WO2020073766A1 - 一种多波长激光器 - Google Patents

一种多波长激光器 Download PDF

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WO2020073766A1
WO2020073766A1 PCT/CN2019/105301 CN2019105301W WO2020073766A1 WO 2020073766 A1 WO2020073766 A1 WO 2020073766A1 CN 2019105301 W CN2019105301 W CN 2019105301W WO 2020073766 A1 WO2020073766 A1 WO 2020073766A1
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frequency
signal
laser
wavelength
slave
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PCT/CN2019/105301
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English (en)
French (fr)
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赵家霖
桂成程
付生猛
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华为技术有限公司
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Priority to EP19870386.0A priority Critical patent/EP3855646A4/en
Publication of WO2020073766A1 publication Critical patent/WO2020073766A1/zh
Priority to US17/226,977 priority patent/US12040593B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1092—Multi-wavelength lasing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/10053—Phase control
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
    • H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar
    • H01S5/4087—Array arrangements, e.g. constituted by discrete laser diodes or laser bar emitting more than one wavelength
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/02—Structural details or components not essential to laser action
    • H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/068—Stabilisation of laser output parameters
    • H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
    • H01S5/0687—Stabilising the frequency of the laser
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/503—Laser transmitters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/506—Multiwavelength transmitters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/50—Transmitters
    • H04B10/572—Wavelength control
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
    • H01S3/1304—Stabilisation of laser output parameters, e.g. frequency or amplitude by using an active reference, e.g. second laser, klystron or other standard frequency source
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
    • H01S3/139—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
    • H01S3/1398—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length by using a supplementary modulation of the output
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/005—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping
    • H01S5/0085—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping for modulating the output, i.e. the laser beam is modulated outside the laser cavity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
    • H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-section lasers
    • H01S5/06255—Controlling the frequency of the radiation
    • H01S5/06256—Controlling the frequency of the radiation with DBR-structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/14—External cavity lasers
    • H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon

Definitions

  • This application relates to the technical field of optical fiber communication, and in particular to a multi-wavelength tunable laser.
  • the wavelength-tunable laser is one of the very important optoelectronic devices in the optical fiber communication system. It can be used as both a light source at the transmitting end and a local oscillator laser at the coherent receiving end.
  • the single-wavelength transmission capacity can be increased to 100Gbit / s, 200Gbit / s, or even 400Gbit / s and higher.
  • the increase in baud rate and modulation order will limit the performance of single-wave large-capacity transmission, resulting in a reduction in transmission distance.
  • Multi-channel parallel transmission can reduce the single-wave rate and increase the transmission distance on the premise of increasing the transmission capacity. Therefore, in order to achieve ultra-large capacity long-distance transmission exceeding 400Gbit / s, multi-channel parallel transmission is a key technology.
  • single-wavelength tunable lasers need to have high output power, narrow linewidth, high side mode suppression ratio (Side mode suppression ratio, SMSR), high optical signal-to-noise ratio (Optical Signal Nosie Ratio, OSNR) and other characteristics .
  • the ultra-large capacity coherent multi-channel parallel transmission system requires a multi-wavelength light source, and the performance of the multi-wavelength light source needs to have precise frequency intervals and adjustable frequency intervals in addition to being consistent with a single wavelength.
  • the frequency interval of the multi-wavelength light source output can be set to 37.5 GHz, 50 GHz, and 75 GHz.
  • the frequency interval is optional and the interval can be fine-tuned within a certain frequency range.
  • FIG. 1 An existing multi-wavelength light source technology is shown in FIG. 1, which is achieved by integrating multiple tunable laser arrays on a single chip, and then using a common wave lock device to achieve frequency locking of each tunable laser.
  • the problem of low offset accuracy can only achieve frequency offset accuracy of less than 100MHz, so it cannot be applied in scenarios where higher frequency offset accuracy is required.
  • the purpose of the present application is to provide a multi-wavelength laser, which solves the problems of low frequency deviation accuracy of existing multi-wavelength light sources and limited application scenarios.
  • a multi-wavelength laser including: N wavelength-tunable lasers, N beam splitters, phase modulators, and N-1 frequency difference detection devices, where N is a positive integer not less than 2;
  • a first wavelength tunable laser configured to generate a first laser signal, and send the first laser signal to a first beam splitter among the N beam splitters, wherein the N wavelength tunable lasers include The first wavelength tunable laser;
  • the first beam splitter configured to split the first laser signal into at least two beams, and send the first beam of the first laser signal to the phase modulator, wherein, the first The two beams of the first laser signal are one output of the multi-wavelength laser;
  • the phase modulator is used to modulate the first beam of the first laser to generate a multi-wavelength optical signal and send the multi-wavelength optical signal
  • the N-1 frequency difference detection devices include a first frequency difference detection device, the frequency interval of adjacent wavelengths in the multi-wavelength optical signal is the same;
  • the frequency interval of multiple wavelength-tunable lasers can be calibrated to reduce the error of the frequency interval.
  • the multi-wavelength laser further includes: a power divider; and the phase modulator is used to convert the Multi-wavelength optical signals are sent to the power splitter; the power splitter divides the multi-wavelength optical signals into at least N-1 multi-wavelength optical signals, and sends the first multi-wavelength optical signals to the first Frequency difference detection device, sending the second multi-wavelength optical signal to the second frequency difference detection device, wherein the N-1 frequency difference detection device includes a second frequency difference detection device; a third wavelength tunable laser, used Generating a third laser signal, and sending the third laser signal to a third beam splitter among the N beam splitters, wherein the N wavelength tunable lasers include the third wavelength tunable laser
  • the third beam splitter is used to split the third laser signal into at least two beams and send the first beam of the third laser signal to the second frequency difference detection device, wherein the second beam of third laser The signal is one
  • the multi-wavelength laser further includes a radio frequency signal source, and the radio frequency signal source is used for Generating a radio frequency signal and sending it to the phase modulator; the modulator is used to modulate the first laser beam according to the radio frequency signal to generate a multi-wavelength optical signal, wherein the multi-wavelength light
  • the interval of adjacent wavelengths in the signal is related to the frequency of the radio frequency signal.
  • the frequency interval of the generated multi-wavelength optical signal can be adjusted by adjusting the frequency of the radio frequency signal.
  • the target frequency of the slave wavelength tunable laser and the multi-wavelength optical signal Where the frequency difference between the corresponding subcarriers is less than the frequency difference between the target frequency and other subcarriers in the multi-wavelength optical signal, then the frequency difference between the initial frequency of the slave wavelength tunable laser and the corresponding subcarriers is less than the The difference between the initial frequency of the slave wavelength tunable laser and the frequency of the other subcarriers, wherein the slave wavelength tunable laser is any one of the N wavelength tunable lasers except the first wavelength tunable laser.
  • This embodiment discloses the condition that the initial frequency of the slave wavelength tunable laser must meet, which is beneficial to the frequency adjustment of the multi-wavelength laser.
  • a fourth possible implementation manner of the first aspect if the target frequency of the slave wavelength tunable laser is greater than the frequency of the corresponding subcarrier, then the The initial frequency set by the slave wavelength tunable laser is greater than the frequency of the corresponding subcarrier; if the target frequency of the slave wavelength tunable laser is less than the frequency of the corresponding subcarrier, the initial frequency set by the slave wavelength tunable laser Less than the frequency of the corresponding subcarrier.
  • a fifth possible implementation manner of the first aspect if the target frequency of the dependent wavelength tunable laser is greater than the frequency of the corresponding subcarrier, then The frequency obtained by subtracting the maximum frequency error value of the slave wavelength tunable laser from the initial frequency set by the slave wavelength tunable laser is greater than the frequency of the corresponding subcarrier; if the target frequency of the slave wavelength tunable laser is less than the corresponding For the frequency of the subcarrier, the frequency obtained by adding the initial frequency set by the slave wavelength tunable laser and the maximum frequency error value of the slave wavelength tunable laser is smaller than the frequency of the corresponding subcarrier.
  • the initial frequency difference set by the subordinate wavelength tunable laser is further limited, which can avoid that the frequency difference detection device can only obtain the initial frequency and the corresponding subcarrier frequency in the multi-wavelength optical signal The difference between them, the size between the two cannot be sensed, resulting in the problem of adjusting to the wrong frequency.
  • the frequency difference detection device includes a coupler, Photodetector, low-pass filter, frequency detector and signal source; the coupler is used to receive the multi-wavelength optical signal and laser signal, interfering with the multi-wavelength optical signal and laser signal, The optical signal is sent to the photodetector; the photodetector is used to photoelectrically convert the interfering optical signal and send the converted interference signal to the filter; the low-pass filter For low-pass filtering the converted interference signal and sending the filtered interference signal to the frequency detector; the signal source is used to generate a reference signal and send the reference signal to the A frequency detector; the frequency detector is configured to detect a frequency difference between the filtered interference signal and the reference signal, obtain a control signal, and send the control signal.
  • the frequency detector includes a phase-locked loop circuit, a loop filter, and a controller; the phase-locked A loop circuit for acquiring the reference signal, detecting the frequency difference between the filtered interference signal and the reference signal, obtaining the frequency difference signal, and sending the frequency difference signal to the loop filter
  • the loop filter is used to perform loop gain and filtering on the frequency difference signal and then sent to the controller; the controller is used to generate the control signal based on the received signal, Send the control signal.
  • the above two embodiments provide a configuration method of a frequency difference detection device.
  • the frequency of the reference signal is set in advance, and the frequency of the filtered interference signal is adjusted to be the same as the frequency of the reference signal, thereby adjusting the multi-wavelength laser The purpose of the frequency interval.
  • the frequency detector further includes a first frequency divider and a second frequency divider; the first A frequency divider, configured to receive the filtered interference signal, divide the filtered interference signal to obtain a low-frequency interference signal, and send the low-frequency interference signal to the phase-locked loop circuit; A second frequency divider for receiving the reference signal, performing frequency division processing on the reference signal to obtain a low frequency reference signal, and sending the low frequency reference signal to the phase locked loop circuit; the phase locked loop circuit For detecting the frequency difference between the low-frequency interference signal and the low-frequency reference signal, obtaining the frequency difference signal, and sending the frequency difference signal to the loop filter.
  • the embodiment of the present application uses two frequency dividers to respectively reduce the frequency of the filtered interference signal and the reference signal, which can reduce the bandwidth requirement of the phase-locked loop circuit and is easier to implement.
  • the frequency detector includes a phase / frequency detector (PFD), a low-pass filter, a subtractor, Loop filter and controller;
  • PFD phase / frequency detector
  • the low-pass filter Is used to perform low-pass filtering on the received signal and send the filtered signal to the subtractor;
  • the subtractor is used to subtract the preset voltage reference signal from the filtered signal to obtain Frequency difference signal, the frequency difference signal is sent to the loop filter;
  • the loop filter is used for loop gain and filtering of the frequency difference signal, and then sent to the controller;
  • the controller is configured to generate the control signal according to the received signal and send the control signal.
  • the sixth and ninth possible implementations provide another way to configure the frequency difference detection device. It is also necessary to set the frequency of the reference signal in advance, and adjust the frequency of the filtered interference signal to make it match the reference signal. The frequency is the same, to achieve the purpose of adjusting the frequency interval of the multi-wavelength laser.
  • the frequency detector further includes a first frequency divider and a second frequency divider; the first A frequency divider, configured to receive the filtered interference signal, divide the filtered interference signal to obtain a low-frequency interference signal, and send the low-frequency interference signal to the phase-locked loop circuit;
  • the second frequency divider is used to receive the reference signal, divide the frequency of the reference signal to obtain a low frequency reference signal, and send the low frequency reference signal to the PFD;
  • the PFD is used to The low-frequency interference signal and the low-frequency reference signal generate a signal related to the frequency difference and send it to the low-pass filter.
  • the embodiment of the present application uses two frequency dividers to respectively reduce the frequency of the filtered interference signal and the reference signal, which can reduce the bandwidth requirement of the PFD and is easier to implement.
  • the frequency of the reference signal is the slave wavelength tunable laser
  • the frequency of the reference signal is the target frequency of the slave wavelength tunable laser and M / N of the difference between the corresponding subcarrier frequencies in the multi-wavelength optical signal, where N and M are the frequency division ratios of the first frequency divider and the second frequency divider, respectively, and are both greater than 1;
  • the frequency difference between the target frequency and the corresponding subcarrier is smaller than the frequency difference between the target frequency and other subcarriers in the multi-wavelength optical signal.
  • the multi-wavelength laser further includes N -1 power detectors, the N-1 power detectors correspond one-to-one to N-1 slave wavelength tunable lasers, the slave wavelength tunable laser is the first of the N wavelength tunable lasers Any one other than a wavelength-tunable laser; a subordinate beam splitter, which is used to split the received laser signal into at least three beams, and one beam is sent to the corresponding frequency detection device, and the other beam is sent to the power detector.
  • the slave beam splitter is any one of the N beam splitters except the beam splitter connected to the first wavelength tunable laser; the power The detector is used for measuring the power of the laser signal emitted by the corresponding slave wavelength tunable laser, and sending the power value to the controller.
  • the controller can better control the output characteristics such as the output power of the corresponding wavelength tunable laser.
  • the N beam splitters, The phase modulator and the power splitter are both polarization maintaining devices, and the connection between the wavelength tunable laser and the corresponding frequency difference detection device is any one or more of polarization maintaining fiber, optical waveguide, and spatial light Species. Ensure the polarization-maintaining characteristics of each device, which can stabilize the polarization state of the transmitted signal, which is beneficial to the adjustment of multi-wavelength lasers.
  • a frequency control method for a multi-wavelength laser includes N tunable lasers, N beam splitters, phase modulators, and N-1 frequency difference detection devices, where N A wavelength tunable laser includes a reference wavelength tunable laser and N-1 slave wavelength tunable lasers; the reference wavelength tunable laser is connected to a beam splitter, and the beam splitter includes a first output port and a second output Port, the first output port is used as the output port of the multi-wavelength laser, the second output port is connected to the phase modulator; the phase modulator is connected to the N-1 frequency difference detection devices respectively.
  • the N-1 slave wavelength tunable lasers correspond to the remaining N-1 beam splitters and N-1 frequency difference detection devices, respectively, and the slave wavelength tunable lasers are connected to corresponding beam splitters ,
  • the corresponding beam splitter includes a third output port and a fourth output port, the third output port serves as an output port of the multi-wavelength laser, and the fourth output port is associated with a
  • the frequency interval is the drive signal frequency of the phase modulator; a part of the laser signal and the multi-wavelength optical signal separated by the slave wavelength tunable laser are sent to the frequency difference detection device to generate the slave wavelength
  • a control signal corresponding to a tuned laser wherein the frequency difference between the target frequency of the slave wavelength tunable laser and the corresponding subcarrier in the multi-wavelength optical signal is less than the target frequency and the other subcarriers in the multi-wavelength optical signal Frequency difference; the frequency difference between the initial frequency set by the slave wavelength laser and the corresponding subcarrier is less than the frequency difference between the initial frequency and other subcarriers in the multi-wavelength optical signal; the wavelength can be changed by the control signal Adjust the output frequency of the laser so that the actual frequency intervals of the laser signals output
  • the multi-wavelength optical signal with precise frequency interval generated by the phase modulator is used as a reference to calibrate the frequency interval of multiple wavelength-tunable lasers to reduce the error of the frequency interval.
  • the initial setting of the slave tunable laser The frequency is greater than the frequency of the corresponding subcarrier; if the target frequency of the slave wavelength tunable laser is less than the frequency of the corresponding subcarrier, the initial frequency set by the slave wavelength tunable laser is less than the frequency of the corresponding subcarrier .
  • the initial setting of the slave wavelength tunable laser The frequency obtained by subtracting the maximum frequency error value of the subordinate wavelength tunable laser is greater than the frequency of the corresponding subcarrier; if the target frequency of the subordinate wavelength tunable laser is less than the frequency of the corresponding subcarrier, then the The frequency obtained by adding the initial frequency set by the slave wavelength tunable laser and the maximum frequency error value of the slave wavelength tunable laser is smaller than the frequency of the corresponding subcarrier.
  • the initial frequency difference set by the subordinate wavelength tunable laser is further defined to avoid the occurrence of the fact that the frequency difference detection device can only obtain the subcarrier frequency corresponding to the initial frequency and the multi-wavelength optical signal The difference between them, the size between the two cannot be sensed, resulting in the problem of adjusting to the wrong frequency.
  • the wavelength tunable laser includes a first mirror and a second reflection A mirror, a gain chip, a phase zone, and a filter; the method further includes: loading a jitter signal on any one or more of the first mirror, the second mirror, and the filter; Detecting the output power of the wavelength-tunable laser, and obtaining the relative position of the center frequency of the filter spectrum of the filter and the output frequency of the wavelength-tunable laser according to the detected power value; The center frequency of the filter spectrum of the filter is adjusted. It can ensure that the output frequency of the N-1 tunable lasers keeps the dynamic alignment with the center wavelength of the filter spectrum of the respective filters, thereby ensuring that the power and SMSR performance of the tunable lasers will not deteriorate significantly.
  • the embodiments of the present application use the multi-wavelength optical signal with precise frequency interval generated by the phase modulator as a reference, and can calibrate the frequency interval of multiple wavelength-tunable lasers to reduce the error of the frequency interval; since the laser signal output by the multi-wavelength laser directly It comes from the wavelength-tunable laser. Therefore, the output laser signal of the multi-wavelength laser has the same characteristics of high output power, narrow linewidth, high SMSR, and high OSNR as the single wavelength tunable laser.
  • Figure 1 is a structural diagram of a multi-wavelength laser in the prior art
  • Figure 2 is a schematic diagram of a multi-channel parallel transmission system
  • FIG. 3 is a structural diagram of a multi-wavelength laser provided by an embodiment of the present application.
  • FIG. 4 is a structural diagram of a multi-wavelength laser provided by another embodiment of the present application.
  • FIG. 5 is a schematic diagram of a multi-wavelength optical signal generated by a phase modulator
  • FIG. 6 is a structural diagram of a frequency detection device in a multi-wavelength laser provided by another embodiment of the present application.
  • FIG. 7 is a structural diagram of a frequency detector in a frequency detection device provided by another embodiment of this application.
  • FIG. 8 is a diagram of the correspondence between a multi-wavelength optical signal, a target frequency of a multi-wavelength laser, and an initial frequency of the multi-wavelength laser;
  • FIG. 9 is a structural diagram of a frequency detector in a frequency detection device according to another embodiment of this application.
  • FIG. 10 is a structural diagram of a multi-wavelength laser provided by another embodiment of this application.
  • 11 is a structural diagram of a wavelength-tunable laser
  • FIG. 12 is a flowchart of a frequency control method of a multi-wavelength laser according to another embodiment of the present application.
  • the multi-wavelength laser provided by the embodiment of the present application can be applied to an optical communication system requiring multiple wavelength lasers, for example, a multi-channel parallel transmission system, a dense wavelength division multiplexing system (Dense Wavelength Division Multiplexing, DWDM), etc.
  • 2 is a schematic diagram of a multi-channel parallel transmission system.
  • the optical device at the transmitting end includes a multi-wavelength laser and a multi-channel modulator.
  • the frequency interval of the multi-wavelength laser is precisely set.
  • each laser After each laser is loaded with amplitude and phase modulation signals through a modulator, it is coupled into the transmission fiber through the wavelength division multiplexer; after demultiplexing at the receiving end, the multi-wavelength laser is loaded.
  • the modulated optical signal and the optical signal emitted by the multi-channel local oscillator light source also a multi-wavelength light source
  • enter the multi-channel integrated coherent receiver Integrated Coherent Receiver, ICR for processing at the receiving end.
  • ICR integrated Coherent Receiver
  • the multi-channel joint processing algorithm can reduce the nonlinear cost of optical signal transmission in light and improve the receiving performance; in a multi-channel parallel transmission system, it can also reduce the filtering cost by reducing the frequency interval between multi-wavelength laser signals , And then use the algorithm to compensate for the impact of crosstalk between wavelengths, so as to obtain higher spectrum utilization and better performance.
  • FIG. 3 is a schematic block diagram of a multi-wavelength laser 300 according to an embodiment of the present application.
  • the multi-wavelength laser 300 includes: N wavelength-tunable lasers 301, N beam splitters 302, a phase modulator 303, and N-1 frequency difference detection devices 304, where N is a positive integer not less than 2, N
  • the wavelength tunable laser 301 includes a first wavelength tunable laser and a second wavelength tunable laser;
  • the first wavelength tunable laser 3011 is used to generate a first laser signal and send the first laser signal to the first beam splitter 3021 out of N beam splitters;
  • the first beam splitter 3021 is used to split the first laser signal into at least two beams, and send the first beam of the first laser signal to the phase modulator 303, wherein the second beam of the first laser signal is a path of the multi-wavelength laser 300 Output; where the splitting ratio of the first beam splitter can be 90:10, other splitting ratios can also be used, usually a high-power laser beam as the output light of the multi-wavelength laser; the beam splitters mentioned later can be Use different split ratios such as 90:10 and 80:20.
  • the phase modulator 303 is used to modulate the first laser beam to generate a multi-wavelength optical signal, and send the multi-wavelength optical signal to the first frequency difference detection device 3041, where the N-1 frequency difference detection devices include the first A frequency difference detection device, the frequency interval of adjacent wavelengths in the multi-wavelength optical signal is the same.
  • the multi-wavelength laser 300 further includes a radio frequency signal source 305 for generating a radio frequency signal and sending the radio frequency signal to a phase modulator 303; the modulator 303 is used for the first beam of the first laser according to the radio frequency signal Modulation is performed to generate a multi-wavelength optical signal, wherein the interval between adjacent wavelengths in the multi-wavelength optical signal is related to the frequency of the radio frequency signal.
  • a radio frequency signal to the phase modulator 303, a multi-wavelength optical signal with a precise frequency interval can be generated.
  • the frequency of the radio frequency signal is the same as the frequency interval of adjacent wavelengths in the multi-wavelength optical signal.
  • the multi-wavelength laser 300 further includes an amplifier 307, located between the RF signal source 305 and the phase modulator 303, used to amplify the RF signal, and then sent to the phase modulator 303 to solve the problem of insufficient RF signal power.
  • the second wavelength tunable laser 3012 is used to generate a second laser signal and send the second laser signal to the second beam splitter 3022 of the N beam splitters;
  • the second beam splitter 3022 is used to split the second laser signal into at least two beams, and send the first beam second laser signal to the first frequency difference detection device 3041, wherein the second beam second laser signal is a multi-wavelength laser Another output of 300;
  • the first frequency difference detection device 3041 is used to obtain a first control signal based on the multi-wavelength optical signal and the first beam of the second laser signal, and send the first control signal to the second wavelength tunable laser 3012, where the first control The signal is used to adjust the output wavelength of the second wavelength tunable laser so that the actual frequency interval between the second laser signal and the first laser signal is equal to the target frequency interval between the second laser signal and the first laser signal.
  • the output laser signal of each tunable laser will be initially set with reference to the target frequency interval. Due to the limited frequency accuracy of the tunable laser, the actual output wavelength of multiple tunable lasers There will be deviations. In this embodiment, due to the accuracy of the wavelength-tunable laser, before the second wavelength-tunable laser receives the first control signal, the actual frequency interval between the first laser signal and the second laser signal is between the target frequency interval There will be differences.
  • the phase modulator 303 may be directly connected to the first frequency difference detection device 3041, and directly send the multi-wavelength optical signal to the first frequency difference detection device 3041, the multi-wavelength laser 300 at this time
  • the structure is shown in Figure 4.
  • N wavelength tunable lasers include a third wavelength tunable laser 3023, and N-1 frequency difference detection devices 304 include a second frequency difference detection device 3042; at this time, the multi-wavelength laser 300 also includes a power divider 306, the specific structure is still shown in FIG.
  • the phase modulator 303 sends the multi-wavelength optical signal to the power splitter 306; the power divider 306 divides the multi-wavelength optical signal into at least N-1 multi-wavelength optical signals, and sends the first multi-wavelength optical signal to the first
  • the frequency difference detection device 3041 sends the second multi-wavelength optical signal to the second frequency difference detection device 3042; it should be understood that the function of the power divider is to divide one signal into multiple channels according to power, and the wavelength information of each signal is The signal before entering the power splitter is consistent.
  • the third wavelength tunable laser 3013 is used to generate a third laser signal and send the third laser signal to the third beam splitter 3023 of the N beam splitters; the third beam splitter 3023 is used to convert the third laser The signal is divided into at least two beams, and the first beam of the third laser signal is sent to the second frequency difference detection device 3042, wherein the second beam of the third laser signal is an output of the multi-wavelength laser 300;
  • the second frequency difference detection device 3042 is used to obtain a second control signal based on the second multi-wavelength optical signal and the first beam of the third laser signal, and send the second control signal to the third wavelength tunable laser 3013, wherein, The second control signal is used to adjust the output wavelength of the third wavelength tunable laser 3013 so that the actual frequency interval between the third laser signal and the first laser signal is equal to the target frequency interval between the third laser signal and the first laser signal. It should be understood that before the third wavelength tunable laser receives the second control signal, there will also be a difference between the actual frequency interval between the first laser signal and the third laser signal and the target frequency interval between the two.
  • the value of N is subject to actual conditions, and is not limited in the embodiments of the present application.
  • the frequency accuracy of the commercially available single-channel wavelength tunable laser is about ⁇ 1.5GHz, that is, assuming that the target frequency interval of the first wavelength tunable laser and the second wavelength tunable laser is 25GHz, according to this frequency interval, the two The wavelength tunable laser is initially set to f1 and f2, but in fact, the possible frequency range of the first wavelength tunable laser is f1 ⁇ 1.5GHz, and the possible frequency range of the second wavelength tunable laser is f2 ⁇ 1.5GHz, the actual frequency interval between each other may be any value between 22-28GHz, the error reached 3GHz, which is unacceptable in multi-wavelength lasers.
  • the frequency interval of multiple wavelength-tunable lasers can be calibrated to reduce the error of the frequency interval.
  • the frequency of the first laser signal output by the first wavelength tunable laser is f1; in the laser signals output by the multi-wavelength laser, the target frequency interval of laser signals with adjacent wavelengths is F. Since the phase modulator modulates the first laser signal, the multi-wavelength optical signal generated by the phase modulator is centered at f1, and the center frequency of each subcarrier is f1 + k * f RF , as shown in FIG. 5 Where f RF is the frequency of the drive signal of the phase modulator; k is an integer, and k is a negative value indicating that the subcarrier is located on the low frequency side of f1, whereas the subcarrier is located on the high frequency side of f1.
  • the target frequency interval F of the second laser signal and the first laser signal is the same as or close to f RF , and the target frequency f1 + F of the second laser signal; after the initial setting, the frequency f2 of the second laser signal will be Set near f1 + f RF ; due to the limited frequency accuracy of the tunable laser, even if the theoretical value of f2 is set to f1 + f RF , there will be a deviation between the actual value of f2 and f1 + f RF , that is f2 There will be a deviation between the actual frequency interval from f1 and the target frequency interval.
  • the first error detection device After receiving the second laser signal and the multi-wavelength optical signal, the first error detection device will obtain the frequency between the second laser signal and f1 + f RF The frequency difference between the two will also receive the reference signal, and adjust the second tunable laser according to the difference between the frequency difference and the reference signal so that the output wavelength is the same as f1 + F, so as to ensure that the actual frequency interval between f2 and f1 is equal to the target Frequency interval.
  • the frequency of the reference signal can be set close to 0, for example, 1 ⁇ 10MHz, etc., by adjusting The output wavelength of the second-tunable laser can be adjusted until the difference between the frequency difference and the reference signal is 0; if there is a certain difference between the value of f RF and F, such as a difference of 1 GHz, the frequency difference can be adjusted to 1 GHz. Realize that f2 is the same as the target frequency, that is, the frequency of the reference signal can be set to 1 GHz.
  • F and f RF are close, and it can be understood that the frequency difference between F and f RF is less than the frequency difference between F and k * f RF (k ⁇ 1), and the frequencies that appear below are understood as such; f2 will be Set in the vicinity of f1 + f RF , it can be understood that the frequency difference between f2 and f1 + f RF is less than the frequency difference between f2 and f1 + k * f RF (k ⁇ 1), the following appears to set the frequency of the laser signal to a certain The frequency vicinity is understood accordingly.
  • the error detection device will obtain the frequency difference between the third laser signal and f1-2 * f RF , and also receive the reference signal, according to the frequency difference and the reference signal Adjust the third tunable laser so that the output wavelength is the same as f1-2F, so as to ensure that the actual frequency interval between f3 and f1 is equal to the target frequency interval.
  • the frequency difference can be adjusted to 0 to achieve the same f3 as the target frequency, that is, the frequency of the reference signal can be set close to 0, for example, 1-10MHz, etc. ; If the value of f RF has a certain difference with F, for example, there is a difference of 1 GHz, then the difference between f1-2 * f RF and f1-2F is 2 GHz, and the frequency difference can be adjusted to 2 GHz to achieve the same f3 as the target frequency, that is, reference The frequency of the signal can be set to 2 GHz, and the output wavelength of the tunable laser can be adjusted by adjusting the second wavelength until the difference between the frequency difference and the reference signal is zero.
  • the multi-wavelength optical signals generated by the phase modulator have precise frequency intervals, in the laser signals output by the multi-wavelength lasers disclosed in the embodiments of the present application, the deviation of the actual frequency intervals of different laser signals from their respective target frequency intervals Very small. Since the laser signal output by the multi-wavelength laser comes directly from the wavelength-tunable laser, the output laser signal of the multi-wavelength laser has the same characteristics of high output power, narrow linewidth, high SMSR and high OSNR as the single wavelength tunable laser .
  • the laser signal adjacent to the wavelength of the first laser signal refers to the frequency of the first laser signal on the high-frequency side and the low-frequency side of the first laser signal, respectively The laser signal with the smallest gap.
  • the frequencies of the first laser signal, the second laser signal, the third laser signal, and the fourth laser signal are 50 GHz, 75 GHz, 25 GHz, and 100 GHz, respectively.
  • the signal wavelength is adjacent to the second laser signal and the third laser signal
  • the second laser signal is adjacent to the first laser signal and the fourth laser signal
  • the third laser signal is adjacent to the first laser signal
  • Next to the wavelength of the fourth laser signal is the second laser signal.
  • the value of f RF can be set to one-nth of F, and n is a positive integer, for example, F is 75 GHz, and f RF can be set to 25 GHz or 37.5 GHz; F is 100GHz, f RF may be set to 25GHz or 50GHz; f RF values also may be set with a frequency difference exists one n F, e.g., F is 75GHz, f RF may be set to 37GHz or 24.5GHz; F For 100 GHz, f RF can be set to 25.5 GHz or 50.5 GHz.
  • the frequency f2 of the second laser signal is located on the high frequency side of the frequency f1 of the first laser signal, and among the laser signals output by the multi-wavelength laser, the The wavelength is adjacent to the wavelength of the first laser signal, after the initial setting, f2 will be set near f1 + 3 * f RF ; due to the limited frequency accuracy of the tunable laser, f2 and f1 + 3 * f RF There will be a deviation between the actual frequency interval between f2 and f1 and the target frequency interval.
  • the first error detection device will obtain the second laser signal after receiving the second laser signal and the multi-wavelength optical signal
  • the frequency difference between f1 + 3 * f RF and the reference signal is also received.
  • the frequency f3 of the third laser signal is on the high-frequency side of f2, and in the laser signal output by the multi-wavelength laser, the wavelength of the third laser signal is adjacent to the wavelength of the second laser signal, then the initial setting After that, f3 will be set near f1 + 6 * f RF ; after receiving the third laser signal and the multi-wavelength optical signal, the second error detection device will obtain the difference between the third laser signal and f1 + 6 * f RF The frequency difference will also receive the reference signal. Since the target value of f3 is f1 + 2F, that is f1 + 6 * f RF + 3GHz, the value of the reference frequency needs to be set to 3GHz. According to the difference between the frequency and the reference frequency The difference adjusts the third tunable laser so that its output wavelength is the same as f1 + 2F, thereby ensuring that the actual frequency interval between f3 and f2 is equal to the target frequency interval.
  • the multi-wavelength laser disclosed in the embodiments of the present application can output a multi-wavelength laser signal with a larger frequency interval, and does not require a large-bandwidth phase modulator, which is easier to implement.
  • a multi-wavelength laser includes three output lasers, where The frequency f2 of the second laser signal is located on the high frequency side of the frequency f1 of the first laser signal, and is separated from the target frequency of f1 by 25 GHz; the frequency f3 of the third laser signal is located on the low frequency side of f1, and is separated from the target frequency of f1 by 50 GHz ; Set the frequency f RF of the drive signal of the phase modulator to 25 GHz. In the initial setting, set f2 near f1 + f RF , and set f3 near f1-2 * f RF . The rest The steps are the same as the previous embodiments, and will not be described in detail.
  • the frequency difference detection device 304 includes a coupler 601, an optical detector 602, a low-pass filter 603, a frequency difference detector 604, and a signal source 605, specifically The connection relationship is shown in Figure 6;
  • the coupler 601 is used for receiving multi-wavelength optical signals and laser signals, interfering with the multi-wavelength optical signals and laser signals, and sending the interfering optical signals to the optical detector 602; the optical detector 602 is used for interfering
  • the optical signal is photoelectrically converted, and the converted interference signal is sent to a low-pass filter 603; the low-pass filter 603 is used to perform low-pass filtering on the converted interference signal, and send the filtered interference signal to frequency difference detection 604; signal source 605, used to generate a reference signal, send the reference signal to the frequency difference detection request 604; frequency difference detector 604, used to obtain the reference signal, detect the frequency difference between the filtered interference signal and the reference signal , Get the control signal, and send the control signal out.
  • the frequency difference detection device 304 further includes an amplifier 606 for receiving the filtered interference signal, amplifying the signal, and sending the amplified signal to the frequency difference detector 604.
  • the frequency difference detector 604 includes a phase-locked loop circuit 701, a loop filter 702, and a controller 703.
  • the phase-locked loop circuit 701 is used to detect the filtered interference signal and the reference signal. The frequency difference between them, get the frequency difference signal, and send the frequency difference signal to the loop filter 702; the loop filter 702 is used to perform loop gain and filtering on the frequency difference signal, and then send it to the controller 703; the controller 703, used to generate a control signal according to the received signal and send the control signal.
  • the following uses a four-wavelength laser as an example to describe the function of the frequency difference detection device in detail. Assuming that the frequency of the first laser signal is f1, among the laser signals output by the multi-wavelength laser, the target frequency interval of laser signals with adjacent wavelengths is F.
  • the multi-wavelength optical signal generated by the phase modulator is centered on f1, and the center frequency of each subcarrier is f1 + k * f RF , as shown in Figure 5
  • f RF is the frequency of the drive signal of the phase modulator
  • k is an integer and k is a negative value indicating that the subcarrier is located on the low frequency side of f1
  • k is a positive value indicating that the subcarrier is located on the high frequency side of f1.
  • the frequency f2 of the second laser signal is set near f1-f RF
  • the frequency f3 of the third laser signal is set near f1 + f RF
  • the frequency of the fourth laser signal is set f4 is set near f1 + 2f RF ; due to the limited frequency accuracy of the wavelength-tunable laser, there will be a deviation ⁇ f1 between f2 and f1-f RF ,
  • the two signals will interfere at the coupler to obtain the interfering optical signal, where the interfering optical signal also It includes multiple subcarriers with different frequencies, and the frequency of each subcarrier in the interfering optical signal is the modulus of the difference between the frequency f2 of the second laser signal and the frequency of each subcarrier in the multi-wavelength optical signal, so ,
  • the lowest frequency is
  • the optical signal after the interference is photoelectrically converted by the photodetector, and the converted interference signal is sent to the low-pass filter; by appropriately setting the bandwidth of the low-pass filter, the frequency of the interference signal can be divided into All subcarriers except the subcarrier of
  • the filtered interference signal and the reference signal are processed through a phase-locked loop circuit to obtain a frequency difference signal, and the frequency difference signal is sent to the controller.
  • the wavelength of the laser signal output by the second wavelength tunable laser is adjusted by the controller until the frequency of the filtered interference signal is the same as the frequency of the reference signal.
  • the frequency f ref of the reference signal is related to the target frequency interval F; assuming that the target frequency interval of a certain laser signal and the first laser signal is Fn, and the frequency interval of each subcarrier in the multi-wavelength optical signal is f RF , Fn and The difference of b * f RF is less than the difference between Fn and other multiples of f RF , then the reference signal frequency of the frequency detection device corresponding to this laser signal is the difference between Fn and b * f RF , and b is a positive integer.
  • the target frequency of f2 is f1-F. If f2 has been tuned to the target frequency, the deviation between f2 and f1-f RF must satisfy the following relationship:
  • the target frequency of f3 is f1 + F. If f3 has been adjusted to the target frequency, the deviation between f3 and f1 + f RF must satisfy the following relationship:
  • the target frequency of f4 is f1 + 2F.
  • the target frequency of f2 is f1-F
  • the deviation between f2 and f1-2f RF must meet the following relationship :
  • the frequency f ref of the reference signal needs to be set to
  • the target frequency of f3 is f1 + F.
  • the deviation between f3 and f1 + f RF must satisfy the following relationship:
  • the target frequency of f4 is f1 + 2F.
  • the deviation between f4 and f1 + 4f RF must satisfy the following relationship:
  • 2 *
  • , the third corresponding to the third laser signal The reference signal of the two-frequency difference detection device can be set as f ref
  • the adjustment can be started. Assuming that the target frequency interval between the frequency f1 of the first laser signal and the frequency f2 of the second laser signal is F1, the value of F1 is the same as or close to n * f RF , and the frequency f2 of the second laser signal is set at f1-n * f Near RF .
  • the frequency of the filtered interference signal is the difference between the frequency f2 and f1-n * f RF of the second laser signal, but the size between f2 and f1-n * f RF cannot be distinguished; after adjusting the filtered interference signal
  • the target frequency of f2 is f1-n * f RF + f ref , so the second case will meet the requirements; if the first case occurs, f2 will be adjusted to f1-n * f RF -f ref , unable to meet the requirements.
  • the embodiment of the present application proposes the following solution: let the initial frequency f2 of the second laser signal output by the second wavelength tunable laser meet certain conditions. If f1-F1 is greater than f1-n * f RF , then f2 is initially set on the high-frequency side of f1-n * f RF , that is, f2> f1-n * f RF , and the frequency of f2 and f1-n * f RF The difference is less than the frequency difference between f2 and f1 + k * f RF (k ⁇ -n); considering the accuracy of the wavelength-tunable laser, assuming the accuracy is ⁇ ⁇ f, the setting value of f2 can be greater than f1-n * f RF The value of + ⁇ f, so that even if the output wavelength of the tunable laser is deviated, the actual value of f2 will not be less than f1-n * f RF
  • f2 is initially set on the low-frequency side of f1-n * f RF , that is, f2 is less than the value of f1-n * f RF , and f2 and f1-n * f RF
  • the frequency difference is less than the frequency difference between f2 and f1 + k * f RF (k ⁇ -n); considering the accuracy of the wavelength-tunable laser, the setting value of f2 can also be less than f1-n * f RF - ⁇ f value.
  • the problem of adjusting f2 to the wrong frequency due to the interference of the positive value of the optical signal and the inability to distinguish the size between f2 and f1-n * f RF can be avoided.
  • the frequency setting of other laser signals can also be performed by referring to the same manner, which will not be repeated in the embodiments of the present application. It should be noted that, in any embodiment of the present application, this solution may be used to initially set the frequency of the laser signal.
  • the frequency difference detector further includes a first frequency divider 704 and a second frequency divider 705, as shown in FIG. 7; the first frequency divider 704 is used to receive the filtered interference signal and convert the filtered The interference signal is frequency-divided to obtain a low-frequency interference signal, and the low-frequency interference signal is sent to a phase-locked loop circuit 701; a second frequency divider 705 is used to receive the reference signal and divide the reference signal to obtain a low-frequency reference signal, Send the low-frequency reference signal to the phase-locked loop circuit 701; the phase-locked loop circuit 701 is used to detect the frequency difference between the low-frequency interference signal and the low-frequency reference signal to obtain a frequency difference signal, and send the frequency difference signal to the loop filter 702 Loop gain and filtering are performed, and then sent to the controller 703.
  • the controller 703 adjusts the wavelength of the laser signal output by the corresponding wavelength-tunable laser until the frequency of the low-frequency interference signal is the same as the frequency of the low-frequency reference signal.
  • the frequency division ratio of the first frequency divider is N
  • the frequency of the low-frequency interference signal is one-Nth before frequency division
  • the frequency division ratio of the second frequency divider is M
  • the frequency of the low-frequency reference signal is the frequency before frequency division One-Mth
  • the target frequency interval Fn of one laser signal and the first laser signal is close to the value of n * f RF
  • the target frequency interval between the frequency f2 of the second laser signal and the frequency f1 of the first laser signal is F
  • the target frequency of f2 is f1-F
  • the deviation between f2 and f1-f RF must satisfy the following relationship:
  • the frequency f ref of the reference signal needs to be set to (M / N) *
  • the frequency of the low-frequency interference signal is adjusted to fref , thereby achieving the purpose of adjusting f2 to the target frequency.
  • Using two frequency dividers to reduce the frequency of the filtered interference signal and reference signal separately can reduce the bandwidth requirement of the phase-locked loop circuit and is easier to implement; the frequency division ratio of the two frequency dividers can be the same or different
  • the embodiment of the present application is not limited.
  • the frequency difference detector may also include only one frequency divider, for example, only the first frequency divider, then the frequency f ref of the reference signal is set to (1 / N) *
  • the frequency difference detector 304 may include a phase / frequency detector (Phase-Frequency Detector, PFD) 901, a frequency difference signal generator 902, and a controller 903, as shown in FIG. 9
  • PFD 901 is used to receive the filtered interference signal and the reference signal, detect the frequency difference between the filtered interference signal and the reference signal, and send the detected signal to the frequency difference signal generator 902; the frequency difference signal
  • the generator 902 is used to generate a frequency difference signal according to the detected signal and send it to the controller 893;
  • the controller 903 is used to generate a control signal according to the difference frequency signal and send the control signal.
  • the frequency difference signal generator 902 includes a low-pass filter, a subtractor, and a loop filter; the low-pass filter is used to receive the signal from the PFD 901, and perform low-pass filtering on it, and send the filtered signal to The subtractor is used to subtract the preset voltage reference signal from the filtered signal to obtain the frequency difference signal and send the frequency difference signal to the loop filter; the loop filter is used to perform loop gain and Filter, and then send to the controller 903.
  • the frequency detector 304 may further include a first frequency divider 904 and a second frequency divider 905; the first frequency divider 904 is used to receive the filtered interference signal and perform the filtered interference signal Frequency division processing to obtain low-frequency interference signals, and send the low-frequency interference signals to PFD901; the second frequency divider 905 is used to receive the reference signal, divide the reference signal to obtain the low-frequency reference signal, and send the low-frequency reference signal to PFD901; PFD901, used to receive low-frequency interference signals and low-frequency reference signals, detect the frequency difference between low-frequency interference signals and low-frequency reference signals, and send the detected signals to frequency difference signal generator 902.
  • the specific functions of the frequency difference detection device have been described in detail in the previous embodiment, and will not be repeated in the embodiments of the present application.
  • the beam splitter, the coupler, the phase modulator, the power splitter, and the photodetector in the above embodiments are polarization-dependent devices, which can be implemented by means of integrated optical paths or spatial optics; the above-mentioned devices can also be Discrete devices, the connection between them can be achieved through polarization maintaining fiber.
  • the above-mentioned devices may also be partially integrated and partially separated, and the embodiments of the present application are not specifically limited.
  • the multi-wavelength laser includes the device of the multi-wavelength laser shown in FIG. 3, and further includes N-1 power detectors 1001;
  • the other beam splitter 302 includes two cascaded couplers (1002, 1003), one of which is a coupler 1002, which is used to divide the received laser signal into two, and one is sent to the other for coupling 1003, one part is sent to the frequency difference detection device 304; another coupler 1003 is used to divide the received laser signal into two parts, one part is sent to the power detector 1001, and one part is used as the output of the multi-wavelength laser;
  • one of the couplers 1002 is used to divide the received laser signal into two, one is sent to the other coupler 1003, and the other is sent to the power detector 1001; the other coupler 1003 is used to divide the received The laser signal is divided into two parts, one part is sent to the frequency difference detection device 304, and the other part is used
  • the other beam splitter 302 can also be implemented by a beam splitter including at least three output ports, which divides the received laser signal into at least three parts, and one part is sent to the frequency difference detection device 304, and one part is sent For the power detector 1001, the remaining part is used as the output of the multi-wavelength laser.
  • the power detector 1001 is used to measure the power of the laser signal emitted by the corresponding wavelength tunable laser and send the power value to the controller (703, 903); the controller can better control the output of the corresponding wavelength tunable laser Output characteristics such as power.
  • the wavelength-tunable laser may be a distributed Bragg reflector (DBR) laser, external cavity laser, etc.
  • DBR distributed Bragg reflector
  • the structure of the wavelength-tunable laser shown in FIG. 11 is taken as an example to illustrate the power value pair.
  • the wavelength-tunable laser includes a mirror 1, a mirror 2, a gain chip, a phase zone, a filter 1, and a filter 2. Two mirrors are used to realize the feedback of the laser resonator.
  • the driving signal is provided by the controller (703, 903); the mirror 1 It can also be realized by plating a reflective film on one side of the gain chip.
  • the gain chip is used to provide light generation and light amplification, and the phase zone is used to finely adjust the laser frequency.
  • Filter 1 and filter 2 have periodic filter spectra, respectively, to jointly adjust the laser wavelength and obtain the wavelength range covering the C-band .
  • the frequency accuracy is about ⁇ 1.5GHz. Therefore, when the frequency of the laser signal output by the wavelength-tunable laser is adjusted by the control signal, the output frequency of the wavelength-tunable laser may deviate significantly from the center of the filter spectrum of the filter 1 and the filter 2, resulting in deterioration of the laser performance. Therefore, the multi-wavelength laser may further include a disturbance signal source, and the generated disturbance signal is loaded on the mirror 1 and / or the mirror 2, and the output optical power of the wavelength-tunable laser will also generate disturbance at the same frequency.
  • the transmitter can obtain the disturbance optical power and send it to the controller for processing; the controller judges the relative position of the center of the total filtering spectrum of the filter 1 and the filter 2 and the output frequency of the laser, and feedback-adjusts the filter 1 and the filter 2 respectively
  • the filter spectrum ensures that the output frequency of the N-1 tunable lasers is dynamically aligned with the center wavelength of the total filter spectrum of each of the two filters, which can ensure that the power and SMSR performance of the tunable lasers will not be obvious deterioration.
  • a disturbance signal can also be added to the filter 1 and / or the filter 2 of the tunable wavelength laser, and the output optical power of the tunable wavelength laser will also generate fluctuations at the same frequency as the disturbance signal loaded on the filter.
  • the disturbance optical power can be obtained through a power detector and sent to the controller for processing; the controller judges the relative position of the filter spectrum center of the filter 1 and the filter 2 and the output wavelength of the tunable laser, and then separately through the controller
  • the filter spectrum of the filter 1 and the filter 2 is adjusted by feedback to ensure that the output wavelengths of the N-1 tunable lasers are dynamically aligned with the center wavelength of the filter spectrum of the respective filters.
  • the wavelength-tunable laser includes two filters, and does not exclude the case of including other numbers of filters.
  • the wavelength-tunable laser may include one filter and three filters Wait, the principle has not changed.
  • FIG. 12 Another embodiment of the present application describes a frequency control method for a multi-wavelength laser. As shown in FIG. 12, it is applicable to the multi-wavelength lasers shown in FIGS. 3-4, 6, and 8-10:
  • the center frequency of each sub-carrier in the multi-wavelength optical signal is f1 + k * f RF , k is an integer, and k is a negative value means that the sub-carrier is located on the low frequency side of f1; A positive value indicates that the subcarrier is located on the high frequency side of f1.
  • the 1202 Send a part of the laser signal and the multi-wavelength optical signal separated from each of the remaining N-1 wavelength-tunable lasers to the frequency difference detection device to generate control signals corresponding to the respective wavelength-tunable lasers.
  • the other part of the laser signal divided by the N-1 wavelength tunable lasers is the output signal of the multi-wavelength laser, and the process of the frequency difference detection device generating the control signal according to the laser signal and the multi-wavelength optical signal is in the previous device embodiment It has been described in detail in this example, and this embodiment will not repeat them here.
  • the output frequency must be initially set.
  • the frequency difference between the set value and the corresponding subcarrier in the multi-wavelength optical signal is less than the set value and the other in the multi-wavelength optical signal.
  • the setting value is determined according to the target frequency of the wavelength-tunable laser and the frequency of the corresponding subcarrier, and the specific relationship is as follows:
  • the frequency of the first wavelength tunable laser is f1
  • the frequency of the initial wavelength tunable laser needs to be f2
  • the target frequency of f2 is f1-F
  • the frequency of the corresponding subcarrier is f1-f RF , if f1-F If it is greater than f1-f RF , f2 is initially set on the high-frequency side of f1-f RF , that is, f2> f1-f RF , and the frequency difference between f2 and f1-f RF is less than f2 and f1 + k * f RF (k ⁇ -1) frequency difference; taking into account the accuracy of the wavelength-tunable laser, assuming the accuracy is ⁇ ⁇ f, the setting value of f2 can be greater than the value of f1-f RF + ⁇ f, so even if the output wavelength of the wavelength-tunable laser There is a deviation, and the actual value of f2 will not be less than
  • f2 is initially set on the low-frequency side of f1-f RF , that is, f2 is less than the value of f1-f RF , and the frequency difference between f2 and f1-f RF is less than f2 and f1 + The frequency difference of k * f RF (k ⁇ -1); considering the accuracy of the wavelength-tunable laser, the setting value of f2 can also be made smaller than the value of f1-f RF - ⁇ f.
  • the phase area and the gain chip of the wavelength-tunable laser are controlled by the control signal, and the output frequency of the wavelength-tunable laser is changed so that the actual frequency interval of the N wavelength-tunable lasers is equal to the target frequency interval.
  • the phase zone is used to compensate for slow-changing, large-scale frequency changes; the gain chip is used to compensate for fast-changing, small-amplitude frequency changes.
  • the temperature control unit can be used to replace the role of the phase zone, so the temperature control unit and gain chip of the wavelength tunable laser can also be controlled by the control signal to change the output frequency of the wavelength tunable laser , So that the actual frequency interval of the N wavelength tunable lasers is equal to the target frequency interval, where the temperature control unit adjusts the output frequency of the laser by changing the operating temperature of the laser, which can be used to compensate for the slow-changing, larger amplitude frequency changes .
  • the electrical signal processing part in the embodiment of the present application may be implemented in whole or in part by a processor, and the electrical signal processing part is the part between the low-pass filter and the controller; and in the embodiment of the present application
  • the processor involved can be a Central Processing Unit (“CPU") or other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), and ready-made programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • the general-purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the disclosed device and method may be implemented in other ways.
  • the device embodiments described above are only schematic.
  • the division of the units is only a division of logical functions.
  • there may be other divisions 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 couplings or direct couplings or communication connections may be indirect couplings or communication connections through some interfaces, devices, or units, and may also be electrical, mechanical, or other forms of connection.

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Abstract

一种多波长激光器，包括基准波长可调激光器，N-1个从属波长可调激光器，N个分束器，相位调制器以及N-1个频差检测装置；基准波长可调激光器与一个分束器相连，该分束器包括两个输出端口，其中一个输出端口与相位调制器相连；相位调制器与N-1个频差检测装置分别相连；N-1个从属波长可调激光器分别与剩余的N-1个分束器以及N-1个频差检测装置一一对应，从属波长可调激光器与对应的分束器相连，对应的分束器包括两个输出端口，其中一个输出端口与对应的频差检测装置相连；N为不小于2的正整数。由于相位调制器生成的多波长光信号具有精准的频率间隔，因此该多波长激光器具有更高的频偏精度。

Description

一种多波长激光器
本申请要求于2018年10月12日提交中国国家知识产权局、申请号为201811190205.5、申请名称为“一种多波长激光器”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及光纤通信技术领域，尤其涉及一种多波长可调激光器。
背景技术
目前，波长可调激光器是光纤通信系统中非常重要的光电子器件之一，它既可以用作发射端的光源，又可以用作相干接收端的本振激光器。随着人们对系统传输容量需求的不断增加，通过增加传输信号的波特率和调制阶数可以使单波长传输容量提高至100G bit/s、200Gbit/s、甚至400G bit/s及更高，但是波特率和调制阶数的增加会使单波大容量传输的性能受限，导致传输距离减小。多通道并行传输可以在提升传输容量的前提下，降低单波速率、增加传输距离，因此为了实现超过400Gbit/s的超大容量长距传输，多通道并行传输是一个关键技术。
在长途相干通信系统中，单波长可调激光器需要具有高输出功率、窄线宽、高边模抑制比(Side mode suppression ratio,SMSR)、高光信噪比(Optical Signal Nosie Ratio，OSNR)等特性。超大容量相干多通道并行传输系统需要多波长光源，而多波长光源的性能除了要与单波长一致以外，还需要具有精确的频率间隔和频率间隔可调节功能。例如，多波长光源输出的频率间隔需要可以设定为37.5GHz、50GHz和75GHz，频率间隔可选且间隔可在一定频率范围内微调。
现有的一个多波长光源技术如图1所示，通过将多个可调谐激光器阵列单片集成，然后利用一个共用的波锁装置实现各个可调谐激光器的频率锁定来实现，但该方案存在频偏精度低的问题，只能实现小于100MHz的频偏精度，因此在频偏精度要求更高的场景中无法适用。
发明内容
本申请的目的在于提供一种多波长激光器，解决了现有多波长光源频偏精度较低，应用场景受限的问题。
第一方面，提供一种多波长激光器，包括：N个波长可调激光器，N个分束器，相位调制器以及N-1个频差检测装置，其中，N为不小于2的正整数；第一波长可调激光器，用于生成第一激光信号，将所述第一激光信号发送给所述N个分束器中的第一分束器，其中，所述N个波长可调激光器包括所述第一波长可调激光器；所述第一分束器，用于将所述第一激光信号分成至少两束，将第一束第一激光信号发给所述相位调制器，其中，第二 束第一激光信号为所述多波长激光器的一路输出；所述相位调制器，用于对所述第一束第一激光进行调制，生成多波长光信号，将所述多波长光信号发送给第一频差检测装置，其中，所述N-1个频差检测装置包括第一频差检测装置，所述多波长光信号中相邻波长的频率间隔相同；第二波长可调激光器，用于生成第二激光信号，将所述第二激光信号发送给所述N个分束器中的第二分束器，其中，所述N个波长可调激光器包括所述第二波长可调激光器；所述第二分束器，用于将所述第二激光信号分成至少两束，将第一束第二激光信号发给所述第一频差检测装置，其中，第二束第二激光信号为所述多波长激光器的另一路输出；所述第一频差检测装置，用于根据所述多波长光信号和所述第一束第二激光信号，得到第一控制信号，将所述第一控制信号发送给所述第二波长可调激光器，其中，所述第一控制信号用于调节所述第二波长可调激光器的输出波长，使得所述第二激光信号与所述第一激光信号的实际频率间隔等于所述第二激光信号与所述第一激光信号的目标频率间隔。
在本申请实施例公开的多波长激光器中，利用相位调制器生成的频率间隔精准的多波长光信号作为基准，可以对多个波长可调激光器的频率间隔进行校准，降低频率间隔的误差。
结合第一方面，在第一方面的第一种可能的实现方式中，在N大于2的情况下，所述多波长激光器还包括：功分器；所述相位调制器，用于将所述多波长光信号发送给所述功分器；所述功分器，将所述多波长光信号分成至少N-1路多波长光信号，将第一路多波长光信号发送给所述第一频差检测装置，将第二路多波长光信号发送给第二频差检测装置，其中，所述N-1个频差检测装置包括第二频差检测装置；第三波长可调激光器，用于生成第三激光信号，将所述第三激光信号发送给所述N个分束器中的第三分束器，其中，所述N个波长可调激光器包括所述第三波长可调激光器；所述第三分束器，用于将所述第三激光信号分成至少两束，将第一束第三激光信号发给所述第二频差检测装置，其中，第二束第三激光信号为所述多波长激光器的一路输出；所述第二频差检测装置，用于根据所述第二路多波长光信号和所述第一束第三激光信号，得到第二控制信号，将所述第二控制信号发送给所述第三波长可调激光器，其中，所述第二控制信号用于调节所述第三波长可调激光器的输出波长，使得所述第三激光信号与所述第一激光信号的实际频率间隔等于所述第三激光信号与所述第一激光信号的目标频率间隔。
结合第一方面及第一方面的第一种可能的实现方式，在第一方面的第二种可能的实现方式中，所述多波长激光器还包括射频信号源，所述射频信号源，用于生成射频信号，发给所述相位调制器；所述调制器，用于根据所述射频信号，对所述第一束第一激光进行调制，生成多波长光信号，其中，所述多波长光信号中相邻波长的间隔与所述射频信号的频率相关。在本实施例中，可以通过调节射频信号的频率，来达到调节生成的多波长光信号的频率间隔的目的。
结合第一方面及第一方面的第一种或第二种可能的实现方式，在第一方面的第三种可能的实现方式中，从属波长可调激光器的目标频率与所述多波长光信号中对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差，则所述从属波长可调激光器的初始频率与所述对应子载波的频率差小于所述从属波长可调激光器的初始频率与所述其他子载波的频率差，其中，所述从属波长可调激光器为所述N个波长可调激光器 中除第一波长可调激光器之外的任意一个。本实施例公开了从属波长可调激光器的初始频率要满足的条件，有益于多波长激光器的频率调节。
结合第一方面的第三种可能的实现方式，在第一方面的第四种可能的实现方式中，如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率大于所述对应子载波的频率；如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率小于所述对应子载波的频率。
结合第一方面的第三种可能的实现方式，在第一方面的第五种可能的实现方式中，如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率减去所述从属波长可调激光器的最大频率误差值得到的频率大于所述对应子载波的频率；如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率加上所述从属波长可调激光器的最大频率误差值得到的频率小于所述对应子载波的频率。
在上述两个实施例中，对从属波长可调激光器设置的初始频率差做了进一步地限定，可以避免出现由于频差检测装置只能获取到初始频率与多波长光信号中对应的子载波频率之间的差值，无法感知两者之间的大小，导致的调节到错误频率的问题。
结合第一方面及第一方面的第一种至第五种可能的实现方式中的任意一种，在第一方面的第六种可能的实现方式中，所述频差检测装置包括耦合器，光探测器、低通滤波器、频率检测器和信号源；所述耦合器，用于接收所述多波长光信号和激光信号，对所述多波长光信号和激光信号进行干涉，将干涉后的光信号发送给所述光探测器；所述光探测器，用于对所述干涉后的光信号进行光电转换，将转换后的干涉信号发给所述滤波器；所述低通滤波器，用于对所述转换后的干涉信号进行低通滤波，将滤波后的干涉信号发给所述频率检测器；所述信号源，用于生成参考信号，将所述参考信号发送给所述频率检测器；所述频率检测器，用于检测所述滤波后的干涉信号与所述参考信号之间的频率差，得到控制信号，将所述控制信号发送出去。
结合第一方面的第六种可能的实现方式，在第一方面的第七种可能的实现方式中，所述频率检测器包括锁相环电路、环路滤波器和控制器；所述锁相环电路，用于获取所述参考信号，检测所述滤波后的干涉信号与所述参考信号之间的频率差，得到所述频差信号，将所述频差信号发送给所述环路滤波器；所述环路滤波器，用于对所述频差信号进行环路增益和滤波，然后发给所述控制器；所述控制器，用于根据接收到的信号生成所述控制信号，将所述控制信号发送出去。
上述两个实施例给出了一种频差检测装置的构成方式，预先设置好参考信号的频率，通过调节滤波后的干涉信号的频率，使其与参考信号的频率相同，达到调节多波长激光器的频率间隔的目的。
结合第一方面的第七种可能的实现方式，在第一方面的第八种可能的实现方式中，所述频率检测器还包括第一分频器和第二分频器；所述第一分频器，用于接收所述滤波后的干涉信号，将所述滤波后的干涉信号进行分频处理，得到低频干涉信号，将所述低频干涉信号发送给所述锁相环电路；所述第二分频器，用于接收所述参考信号，对所述参考信号进行分频处理，得到低频参考信号，将所述低频参考信号发送给所述锁相环电路；所述锁 相环电路，用于检测所述低频干涉信号与所述低频参考信号之间的频率差，得到所述频差信号，将所述频差信号发送给所述环路滤波器。本申请实施例利用两个分频器分别对滤波后的干涉信号以及参考信号进行降频，可以降低对锁相环电路的带宽要求，更容易实现。
结合第一方面的第六种可能的实现方式，在第一方面的第九种可能的实现方式中，所述频率检测器包括相位/频率检测器(PFD)、低通滤波器、减法器、环路滤波器和控制器；所述PFD，用于接收所述滤波后的干涉信号和所述参考信号，产生与频率差相关的信号并发送给所述低通滤波器；所述低通滤波器，用于对接收的信号进行低通滤波处理，将滤波后的信号发给所述减法器；所述减法器，用于将所述滤波后的信号减去预设的电压参考信号，得到频差信号，将所述频差信号发送给所述环路滤波器；所述环路滤波器，用于对所述频差信号进行环路增益和滤波，然后发给所述控制器；所述控制器，用于根据接收到的信号生成所述控制信号，将所述控制信号发送出去。
第六种和第九种可能的实现方式给出了另一种频差检测装置的构成方式，同样需要预先设置好参考信号的频率，通过调节滤波后的干涉信号的频率，使其与参考信号的频率相同，达到调节多波长激光器的频率间隔的目的。
结合第一方面的第九种可能的实现方式，在第一方面的第十种可能的实现方式中，所述频率检测器还包括第一分频器和第二分频器；所述第一分频器，用于接收所述滤波后的干涉信号，将所述滤波后的干涉信号进行分频处理，得到低频干涉信号，将所述低频干涉信号发送给所述锁相环电路；所述第二分频器，用于接收所述参考信号，对所述参考信号进行分频处理，得到低频参考信号，将所述低频参考信号发送给所述PFD；所述PFD，用于根据所述低频干涉信号与所述低频参考信号，生成与频率差相关的信号，并发送给所述低通滤波器。本申请实施例利用两个分频器分别对滤波后的干涉信号以及参考信号进行降频，可以降低对PFD的带宽要求，更容易实现。
结合第一方面的第六种、第七种或第九种可能的实现方式，在第一方面的第十一种可能的实现方式中，所述参考信号的频率为所述从属波长可调激光器的目标频率与所述多波长光信号中对应子载波频率的差值，其中，所述目标频率与所述对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差。
结合第一方面的第八种或第十种可能的实现方式，在第一方面的第十二种可能的实现方式中，所述参考信号的频率为所述从属波长可调激光器的目标频率与所述多波长光信号中对应子载波频率的差值的M/N，其中，N和M分别为所述第一分频器和所述第二分频器的分频比，均大于1；所述目标频率与所述对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差。上述两个实施例给出了不同情况下，参考信号的频率需满足的条件。
结合第一方面及第一方面的第一种至第十二种可能的实现方式中的任一种，在第一方面的第十三种可能的实现方式中，所述多波长激光器还包括N-1个功率检测器，所述N-1个功率检测器与N-1个从属波长可调激光器一一对应，所述从属波长可调激光器为所述N个波长可调激光器中除第一波长可调激光器之外的任意一个；从属分束器，用于将接收到的激光信号分成至少三束，将其中一束发给对应的频率检测装置，另一束发送给功率检测器，第三束作为多波长激光器的输出，其中，所述从属分束器为所述N个分束器中除与所述第一波长可调激光器连接的分束器之外的任意一个；所述功率检测器，用于测量对应的 从属波长可调激光器发出的激光信号的功率，将功率值发送给所述控制器。可以使控制器更好地控制对应的波长可调激光器的输出功率等输出特性。
结合第一方面及第一方面的第一种至第十三种可能的实现方式中的任一种，在第一方面的第十四种可能的实现方式中，所述N个分束器、所述相位调制器以及所述功分器均为保偏器件，波长可调激光器与对应的频差检测装置之间包括的连接为保偏光纤，光波导和空间光中的任意一种或多种。保证各个器件的保偏特性，可以稳定传输信号的偏振态，有益于多波长激光器的调节。
第二方面，提供一种多波长激光器的频率控制方法，所述多波长激光器包括N个波长可调激光器，N个分束器，相位调制器以及N-1个频差检测装置，其中，N个波长可调激光器包括基准波长可调激光器和N-1个从属波长可调激光器；所述基准波长可调激光器与一个分束器相连，所述分束器包括第一输出端口和第二输出端口，所述第一输出端口作为所述多波长激光器的输出端口，所述第二输出端口与所述相位调制器相连；所述相位调制器与所述N-1个频差检测装置分别相连；所述N-1个从属波长可调激光器分别与剩余的N-1个分束器以及N-1个频差检测装置一一对应，所述从属波长可调激光器与对应的分束器相连，所述对应的分束器包括第三输出端口和第四输出端口，所述第三输出端口作为所述多波长激光器的输出端口，所述第四输出端口与对应的频差检测装置相连；其中，N为不小于2的正整数；所述频率控制方法包括：
将第一波长可调激光器输出的第一激光信号的一部分发送给相位调制器，生成多波长光信号，其中，所述多波长光信号的中心频率为所述第一波长可调激光器的输出频率，频率间隔为所述相位调制器的驱动信号频率；将所述从属波长可调激光器分出的一部分激光信号与所述多波长光信号发送给所述频差检测装置，生成所述从属波长可调激光器对应的控制信号，其中，所述从属波长可调激光器的目标频率与所述多波长光信号中对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差；所述从属波长激光器设置的初始频率与所述对应子载波的频率差小于所述初始频率与多波长光信号中其他子载波的频率差；通过所述控制信号来改变所述波长可调激光器的输出频率，使得所述N个波长可调激光器输出的激光信号彼此的实际频率间隔等于目标频率间隔。
在本申请实施例中，利用相位调制器生成的频率间隔精准的多波长光信号作为基准，可以对多个波长可调激光器的频率间隔进行校准，降低频率间隔的误差。
结合第二方面，在第二方面的第一种可能的实现方式中，如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率大于所述对应子载波的频率；如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率小于所述对应子载波的频率。
结合第二方面，在第二方面的第二种可能的实现方式中，如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率减去所述从属波长可调激光器的最大频率误差值得到的频率大于所述对应子载波的频率；如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率加上所述从属波长可调激光器的最大频率误差值得到的频率小于所述对应子载波的频率。
在上述两个实施例中，对从属波长可调激光器设置的初始频率差做了进一步地限定， 可以避免出现由于频差检测装置只能获取到初始频率与多波长光信号中对应的子载波频率之间的差值，无法感知两者之间的大小，导致的调节到错误频率的问题。
结合第二方面及第二方面的第一种或第二种可能的实现方式，在第二方面的第三种可能的实现方式中，所述波长可调激光器包括第一反射镜、第二反射镜、增益芯片、相位区和滤波器；所述方法还包括：在所述第一反射镜、所述第二反射镜和所述滤波器中的任一种或多种器件上加载抖动信号；检测所述波长可调激光器的输出功率，根据检测到的功率值，得到所述滤波器的滤波谱中心频率与所述波长可调激光器输出频率的相对位置；根据所述相对位置，对所述滤波器的滤波谱中心频率进行调节。可以保证N-1个波长可调激光器的输出频率与各自的滤波器的滤波谱中心波长保持动态对准，从而保证波长可调激光器的功率、SMSR等性能不会出现明显恶化。
本申请实施例利用相位调制器生成的频率间隔精准的多波长光信号作为基准，可以对多个波长可调激光器的频率间隔进行校准，降低频率间隔的误差；由于多波长激光器输出的激光信号直接来自于波长可调激光器，因此，多波长激光器的输出激光信号具有与单个波长可调激光器相同的高输出功率、窄线宽、高SMSR以及高OSNR等特性。
附图说明
图1为现有技术中多波长激光器的结构图；
图2为多通道并行传输系统的示意图；
图3为本申请实施例提供的一种多波长激光器的结构图；
图4为本申请另一实施例提供的一种多波长激光器的结构图；
图5为相位调制器生成的多波长光信号的示意图；
图6为本申请另一实施例提供的多波长激光器中频率检测装置的结构图；
图7为本申请另一实施例提供的频率检测装置中频率检测器的结构图；
图8为多波长光信号，多波长激光器的目标频率以及多波长激光器的初始频率之间的对应关系图；
图9为本申请另一实施例提供的频率检测装置中频率检测器的结构图；
图10为本申请另一实施例提供的一种多波长激光器的结构图；
图11为一种波长可调激光器的结构图；
图12为本申请另一实施例提供的多波长激光器的频率控制方法流程图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。
本申请实施例提供的多波长激光器可以应用于需要多个波长激光的光通信系统中，例如，多通道并行传输系统，密集波分复用系统(Dense Wavelength Division Multiplexing，DWDM)等。图2为多通道并行传输系统的示意图，发射端的光器件包括多波长激光器以及多通道调制器。多波长激光器的频率间隔精准设置，每路激光经过一路调制器加载上幅度和相位调制信号后，经过波分复用器耦合进入传输光纤中；在接收端解复用后，多波长激光上加载的调制光信号与多通道本振光源(也是多波长的光源)发出的光信号共同进入多通道集成相干接收机(Integrated Coherent Receiver，ICR)中进行接收端的处理。通 过多通道联合处理算法，可以降低光信号在光线中传输的非线性代价，提升接收性能；在多通道并行传输系统中，还可以通过减小多波长激光信号之间的频率间隔，降低滤波代价，再利用算法补偿波长间串扰带来的影响，从而获取更高的频谱利用率和更优的性能。
下面结合图3详细说明本申请提供的一种多波长激光器300，图3是本申请一个实施例的一种多波长激光器300的示意性框图。
该多波长激光器300包括：N个波长可调激光器301，N个分束器302，相位调制器303以及N-1个频差检测装置304，其中，N为不小于2的正整数，N个波长可调激光器301包括第一波长可调激光器和第二波长可调激光器；
第一波长可调激光器3011，用于生成第一激光信号，将第一激光信号发送给N个分束器中的第一分束器3021；
第一分束器3021，用于将第一激光信号分成至少两束，将第一束第一激光信号发给相位调制器303，其中，第二束第一激光信号为多波长激光器300的一路输出；其中，第一分束器的分光比可以为90:10，也可以采用其他的分光比，通常功率高的一束激光作为多波长激光器的输出光；后续提到的分束器均可以采用90:10、80:20等不同的分光比。
相位调制器303，用于对第一束第一激光进行调制，生成多波长光信号，将多波长光信号发送给第一频差检测装置3041，其中，N-1个频差检测装置包括第一频差检测装置，多波长光信号中相邻波长的频率间隔相同。
可选地，该多波长激光器300还包括射频信号源305，用于生成射频信号，将该射频信号发给相位调制器303；调制器303用于根据该射频信号，对第一束第一激光进行调制，生成多波长光信号，其中，多波长光信号中相邻波长的间隔与射频信号的频率相关。具体地，通过在相位调制器303上施加射频信号，可以生成频率间隔精准的多波长光信号，射频信号的频率与多波长光信号中相邻波长的频率间隔相同，可以通过改变射频信号的频率，来改变生成的多波长光信号中相邻波长的频率间隔。进一步地，该多波长激光器300还包括放大器307，位于射频信号源305与相位调制器303之间，用于将射频信号放大之后，再发送给相位调制器303，解决射频信号功率不足的问题。
第二波长可调激光器3012，用于生成第二激光信号，将第二激光信号发送给N个分束器中的第二分束器3022；
第二分束器3022，用于将第二激光信号分成至少两束，将第一束第二激光信号发给第一频差检测装置3041，其中，第二束第二激光信号为多波长激光器300的另一路输出；
第一频差检测装置3041，用于根据多波长光信号和第一束第二激光信号，得到第一控制信号，将第一控制信号发送给第二波长可调激光器3012，其中，第一控制信号用于调节第二波长可调激光器的输出波长，使得第二激光信号与第一激光信号的实际频率间隔等于第二激光信号与第一激光信号的目标频率间隔。
在多波长激光器的实际应用中，每个波长可调激光器的输出激光信号都会参照目标频率间隔进行初始设定，由于波长可调激光器的频率精度有限，故多个波长可调激光器的实际输出波长会出现偏差。在本实施例中，由于波长可调激光器的精度问题，在第二波长可调激光器接收到第一控制信号之前，第一激光信号与第二激光信号之间的实际频率间隔与目标频率间隔之间会存在差异。
可选地，当N＝2时，相位调制器303可以直接与第一频差检测装置3041相连，将多波长光信号直接发送给该第一频差检测装置3041，此时的多波长激光器300结构如图4所示。
可选地，当N大于2时，N个波长可调激光器包括第三波长可调激光器3023，N-1个频差检测装置304包括第二频差检测装置3042；此时，该多波长激光器300还包括功分器306，具体结构仍如图3所示。
其中，相位调制器303将多波长光信号发送给功分器306；功分器306将多波长光信号分成至少N-1路多波长光信号，将第一路多波长光信号发送给第一频差检测装置3041，将第二路多波长光信号发送给第二频差检测装置3042；应理解，功分器的作用是将一路信号按照功率分成多路，每路信号的波长信息均与进入功分器之前的信号一致。
第三波长可调激光器3013，用于生成第三激光信号，将第三激光信号发送给N个分束器中的第三分束器3023；第三分束器3023，用于将第三激光信号分成至少两束，将第一束第三激光信号发给第二频差检测装置3042，其中，第二束第三激光信号为多波长激光器300的一路输出；
第二频差检测装置3042，用于根据第二路多波长光信号和第一束第三激光信号，得到第二控制信号，将第二控制信号发送给第三波长可调激光器3013，其中，第二控制信号用于调节第三波长可调激光器3013的输出波长，使得第三激光信号与第一激光信号的实际频率间隔等于第三激光信号与第一激光信号的目标频率间隔。应理解，在第三波长可调激光器接收到第二控制信号之前，第一激光信号与第三激光信号之间的实际频率间隔与两者之间的目标频率间隔也会存在差异。
需要说明的是，当N等于4时，本申请实施例的多波长激光器还可以包括第四波长可调激光器、第四分束器、第三频差检测装置；而当N＝5时，该多波长激光器还可以进一步包括第五波长可调激光器、第五分束器、第四频差检测装置，N的取值以实际情况为准，本申请实施例不做限制。
现在商用的单通道波长可调激光器的频率精度大约为±1.5GHz，也就是说，假设第一波长可调激光器和第二波长可调激光器的目标频率间隔为25GHz，按照该频率间隔对两个波长可调激光器进行初始设定，分别设定为f1和f2，但实际上，第一波长可调激光器可能的频率范围是f1±1.5GHz，第二波长可调激光器可能的频率范围是f2±1.5GHz，彼此之间的实际频率间隔可能为22-28GHz中的任意值，误差达到了3GHz，这在多波长激光器中是无法接受的。在本申请实施例公开的多波长激光器300中，利用相位调制器生成的频率间隔精准的多波长光信号作为基准，可以对多个波长可调激光器的频率间隔进行校准，降低频率间隔的误差。
具体地，假设第一波长可调激光器输出的第一激光信号的频率为f1；多波长激光器输出的激光信号中，波长相邻的激光信号的目标频率间隔均为F。由于相位调制器是对第一激光信号进行调制的，因此，相位调制器生成的多波长光信号是以f1为中心频率，各子载波的中心频率为f1+k*f RF，如图5所示，其中，f RF为相位调制器的驱动信号的频率；k为整数，k为负值表示子载波位于f1的低频侧，反之子载波位于f1的高频侧。
假设第二激光信号与第一激光信号的目标频率间隔F与f RF相同或接近，且第二激光信号的目标频率f1+F；则在初始设定之后，第二激光信号的频率f2将被设置在f1+f RF附 近；由于波长可调激光器的频率精度有限，即使将f2的理论值设为f1+f RF，f2的实际值与f1+f RF之间也会存在一个偏差，即f2与f1的实际频率间隔与目标频率间隔之间会存在一个偏差，第一误差检测装置在接收到第二激光信号和多波长光信号之后，会获得第二激光信号频率与f1+f RF之间的频率差，还会接收到参考信号，根据该频率差与参考信号的差值来调节第二可调激光器，使其输出波长与f1+F相同，从而保证f2与f1的实际频率间隔等于目标频率间隔。其中，如果f RF的值与F相同，则将该频率差调成0才可实现f2与目标频率相同；此时参考信号的频率可以设定接近于0，例如，1～10MHz等，通过调节第二波长可调激光器的输出波长，直到该频率差与参考信号的差值为0即可；如果f RF的值与F有一定差别，例如相差1GHz，则将该频率差调成1GHz才可实现f2与目标频率相同，即参考信号的频率可以设定为1GHz。
应理解，F与f RF的值接近，可以理解为F与f RF的频率差小于F与k*f RF(k≠1)的频率差，下面出现的频率接近均按此理解；f2将被设置在f1+f RF附近，可以理解为f2与f1+f RF的频率差小于f2与f1+k*f RF(k≠1)的频率差，下面出现的将激光信号的频率设置在某一频率附近均按此理解。
假设第三激光信号的频率f3与第一激光信号的目标频率间隔为2F，且f3位于f1的低频侧，则在初始设定之后，f3将被设置在f1-2*f RF附近；第二误差检测装置在接收到第三激光信号和多波长光信号之后，会获得第三激光信号与f1-2*f RF之间的频率差，还会接收到参考信号，根据该频率差与参考信号的差值来调节第三可调激光器，使其输出波长与f1-2F相同，从而保证f3与f1的实际频率间隔等于目标频率间隔。同理，如果将f RF的值设为与F相同，则将该频率差调成0才可实现f3与目标频率相同，即参考信号的频率可以设定接近于0，例如，1～10MHz等；如果f RF的值与F有一定差别，例如相差1GHz，则f1-2*f RF与f1-2F之间相差2GHz，将该频率差调成2GHz才可实现f3与目标频率相同，即参考信号的频率可以设定为2GHz，通过调节第二波长可调激光器的输出波长，直到该频率差与参考信号的差值为0即可。依此类推，可以保证在多波长激光器输出的激光信号中，不同激光信号的实际频率间隔等于各自的目标频率间隔。
由于在相位调制器生成的多波长光信号具有精准的频率间隔，因此，在本申请实施例公开的多波长激光器输出的激光信号中，不同激光信号的实际频率间隔与各自的目标频率间隔的偏差很小。又由于多波长激光器输出的激光信号直接来自于波长可调激光器，因此，多波长激光器的输出激光信号具有与单个波长可调激光器相同的高输出功率、窄线宽、高SMSR以及高OSNR等特性。
应理解，在多波长激光器输出的激光信号中，与第一激光信号的波长相邻的激光信号指的是，在第一激光信号的高频侧和低频侧，分别与第一激光信号的频率差距最小的激光信号。以多波长激光器包括四路输出为例，假设第一激光信号、第二激光信号、第三激光信号和第四激光信号的频率分别为50GHz、75GHz、25GHz和100GHz，此时，与第一激光信号波长相邻的是第二激光信号和第三激光信号，与第二激光信号波长相邻的是第一激光信号和第四激光信号，与第三激光信号波长相邻的是第一激光信号，与第四激光信号波长相邻的是第二激光信号。
进一步地，在目标频率间隔F比较大的情况下，可以将f RF的值设为F的n分之一，n为正整数，例如，F为75GHz，f RF可以设为25GHz或37.5GHz；F为100GHz，f RF可以 设为25GHz或50GHz；也可以将f RF的值设为与F的n分之一存在频率差，例如，F为75GHz，f RF可以设为24.5GHz或37GHz；F为100GHz，f RF可以设为25.5GHz或50.5GHz。
以F为75GHz，f RF为24.5GHz为例，假设第二激光信号的频率f2位于第一激光信号的频率f1的高频侧，且在多波长激光器输出的激光信号中，第二激光信号的波长与第一激光信号的波长相邻，则在初始设定之后，f2将被设置在f1+3*f RF附近；由于波长可调激光器的频率精度有限，f2与f1+3*f RF之间会存在一个偏差，即f2与f1的实际频率间隔与目标频率间隔之间会存在一个偏差，第一误差检测装置在接收到第二激光信号和多波长光信号之后，会获得第二激光信号与f1+3*f RF之间的频率差，还会接收到参考信号，根据该频率差与参考信号的差值来调节第二可调激光器，使其输出波长与f1+3*f RF相同，从而保证f2与f1的实际频率间隔等于目标频率间隔；由于F＝3f RF+1.5GHz，f1+3*f RF与f2的目标值相差1.5GHz，需要将该频率差调成1.5GHz，即参考信号的频率可以设定为1.5GHz。同理，如果第三激光信号的频率f3在f2的高频侧，且在多波长激光器输出的激光信号中，第三激光信号的波长与第二激光信号的波长相邻，则在初始设定之后，f3将被设置在f1+6*f RF附近；第二误差检测装置在接收到第三激光信号和多波长光信号之后，会获得第三激光信号与f1+6*f RF之间的频率差，还会接收到参考信号，由于f3的目标值为f1+2F，即f1+6*f RF+3GHz，因此需将参考频率的值设定为3GHz，根据该频率差与参考频率的差值调节第三可调激光器，使其输出波长与f1+2F相同，从而保证f3与f2的实际频率间隔等于目标频率间隔。
采用上述方式，本申请实施例公开的多波长激光器可以输出具有更大频率间隔的多波长激光信号，而且不需要大带宽的相位调制器，更容易实现。
应理解，上述实施例均以目标频率间隔相同为例进行说明，本申请的技术方案还包括不同激光信号之间的目标频率间隔不同的情况，例如，多波长激光器包括三路输出激光，其中，第二激光信号的频率f2位于第一激光信号的频率f1的高频侧，与f1的目标频率间隔为25GHz；第三激光信号的频率f3位于f1的低频侧，与f1的目标频率间隔为50GHz；将相位调制器的驱动信号的频率f RF设为25GHz，则在初始设定时，将f2设置在f1+f RF附近，将f3设置在f1-2*f RF附近即可，剩下的步骤和前面的实施例一致，不再赘述。
可选地，在图3和图4所示的实施例中，频差检测装置304包括耦合器601，光探测器602、低通滤波器603、频差检测器604和信号源605，具体的连接关系如图6所示；
耦合器601，用于接收多波长光信号和激光信号，对多波长光信号和激光信号进行干涉，将干涉后的光信号发送给光探测器602；光探测器602，用于对干涉后的光信号进行光电转换，将转换后的干涉信号发给低通滤波器603；低通滤波器603，用于对转换后的干涉信号进行低通滤波，将滤波后的干涉信号发给频差检测器604；信号源605，用于生成参考信号，将参考信号发送给频差检测请604；频差检测器604，用于获得参考信号，检测滤波后的干涉信号与参考信号之间的频率差，得到控制信号，将控制信号发送出去。可选地，频差检测装置304还包括放大器606，用于接收滤波后的干涉信号，将该信号放大，将放大后的信号发给频差检测器604。
可选地，频差检测器604包括锁相环电路701、环路滤波器702和控制器703，如图7所示，锁相环电路701，用于检测滤波后的干涉信号与参考信号之间的频率差，得到频差 信号，将频差信号发送给环路滤波器702；环路滤波器702，用于对频差信号进行环路增益和滤波，然后发给控制器703；控制器703，用于根据收到的信号，生成控制信号，将控制信号发送出去。
下面以四波长激光器为例，详细描述一下频差检测装置的功能。假设第一激光信号的频率为f1，多波长激光器输出的激光信号中，波长相邻的激光信号的目标频率间隔均为F。由于相位调制器是对第一激光信号进行调制的，因此，相位调制器生成的多波长光信号是以f1为中心频率的，各子载波的中心频率为f1+k*f RF，如图5所示，其中，f RF为相位调制器的驱动信号的频率；k为整数，k为负值表示子载波位于f1的低频侧；k为正值表示子载波位于f1的高频侧。
假设F与f RF的值相同或接近，将第二激光信号的频率f2设置在f1-f RF附近，将第三激光信号的频率f3设置在f1+f RF附近，将第四激光信号的频率f4设置在f1+2f RF附近；由于波长可调激光器的频率精度有限，f2与f1-f RF之间会存在一个偏差Δf1，|Δf1|＝|f2-(f1-f RF)|。
当多波长光信号和第二激光信号输入到第一频差检测装置的耦合器时，两个信号会在耦合器处发生干涉，得到干涉后的光信号，其中，该干涉后的光信号也包括多个不同频率的子载波，该干涉后的光信号中各子载波的频率为第二激光信号的频率f2分别与多波长光信号中每个子载波的频率之间的差的模值，因此，该干涉后的光信号的子载波中，频率最低为|Δf1|＝|f2-(f1-f RF)|，其他各个子载波的频率为|Δf1±a*f RF|，其中，a为正整数。然后，通过光探测器对该干涉后的光信号进行光电转换，将转换后的干涉信号发给低通滤波器；通过适当设置低通滤波器的带宽，就可以将该干涉信号中除频率为|Δf1|的子载波之外的所有子载波滤掉，即滤波后的干涉信号变为频率为|Δf1|的电信号。然后，通过锁相环电路对滤波后的干涉信号与参考信号进行处理，得到频差信号，将频差信号发给控制器。通过控制器调节第二波长可调激光器输出的激光信号的波长，直到滤波后的干涉信号的频率与参考信号的频率相同为止。
其中，参考信号的频率f ref与目标频率间隔F相关；假设某一路激光信号与第一激光信号的目标频率间隔为Fn，多波长光信号中的各个子载波的频率间隔为f RF，Fn与b*f RF的差值小于Fn与f RF其他倍数之间的差值，则该路激光信号对应的频率检测装置的参考信号频率为Fn与b*f RF的差值，b为正整数。
对第一频差检测装置来说，f2的目标频率为f1-F，如果f2已经调到目标频率，则f2与f1-f RF之间的偏差必然满足如下关系：|Δf1|＝|(f1-F)-(f1-f RF)|＝|f RF-F|，反过来说，必须满足这个关系，f2才能调到目标频率。因此，需要将参考信号的频率f ref设为|f RF-F|，通过锁相环电路将滤波后的干涉信号的频率调节到f ref，从而实现将f2调到目标频率的目的。对第二频差检测装置来说，f3的目标频率为f1+F，如果f3已经调到目标频率，则f3与f1+f RF之间的偏差必然满足如下关系：|Δf2|＝|(f1+F)-(f1+f RF)|＝|F-f RF|，同理，需要将参考信号的频率设为|F-f RF|。对第三频差检测装置来说，f4的目标频率为f1+2F，如果f4已经调到目标频率，则f4与f1+2f RF之间的偏差必然满足如下关系：|Δf3|＝|(f1+2F)-(f1+2f RF)|＝2*|F-f RF|，同理，需要将参考信号的频率设为2*|F-f RF|。
如果F与2f RF的值接近，将第二激光信号的频率f2设置在f1-2f RF附近，将第三激光信号的频率f3设置在f1+2f RF附近，将第四激光信号的频率f4设置在f1+4f RF附近；则对 第一频差检测装置来说，f2的目标频率为f1-F，如果f2已经调到目标频率，则f2与f1-2f RF之间的偏差必然满足如下关系：|Δf1|＝|(f1-F)-(f1-2f RF)|＝|2f RF-F|，反过来说，必须满足这个关系，f2才能调到目标频率。因此，需要将参考信号的频率f ref设为|2f RF-F|，通过锁相环电路将滤波后的干涉信号的频率调节到f ref，从而实现将f2调到目标频率的目的。对第二频差检测装置来说，f3的目标频率为f1+F，如果f3已经调到目标频率，则f3与f1+f RF之间的偏差必然满足如下关系：|Δf2|＝|(f1+F)-(f1+2f RF)|＝|F-2f RF|，通过锁相环电路将滤波后的干涉信号的频率调节到|F-2f RF|，从而实现将f3调到目标频率的目的。对第三频差检测装置来说，f4的目标频率为f1+2F，如果f4已经调到目标频率，则f4与f1+4f RF之间的偏差必然满足如下关系：|Δf3|＝|(f1+2F)-(f1+4f RF)|＝2*|F-2f RF|，通过锁相环电路将滤波后的干涉信号的频率调节到2*|F-2f RF|，从而实现将f4调到目标频率的目的。
应理解，在多波长激光器输出的激光信号中，波长相邻的激光信号的目标频率间隔也可以不相同，例如，第二激光信号位于第一激光信号的低频侧，与第一激光信号目标频率间隔为F1，F1与c*f RF的值接近；第三激光信号位于第一激光信号的高频侧，与第一激光信号的频率间隔为F2，且F2与d*f RF的值接近，其中，c和d均为正整数；则与第二激光信号对应的第一频差检测装置的参考信号可以设为f ref＝|F1-c*f RF|，与第三激光信号对应的第二频差检测装置的参考信号可以设为f ref＝|F2-d*f RF|。
进一步地，每个频差检测装置的参考信号频率设定好之后，就可以开始调节了。假设第一激光信号的频率f1和第二激光信号的频率f2之间的目标频率间隔为F1，F1的值与n*f RF相同或接近，第二激光信号的频率f2设置在f1-n*f RF附近。滤波后的干涉信号的频率为第二激光信号的频率f2与f1-n*f RF的差值，但是无法分辨f2与f1-n*f RF之间的大小；在调节滤波后的干涉信号的频率等于第一频差检测装置的参考信号频率f ref时，可能出现(f1-n*f RF)-f2＝f ref和f2-(f1-n*f RF)＝f ref两种情况，其中只有一种情况满足要求。如图8所示，f2的目标频率为f1-n*f RF+f ref，故第二种情况才满足要求；如果出现第一种情况，f2将被调节成f1-n*f RF-f ref，无法满足要求。
为了解决上述问题，本申请实施例提出如下方案：让第二波长可调激光器输出的第二激光信号的初始频率f2满足特定条件。如果f1-F1大于f1-n*f RF，则f2初始化设定在f1-n*f RF的高频侧，即f2>f1-n*f RF，且f2与f1-n*f RF的频率差小于f2与f1+k*f RF(k≠-n)的频率差；考虑到波长可调激光器的精度问题，假设精度为±Δf，可以让f2的设定值大于f1-n*f RF+Δf的值，这样就算波长可调激光器输出波长出现了偏差，f2的实际值也不会小于f1-n*f RF。
如果f1-F1小于f1-n*f RF，则f2初始化设定在f1-n*f RF的低频侧，即f2要小于f1-n*f RF的值，且f2与f1-n*f RF的频率差小于f2与f1+k*f RF(k≠-n)的频率差；考虑到波长可调激光器的精度问题，还可以让f2的设定值小于f1-n*f RF-Δf的值。如果f1-F1＝f1-n*f RF，则只需满足f2与f1-n*f RF的频率差小于f2与f1+k*f RF(k≠-n)的频率差即可。
只要f2的初始设定值满足上述条件，就可以避免出现由于干涉后的光信号的值是正数，无法分辨f2与f1-n*f RF之间的大小，导致将f2调整到错误频率的问题。对其他激光信号的频率设定也可以参照同样的方式进行，本申请实施例不再赘述。需要说明的是，在本申请的任何实施例中，均可采用本方案对激光信号的频率进行初始设定。
可选地，频差检测器还包括第一分频器704和第二分频器705，如图7所示；第一分 频器704，用于接收滤波后的干涉信号，将滤波后的干涉信号进行分频处理，得到低频干涉信号，将低频干涉信号发送给锁相环电路701；第二分频器705，用于接收参考信号，对参考信号进行分频处理，得到低频参考信号，将低频参考信号发送给锁相环电路701；锁相环电路701，用于检测低频干涉信号与低频参考信号之间的频率差，得到频差信号，将频差信号发送给环路滤波器702进行环路增益和滤波，然后再发送给控制器703。通过控制器703调节对应的波长可调激光器输出的激光信号的波长，直到低频干涉信号的频率与低频参考信号的频率相同为止。
假设第一分频器的分频比为N，低频干涉信号的频率为分频之前的N分之一；第二分频器的分频比为M，低频参考信号的频率为分频之前的M分之一；其中一路激光信号与第一激光信号的目标频率间隔Fn与n*f RF的值接近，则与该路激光信号对应的频率检测装置中参考信号的频率满足如下关系：f ref＝(M/N)*|Fn-n*f RF|，其中，n为正整数，N和M的值可以相同，也可以不同，均大于1。
以第一频差检测装置为例，假设第二激光信号的频率f2与第一激光信号的频率f1之间的目标频率间隔为F，f2的目标频率为f1-F；如果F的值与f RF接近，f2已经调到目标频率，则f2与f1-f RF之间的偏差必然满足如下关系：|Δf1|＝|(f1-F)-(f1-f RF)|＝|f RF-F|。由于滤波后的干涉信号和参考信号分别经过N倍和M倍的分频，故需要将参考信号的频率f ref设为(M/N)*|f RF-F|，通过锁相环电路将低频干涉信号的频率调节到f ref，从而实现将f2调到目标频率的目的。利用两个分频器分别对滤波后的干涉信号以及参考信号进行降频，可以降低对锁相环电路的带宽要求，更容易实现；两个分频器的分频比可以相同，也可以不同，本申请实施例不做限定。
可选地，频差检测器还可以只包括一个分频器，例如，只包括第一分频器，则参考信号的频率f ref设为(1/N)*|f RF-F|；只包括第二分频器，则参考信号的频率f ref设为M*|f RF-F|。
可选地，在本申请另一实施例中，频差检测器304可以包括相位/频率检测器(Phase-Frequency Detector，PFD)901、频差信号发生器902和控制器903，如图9所示，该PFD 901，用于接收滤波后的干涉信号和参考信号，对滤波后的干涉信号和参考信号的频率差进行检测，将检测后的信号发送给频差信号发生器902；频差信号发生器902，用于根据检测后的信号，生成频差信号，并发送给控制器893；控制器903，用于根据该差频信号，生成控制信号，将控制信号发送出去。
进一步地，频差信号发生器902包括低通滤波器、减法器和环路滤波器；低通滤波器用于从PFD 901接收信号，并对其进行低通滤波处理，将滤波后的信号发给减法器；减法器用于将滤波后的信号减去预设的电压参考信号，得到频差信号，将频差信号发送给环路滤波器；环路滤波器用于对频差信号进行环路增益和滤波，然后再发给控制器903。
在本实施例中，频率检测器304还可以包括第一分频器904和第二分频器905；第一分频器904，用于接收滤波后的干涉信号，将滤波后的干涉信号进行分频处理，得到低频干涉信号，将低频干涉信号发送给PFD 901；第二分频器905，用于接收参考信号，对参考信号进行分频处理，得到低频参考信号，将低频参考信号发送给PFD 901；PFD 901，用于接收低频干涉信号和低频参考信号，对低频干涉信号和低频参考信号的频率差进行检测，将检测后的信号发送给频差信号发生器902。频差检测装置的具体功能已经在上个实 施例中详细描述，本申请实施例不再赘述。
需要说明的是，上述实施例中的分束器、耦合器、相位调制器、功分器以及光探测器均为偏振相关器件，可以通过集成光路或空间光学的方式实现；上述器件也可以为分立的器件，彼此之间涉及的连接可以通过保偏光纤实现。当然，上述器件也可以部分集成、部分分立，本申请实施例并不做具体限定。
本申请另一实施例提供一种多波长激光器，如图10所示，该多波长激光器包括图3所示多波长激光器的器件，还包括N-1个功率检测器1001；其中，除第一分束器之外，其他的分束器302包括2个级联的耦合器(1002，1003)，其中一个耦合器1002，用于将接收的激光信号分成两份，一份发给另一个耦合器1003，一份发给频差检测装置304；另一个耦合器1003，用于将收到的激光信号分成两份，一份发送给功率检测器1001，一份作为多波长激光器的一路输出；或者，其中一个耦合器1002，用于将接收的激光信号分成两份，一份发给另一个耦合器1003，一份发给功率检测器1001；另一个耦合器1003，用于将收到的激光信号分成两份，一份发送给频差检测装置304，一份作为多波长激光器的一路输出。需要说明的是，其他的分束器302也可以采用包括至少三个输出端口的分束器来实现，将接收的激光信号分成至少三份，一份发送给频差检测装置304，一份发送给功率检测器1001，剩下的一份作为多波长激光器的输出。
功率检测器1001，用于测量对应的波长可调激光器发出的激光信号的功率，将功率值发送给控制器(703，903)；可以使控制器更好地控制对应的波长可调激光器的输出功率等输出特性。
具体地，波长可调激光器可以为分分布式布拉格反射(Distributed Bragg reflector，DBR)激光器、外腔激光器等，本实施例以图11所示的波长可调激光器的结构为例，说明功率值对控制波长可调激光器输出功率的作用。如图11所示，波长可调激光器包括反射镜1、反射镜2、增益芯片、相位区、滤波器1和滤波器2。两个反射镜用来实现激光器谐振腔的反馈，可选地，其位置可以由压电陶瓷(piezoelectric ceramic transformer，PZT)来进行微调，驱动信号由控制器(703，903)提供；反射镜1也可以由增益芯片一侧镀反射膜实现。增益芯片用来提供光产生和光放大，相位区用来精细调节激光器频率，滤波器1和滤波器2分别具有周期性的滤波谱，用来共同实现激光器波长的调节，获得覆盖C波段的波长范围。
对于现在商用的波长可调激光器，其频率精度大约为±1.5GHz。因此，在通过控制信号调节波长可调激光器输出的激光信号的频率时，波长可调激光器的输出频率可能会显著偏离滤波器1和滤波器2的滤波谱中心，从而导致激光器性能恶化。因此，该多波长激光器还可以包括扰动信号源，将生成的扰动信号加载到反射镜1和/或反射镜2上，波长可调激光器的输出光功率也会产生同频率的扰动，通过功率检测器可以获取该扰动光功率，将其发送给控制器进行处理；控制器判断滤波器1和滤波器2的总滤波谱中心与激光器输出频率的相对位置，分别反馈调节滤波器1和滤波器2的滤波谱，保证N-1个波长可调激光器的输出频率与各自的两个滤波器的总滤波谱中心波长保持动态对准，可以保证波长可调激光器的功率、SMSR等性能不会出现明显恶化。
可选地，还可以在波长可调激光器的滤波器1和/或滤波器2上加扰动信号，波长可 调激光器的输出光功率也会产生与滤波器上加载的扰动信号同频率的波动，通过功率检测器可以获取该扰动光功率，将其发送给控制器进行处理；控制器判断滤波器1和滤波器2的滤波谱中心与波长可调激光器输出波长的相对位置，再通过控制器分别反馈调节滤波器1和滤波器2的滤波谱，保证N-1个波长可调激光器的输出波长与各自的滤波器的滤波谱中心波长动态对准。
应理解，本申请实施例是以波长可调激光器包括两个滤波器为例进行描述，并不排除包括其他数量滤波器的情况，例如，波长可调激光器可以包括一个滤波器、三个滤波器等，原理并没有改变。
本申请另一实施例描述了多波长激光器的频率控制方法，如图12所示，适用于如图3-4，图6，图8-10所示的多波长激光器：
1201，将第一波长可调激光器输出的第一激光信号的一部分发送给相位调制器，生成多波长光信号，该多波长光信号的中心频率为第一波长可调激光器的输出频率f1，频率间隔为相位调制器的驱动信号频率f RF。其中，另一部分为多波长激光器的一路输出，多波长光信号中各子载波的中心频率为f1+k*f RF，k为整数，k为负值表示子载波位于f1的低频侧；k为正值表示子载波位于f1的高频侧。
1202，将剩余的N-1个波长可调激光器各自分出的一部分激光信号与多波长光信号发送给频差检测装置，生成各自波长可调激光器对应的控制信号。其中，N-1个波长可调激光器各自分出的另一部分激光信号即为多波长激光器的输出信号，频差检测装置根据激光信号和多波长光信号产生控制信号的过程在之前的装置实施例中有过详细描述，本实施例在此不再赘述。
具体的，在剩余的N-1个波长可调激光器工作之前，要对输出的频率进行初始设置，设置值与多波长光信号中对应子载波的频率差小于设置值与多波长光信号中其他子载波的频率差。进一步地，设置值是根据波长可调激光器的目标频率与该对应子载波的频率大小来确定的，具体关系如下：
假设第一波长可调激光器的频率为f1，需要初始设置的波长可调激光器的频率为f2，且f2的目标频率为f1-F，对应子载波的频率为f1-f RF，如果f1-F大于f1-f RF，则f2初始化设定在f1-f RF的高频侧，即f2>f1-f RF，且f2与f1-f RF的频率差小于f2与f1+k*f RF(k≠-1)的频率差；考虑到波长可调激光器的精度问题，假设精度为±Δf，可以让f2的设定值大于f1-f RF+Δf的值，这样就算波长可调激光器的输出波长出现了偏差，f2的实际值也不会小于f1-f RF。
如果f1-F小于f1-f RF，则f2初始化设定在f1-f RF的低频侧，即f2要小于f1-f RF的值，且f2与f1-f RF的频率差小于f2与f1+k*f RF(k≠-1)的频率差；考虑到波长可调激光器的精度问题，还可以让f2的设定值小于f1-f RF-Δf的值。
如果f1-F＝f1-f RF，则只需满足f2与f1-f RF的频率差小于f2与f1+k*f RF(k≠-1)的频率差即可。
1203，通过控制信号来控制波长可调激光器的相位区和增益芯片，改变波长可调激光器的输出频率，使得N个波长可调激光器彼此的实际频率间隔等于目标频率间隔。其中，相位区用来补偿慢变的、大幅度频率变化；增益芯片用来补偿快变的、小幅度频率变化。
可选地，在波长可调激光器中，可用温度控制单元来代替相位区的作用，故还可以通过控制信号来控制波长可调激光器的温度控制单元和增益芯片，改变波长可调激光器的输出频率，使得N个波长可调激光器彼此的实际频率间隔等于目标频率间隔，其中，温度控制单元通过改变激光器的工作温度来调节激光器的输出频率，可以用来补偿慢变的、较大幅度的频率变化。
进一步可以理解的是，本申请实施例中的电信号处理部分可以全部或部分用处理器来实现，电信号处理部分即为低通滤波器到控制器之间的部分；而在本申请实施例中涉及的处理器可以是中央处理单元(Central Processing Unit，简称为“CPU”)，还可以是其他通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现成可编程门阵列(FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
在本申请所提供的几个实施例中，应该理解到，所揭露的装置和方法，可以通过其它的方式实现。例如，以上所描述的装置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。另外，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、装置或单元的间接耦合或通信连接，也可以是电的，机械的或其它的形式连接。
以上所述仅为本发明技术方案的较佳实施例而已，并非用于限定本发明的保护范围。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (18)

  1. 一种多波长激光器，其特征在于，包括：N个波长可调激光器，N个分束器，相位调制器以及N-1个频差检测装置，其中，N为不小于2的正整数；
    第一波长可调激光器，用于生成第一激光信号，将所述第一激光信号发送给所述N个分束器中的第一分束器，其中，所述N个波长可调激光器包括所述第一波长可调激光器；
    所述第一分束器，用于将所述第一激光信号分成至少两束，将第一束第一激光信号发给所述相位调制器，其中，第二束第一激光信号为所述多波长激光器的一路输出；
    所述相位调制器，用于对所述第一束第一激光进行调制，生成多波长光信号，将所述多波长光信号发送给第一频差检测装置，其中，所述N-1个频差检测装置包括第一频差检测装置，所述多波长光信号中相邻波长的频率间隔相同；
    第二波长可调激光器，用于生成第二激光信号，将所述第二激光信号发送给所述N个分束器中的第二分束器，其中，所述N个波长可调激光器包括所述第二波长可调激光器；
    所述第二分束器，用于将所述第二激光信号分成至少两束，将第一束第二激光信号发给所述第一频差检测装置，其中，第二束第二激光信号为所述多波长激光器的另一路输出；
    所述第一频差检测装置，用于根据所述多波长光信号和所述第一束第二激光信号，得到第一控制信号，将所述第一控制信号发送给所述第二波长可调激光器，其中，所述第一控制信号用于调节所述第二波长可调激光器的输出波长，使得所述第二激光信号与所述第一激光信号的实际频率间隔等于所述第二激光信号与所述第一激光信号的目标频率间隔。
  2. 根据权利要求1所述的多波长激光器，其特征在于，在N大于2的情况下，所述多波长激光器还包括：功分器；
    所述相位调制器，用于将所述多波长光信号发送给所述功分器；
    所述功分器，将所述多波长光信号分成至少N-1路多波长光信号，将第一路多波长光信号发送给所述第一频差检测装置，将第二路多波长光信号发送给第二频差检测装置，其中，所述N-1个频差检测装置包括第二频差检测装置；
    第三波长可调激光器，用于生成第三激光信号，将所述第三激光信号发送给所述N个分束器中的第三分束器，其中，所述N个波长可调激光器包括所述第三波长可调激光器；
    所述第三分束器，用于将所述第三激光信号分成至少两束，将第一束第三激光信号发给所述第二频差检测装置，其中，第二束第三激光信号为所述多波长激光器的一路输出；
    所述第二频差检测装置，用于根据所述第二路多波长光信号和所述第一束第三激光信号，得到第二控制信号，将所述第二控制信号发送给所述第三波长可调激光器，其中，所述第二控制信号用于调节所述第三波长可调激光器的输出波长，使得所述第三激光信号与所述第一激光信号的实际频率间隔等于所述第三激光信号与所述第一激光信号的目标频率间隔。
  3. 根据权利要求1或2所述的多波长激光器，其特征在于，所述多波长激光器还包括射频信号源，
    所述射频信号源，用于生成射频信号，发给所述相位调制器；
    所述调制器，用于根据所述射频信号，对所述第一束第一激光进行调制，生成多波长 光信号，其中，所述多波长光信号中相邻波长的间隔与所述射频信号的频率相关。
  4. 根据权利要求1-3任一项所述的多波长激光器，其特征在于，
    从属波长可调激光器的目标频率与所述多波长光信号中对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差，则所述从属波长可调激光器的初始频率与所述对应子载波的频率差小于所述从属波长可调激光器的初始频率与所述其他子载波的频率差，其中，所述从属波长可调激光器为所述N个波长可调激光器中除第一波长可调激光器之外的任意一个。
  5. 根据权利要求4所述的多波长激光器，其特征在于，如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率大于所述对应子载波的频率；如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率小于所述对应子载波的频率。
  6. 根据权利要求4所述的多波长激光器，其特征在于，如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率减去所述从属波长可调激光器的最大频率误差值得到的频率大于所述对应子载波的频率；如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率加上所述从属波长可调激光器的最大频率误差值得到的频率小于所述对应子载波的频率。
  7. 根据权利要求1-6任一项所述的多波长激光器，其特征在于，所述频差检测装置包括耦合器，光探测器、低通滤波器、频率检测器和信号源；
    所述耦合器，用于接收所述多波长光信号和激光信号，对所述多波长光信号和激光信号进行干涉，将干涉后的光信号发送给所述光探测器；
    所述光探测器，用于对所述干涉后的光信号进行光电转换，将转换后的干涉信号发给所述滤波器；
    所述低通滤波器，用于对所述转换后的干涉信号进行低通滤波，将滤波后的干涉信号发给所述频率检测器；
    所述信号源，用于生成参考信号，将所述参考信号发送给所述频率检测器；
    所述频率检测器，用于检测所述滤波后的干涉信号与所述参考信号之间的频率差，得到控制信号，将所述控制信号发送出去。
  8. 根据权利要求7所述的多波长激光器，其特征在于，所述频率检测器包括锁相环电路、环路滤波器和控制器；
    所述锁相环电路，用于获取所述参考信号，检测所述滤波后的干涉信号与所述参考信号之间的频率差，得到所述频差信号，将所述频差信号发送给所述环路滤波器；
    所述环路滤波器，用于对所述频差信号进行环路增益和滤波，然后发给所述控制器；
    所述控制器，用于根据接收到的信号生成所述控制信号，将所述控制信号发送出去。
  9. 根据权利要求8所述的多波长激光器，其特征在于，所述参考信号的频率为所述从属波长可调激光器的目标频率与所述多波长光信号中对应子载波频率的差值，其中，所述目标频率与所述对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差。
  10. 根据权利要求8所述的多波长激光器，其特征在于，所述频率检测器还包括第一 分频器和第二分频器；
    所述第一分频器，用于接收所述滤波后的干涉信号，将所述滤波后的干涉信号进行分频处理，得到低频干涉信号，将所述低频干涉信号发送给所述锁相环电路；
    所述第二分频器，用于接收所述参考信号，对所述参考信号进行分频处理，得到低频参考信号，将所述低频参考信号发送给所述锁相环电路；
    所述锁相环电路，用于检测所述低频干涉信号与所述低频参考信号之间的频率差，得到所述频差信号，将所述频差信号发送给所述环路滤波器。
  11. 根据权利要求10所述的多波长激光器，其特征在于，所述参考信号的频率为所述从属波长可调激光器的目标频率与所述多波长光信号中对应子载波频率的差值的M/N，其中，N和M分别为所述第一分频器和所述第二分频器的分频比，均大于1；所述目标频率与所述对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差。
  12. 根据权利要求7所述的多波长激光器，其特征在于，所述频率检测器包括相位/频率检测器(PFD)、低通滤波器、减法器、环路滤波器和控制器；
    所述PFD，用于接收所述滤波后的干涉信号和所述参考信号，产生与频率差相关的信号并发送给所述低通滤波器；
    所述低通滤波器，用于对接收的信号进行低通滤波处理，将滤波后的信号发给所述减法器；
    所述减法器，用于将所述滤波后的信号减去预设的电压参考信号，得到频差信号，将所述频差信号发送给所述环路滤波器；
    所述环路滤波器，用于对所述频差信号进行环路增益和滤波，然后发给所述控制器；
    所述控制器，用于根据接收到的信号生成所述控制信号，将所述控制信号发送出去。
  13. 根据权利要求8-12所述的多波长激光器，其特征在于，所述多波长激光器还包括N-1个功率检测器，所述N-1个功率检测器与N-1个从属波长可调激光器一一对应，所述从属波长可调激光器为所述N个波长可调激光器中除第一波长可调激光器之外的任意一个；
    从属分束器，用于将接收到的激光信号分成至少三束，将其中一束发给对应的频率检测装置，另一束发送给功率检测器，第三束作为多波长激光器的输出，其中，所述从属分束器为所述N个分束器中除与所述第一波长可调激光器连接的分束器之外的任意一个；
    所述功率检测器，用于测量对应的从属波长可调激光器发出的激光信号的功率，将功率值发送给所述控制器。
  14. 根据权利要求1-13所述的多波长激光器，其特征在于，所述N个分束器、所述相位调制器以及所述功分器均为保偏器件，波长可调激光器与对应的频差检测装置之间包括的连接为保偏光纤，光波导和空间光中的任意一种或多种。
  15. 一种多波长激光器的频率控制方法，其特征在于，所述多波长激光器包括N个波长可调激光器，N个分束器，相位调制器以及N-1个频差检测装置，其中，N个波长可调激光器包括基准波长可调激光器和N-1个从属波长可调激光器；所述基准波长可调激光器与一个分束器相连，所述分束器包括第一输出端口和第二输出端口，所述第一输出端口作 为所述多波长激光器的输出端口，所述第二输出端口与所述相位调制器相连；所述相位调制器与所述N-1个频差检测装置分别相连；所述N-1个从属波长可调激光器分别与剩余的N-1个分束器以及N-1个频差检测装置一一对应，所述从属波长可调激光器与对应的分束器相连，所述对应的分束器包括第三输出端口和第四输出端口，所述第三输出端口作为所述多波长激光器的输出端口，所述第四输出端口与对应的频差检测装置相连；其中，N为不小于2的正整数；所述频率控制方法包括：
    将第一波长可调激光器输出的第一激光信号的一部分发送给相位调制器，生成多波长光信号，其中，所述多波长光信号的中心频率为所述第一波长可调激光器的输出频率，频率间隔为所述相位调制器的驱动信号频率；
    将所述从属波长可调激光器分出的一部分激光信号与所述多波长光信号发送给所述频差检测装置，生成所述从属波长可调激光器对应的控制信号，其中，所述从属波长可调激光器的目标频率与所述多波长光信号中对应子载波的频率差小于所述目标频率与所述多波长光信号中其他子载波的频率差；所述从属波长激光器设置的初始频率与所述对应子载波的频率差小于所述初始频率与多波长光信号中其他子载波的频率差；
    通过所述控制信号来改变所述波长可调激光器的输出频率，使得所述N个波长可调激光器输出的激光信号彼此的实际频率间隔等于目标频率间隔。
  16. 根据权利要求15所述的频率控制方法，其特征在于，
    如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率大于所述对应子载波的频率；
    如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率小于所述对应子载波的频率。
  17. 根据权利要求15所述的频率控制方法，其特征在于，
    如果所述从属波长可调激光器的目标频率大于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率减去所述从属波长可调激光器的最大频率误差值得到的频率大于所述对应子载波的频率；
    如果所述从属波长可调激光器的目标频率小于所述对应子载波的频率，则所述从属波长可调激光器设置的初始频率加上所述从属波长可调激光器的最大频率误差值得到的频率小于所述对应子载波的频率。
  18. 根据权利要求15-17任一项所述的频率控制方法，其特征在于，所述波长可调激光器包括第一反射镜、第二反射镜、增益芯片、相位区和滤波器；所述方法还包括：
    在所述第一反射镜、所述第二反射镜和所述滤波器中的任一种或多种器件上加载抖动信号；
    检测所述波长可调激光器的输出功率，根据检测到的功率值，得到所述滤波器的滤波谱中心频率与所述波长可调激光器输出频率的相对位置；
    根据所述相对位置，对所述滤波器的滤波谱中心频率进行调节。
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100914559B1 (ko) * 2008-04-14 2009-09-02 한국과학기술원 발진 파장을 자동으로 조절하는 파장 가변 레이저 장치 및방법, 및 이를 구비한 파장 분할 다중방식 광전송 시스템및 수동형 광 가입자망
CN102608825A (zh) * 2012-03-02 2012-07-25 北京航空航天大学 一种实现多频光梳的方法和系统
CN102771066A (zh) * 2009-12-24 2012-11-07 韩国科学技术院 用于控制可调谐激光器的激射波长的设备及方法以及包括该设备的波分复用无源光网络
CN103197439A (zh) * 2013-03-01 2013-07-10 西南交通大学 一种可实现复系数的微波光子滤波器结构
CN105589074A (zh) * 2015-11-27 2016-05-18 中国人民解放军国防科学技术大学 基于飞秒光梳同步锁频的多波长干涉实时绝对测距装置

Family Cites Families (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3453559A (en) * 1966-04-01 1969-07-01 Sperry Rand Corp Multiple laser amplifier phase control system
DE59808542D1 (de) * 1997-03-26 2003-07-03 Infineon Technologies Ag Lasermodul mit wellenlängenstabilisierung
GB0025662D0 (en) 2000-10-19 2000-12-06 Secr Defence Frequency synthesiser
US6430336B1 (en) * 2000-12-18 2002-08-06 Ciena Corporation Device and method for minimizing optical channel drift
JP3732788B2 (ja) * 2002-02-08 2006-01-11 日本電信電話株式会社 光波長多重アクセスネットワーク
US6961356B2 (en) * 2002-12-16 2005-11-01 Alcatel Integrated wavelength combiner/locker
US20040213303A1 (en) * 2003-04-22 2004-10-28 General Instrument Corporation Optical frequency synthesizer
EP1696201A1 (de) * 2005-02-23 2006-08-30 Leica Geosystems AG Phasenrauschkompensation für interferometrische Absolutdistanzmesser
JP4402071B2 (ja) * 2006-04-28 2010-01-20 日本電信電話株式会社 高密度多波長光源
US7986413B2 (en) * 2008-01-14 2011-07-26 New Jersey Institute Of Technology Methods and apparatus for rapid scanning continuous wave terahertz spectroscopy and imaging
US7995630B2 (en) 2008-04-01 2011-08-09 Rakuljic George A High performance tunable lasers utilizing optical phase-locked loops
WO2009137263A2 (en) * 2008-04-18 2009-11-12 New Jersey Institute Of Technology Ultra-miniaturized thz communication device and system
CN101321019B (zh) * 2008-07-03 2011-07-20 上海交通大学 产生精确波长间隔和高平坦度的多波长光源的装置和方法
GB2477650B (en) * 2008-10-24 2014-05-14 Spi Lasers Uk Ltd Apparatus for combining laser radiation
US20110280581A1 (en) * 2010-05-12 2011-11-17 Massachusetts Institute Of Technology Systems and methods for producing high-power laser beams
US9124371B2 (en) * 2011-04-01 2015-09-01 Infinera Corporation Apparatus to control carrier spacing in a multi-carrier optical transmitter
CN102637995A (zh) * 2012-04-25 2012-08-15 天津大学 一种功率比例可调的双波长或多波长激光器
CN103067092A (zh) * 2012-12-28 2013-04-24 华为技术有限公司 多波长光源装置
CN103066494A (zh) * 2013-01-05 2013-04-24 华中科技大学 一种可调谐半导体激光器
US9239264B1 (en) * 2014-09-18 2016-01-19 Joseph R. Demers Transceiver method and apparatus having phase modulation and common mode phase drift rejection
US9490902B2 (en) * 2015-01-13 2016-11-08 Huawei Technologies Co., Ltd. Optical power system for digital-to-analog link
US20160204868A1 (en) * 2015-01-13 2016-07-14 Huawei Technologies Co., Ltd. Summation of Parallel Modulated Signals of Different Wavelengths
CN106411413A (zh) * 2016-09-28 2017-02-15 北京无线电计量测试研究所 一种基于光源阵列的梳状谱信号产生装置
US10578494B1 (en) * 2017-02-10 2020-03-03 Lockheed Martin Coherent Technologies, Inc. Compact wavelength meter and laser output measurement device
US10408925B1 (en) * 2017-07-19 2019-09-10 The United States Of America As Represented By The Secretary Of The Navy Low probability of intercept laser range finder

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100914559B1 (ko) * 2008-04-14 2009-09-02 한국과학기술원 발진 파장을 자동으로 조절하는 파장 가변 레이저 장치 및방법, 및 이를 구비한 파장 분할 다중방식 광전송 시스템및 수동형 광 가입자망
CN102771066A (zh) * 2009-12-24 2012-11-07 韩国科学技术院 用于控制可调谐激光器的激射波长的设备及方法以及包括该设备的波分复用无源光网络
CN102608825A (zh) * 2012-03-02 2012-07-25 北京航空航天大学 一种实现多频光梳的方法和系统
CN103197439A (zh) * 2013-03-01 2013-07-10 西南交通大学 一种可实现复系数的微波光子滤波器结构
CN105589074A (zh) * 2015-11-27 2016-05-18 中国人民解放军国防科学技术大学 基于飞秒光梳同步锁频的多波长干涉实时绝对测距装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP3855646A4

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