接收到的本征光与信号光进行相干干涉(即合波处理)，形成干涉信号光。
在一种实施方式中，光耦合模块的类型包括但不局限于：2×1光耦合模块、2×2光耦合模块。其中，2×1光耦合模块代表输入端口为2个，输出端口1个；2×2光耦合模块代表输入端口为2个，输出端口为2个。需要说明的是，光耦合模块的输出端口不局限于1个，2个，还可以是其他更多的数量。
步骤203：对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和/或偏振信息。
本申请实施例中，通过光电探测模块对所述至少一束干涉信号光进行光电 检测，输出光电流，所述光电流包含所述信号光的幅度信息和/或偏振信息。在一种实施方式中，光电探测模块与光耦合模块连接，接收光耦合模块输出的干涉信号光，将该干涉信号光转换成电信号，即光电流输出，这里，光电探测模块可以将信号光与本征光的偏振夹角信息转化为输出信号(即光电流)的相位信息，形成相位噪声。本申请实施例中，光电探测模块的数量与光耦合模块的输出端口的数量相等，在一种实施方式中，所述光电探测模块的数量为两个以上的情况下，两个以上的光电探测模块采用平衡接收机实现。所述光耦合模块包含至少一个输出端口，设置为输出至少一束干涉信号光。
本申请实施例的技术方案，使用圆偏振光作为本征光，采用光耦合模块对信号光和圆偏振光进行相干干涉，从而可以实现偏振解复用和偏振不敏感的低成本相干检测。这里的低成本是指通过光耦合模块加光电探测模块的方式来替换高成本的相干接收机。参照图3和图1，图3中采用光耦合模块加光电探测模块来实现相干检测，图1中采用多个平衡接收机，以及多个偏振分束器和移相器来实现相干检测，显然，图3相对于图1而言，大大节省了成本。
以下结合不同调制方式的信号光对本申请实施例的技术方案进行分情说明。
应用实例一
接收机的接收原理参照图3，本征光采用圆偏振光来实现信号光的偏振不敏感接收。该接收机可以偏振无关地相干检测出以下三种情况的高阶调制信号。
1)线偏振强度调制信号
这里，将调制信号加载在光载波上，形成信号光，其中，所述信号光的偏振态保持不变，所述信号光为线偏振强度调制信号；将所述信号光与本征光进行相干干涉，形成一束干涉信号光，所述本征光为左旋圆偏振光或右旋圆偏振光；对所述一束干涉信号光进行光电检测，输出光电流；对所述光电流进行放大和/或滤波处理，形成外差中频信号，其中，所述外差中频信号的幅度中包含所述信号光的幅度信息；对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息。
在一种实施方式中，采用外差相干检测的情况下，当输入信号光为线偏振强度调制信号(如PAM-4信号或者OOK信号)时，图3所述的接收机包括光耦合模块和光电探测模块，光耦合模块将圆偏振光(左旋/右旋圆偏振光)与信号光进行相干干涉形成干涉信号光送入光电探测模块中，光电探测模块将干涉信号光转换成包含幅度信息的光电流I PD。后续，光电流I PD被送入数字信号处理 (Digital Signal Processing，DSP)模块中进行滤波、时钟恢复、载波恢复、幅度等电域处理。
这里，将调制信号加载在线偏振的光载波上，形成如下信号光：
Figure PCTCN2020079179-appb-000001
其中，E S代表信号光的光场矢量，A S代表信号光的幅度，j代表虚数单位，ω S代表信号光的频率，
Figure PCTCN2020079179-appb-000002
代表信号光的初相位，ψ代表信号光的偏振方向与x轴方向的夹角，
Figure PCTCN2020079179-appb-000003
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000004
代表y轴方向的单位矢量。
通过光耦合模块将所述信号光与左旋圆偏振光进行相干干涉，形成一束干涉信号光；其中，所述左旋圆偏振光为：
Figure PCTCN2020079179-appb-000005
其中，E LO代表左旋圆偏振光的光场矢量，A LO代表左旋圆偏振光的幅度，j代表虚数单位，ω LO代表左旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000006
代表左旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000007
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000008
代表y轴方向的单位矢量；或者，
将所述信号光与右旋圆偏振光进行相干干涉，形成一束干涉信号光；其中，所述右旋圆偏振光为：
Figure PCTCN2020079179-appb-000009
其中，E LO代表右旋圆偏振光的光场矢量，A LO代表右旋圆偏振光的幅度，j代表虚数单位，ω LO代表右旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000010
代表右旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000011
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000012
代表y轴方向的单位矢量。
将产生的一束信号光送入光电探测模块中，经过光电探测模块的光电效应，将干涉信号光转换成包含幅度信息和偏振信息的光电流I PD，可以表示为：
Figure PCTCN2020079179-appb-000013
其中，I PD代表光电流，R代表系数。
其中，信号光的偏振方向与x轴方向的夹角ψ进入三角函数中，变成相位噪声。后续通过DSP模块可以提取出幅度信息。在一种实施方式中，对所述光电流进行放大和滤波处理，得到外差中频信号；对所述外差中频信号进行波形检测和波形恢复处理，得到幅度信息A S。
本申请实施例采用圆偏振光作为本征光，根据上述公式的计算，最后信号光的偏振方向与x轴方向的夹角信息进入三角函数中，形成相位噪声。
2)偏振复用强度调制信号
这里，对光载波进行偏振分束，形成第一方向偏振的第一光载波和第二方向偏振的第二光载波，所述第一方向与所述第二方向垂直；将调制信号分别加载在所述第一光载波上和所述第二光载波上并进行偏振合束，形成信号光，其 中，所述信号光为偏振复用强度调制信号；将所述信号光与本征光进行相干干涉，形成一束干涉信号光，所述本征光为左旋圆偏振光或右旋圆偏振光；对所述一束干涉信号光进行光电检测，输出光电流；对所述光电流进行放大和/或滤波处理，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的幅度信息和偏振信息；对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息和偏振信息。
在一种实施方式中，传统的线偏振强度调制格式受限于自身特性，并不能满足更高要求的高速传输系统的需求。为了提高带宽的利用效率，包含偏振和强度两个维度信息的高阶调制信号也在本实施例中的一个子例中进行了理论分析和研究。采用外差相干检测的情况下，当输入信号光为包含强度信息和偏振信息的偏振复用强度调制信号(如DP-OOK或者DP-PAM4)时，图3所述的接收机也可以做相应的相干接收解调。
如图4所示，当圆偏振光的偏正态旋转到x方向时，此时本征光可以相干检测出信号光中的x偏振态的光信号；而当圆偏振光的偏振态旋转到Y方向时，此时本征光可以相干检测到信号光的y偏振态的光信号。采用圆偏振光作为本征光，类似像雷达扫描的方式一样，在360°方向上不断探测扫描信号光中的两个偏振态信息。
图5为偏振复用强度调制信号(如DP-OOK信号或DP-PAM4信号等)在发端的产生方式架构图。如图5所示，对线偏振的光载波进行偏振分束，形成x轴方向偏振的第一光载波和y轴方向偏振的第二光载波；将调制信号分别加载在所述第一光载波上和所述第二光载波上并进行偏振合束，形成如下信号光：
Figure PCTCN2020079179-appb-000014
其中，E S代表信号光的光场矢量，A S1代表信号光的第一幅度，A S2代表信号光的第二幅度，j代表虚数单位，ω S代表信号光的频率，
Figure PCTCN2020079179-appb-000015
代表信号光的初相位，
Figure PCTCN2020079179-appb-000016
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000017
代表y轴方向的单位矢量。
通过光耦合模块将所述信号光与左旋圆偏振光进行相干干涉，形成一束干涉信号光；其中，所述左旋圆偏振光为：
Figure PCTCN2020079179-appb-000018
其中，E LO代表左旋圆偏振光的光场矢量，A LO代表左旋圆偏振光的幅度，j代表虚数单位，ω LO代表左旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000019
代表左旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000020
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000021
代表y轴方向的单位矢量；或者，
将所述信号光与右旋圆偏振光进行相干干涉，形成一束干涉信号光；其中， 所述右旋圆偏振光为：
Figure PCTCN2020079179-appb-000022
其中，E LO代表右旋圆偏振光的光场矢量，A LO代表右旋圆偏振光的幅度，j代表虚数单位，ω LO代表右旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000023
代表右旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000024
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000025
代表y轴方向的单位矢量。
圆偏振光与包含偏振复用信息的信号光在光耦合器中进行相干干涉后，送入光电探测模块中，经过光电探测模块的光电效应，将干涉信号光转换成包含幅度和偏振信息的光电流I PD，可以表示为：
Figure PCTCN2020079179-appb-000026
其中，I PD代表光电流，R代表系数。
其中，两个复用的幅度信息变成第四和第五项三角函数前振幅信息。
参照图6，光电流I PD后续通过DSP模块进行处理，在一种实施方式中，对所述光电流进行放大和滤波处理，得到外差中频信号；对所述外差中频信号分为两束进行波形检测和波形恢复处理，得到幅度信息A S1和A S2。这里，光电探测模块检测到的光电流I PD先送入RF放大器和滤波器中得到我们所需的外差中频信号，之后分为两路做相应的波形检波与恢复，得到公式中的正弦和余弦量前的所需幅度信息A S1和A S2。
3)偏振调制信号
这里，将调制信号加载在光载波上，形成信号光，其中，所述信号光的偏振态随所述调制信号的变化而变化，所述信号光为偏振调制信号；将所述信号光与本征光进行相干干涉，形成一束干涉信号光，所述本征光为左旋圆偏振光或右旋圆偏振光；对所述一束干涉信号光进行光电检测，输出光电流；对所述光电流进行放大和/或滤波处理，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的偏振信息；对所述外差中频信号进行信号恢复，得到所述信号光的偏振信息。
在一种实施方式中，在光纤传感中广泛使用的偏振调制技术，也可以作为一种新型的高阶调制信号来提高数据的传输速率，利用线偏振光的不同偏振状态来表征不同的数据比特。在偏振调制信号中，不同的偏振态对应X偏振和Y偏振方向的信号电压幅度不同，用来映射不同的线偏振光。采用外差相干检测的情况下，当输入信号光为偏振调制信号时，图3所述的接收机也可以做相应的相干接收解调。
将调制信号加载在光载波上，所述光载波的线偏振态随所述调制信号的变化而变化，形成如下信号光：
Figure PCTCN2020079179-appb-000027
其中，E S代表信号光的光场矢量，A S1代表信号光的第一幅度，A S2代表信号光的第二幅度，j代表虚数单位，ω S代表信号光的频率，
Figure PCTCN2020079179-appb-000028
代表信号光的初相位，
Figure PCTCN2020079179-appb-000029
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000030
代表y轴方向的单位矢量。
这里，偏振调制信号和偏振复用信号实现方式上主要是在电域的映射不同。
如图7所示，采用偏振调制器可以在发端产生线偏振态随所加射频信号变化的信号光。该信号光本质上和各偏振态信号光的强度一致，但信号光的偏振角度发生变化，与所加射频信号相关。
通过光耦合模块将所述信号光与左旋圆偏振光进行相干干涉，形成一束干涉信号光；其中，所述左旋圆偏振光为：
Figure PCTCN2020079179-appb-000031
其中，E LO代表左旋圆偏振光的光场矢量，A LO代表左旋圆偏振光的幅度，j代表虚数单位，ω LO代表左旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000032
代表左旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000033
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000034
代表y轴方向的单位矢量；或者，
将所述信号光与右旋圆偏振光进行相干干涉，形成一束干涉信号光；其中，所述右旋圆偏振光为：
Figure PCTCN2020079179-appb-000035
其中，E LO代表右旋圆偏振光的光场矢量，A LO代表右旋圆偏振光的幅度，j代表虚数单位，ω LO代表右旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000036
代表右旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000037
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000038
代表y轴方向的单位矢量。
圆偏振光与包含偏振复用信息的信号光在光耦合器中进行相干干涉后，送入光电探测模块中，经过光电探测模块的光电效应，将干涉信号光转换成包含幅度和偏振信息的光电流I PD，可以表示为：
Figure PCTCN2020079179-appb-000039
其中，I PD代表光电流，R代表系数。
其中，两个复用的幅度信息变成第四和第五项三角函数前振幅信息。
参照图6，光电流I PD后续通过DSP模块进行处理，在一种实施方式中，对所述光电流进行放大和滤波处理，得到外差中频信号；对所述外差中频信号分为两束进行波形检测和波形恢复处理，得到幅度信息A S1和A S2。这里，光电探测模块检测到的光电流I PD先送入RF放大器和滤波器中得到我们所需的外差中频 信号，之后分为两路做相应的波形检波与恢复，得到公式中的正弦和余弦量前的所需幅度信息A S1和A S2。
应用实例二
接收机的接收原理参照图8，本征光采用圆偏振光来实现信号光的偏振不敏感接收。该方案采用一个平衡接收机消除了实施例一中的直流分量、共模噪声，提高实施例一中接收信号的信噪比，对接收灵敏度有一定的提高，但相应的会增加光路上的成本。该接收机可以偏振无关地相干检测出以下三种情况的高阶调制信号。
1)线偏振强度调制信号
这里，将调制信号加载在光载波上，形成信号光，其中，所述信号光的偏振态保持不变，所述信号光为线偏振强度调制信号；将所述信号光与本征光进行相干干涉，形成两束干涉信号光，所述本征光为左旋圆偏振光或右旋圆偏振光；对所述两束干涉信号光进行平衡光电检测，输出光电流；对所述光电流进行放大和/或滤波处理，形成外差中频信号，其中，所述外差中频信号的幅度中包含所述信号光的幅度信息；对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息。
在一种实施方式中，采用外差相干检测的情况下，当输入信号光为线偏振强度调制信号(如PAM-4信号或者OOK信号)时，图8所述的接收机包括光耦合模块和光电探测模块，光耦合模块将圆偏振光(左旋/右旋圆偏振光)与信号光进行相干干涉形成干涉信号光送入光电探测模块中，光电探测模块将干涉信号光转换成包含幅度信息的光电流I PD。后续，光电流I PD被送入数字信号处理(Digital Signal Processing，DSP)模块中进行滤波、时钟恢复、载波恢复、幅度等电域处理。
这里，将调制信号加载在线偏振的光载波上，形成如下信号光：
Figure PCTCN2020079179-appb-000040
其中，E S代表信号光的光场矢量，A S代表信号光的幅度，j代表虚数单位，ω S代表信号光的频率，
Figure PCTCN2020079179-appb-000041
代表信号光的初相位，ψ代表信号光的偏振方向与x轴方向的夹角，
Figure PCTCN2020079179-appb-000042
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000043
代表y轴方向的单位矢量。
通过光耦合模块将所述信号光与左旋圆偏振光进行相干干涉，形成两束干涉信号光；其中，所述左旋圆偏振光为：
Figure PCTCN2020079179-appb-000044
其中，E LO代表左旋圆偏振光的光场矢量，A LO代表左旋圆偏振光的幅度，j代表虚 数单位，ω LO代表左旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000045
代表左旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000046
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000047
代表y轴方向的单位矢量；或者，
将所述信号光与右旋圆偏振光进行相干干涉，形成两束干涉信号光；其中，所述右旋圆偏振光为：
Figure PCTCN2020079179-appb-000048
其中，E LO代表右旋圆偏振光的光场矢量，A LO代表右旋圆偏振光的幅度，j代表虚数单位，ω LO代表右旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000049
代表右旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000050
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000051
代表y轴方向的单位矢量。
这里，两束干涉信号光可以表示为：
Figure PCTCN2020079179-appb-000052
Figure PCTCN2020079179-appb-000053
其中，E 1代表第一束干涉信号光，E 2代表第二束干涉信号光。
将产生的两束信号光送入光电探测模块中，经过光电探测模块的光电效应，将干涉信号光转换成包含幅度信息和偏振信息的光电流I PD，可以表示为：
Figure PCTCN2020079179-appb-000054
其中，I PD代表光电流，R代表系数。
其中，信号光的偏振方向与x轴方向的夹角ψ进入三角函数中，变成相位噪声。后续通过DSP模块可以提取出幅度信息。在一种实施方式中，对所述光电流进行放大和滤波处理，得到外差中频信号；对所述外差中频信号进行波形检测和波形恢复处理，得到幅度信息A S。
2)偏振复用强度调制信号
这里，对光载波进行偏振分束，形成第一方向偏振的第一光载波和第二方向偏振的第二光载波，所述第一方向与所述第二方向垂直；将调制信号分别加载在所述第一光载波上和所述第二光载波上并进行偏振合束，形成信号光，其中，所述信号光为偏振复用强度调制信号；将所述信号光与本征光进行相干干涉，形成两束干涉信号光，所述本征光为左旋圆偏振光或右旋圆偏振光；对所述两束干涉信号光进行平衡光电检测，输出光电流；对所述光电流进行放大和/或滤波处理，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的幅度信息和偏振信息；对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息和偏振信息。
在一种实施方式中，采用外差相干检测的情况下，当输入信号光为包含强度信息和偏振信息的偏振复用强度调制信号(如DP-OOK或者DP-PAM4)时， 图8所述的接收机也可以做相应的相干接收解调。
如图4所示，当圆偏振光的偏正态旋转到x方向时，此时本征光可以相干检测出信号光中的x偏振态的光信号；而当圆偏振光的偏振态旋转到Y方向时，此时本征光可以相干检测到信号光的y偏振态的光信号。采用圆偏振光作为本征光，类似像雷达扫描的方式一样，在360°方向上不断探测扫描信号光中的两个偏振态信息。
图5为偏振复用强度调制信号(如DP-OOK信号或DP-PAM4信号等)在发端的产生方式架构图。如图5所示，对线偏振的光载波进行偏振分束，形成x轴方向偏振的第一光载波和y轴方向偏振的第二光载波；将调制信号分别加载在所述第一光载波上和所述第二光载波上并进行偏振合束，形成如下信号光：
Figure PCTCN2020079179-appb-000055
其中，E S代表信号光的光场矢量，A S1代表信号光的第一幅度，A S2代表信号光的第二幅度，j代表虚数单位，ω S代表信号光的频率，
Figure PCTCN2020079179-appb-000056
代表信号光的初相位，
Figure PCTCN2020079179-appb-000057
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000058
代表y轴方向的单位矢量。
通过光耦合模块将所述信号光与左旋圆偏振光进行相干干涉，形成两束干涉信号光；其中，所述左旋圆偏振光为：
Figure PCTCN2020079179-appb-000059
其中，E LO代表左旋圆偏振光的光场矢量，A LO代表左旋圆偏振光的幅度，j代表虚数单位，ω LO代表左旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000060
代表左旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000061
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000062
代表y轴方向的单位矢量；或者，
将所述信号光与右旋圆偏振光进行相干干涉，形成两束干涉信号光；其中，所述右旋圆偏振光为：
Figure PCTCN2020079179-appb-000063
其中，E LO代表右旋圆偏振光的光场矢量，A LO代表右旋圆偏振光的幅度，j代表虚数单位，ω LO代表右旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000064
代表右旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000065
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000066
代表y轴方向的单位矢量。
这里，两束干涉信号光可以表示为：
Figure PCTCN2020079179-appb-000067
Figure PCTCN2020079179-appb-000068
其中，E 1代表第一束干涉信号光，E 2代表第二束干涉信号光。
圆偏振光与包含偏振复用信息的信号光在光耦合器中进行相干干涉后，送入光电探测模块中，经过光电探测模块的光电效应，将干涉信号光转换成包含幅度和偏振信息的光电流I PD，可以表示为：
Figure PCTCN2020079179-appb-000069
其中，I PD代表光电流，R代表系数。
其中，两个复用的幅度信息变成三角函数前的振幅信息。
参照图6，光电流I PD后续通过DSP模块进行处理，在一种实施方式中，对所述光电流进行放大和滤波处理，得到外差中频信号；对所述外差中频信号分为两束进行波形检测和波形恢复处理，得到幅度信息A S1和A S2。这里，光电探测模块检测到的光电流I PD先送入RF放大器和滤波器中得到我们所需的外差中频信号，之后分为两路做相应的波形检波与恢复，得到公式中的正弦和余弦量前的所需幅度信息A S1和A S2。
3)偏振调制信号
这里，将调制信号加载在光载波上，形成信号光，其中，所述信号光的偏振态随所述调制信号的变化而变化，所述信号光为偏振调制信号；将所述信号光与本征光进行相干干涉，形成两束干涉信号光，所述本征光为左旋圆偏振光或右旋圆偏振光；对所述两束干涉信号光进行平衡光电检测，输出光电流；对所述光电流进行放大和/或滤波处理，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的偏振信息；对所述外差中频信号进行信号恢复，得到所述信号光的偏振信息。
在一种实施方式中，采用外差相干检测的情况下，当输入信号光为偏振调制信号时，图8所述的接收机也可以做相应的相干接收解调。
将调制信号加载在光载波上，所述光载波的线偏振态随所述调制信号的变化而变化，形成如下信号光：
Figure PCTCN2020079179-appb-000070
其中，E S代表信号光的光场矢量，A S1代表信号光的第一幅度，A S2代表信号光的第二幅度，j代表虚数单位，ω S代表信号光的频率，
Figure PCTCN2020079179-appb-000071
代表信号光的初相位，
Figure PCTCN2020079179-appb-000072
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000073
代表y轴方向的单位矢量。
这里，偏振调制信号和偏振复用信号实现方式上主要是在电域的映射不同。
如图7所示，采用偏振调制器可以在发端产生线偏振态随所加射频信号变化的信号光。该信号光本质上和各偏振态信号光的强度一致，但信号光的偏振角度发生变化，与所加射频信号相关。
通过光耦合模块将所述信号光与左旋圆偏振光进行相干干涉，形成两束干涉信号光；其中，所述左旋圆偏振光为：
Figure PCTCN2020079179-appb-000074
其 中，E LO代表左旋圆偏振光的光场矢量，A LO代表左旋圆偏振光的幅度，j代表虚数单位，ω LO代表左旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000075
代表左旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000076
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000077
代表y轴方向的单位矢量；或者，
将所述信号光与右旋圆偏振光进行相干干涉，形成两束干涉信号光；其中，所述右旋圆偏振光为：
Figure PCTCN2020079179-appb-000078
其中，E LO代表右旋圆偏振光的光场矢量，A LO代表右旋圆偏振光的幅度，j代表虚数单位，ω LO代表右旋圆偏振光的频率，
Figure PCTCN2020079179-appb-000079
代表右旋圆偏振光的初相位，
Figure PCTCN2020079179-appb-000080
代表x轴方向的单位矢量，
Figure PCTCN2020079179-appb-000081
代表y轴方向的单位矢量。
这里，两束干涉信号光可以表示为：
Figure PCTCN2020079179-appb-000082
Figure PCTCN2020079179-appb-000083
其中，E 1代表第一束干涉信号光，E 2代表第二束干涉信号光。
圆偏振光与包含偏振复用信息的信号光在光耦合器中进行相干干涉后，送入光电探测模块中，经过光电探测模块的光电效应，将干涉信号光转换成包含幅度和偏振信息的光电流I PD，可以表示为：
Figure PCTCN2020079179-appb-000084
其中，I PD代表光电流，R代表系数。
其中，两个复用的幅度信息变成第四和第五项三角函数前振幅信息。
参照图6，光电流I PD后续通过DSP模块进行处理，在一种实施方式中，对所述光电流进行放大和滤波处理，得到外差中频信号；对所述外差中频信号分为两束进行波形检测和波形恢复处理，得到幅度信息A S1和A S2。这里，光电探测模块检测到的光电流I PD先送入RF放大器和滤波器中得到我们所需的外差中频信号，之后分为两路做相应的波形检波与恢复，得到公式中的正弦和余弦量前的所需幅度信息A S1和A S2。
应用示例二相对于应用示例一而言，采用一个平衡接收机消除了应用示例一中光电流I PD中的直流分量、共模噪声，提高了接收信号的信噪比，对接收灵敏度有一定的提高。
图9为本申请实施例提供的相干接收机的结构组成示意图，如图9所示，所述相干接收机包括：接收模块901，设置为接收信号光，所述信号光由调制信号加载在光载波上形成；本征光源902，设置为产生圆偏振光作为本征光；光耦合模块903，与所述本征光源902和所述接收模块901相连，设置为将所述信号 光与所述本征光进行相干干涉，形成至少一束干涉信号光；光电探测模块904，所述光电探测模块904与所述光耦合模块903相连，设置为对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和/或偏振信息。
在一实施方式中，所述光耦合模块903包含两个输入端口，所述两个输入端口分别位于所述信号光和所述本征光的传输路径上，设置为将所述调制信号光和所述本征光进行相干干涉，形成至少一束干涉信号光。
在一实施方式中，所述光电探测模块904的数量与所述光耦合模块903输出端口的数量一致。
在一实施方式中，所述光电探测模块904的数量为两个以上的情况下，两个以上的光电探测模块采用平衡接收机实现。
在一实施方式中，所述光耦合模块903包含至少一个输出端口，设置为输出至少一束干涉信号光。
在一实施方式中，所述圆偏振光为左旋圆偏振光或者右旋圆偏振光，其中，所述圆偏振光的波长与所述干涉信号光的波长不同。
本领域技术人员应当理解，图9所示的相干接收机中的各单元的实现功能可参照前述相干检测方法的相关描述而理解。图9所示的相干接收机中的光耦合模块和光电探测模块可通过具体的逻辑电路来实现。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、相干接收机和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、相干接收机和方法，可以通过其它的方式实现。例如，以上所描述的相干接收机实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之 间的耦合或直接耦合或通信连接可以是通过一些接口，相干接收机或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案。

Claims (17)

  1. 一种相干检测方法，包括：
    接收信号光，所述信号光由调制信号加载在光载波上形成；
    将所述信号光与本征光进行相干干涉，形成至少一束干涉信号光，所述本征光为圆偏振光；
    对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和偏振信息中的至少一种。
  2. 根据权利要求1所述的方法，还包括：
    将调制信号加载在光载波上，形成信号光，其中，所述信号光的偏振态保持不变，所述信号光为线偏振强度调制信号。
  3. 根据权利要求2所述的方法，在形成一束干涉信号光的情况下，对所述一束干涉信号光进行光电检测，输出光电流；所述方法还包括：
    对所述光电流进行放大和滤波处理中的至少一种，形成外差中频信号，其中，所述外差中频信号的幅度中包含所述信号光的幅度信息；
    对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息。
  4. 根据权利要求2所述的方法，其中，在形成两束干涉信号光的情况下，对所述两束干涉信号光进行平衡光电检测，输出光电流；所述方法还包括：
    对所述光电流进行放大和滤波处理中的至少一种，形成外差中频信号，其中，所述外差中频信号的幅度中包含所述信号光的幅度信息；
    对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息。
  5. 根据权利要求1所述的方法，还包括：
    对所述光载波进行偏振分束，形成第一方向偏振的第一光载波和第二方向偏振的第二光载波，所述第一方向与所述第二方向垂直；
    将调制信号分别加载在所述第一光载波上和所述第二光载波上并进行偏振合束，形成信号光，其中，所述信号光为偏振复用强度调制信号。
  6. 根据权利要求5所述的方法，其中，在形成一束干涉信号光的情况下，对所述一束干涉信号光进行光电检测，输出光电流；所述方法还包括：
    对所述光电流进行放大和滤波处理中的至少一种，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的幅度信息和偏振信息；
    对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息和偏振信息。
  7. 根据权利要求5所述的方法，其中，在形成两束干涉信号光的情况下， 对所述两束干涉信号光进行平衡光电检测，输出光电流；所述方法还包括：
    对所述光电流进行放大和滤波处理中的至少一种，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的幅度信息和偏振信息；
    对所述外差中频信号进行信号恢复，得到所述信号光的幅度信息和偏振信息。
  8. 根据权利要求1所述的方法，还包括：
    将调制信号加载在光载波上，形成信号光，其中，所述信号光的偏振态随所述调制信号的变化而变化，所述信号光为偏振调制信号。
  9. 根据权利要求8所述的方法，其中，在形成一束干涉信号光的情况下，对所述一束干涉信号光进行光电检测，输出光电流；所述方法还包括：
    对所述光电流进行放大和滤波处理中的至少一种，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的偏振信息；
    对所述外差中频信号进行信号恢复，得到所述信号光的偏振信息。
  10. 根据权利要求8所述的方法，其中，在形成两束干涉信号光的情况下，对所述两束干涉信号光进行平衡光电检测，输出光电流；所述方法还包括：
    对所述光电流进行放大和滤波处理中的至少一种，形成外差中频信号，其中，所述外差中频信号的幅度和相位中包含所述信号光的偏振信息；
    对所述外差中频信号进行信号恢复，得到所述信号光的偏振信息。
  11. 根据权利要求1至10中任一项所述的方法，其中，所述将所述信号光与本征光进行相干干涉，形成至少一束干涉信号光，包括：
    通过光耦合器将所述信号光与所述本征光进行相干干涉，形成至少一束干涉信号光，其中，所述干涉信号光的数量与所述光耦合器输出端口的数量一致。
  12. 一种相干接收机，包括：
    接收模块，设置为接收信号光，所述信号光由调制信号加载在光载波上形成；
    本征光源，设置为产生圆偏振光作为本征光；
    光耦合模块，与所述本征光源和所述接收模块相连，设置为将所述信号光与所述本征光进行相干干涉，形成至少一束干涉信号光；
    光电探测模块，所述光电探测模块与所述光耦合模块相连，设置为对所述至少一束干涉信号光进行光电检测，输出光电流，所述光电流包含所述信号光的幅度信息和偏振信息中的至少一种。
  13. 根据权利要求12所述的相干接收机，其中，所述光耦合模块包含两个输入端口，所述两个输入端口分别位于所述信号光和所述本征光的传输路径上，所述光耦合模块设置为将所述调制信号光和所述本征光进行相干干涉，形成至少一束干涉信号光。
  14. 根据权利要求12或13所述的相干接收机，其中，所述光电探测模块的数量与所述光耦合模块输出端口的数量一致。
  15. 根据权利要求14所述的相干接收机，其中，在所述光电探测模块的数量为两个以上的情况下，两个以上的光电探测模块采用平衡接收机实现。
  16. 根据权利要求14所述的相干接收机，其中，所述光耦合模块包含至少一个输出端口，设置为输出至少一束干涉信号光。
  17. 根据权利要求12至16中任一项所述的相干接收机，其中，所述圆偏振光为左旋圆偏振光或者右旋圆偏振光，其中，所述圆偏振光的波长与所述信号光的波长不同。
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CN102545024A (zh) * 2012-01-11 2012-07-04 哈尔滨工业大学 基于圆偏振光干涉的双纵模偏频锁定方法与装置
CN109211289A (zh) * 2018-10-19 2019-01-15 华南师范大学 基于圆偏振光干涉的自发布里渊散射光纤传感方法与装置

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