WO2024095306A1 - Système de transmission de lumière, dispositif de réception de lumière et procédé de transmission de lumière - Google Patents

Système de transmission de lumière, dispositif de réception de lumière et procédé de transmission de lumière Download PDF

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Publication number
WO2024095306A1
WO2024095306A1 PCT/JP2022/040607 JP2022040607W WO2024095306A1 WO 2024095306 A1 WO2024095306 A1 WO 2024095306A1 JP 2022040607 W JP2022040607 W JP 2022040607W WO 2024095306 A1 WO2024095306 A1 WO 2024095306A1
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Prior art keywords
light
optical
unit
signal
polarization
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PCT/JP2022/040607
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English (en)
Japanese (ja)
Inventor
雪暢 中島
由明 木坂
由明 曽根
圭 北村
政則 中村
寛樹 谷口
隆志 才田
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日本電信電話株式会社
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Priority to PCT/JP2022/040607 priority Critical patent/WO2024095306A1/fr
Publication of WO2024095306A1 publication Critical patent/WO2024095306A1/fr

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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
    • H04B10/63—Homodyne, i.e. coherent receivers where the local oscillator is locked in frequency and phase to the carrier signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/06—Polarisation multiplex systems

Definitions

  • the present invention relates to an optical transmission system, an optical receiving device, and an optical transmission method.
  • the self-homodyne method is a method in which an optical transmitter transmits signal light and local light output from the same laser to an optical receiver via different optical transmission paths (for example, optical fiber), and performs coherent detection using the signal light and local light received by the optical receiver.
  • Figure 6 is a diagram showing an example of a self-homodyne optical transmission system.
  • the light generated by the optical output unit is split into two, one of which is output to the optical modulation unit, and the other is output to an optical transmission line as local light.
  • the optical modulation unit generates polarization division multiplexed signal light by modulating the light generated by the optical output unit using an electrical signal input from a digital signal processing unit.
  • the optical modulation unit outputs the generated signal light to an optical transmission line different from the local light.
  • the optical receiving device receives the signal light and the local light.
  • the optical detection unit performs homodyne detection of the signal light using the local light whose polarization is controlled by the polarization control unit.
  • the digital signal processing unit demodulates the homodyne detected signal light.
  • the polarization control unit performs polarization control of the local light signal as follows. That is, the photoelectric conversion unit inputs a portion of the local light that has been polarization-controlled by the polarization control device unit, and converts the input local light into an electrical signal.
  • the ADC unit converts the converted electrical signal from an analog signal to a digital signal.
  • the digital signal processing unit generates local light polarization control information based on the converted digital signal.
  • the local light polarization control information is information used to compensate for polarization rotation and polarization mode dispersion that the local light undergoes when transmitting through the optical transmission line.
  • the ADC unit converts the local light polarization control information from a digital signal to an analog signal.
  • the electrical signal amplifier unit amplifies the local light polarization control information.
  • the polarization control device unit uses the amplified local light polarization control information to perform polarization control of the local light signal received from the optical transmission device, and outputs it to the optical detection unit.
  • the self-homodyne method can suppress the effects of laser phase noise and eliminate frequency offset because the signal light and local light have the same center frequency and reference phase. Therefore, it has the following advantages over a method that performs coherent detection using a local light installed in an optical receiving device.
  • One is that it is possible to use a laser with a wide linewidth and low frequency accuracy as the optical output section of the optical receiving device.
  • the other is that it simplifies the signal processing for phase noise compensation and frequency offset compensation performed by the digital signal processing section after coherent detection is performed in the optical detection section of the optical receiving device.
  • Non-Patent Document 1 a photoelectric conversion unit, an ADC unit, a digital signal processing unit, a DAC unit, an electric signal amplifier unit, and a polarization control device unit are required to control the polarization of the local light transmitted from the optical transmitting device. This places a constraint on reducing power consumption and miniaturization.
  • the present invention aims to provide an optical transmission system, an optical receiving device, and an optical transmission method that can reduce power consumption and downsize the device in self-homodyne optical transmission.
  • One aspect of the present invention is an optical transmission system having an optical transmitter and an optical receiver, the optical transmitter comprising an optical output unit that outputs light of a single wavelength, a branching unit that branches the light output by the optical output unit into light for signal generation and local light, and an optical modulation unit that modulates the light for signal generation into polarization-multiplexed signal light, the optical receiver comprising an optical detection unit that performs coherent detection of the signal light transmitted through an optical transmission path using the local light transmitted through an optical transmission path different from the optical transmission path through which the signal light was transmitted, a signal processing unit that generates local light polarization control information based on the signal obtained by the coherent detection to compensate for fluctuations in the polarization of the local light during transmission, and a polarization control unit that performs polarization control of the local light used by the optical detection unit for coherent detection based on the local light polarization control information.
  • One aspect of the present invention is an optical receiving device that includes: an optical transmitting device that splits light of a single wavelength into light for signal generation and local light, and generates polarization-multiplexed signal light by modulating the light for signal generation; an optical detection unit that inputs the signal light and the local light transmitted via different optical transmission paths from the optical transmitting device, and coherently detects the signal light using the local light; a signal processing unit that generates local light polarization control information based on the signal obtained by the coherent detection to compensate for fluctuations in the polarization of the local light during transmission; and a polarization control unit that performs polarization control of the local light used by the optical detection unit for coherent detection based on the local light polarization control information.
  • One aspect of the present invention is an optical transmission method in an optical transmission system having an optical transmitter and an optical receiver, comprising: an optical output step in which the optical transmitter outputs light of a single wavelength; a branching step in which the optical transmitter branches the light output in the optical output step into light for signal generation and local light; an optical modulation step in which the optical transmitter modulates the light for signal generation into polarization-multiplexed signal light; an optical detection step in which the optical receiver coherently detects the signal light transmitted through an optical transmission path using the local light transmitted through an optical transmission path different from the optical transmission path through which the signal light was transmitted; a signal processing step in which the optical receiver generates local light polarization control information for compensating for fluctuations in the polarization of the local light during transmission based on a signal obtained by coherent detection; and a polarization control step in which the optical receiver performs polarization control of the local light used for the coherent detection based on the local light polarization control information.
  • This invention makes it possible to reduce power consumption and miniaturize devices in self-homodyne optical transmission.
  • FIG. 1 is a diagram illustrating an example of a configuration of an optical transmission system according to a first embodiment of the present invention.
  • 1 is a diagram illustrating an example of a configuration of an optical transmission system according to a first embodiment
  • FIG. 11 is a diagram illustrating an example of a configuration of an optical transmission system according to a second embodiment.
  • FIG. 11 is a diagram illustrating an example of a configuration of an optical transmission system according to a second embodiment.
  • FIG. 13 is a diagram illustrating an example of the configuration of an optical transmission system according to a third embodiment.
  • FIG. 1 is a diagram illustrating an example of the configuration of a conventional optical transmission system.
  • This embodiment relates to an optical transmission system using a self-homodyne method.
  • An optical transmitter transmits signal light and local light of the same wavelength output from the same laser to an optical receiver via different optical fibers.
  • the optical receiver performs coherent detection of the received signal light using the received local light.
  • the optical receiver has a digital signal processor that generates local light polarization control information for compensating for fluctuations in the polarization of the local light during transmission through the optical fiber based on the output signal of the coherent detection, and a polarization controller that performs polarization control of the local light using the local light polarization control information. This reduces the number of functional blocks for polarization control of the local light transmitted from the optical transmitter, and efficiently performs polarization control.
  • Fig. 1 is a block diagram showing the configuration of an optical transmission system 1 according to the first embodiment.
  • thin solid arrows indicate paths of electrical data signals
  • thick solid arrows indicate paths of optical data signals
  • thin dashed arrows indicate paths of electrical control signals. The same is true in other figures unless otherwise defined.
  • the optical transmission system 1 includes an optical transmitting device 10 and an optical receiving device 20.
  • the optical transmitting device 10 and the optical receiving device 20 are connected by a plurality of optical transmission paths 30.
  • the M (M is an integer of 2 or more) optical transmission paths 30 are referred to as optical transmission paths 30-1 to 30-M.
  • the internal configuration of the optical transmitting device 10 and the optical receiving device 20 will be described below.
  • the optical transmitter 10 includes N (N is an integer equal to or greater than 2, and N ⁇ M) optical output units 11, N branch units 12, N digital signal processing units 13, N optical modulation units 14, and M wavelength multiplexing units 15.
  • the optical output units 11, branch units 12, and digital signal processing units 13 may be the optical output units, branch units, and digital signal processing units included in the optical transmitter of the prior art shown in FIG. 6.
  • the N optical output units 11 are respectively written as optical output units 11-1 to 11-N
  • the N branch units 12 are respectively written as branch units 12-1 to 12-N
  • the N digital signal processing units 13 are respectively written as digital signal processing units 13-1 to 13-N
  • the N optical modulation units 14 are respectively written as optical modulation units 14-1 to 14-N
  • the M wavelength multiplexing units 15 are respectively written as wavelength multiplexing units 15-1 to 15-M.
  • signal light with wavelength ⁇ i i is an integer between 1 and N
  • local light with wavelength ⁇ i is also referred to as local light ⁇ i.
  • the optical output unit 11 can be configured using, for example, a DFB (Distributed Feedback) laser, an ECL (External Cavity Laser), or a VCSEL (Vertical Cavity Surface Emitting Laser).
  • the optical output unit 11-i generates light of a single wavelength ⁇ i.
  • the branching unit 12-i branches the light generated by the optical output unit 11-i and outputs the branched light to the optical modulation unit 14-i and the wavelength multiplexing unit 15-j (j is an integer between 1 and N, and i ⁇ j).
  • the digital signal processing unit 13 can be configured using, for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-programmable Gate Array).
  • the digital signal processing unit 13-i generates an electrical signal and outputs the generated electrical signal to the optical modulation unit 14-i.
  • the optical modulation unit 14 can be configured using, for example, a Mach-Zehnder type optical modulator.
  • the light of wavelength ⁇ i output by the optical output unit 11-i and branched by the branch unit 12-i is input to the optical modulation unit 14-i.
  • the optical modulation unit 14-i modulates the input light of wavelength ⁇ i using an electrical signal input from the digital signal processing unit 13-i, generating signal light with a power ratio of 1:1 between x-polarized and y-polarized waves.
  • the optical modulation unit 14-i outputs the generated signal light of wavelength ⁇ i to the wavelength multiplexing unit 15-m (m is an integer between 1 and M).
  • i m.
  • the wavelength multiplexing unit 15 can be configured using, for example, a PLC (Planer Lightwave Circuit) or a MEMS (Micro Electro Mechanical Systems).
  • the wavelength multiplexing unit 15 multiplexes the input light of different wavelengths by wavelength division multiplexing.
  • the wavelength multiplexing unit 15-m receives the signal light of wavelength ⁇ i modulated by the optical modulation unit 14-i and the local light of wavelength ⁇ j output by the optical output unit 11-j and branched by the branching unit 12-j.
  • the wavelength multiplexing unit 15-m multiplexes the signal light of wavelength ⁇ i and the local light of wavelength ⁇ j, and outputs the combined light to the optical transmission path 30-m.
  • the optical receiving device 20 includes M wavelength separation units 21, N polarization control units 22, N optical detection units 23, and N digital signal processing units 24.
  • the M wavelength separation units 21 are respectively written as wavelength separation units 21-1 to 21-M
  • the N polarization control units 22 are respectively written as polarization control units 22-1 to 22-N
  • the N optical detection units 23 are respectively written as optical detection units 23-1 to 23-N
  • the N digital signal processing units 24 are respectively written as digital signal processing units 24-1 to 24-N.
  • the polarization control unit 22 includes a polarization control device unit 221 and an electrical signal amplifier unit 222.
  • the polarization control device unit 221 and electrical signal amplifier unit 222 included in the polarization control unit 22-i are respectively referred to as the polarization control device unit 221-i and the electrical signal amplifier unit 222-i.
  • the digital signal processing unit 24 includes an adaptive equalization unit 241, an information conversion unit 242, and a DAC (digital-to-analog conversion) unit 243.
  • the adaptive equalization unit 241, the information conversion unit 242, and the DAC unit 243 included in the digital signal processing unit 24-i are respectively referred to as the adaptive equalization unit 241-i, the information conversion unit 242-i, and the DAC unit 243-i.
  • the wavelength separation unit 21 can be configured using, for example, a PLC, MEMS, etc.
  • the wavelength separation unit 21-m separates the multiplexed light by wavelength and outputs the separated light of each wavelength to a different path.
  • the wavelength separation unit 21-m separates the light input from the optical transmission path 30-m by wavelength.
  • the wavelength separation unit 21-m outputs the separated signal light of wavelength ⁇ i to the optical detection unit 23-i, and outputs the separated local light of wavelength ⁇ j to the polarization control device unit 221-j of the polarization control unit 22-j.
  • the polarization control device unit 221 can be configured using, for example, an optical waveguide.
  • the polarization control device unit 221 performs polarization control of the local light using the local light polarization control information.
  • the polarization control of the local light in the polarization control device unit 221 may be, for example, control so that the power ratio of the x polarization and the y polarization becomes 1:1, or control so that the polarization direction becomes a single direction such as the x polarization or the y polarization, and control so that the power ratio of the x polarization and the y polarization of the local light in the optical detection unit 23 becomes 1:1.
  • the polarization control device unit 221-j performs polarization control related to polarization rotation and polarization mode dispersion for the local light of wavelength ⁇ j input from the wavelength separation unit 21-m using the local light polarization control information input from the electric signal amplifier 222-j.
  • the local light polarization control information represents fluctuations such as polarization rotation and polarization mode dispersion that the polarization of the local light of wavelength ⁇ j undergoes when it transmits through the optical transmission path 30.
  • the polarization control device unit 221-j outputs the polarization-controlled local light with wavelength ⁇ j to the optical detection unit 23-j.
  • the electric signal amplifier 222 can be configured using, for example, a driver.
  • the electric signal amplifier 222-j receives local light polarization control information from the digital signal processor 24-i, which has processed the results of coherent detection of the signal light of wavelength ⁇ i that was multiplexed with the local light of wavelength ⁇ j.
  • the electric signal amplifier 222-j amplifies the received local light polarization control information and outputs the amplified local light polarization control information to the polarization control device unit 221-j.
  • the optical detection unit 23 can be configured using, for example, a 90-degree hybrid and a BPD (Balanced Photo Diode).
  • the optical detection unit 23 performs coherent detection of the signal light using local light and converts the signal light into an electrical signal.
  • the optical detection unit 23-i performs coherent detection of the signal light of wavelength ⁇ i input from the wavelength separation unit 21-i using local light of wavelength ⁇ i input from the polarization control device unit 221-i, and generates an electrical signal.
  • the optical detection unit 23-i outputs the generated electrical signal to the adaptive equalization unit 241-i of the digital signal processing unit 24-i.
  • the adaptive equalization unit 241 can be configured using, for example, an ASIC, an FPGA, etc.
  • the adaptive equalization unit 241-i compensates for polarization rotation and polarization mode dispersion of the electrical signal input from the optical detection unit 23-i, for example, using a blind equalization algorithm (CMA: Constant Modulus Algorithm).
  • CMA Constant Modulus Algorithm
  • the adaptive equalization unit 241-i outputs tap coefficient information generated when compensating for polarization rotation and polarization mode dispersion of the electrical signal input from the optical detection unit 23-i as signal light polarization control information to the information conversion unit 242-i.
  • the information conversion unit 242 can be configured using, for example, an ASIC, an FPGA, etc.
  • the information conversion unit 242-i generates Jones matrix information, which is local light polarization control information, by performing a Fourier transform on tap coefficient information, which is signal light polarization control information input from the adaptive equalization unit 241-i.
  • the Jones matrix information represents the polarization rotation and polarization mode dispersion that the light has undergone during transmission through the optical transmission path 30-m.
  • the information conversion unit 242-i outputs the local light polarization control information to the DAC unit 243-i.
  • the DAC unit 243-i converts the local light polarization control information generated by the information conversion unit 242-i into an analog signal.
  • the DAC unit 243-i outputs the local light polarization control information converted into an analog signal to the electrical signal amplifier 222-j of the polarization control unit 22-j that corresponds to the local light of wavelength ⁇ j that is multiplexed with the signal light of wavelength ⁇ i and transmitted.
  • the optical transmission paths 30-1 to 30-M can be configured, for example, using M separate SMFs (Single Mode Fibers). Alternatively, the optical transmission paths 30-1 to 30-M can be configured using a single MCF (Multi Core Fiber). Light input from the wavelength multiplexing unit 15-m of the optical transmitting device 10 is transmitted through the optical transmission path 30-m. The light transmitted through the optical transmission path 30-m is output to the wavelength separation unit 21-m of the optical receiving device 20.
  • MCF Multi Core Fiber
  • the optical transmission system 1 shown in FIG. 1 operates as follows.
  • the optical output unit 11-1 of the optical transmitter 10 generates light of a single wavelength ⁇ 1.
  • the branching unit 12-1 branches the light of wavelength ⁇ 1 output from the optical output unit 11-1 into two.
  • the branching unit 12-1 outputs one of the branched light beams of wavelength ⁇ 1 to the optical modulation unit 14-1.
  • the branching unit 12-1 outputs the other branched light beam of wavelength ⁇ 1 to the wavelength multiplexing unit 15-2 as local light.
  • the optical output unit 11-2 generates light of a single wavelength ⁇ 2.
  • the branching unit 12-2 branches the light of wavelength ⁇ 2 output from the optical output unit 11-2 into two.
  • the branching unit 12-2 outputs one of the branched light of wavelength ⁇ 2 to the optical modulation unit 14-2.
  • the branching unit 12-2 outputs the other branched light of wavelength ⁇ 2 to the wavelength multiplexing unit 15-1 as local light.
  • the optical modulation unit 14-1 generates polarization division multiplexed signal light by modulating light of wavelength ⁇ 1 using the electrical signal generated by the digital signal processing unit 13-1, and outputs the generated signal light to the wavelength multiplexing unit 15-1.
  • the wavelength multiplexing unit 15-1 combines the signal light of wavelength ⁇ 1 input from the optical modulation unit 14-1 with the local light of wavelength ⁇ 2 input from the optical output unit 11-2, and outputs the combined light to the optical transmission path 30-1.
  • the light input from the wavelength multiplexing unit 15-1 is output to the wavelength separation unit 21-1 of the optical receiving device 20 after transmitting through the optical transmission path 30-1.
  • the optical modulation unit 14-2 generates polarization division multiplexed signal light by modulating light of wavelength ⁇ 2 using the electrical signal generated by the digital signal processing unit 13-2, and outputs the generated signal light to the wavelength multiplexing unit 15-2.
  • the wavelength multiplexing unit 15-2 combines the signal light of wavelength ⁇ 2 input from the optical modulation unit 14-2 with the local light of wavelength ⁇ 1 input from the optical output unit 11-1, and outputs the combined light to the optical transmission path 30-2.
  • the light input from the wavelength multiplexing unit 15-2 is output to the wavelength separation unit 21-2 of the optical receiving device 20 after transmitting through the optical transmission path 30-2.
  • the wavelength separation unit 21-1 separates the light input from the optical transmission path 30-1 by wavelength.
  • the wavelength separation unit 21-1 outputs the separated signal light of wavelength ⁇ 1 to the optical detection unit 23-1, and outputs the separated local light of wavelength ⁇ 2 to the polarization control device unit 221-2.
  • the polarization control device unit 221-2 performs polarization control related to polarization rotation and polarization mode dispersion on the local light of wavelength ⁇ 2 input from the wavelength separation unit 21-1, using the local light polarization control information input from the electrical signal amplifier 222-2.
  • the polarization control device unit 221-2 outputs the local light of wavelength ⁇ 2 that has been subjected to polarization control to the optical detection unit 23-2.
  • the wavelength separation unit 21-2 separates the light input from the optical transmission path 30-2 by wavelength.
  • the wavelength separation unit 21-2 outputs the separated signal light of wavelength ⁇ 2 to the optical detection unit 23-2, and outputs the separated local light of wavelength ⁇ 1 to the polarization control device unit 221-1.
  • the polarization control device unit 221-1 performs polarization control related to polarization rotation and polarization mode dispersion on the local light of wavelength ⁇ 1 input from the wavelength separation unit 21-2, using the local light polarization control information input from the electrical signal amplifier 222-1.
  • the polarization control device unit 221-1 outputs the local light of wavelength ⁇ 1 that has been subjected to polarization control to the optical detection unit 23-1.
  • the polarization control device units 221-1 and 221-2 control the polarization without using the local light polarization control information obtained by converting the signal light polarization control information, and after the signal light polarization control information is generated, they control the polarization using the local light polarization control information obtained by converting the signal light polarization control information.
  • the optical detection unit 23-1 performs coherent detection on the signal light of wavelength ⁇ 1 input from the wavelength separation unit 21-1 using the local light of wavelength ⁇ 1 input from the polarization control device unit 221-1 to generate an electrical signal.
  • the optical detection unit 23-1 outputs the generated electrical signal to the adaptive equalization unit 241-1.
  • the adaptive equalization unit 241-1 compensates for polarization rotation and polarization mode dispersion for the electrical signal input from the optical detection unit 23-1.
  • the adaptive equalization unit 241-1 outputs tap coefficient information generated when compensating for polarization rotation and polarization mode dispersion to the information conversion unit 242-1 as signal light polarization control information.
  • the information conversion unit 242-1 generates local light polarization compensation information based on the signal light polarization control information input from the adaptive equalization unit 241-1.
  • the information conversion unit 242-1 outputs the generated local light polarization compensation information to the DAC unit 243-1.
  • the DAC unit 243-1 converts the local light polarization control information into an analog signal, and outputs the local light polarization control information in the analog signal to the electrical signal amplification unit 222-2.
  • the electrical signal amplifier 222-2 amplifies the local light polarization control information input from the DAC unit 243-1 and outputs the amplified local light polarization control information to the polarization control device unit 221-2.
  • the optical detection unit 23-2 performs coherent detection on the signal light of wavelength ⁇ 2 input from the wavelength separation unit 21-2 using the local light of wavelength ⁇ 2 input from the polarization control device unit 221-2 to generate an electrical signal.
  • the optical detection unit 23-2 outputs the generated electrical signal to the adaptive equalization unit 241-2.
  • the adaptive equalization unit 241-2 compensates for polarization rotation and polarization mode dispersion for the electrical signal input from the optical detection unit 23-2.
  • the adaptive equalization unit 241-2 outputs tap coefficient information generated when compensating for polarization rotation and polarization mode dispersion to the information conversion unit 242-2 as signal light polarization control information.
  • the information conversion unit 242-2 generates local light polarization compensation information based on the signal light polarization control information input from the adaptive equalization unit 241-2.
  • the information conversion unit 242-2 outputs the generated local light polarization compensation information to the DAC unit 243-2.
  • the DAC unit 243-2 converts the local light polarization control information into an analog signal, and outputs the local light polarization control information in the analog signal to the electrical signal amplification unit 222-1.
  • the electrical signal amplifier 222-1 amplifies the local light polarization control information input from the DAC unit 243-2 and outputs the amplified local light polarization control information to the polarization control device unit 221-1.
  • each wavelength multiplexer 15 When the optical transmitter 10 generates light with three or more wavelengths, each wavelength multiplexer 15 performs wavelength division multiplexing so that the signal light and local light each have at least one different wavelength, and outputs the multiplexed light to the optical transmission path 30.
  • the optical receiver 20 also includes polarization controllers 22 for the number of wavelengths N, optical detectors 23, and digital signal processors 24.
  • the local light output from the optical transmission path 30 is polarization-controlled by the polarization controllers 22 corresponding to the wavelength of the local light in the optical receiver 20.
  • the signal light and local light are coherently detected by the optical detectors 23 for each wavelength, and the electrical signal obtained by the coherent detection is output to the digital signal processors 24 corresponding to the wavelength.
  • the digital signal processors 24 generate local light polarization control information based on the input electrical signal.
  • the polarization controllers 22 use at least one of the local light polarization control information generated by the signal light that has passed through the same optical transmission path 30 as the local light to be polarized, to control the polarization of the local light.
  • a specific example is shown below.
  • the optical output unit 11-3 of the optical transmitter 10 generates light of a single wavelength ⁇ 3.
  • the branching unit 12-3 branches the light of wavelength ⁇ 3 output from the optical output unit 11-3 into two.
  • the branching unit 12-3 outputs one of the branched lights of wavelength ⁇ 3 to the optical modulation unit 14-3, and outputs the other light as local light to the wavelength multiplexing unit 15-1.
  • the optical modulation unit 14-3 generates polarization division multiplexed signal light by modulating the light of wavelength ⁇ 3 using an electrical signal generated by the digital signal processing unit 13-3, and outputs the generated signal light to the wavelength multiplexing unit 15-2.
  • the wavelength multiplexing unit 15-1 multiplexes the signal light of wavelength ⁇ 1 input from the optical modulation unit 14-1, the local light of wavelength ⁇ 2 input from the optical output unit 11-2, and the local light of wavelength ⁇ 3 input from the optical output unit 11-3, and outputs the multiplexed light to the optical transmission path 30-1.
  • the wavelength multiplexing unit 15-2 multiplexes the local light with wavelength ⁇ 1 input from the optical output unit 11-1, the signal light with wavelength ⁇ 2 input from the optical modulation unit 14-2, and the signal light with wavelength ⁇ 3 input from the optical modulation unit 14-3, and outputs the multiplexed light to the optical transmission path 30-2.
  • the wavelength separation unit 21-1 of the optical receiving device 20 separates the light input from the optical transmission path 30-1 by wavelength.
  • the wavelength separation unit 21-1 outputs the signal light of wavelength ⁇ 1 to the optical detection unit 23-1, outputs the local light of wavelength ⁇ 2 to the polarization control unit 22-2, and outputs the local light of wavelength ⁇ 3 to the polarization control unit 22-3.
  • the wavelength separation unit 21-2 separates the light input from the optical transmission path 30-2 by wavelength.
  • the wavelength separation unit 21-2 outputs the signal light of wavelength ⁇ 2 to the optical detection unit 23-2, outputs the signal light of wavelength ⁇ 3 to the optical detection unit 23-3, and outputs the local light of wavelength ⁇ 1 to the polarization control unit 22-1.
  • the polarization control device unit 221-3 of the polarization control unit 22-3 performs polarization control related to polarization rotation and polarization mode dispersion on the local light of wavelength ⁇ 3 input from the wavelength separation unit 21-1, using the local light polarization control information input from the electrical signal amplifier unit 222-3.
  • the polarization control device unit 221-3 outputs the polarization-controlled local light of wavelength ⁇ 3 to the optical detection unit 23-3.
  • the optical detection unit 23-3 performs coherent detection on the signal light of wavelength ⁇ 3 input from the wavelength separation unit 21-2, using the local light of wavelength ⁇ 3 input from the polarization control device unit 221-3, to generate an electrical signal.
  • the optical detection unit 23-3 outputs the generated electrical signal to the digital signal processing unit 24-3.
  • the digital signal processing unit 24-3 outputs the local light polarization control information generated using the electrical signal input from the optical detection unit 23-3 to the polarization control unit 22-1.
  • the electrical signal amplifier 222-1 of the polarization control unit 22-1 amplifies at least one of the local light polarization control information input from the digital signal processing unit 24-2 and the local light polarization control information input from the digital signal processing unit 24-3, and outputs it to the polarization control device unit 221-1.
  • the digital signal processing unit 24-1 outputs the local light polarization control information generated using the electrical signal input from the optical detection unit 23-1 to the polarization control unit 22-2 and the polarization control unit 22-3.
  • the electrical signal amplifier 222-3 of the polarization control unit 22-3 amplifies the local light polarization control information input from the digital signal processing unit 24-1 and outputs it to the polarization control device unit 221-3.
  • the wavelength multiplexing unit 15-1 of the optical transmitter 10 multiplexes the signal light of wavelength ⁇ 1 and the local light of wavelength ⁇ 3 and outputs the result to the optical transmission path 30-1, the wavelength multiplexing unit 15-2 multiplexes the signal light of wavelength ⁇ 2 and the local light of wavelength ⁇ 1 and outputs the result to the optical transmission path 30-2, and the wavelength multiplexing unit 15-3 (not shown) multiplexes the signal light of wavelength ⁇ 3 and the local light of wavelength ⁇ 2 and outputs the result to the optical transmission path 30-3 (not shown).
  • the wavelength separation unit 21-1 of the optical receiver 20 separates the light input from the optical transmission path 30-1, outputs the signal light of wavelength ⁇ 1 to the optical detection unit 23-1, and outputs the local light of wavelength ⁇ 3 to the polarization control unit 22-3.
  • the wavelength separation unit 21-2 separates the light input from the optical transmission line 30-2, outputs the signal light of wavelength ⁇ 2 to the optical detection unit 23-2, and outputs the local light of wavelength ⁇ 1 to the polarization control unit 22-1.
  • the wavelength separation unit 21-3 (not shown) separates the light input from the optical transmission line 30-3 (not shown), outputs the signal light of wavelength ⁇ 3 to the optical detection unit 23-3, and outputs the local light of wavelength ⁇ 2 to the polarization control unit 22-2.
  • the digital signal processing unit 24-1 outputs the local light polarization control information generated using the electrical signal input from the optical detection unit 23-1 to the polarization control unit 22-3.
  • the digital signal processing unit 24-2 outputs the local light polarization control information generated using the electrical signal input from the optical detection unit 23-2 to the polarization control unit 22-1.
  • the digital signal processing unit 24-3 outputs the local light polarization control information generated using the electrical signal input from the optical detection unit 23-3 to the polarization control unit 22-1.
  • the optical transmission system 1 of the first embodiment performs polarization control of local light by utilizing the signal light polarization control information output from the adaptive equalization unit 241 in optical communication in a self-homodyne system using wavelength division multiplexing and polarization division multiplexing. This makes it possible to eliminate the photoelectric conversion unit and ADC unit that were previously required for polarization control.
  • Fig. 3 is a block diagram showing the configuration of an optical transmission system 2 according to the second embodiment.
  • the optical transmission system 2 includes an optical transmitting device 40 and an optical receiving device 50.
  • the optical transmitting device 40 may be the conventional optical transmitting device shown in Fig. 6.
  • the optical transmitting device 40 and the optical receiving device 50 are connected by optical transmission paths 30-1 and 30-2.
  • the optical transmitter 40 includes an optical output unit 11, a branching unit 12, a digital signal processing unit 13, and an optical modulation unit 14.
  • the optical output unit 11 generates light of a single wavelength ⁇ 1.
  • the branching unit 12 branches the light generated by the optical output unit 11 into two, outputs one of the branched lights to the optical modulation unit 14, and outputs the other light to the optical transmission line 30-2 as local light.
  • the digital signal processing unit 13 outputs the generated electrical signal to the optical modulation unit 14.
  • the optical modulation unit 14 receives the light of wavelength ⁇ 1 output by the optical output unit 11 and branched by the branching unit 12.
  • the optical modulation unit 14 generates polarization division multiplexed signal light with a power ratio of x polarization and y polarization of 1:1 by modulating the light of wavelength ⁇ 1 using the electrical signal input from the digital signal processing unit 13.
  • the optical modulation unit 14 outputs the polarization division multiplexed signal light of wavelength ⁇ 1 to the optical transmission line 30-1.
  • the optical receiving device 50 includes a polarization control unit 22, an optical detection unit 53, and a digital signal processing unit 54.
  • the polarization control unit 22 receives the local light output from the optical transmission path 30-2.
  • the polarization control device unit 221 of the polarization control unit 22 uses the local light polarization control information to perform polarization control of the local light input from the optical transmission path 30-2.
  • the polarization control of the local light in the polarization control device unit 221 may be, for example, control so that the power ratio of x polarization and y polarization becomes 1:1, or control so that the direction of polarization becomes a single direction such as x polarization or y polarization, and control so that the power ratio of x polarization and y polarization of the local light in the optical detection unit 53 becomes 1:1.
  • the polarization control device unit 221 outputs the polarization-controlled local light to the optical detection unit 53.
  • the optical detection unit 53 uses the local light of wavelength ⁇ 1 input from the polarization control device unit 221 to perform homodyne detection of the signal light of wavelength ⁇ 1 input from the optical transmission line 30-1, and converts the signal light into an electrical signal.
  • the optical detection unit 53 inputs electrical signal output power information to the digital signal processing unit 54.
  • the electrical signal output power information is information indicating the output power of the x-polarized and y-polarized electrical signals output after homodyne detection.
  • the signal light is a polarization multiplexed signal, and the power ratio of the x-polarized and y-polarized waves of the signal light is output at 1:1 on the transmitting side, so the power ratio of the x-polarized and y-polarized waves of the received signal light is also ideally 1:1. Therefore, the difference between the output power of the x-polarized waves and the output power of the y-polarized waves indicated by the electrical signal output power information is equivalent to the difference between the output power of the x-polarized waves and the power of the y-polarized waves of the local light.
  • the digital signal processing unit 54 includes an ADC unit 541, an information conversion unit 542, and a DAC unit 543.
  • the ADC unit 541 converts the electrical signal output power information input from the optical detection unit 53 from an analog signal to a digital signal, and outputs the converted electrical signal output power information to the information conversion unit 542.
  • the information conversion unit 542 can be configured using, for example, an ASIC, an FPGA, or the like.
  • the information conversion unit 542 generates local light polarization control information using, for example, the steepest descent method for the electrical signal output power information input from the ADC unit 541.
  • the information conversion unit 542 outputs the generated local light polarization control information to the DAC unit 543.
  • the DAC unit 543 converts the local light polarization control information input from the information conversion unit 542 from a digital signal to an analog signal, and outputs the converted local light polarization control information to the polarization control unit 22.
  • the electrical signal amplifier unit 222 of the polarization control unit 22 amplifies the local light polarization control information input from the DAC unit 543 and outputs it to the polarization control device unit 221.
  • the optical transmitting device may generate light with two or more wavelengths.
  • the optical transmitting device further includes the wavelength multiplexing unit 15 of the first embodiment.
  • the wavelength multiplexing unit 15 wavelength-division multiplexes the signal light and the local light of different wavelengths and outputs the signal light and the local light to the optical transmission path 30.
  • the optical transmitting device further includes the wavelength separation unit 21 of the first embodiment.
  • the optical receiving device further includes a polarization control unit 22, an optical detection unit 53, and a digital signal processing unit 54, each of which corresponds to the number of wavelengths.
  • the wavelength separation unit 21 separates the signal light and the local light.
  • the local light output from the optical transmission path 30 is polarization-controlled by the polarization control unit 22 according to the wavelength.
  • the signal light and the local light are coherently detected by the optical detection unit 53 for each wavelength.
  • the optical detection unit 53 outputs electrical signal output power information obtained as a result of the coherent detection to the digital signal processing unit 54.
  • the digital signal processing unit 54 generates local light polarization control information for each wavelength.
  • the polarization control unit 22 performs polarization control using signal light having the same wavelength as the local light to be controlled and the electrical signal output power generated based on the local light. A specific example is shown below.
  • FIG. 4 is a block diagram showing an example configuration of an optical transmission system 2a that generates light with a number of wavelengths N (N is an integer equal to or greater than 2).
  • N is an integer equal to or greater than 2.
  • the optical transmission system 2a includes an optical transmitter 40a and an optical receiver 50a.
  • the optical transmitter 40a and the optical receiver 50a are connected by optical transmission paths 30-1 and 30-2.
  • the N optical detection units 53 are described as optical detection units 53-1 to 53-N, respectively, and the N digital signal processing units 54 are described as digital signal processing units 54-1 to 54-N, respectively.
  • the ADC unit 541, information conversion unit 542, and DAC unit 543 included in the digital signal processing unit 54-i (i is an integer between 1 and N) are described as ADC unit 541-i, information conversion unit 542-i, and DAC unit 543-i, respectively.
  • the optical transmitting device 40a operates in the same manner as the optical transmitting device 10 of the first embodiment shown in FIG. 1.
  • the wavelength separation unit 21-1 of the optical receiving device 50a separates the light input from the optical transmission path 30-1 by wavelength.
  • the wavelength separation unit 21-1 outputs the signal light of wavelength ⁇ 1 to the optical detection unit 53-1, and outputs the local light of wavelength ⁇ 2 to the polarization control device unit 221-2.
  • the polarization control device unit 221-2 performs polarization control on the local light of wavelength ⁇ 2 using the local light polarization control information input from the electrical signal amplifier unit 222-2.
  • the polarization control device unit 221-2 outputs the polarization-controlled local light of wavelength ⁇ 2 to the optical detection unit 53-2.
  • the wavelength separation unit 21-2 separates the light input from the optical transmission path 30-2 by wavelength.
  • the wavelength separation unit 21-2 outputs the signal light of wavelength ⁇ 2 to the optical detection unit 53-2, and outputs the local light of wavelength ⁇ 1 to the polarization control device unit 221-1.
  • the polarization control device unit 221-1 performs polarization control on the local light of wavelength ⁇ 1 using the local light polarization control information input from the electrical signal amplifier 222-1.
  • the polarization control device unit 221-1 outputs the polarization-controlled local light of wavelength ⁇ 1 to the optical detection unit 53-1.
  • the optical detection unit 53-1 performs coherent detection on the signal light of wavelength ⁇ 1 input from the wavelength separation unit 21-1 using the local light of ⁇ 1 input from the polarization control device unit 221-1 to generate an electrical signal.
  • the optical detection unit 53-1 outputs electrical signal output power information to the digital signal processing unit 54-1.
  • the digital signal processing unit 54-1 outputs local light polarization control information generated using the electrical signal output power information input from the optical detection unit 53-1 to the electrical signal amplification unit 222-1 of the polarization control unit 22-1.
  • the optical detection unit 53-2 performs coherent detection on the signal light of wavelength ⁇ 2 input from the wavelength separation unit 21-2 using the local light of ⁇ 2 input from the polarization control device unit 221-2 to generate an electrical signal.
  • the optical detection unit 53-2 outputs electrical signal output power information to the digital signal processing unit 54-2.
  • the digital signal processing unit 54-2 outputs local light polarization control information generated using the electrical signal output power information input from the optical detection unit 53-2 to the electrical signal amplification unit 222-2 of the polarization control unit 22-2.
  • the optical transmission system 2, 2a of the second embodiment performs polarization control of the local light using electrical signal output power information of the x-polarized and y-polarized waves output after self-homodyne detection of the signal light and the local light in optical communication in a self-homodyne system using polarization division multiplexing. This makes it possible to eliminate the photoelectric conversion unit that was previously required for polarization control of the local light.
  • the optical transmission system of the third embodiment uses a self-homodyne optical communication method that utilizes wavelength division multiplexing and polarization division multiplexing.
  • the optical transmission system of the third embodiment is configured such that the optical receiving device has the functions of the digital signal processing unit of the first embodiment and the functions of the digital signal processing unit of the second embodiment.
  • FIG. 5 is a block diagram showing the configuration of an optical transmission system 3 according to the third embodiment. Thin dashed arrows and thin dashed-dotted arrows indicate paths of electrical control signals.
  • the optical transmission system 3 shown in FIG. 5 differs from the optical transmission system 1 of the first embodiment shown in FIG. 1 in that it includes an optical receiving device 60 instead of the optical receiving device 20.
  • the optical receiving device 60 differs from the optical receiving device 20 of the first embodiment shown in FIG. 1 in that it has N optical detection units 63 instead of the N (N is an integer equal to or greater than 2) optical detection units 23, and that it has N digital signal processing units 64 instead of the N digital signal processing units 24.
  • the N optical detection units 63 are respectively referred to as optical detection units 63-1 to 63-N
  • the N digital signal processing units 64 are respectively referred to as digital signal processing units 64-1 to 64-N.
  • the optical detection unit 63-i (i is an integer between 1 and N) performs coherent detection of the signal light of wavelength ⁇ i using the local light of wavelength ⁇ i output from the polarization control device unit 221-i of the polarization control unit 22-i, and converts the signal light into an electrical signal.
  • the optical detection unit 63-i outputs the generated electrical signal and electrical signal output power information, which is information on the output power of the x polarization and y polarization of the generated electrical signal, to the digital signal processing unit 64-i.
  • the digital signal processing unit 64 includes an adaptive equalization unit 241, an information conversion unit 242, an ADC unit 541, an information conversion unit 542, and a DAC unit 641.
  • the adaptive equalization unit 241, information conversion unit 242, ADC unit 541, information conversion unit 542, and DAC unit 641 included in the digital signal processing unit 64-i are respectively referred to as the adaptive equalization unit 241-i, the information conversion unit 242-i, the ADC unit 541-i, the information conversion unit 542-i, and the DAC unit 243-i.
  • the adaptive equalization unit 241-i and the information conversion unit 242-i of the digital signal processing unit 64-i perform the same processing as in the first embodiment.
  • the information conversion unit 242-i outputs the generated local light polarization control information to the DAC unit 641-i.
  • the DAC unit 641-i converts the local light polarization control information input from the information conversion unit 242-i from a digital signal to an analog signal.
  • the DAC unit 641-i outputs the local light polarization control information converted into an analog signal to the electrical signal amplifier 222-j of the polarization control unit 22-j corresponding to the local light of wavelength ⁇ j (j is an integer between 1 and N, and i ⁇ j) that was multiplexed with the signal light of wavelength ⁇ i and transmitted.
  • the ADC unit 541-i and the information conversion unit 542-i of the digital signal processing unit 64-i perform the same processing as in the second embodiment.
  • the information conversion unit 542-i outputs the generated local light polarization control information to the DAC unit 641-i.
  • the DAC unit 641-i converts the local light polarization control information input from the information conversion unit 542-i from a digital signal to an analog signal.
  • the DAC unit 641-i outputs the local light polarization control information converted into an analog signal to the electrical signal amplifier unit 222-i of the polarization control unit 22-i.
  • the electrical signal amplifier 222-i of the polarization control unit 22-i amplifies either the local light polarization control information input from the digital signal processing unit 64-i or the local light polarization control information input from the digital signal processing unit 64-j, and outputs the amplified information to the polarization control device unit 221-i.
  • the polarization control unit 22 may control the polarization of a local light of a different wavelength that is transmitted by wavelength division multiplexing on the same optical transmission path 30 as the signal light, using local light polarization control information obtained by converting the signal light polarization control information output by the adaptive equalization unit 241 using the information conversion unit 242.
  • the polarization control unit 22 may control the polarization of a local light that is input from an optical transmission path 30 different from the signal light and has the same wavelength as the signal light, using local light polarization control information obtained by converting the electrical signal output power information output by the optical detection unit 63 using the information conversion unit 542.
  • the optical transmission system 3 of the third embodiment converts the signal light polarization control information of the adaptive equalizer 241 into local light polarization control information to perform polarization control of the local light, or converts the electrical signal output power information of the x polarization and y polarization output after self-homodyne detection of the signal light and local light into local light polarization control information to perform polarization control of the local light.
  • This makes it possible to eliminate the photoelectric conversion unit that was previously necessary for polarization control of the local light.
  • At least some of the functions of the digital signal processing units 24, 54, 64 provided in the optical receiving device of the above-mentioned embodiment may be realized by a computer.
  • a program for realizing the functions of the digital signal processing units 24, 54, 64 may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed to realize the functions.
  • the computer system includes, for example, hardware such as a processor, an OS, and peripheral devices.
  • the program of the signal processing device may be recorded on a computer-readable recording medium.
  • the computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or a storage device such as a hard disk built into a computer system.
  • the program of the signal processing device may be transmitted via a telecommunications line.
  • the optical receiving device can reduce the functional blocks for controlling the polarization of the local light transmitted from the optical transmitting device, and perform efficient polarization control.
  • the optical transmission system has an optical transmitting device and an optical receiving device.
  • the optical transmitting device includes an optical output unit, a branching unit, and an optical modulation unit.
  • the optical output unit outputs light of a single wavelength.
  • the branching unit branches the light output by the optical output unit into light for signal generation and local light.
  • the optical modulation unit modulates the light for signal generation into polarization-multiplexed signal light.
  • the optical receiving device includes an optical detection unit, a signal processing unit, and a polarization control unit.
  • the optical detection unit coherently detects the signal light transmitted through the optical transmission line by the local light transmitted through an optical transmission line different from the optical transmission line through which the signal light was transmitted.
  • the signal processing unit generates local light polarization control information for compensating for fluctuations in the polarization of the local light during transmission based on the signal obtained by the coherent detection.
  • the polarization control unit performs polarization control of the local light used by the optical detection unit for coherent detection based on the local light polarization control information.
  • the optical output unit may output light of different wavelengths generated by each of the multiple lasers.
  • the branching unit branches the light of each of the multiple wavelengths output by the optical output unit into light for signal generation and local light.
  • the optical modulation unit modulates the light for signal generation of each of the multiple wavelengths into polarization multiplexed signal light.
  • the optical transmitting device further includes a wavelength multiplexing unit.
  • the wavelength multiplexing unit generates light by multiplexing at least one signal light and local light of a wavelength different from that of the signal light, and transmits each of the generated multiple lights to the optical receiving device via different optical transmission paths.
  • the optical receiving device further includes a wavelength separation unit. The wavelength separation unit separates the light transmitted through each of the different optical transmission paths into signal light and local light according to wavelength.
  • the optical detection unit coherently detects the signal light using local light of the same wavelength as the signal light.
  • the signal processing unit performs one or both of the following processes: compensates for the polarization rotation and polarization mode dispersion of the signal obtained by coherent detection, and generates local light polarization control information for the local light that is multiplexed with the signal light used in coherent detection and transmitted based on the compensation performed on the signal, and generates local light polarization control information for the local light with the same wavelength as the signal light used in coherent detection based on information on the electrical signal output power of the two different polarizations obtained by coherent detection.
  • the signal processing unit may generate local light polarization control information for compensating for the polarization rotation and polarization mode dispersion of the signal light based on information on the electrical signal output power of two different polarizations obtained by coherent detection.
  • the signal processing unit may generate, as local light polarization control information, Jones matrix information obtained by Fourier transforming tap coefficient information generated when compensating for polarization rotation and polarization mode dispersion in a signal obtained by coherent detection.
  • the signal processing unit may generate local light polarization control information by applying the steepest descent method to information on the electrical signal output power of two different polarizations obtained by coherent detection.
  • Optical transmission system 10 Optical transmitter 11, 11-1 to 11-3 Optical output section 12, 12-1 to 12-3 Branching section 13, 13-1 to 13-3 Digital signal processing section 14, 14-1 to 14-3 Optical modulation section 15, 15-1, 15-2 Wavelength multiplexing section 20 Optical receiver 21-1, 21-2 Wavelength demultiplexing section 22, 22-1 to 22-3 Polarization control section 23-1 to 23-3 Optical detection section 24-1 to 24-3 Digital signal processing section 30-1, 30-2 Optical transmission path 40, 40a Optical transmitter 50, 50a Optical receiver 53, 53-1, 53-2 Optical detection section 54, 54-1, 54-2 Digital signal processing section 60 Optical receiver 63-1, 63-2 Optical detection units 64-1, 64-2 Digital signal processing units 221, 221-1 to 221-3 Polarization control device units 222, 222-1 to 222-3 Electric signal amplification units 241-1 to 241-3 Adaptive equalization units 242-1 to 242-3 Information conversion units 243-1 to 243-3 DAC units 541, 541-1, 54

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Abstract

Un dispositif de transmission de lumière selon la présente invention comprend des unités de sortie de lumière, des parties de ramification et des parties de modulation de lumière. Les unités de sortie de lumière émettent une lumière possédant une seule longueur d'onde. Les parties de ramification ramifient la lumière émise en lumière pour la génération de signal et en lumière émise localement. Les parties de modulation de lumière modulent la lumière pour la génération de signal en une lumière de signal qui a été polarisée et multiplexée. Un dispositif de réception de lumière selon la présente invention comprend des unités de détection de lumière, des unités de traitement de signal et des unités de commande de polarisation. Les unités de détection de lumière détectent chacune de manière cohérente la lumière de signal transmise à travers un trajet de transmission de lumière en utilisant la lumière émise localement transmise par une voie de transmission de lumière qui diffère du trajet de transmission de lumière à travers lequel la lumière de signal a été transmise. Sur la base des signaux obtenus par la détection cohérente, les unités de traitement de signal génèrent des informations de commande de polarisation de lumière émise localement pour compenser des variations de polarisation de lumière émise localement pendant la transmission. Les unités de commande de polarisation utilisent les informations de commande de polarisation de lumière émise localement pour commander la polarisation de la lumière émise localement utilisée par les unités de détection de lumière respectives dans la détection cohérente.
PCT/JP2022/040607 2022-10-31 2022-10-31 Système de transmission de lumière, dispositif de réception de lumière et procédé de transmission de lumière WO2024095306A1 (fr)

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JP2011160146A (ja) * 2010-01-29 2011-08-18 Fujitsu Ltd コヒーレント光通信装置及びコヒーレント光通信方法
JP2015070360A (ja) * 2013-09-27 2015-04-13 沖電気工業株式会社 受信器、局側端末、加入者側端末、光ネットワーク、及びコヒーレント通信方法
JP2018042104A (ja) * 2016-09-07 2018-03-15 富士通株式会社 光通信システム
US20220345224A1 (en) * 2019-12-31 2022-10-27 Huawei Technologies Co., Ltd. Coherent Optical Receiving Apparatus and Optical System that Uses Coherent Optical Receiving Apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011160146A (ja) * 2010-01-29 2011-08-18 Fujitsu Ltd コヒーレント光通信装置及びコヒーレント光通信方法
JP2015070360A (ja) * 2013-09-27 2015-04-13 沖電気工業株式会社 受信器、局側端末、加入者側端末、光ネットワーク、及びコヒーレント通信方法
JP2018042104A (ja) * 2016-09-07 2018-03-15 富士通株式会社 光通信システム
US20220345224A1 (en) * 2019-12-31 2022-10-27 Huawei Technologies Co., Ltd. Coherent Optical Receiving Apparatus and Optical System that Uses Coherent Optical Receiving Apparatus

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