WO2008022579A1 - Dispositif et procédé d'alignement du mode d'une source lumineuse, ainsi que système de réseau optique passif - Google Patents

Dispositif et procédé d'alignement du mode d'une source lumineuse, ainsi que système de réseau optique passif Download PDF

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Publication number
WO2008022579A1
WO2008022579A1 PCT/CN2007/070398 CN2007070398W WO2008022579A1 WO 2008022579 A1 WO2008022579 A1 WO 2008022579A1 CN 2007070398 W CN2007070398 W CN 2007070398W WO 2008022579 A1 WO2008022579 A1 WO 2008022579A1
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WIPO (PCT)
Prior art keywords
signal
laser
voltage
temperature control
light source
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PCT/CN2007/070398
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English (en)
French (fr)
Inventor
Xuliang Zhang
Jun Zhao
Tao Jiang
Wei Huang
Huafeng Lin
Yuntao Wang
Guo Wei
Jun Chen
Feng Wang
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Huawei Technologies Co., Ltd.
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Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Publication of WO2008022579A1 publication Critical patent/WO2008022579A1/zh
Priority to US12/367,822 priority Critical patent/US7929584B2/en

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Classifications

    • 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
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
    • H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
    • H04J14/0245—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU
    • H04J14/0246—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for downstream transmission, e.g. optical line terminal [OLT] to ONU using one wavelength per ONU
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
    • H04J14/0241—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths
    • H04J14/0242—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON
    • H04J14/0249—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU
    • H04J14/025—Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths in WDM-PON for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0278—WDM optical network architectures
    • H04J14/0282—WDM tree architectures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/03—WDM arrangements
    • H04J14/0307—Multiplexers; Demultiplexers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/58—Arrangements comprising a monitoring photodetector
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J14/00—Optical multiplex systems
    • H04J14/02—Wavelength-division multiplex systems
    • H04J14/0226—Fixed carrier allocation, e.g. according to service

Definitions

  • the present invention relates to the field of optical communications, and in particular, to a light source mode aligning apparatus and method, and a passive optical network system.
  • WDM-PON Wiband Multiplexer Passive Optical Network
  • PON Passive Optical Network
  • the colorless light source mainly includes an injection-locked Fabry Perot Laser Diode (FP-LD), a Reflective Semiconductor Optical Amplifier (RSOA), and a Superluminescent LED (SLED).
  • FP-LD injection-locked Fabry Perot Laser Diode
  • RSOA Reflective Semiconductor Optical Amplifier
  • SLED Superluminescent LED
  • the cost of injection-locked FP-LD is the lowest, and the most popular.
  • the FP-LD has a plurality of longitudinal modes. If the injection wavelength cannot be aligned with one of the longitudinal modes, the width of the injected light will increase, and the output optical power of the FP-LD will be significantly lower than that at the time of alignment. Moreover, as the external temperature changes, the mode will also change, resulting in a large change in the output optical power.
  • FIG. 1 shows a prior art injection-lock FP-LD solution.
  • the broad-spectrum light emitted by the broad-spectrum light source 10 passes through the circulator 11 and enters a wave decomposition multiplexer (DMUX) 12.
  • the spectrum of the broad-spectrum light is split into a plurality of narrow-spectrum lights by the DMUX 12, and narrow wavelengths of different wavelengths are output from each channel of the DMUX 12.
  • the light is spectrally injected and injected into the corresponding FP-LD laser 13.
  • the FP-LD13 will output light of the same wavelength as the injected light, while suppressing light of other wavelengths.
  • the signal can be loaded into the output light of the FP-LD13 by modulating the drive current of the FP-LD13.
  • the 13 lights of all FP-LDs pass through a wavelength division multiplexer (MUX, the same device as DMUX), which are combined into a multi-channel WDM signal and output through the circulator 11.
  • MUX wavelength
  • the structure of the conventional conventional FP-LD laser module includes an FP-LD chip 21, an MPD (Monitor Photo Detector) 22, and an amplifier 23 (optional).
  • the rear end face of the FP-LD chip is not ideal for total reflection, but has a certain loss, so that a part of the laser energy transmitted by the FP-LD chip is incident through the end face into the MPD located behind the end face. Since the MPD is actually a photodiode, it can convert the incident laser into a current output, which is amplified by the amplifier and used as a feedback input to the laser driver chip to ensure a constant optical power output from the FP-LD laser.
  • the laser assembly typically includes a thermoelectric controller (TEC) and a thermistor 24 (negative temperature coefficient).
  • TEC thermoelectric controller
  • thermistor 24 negative temperature coefficient
  • the temperature-controlled current is adjusted according to the temperature of the LD (laser diode) measured by the thermistor, and the closed-loop negative feedback is realized, so that the LD is kept at a constant temperature, thereby ensuring the stability of power and wavelength.
  • FP-LD is a multi-longitudinal mode laser.
  • the side mode suppression ratio (the ratio of the power of the main mode to the power of the adjacent mode) is relatively low, when the wavelength of the injected light corresponds to the center of the main mode and corresponds to the mode.
  • the output optical power Because of the drift of the AWG (Array Wave Guide) channel and the FP-LD temperature and the inconsistency of the FP-LD longitudinal mode, the output power of the FP-LD is random, and when the injected light is aligned with the vertical mode valley, The threshold for injection locking will also increase.
  • the usual method is to plate the anti-reflection film on the front surface of the FP-LD, weakening the mode of the FP-LD, but introducing a relatively large power penalty (power penalty in the prior art)
  • the mode of the FP-LD is weakened. Since the mode mismatch of -0.2 nm and +0.07 nm will cause a power penalty of 3 dB.
  • Embodiments of the present invention provide a light source mode aligning apparatus and method for achieving automatic alignment of a wavelength with a longitudinal mode of a laser to ensure stability of a laser output power.
  • the embodiment of the invention further provides a passive optical network system, so that the light source in the passive optical network system outputs stable power and ensures reliable operation of the passive optical network system.
  • Embodiments of the present invention provide a light source mode aligning apparatus including a connected laser and a temperature control unit, and a signal processing unit that converts injected light into a current signal, the current signal being amplified and converted into a voltage signal And adjusting a bias voltage of the temperature control unit together with a modulation signal generated by the signal processing unit.
  • the embodiment of the invention further provides a light source mode aligning device, comprising a connected laser and a temperature control unit, further comprising a photodetector and a signal processing unit, wherein the photodetector converts one of the output light into a current signal And the current signal is amplified and converted into a voltage signal, and the bias voltage of the temperature control unit is adjusted together with the modulation signal generated by the signal processing unit.
  • a light source mode aligning device comprising a connected laser and a temperature control unit, further comprising a photodetector and a signal processing unit, wherein the photodetector converts one of the output light into a current signal And the current signal is amplified and converted into a voltage signal, and the bias voltage of the temperature control unit is adjusted together with the modulation signal generated by the signal processing unit.
  • the embodiment of the invention further provides a light source mode alignment method, including:
  • the bias voltage of the laser is adjusted according to the phase relationship.
  • the embodiment of the present invention further provides a passive optical network system, including: an optical line terminal, an optical distribution network, and an optical network unit, including an adaptive mode alignment light source in the optical line terminal and/or the optical network unit;
  • the adaptive mode alignment light source comprises: a connected laser and a temperature control unit, further comprising a signal processing unit, the laser converting the injected light into a current signal, the current signal being amplified and converted into a voltage signal, and the signal processing unit
  • the generated modulated signals collectively adjust the bias voltage of the temperature control unit.
  • An embodiment of the present invention further provides a passive optical network system, including: an optical line terminal, an optical distribution network, and an optical network unit, including an adaptive mode alignment light source in the optical line terminal and/or the optical network unit;
  • the adaptive mode alignment light source comprises: a connected laser and a temperature control unit, further comprising a photodetector and a signal processing unit, wherein the photodetector converts one of the output light into a current signal, the current signal Amplified and converted into a voltage signal, the bias voltage of the temperature control unit is adjusted in conjunction with the modulated signal generated by the signal processing unit.
  • Embodiments of the present invention achieve automatic alignment of wavelengths with longitudinal modes of the laser (without manual calibration) at low cost (which can be used with conventional AWGs, not limited to athermal AWGs) to compensate for the effects of temperature variations. Moreover, under the interference of optical power drift and wavelength drift caused by various factors, the light source mode aligning device of the embodiment of the invention can still achieve mode alignment, because the phase information of the signal is used, which has strong resistance. Interference ability.
  • the light source mode aligning device is used as a light source terminal of the passive optical network system and/or a light source in the optical network unit, and can output stable power to ensure reliable operation of the passive optical network system.
  • Figure 1 is a schematic diagram of a prior art injection locking FP-LD scheme.
  • FIG. 2 is a schematic view showing the structure of a conventional ordinary laser.
  • Figure 3 is a graph showing the output optical power as a function of LD temperature.
  • Figure 4 (a) is a plot of output power as a function of modulation current as the wavelength is aligned with the rising edge of the longitudinal mode.
  • Figure 4 (b) is a plot of output power as a function of modulation current as the wavelength is aligned with the falling edge of the longitudinal mode.
  • Figure 4 (c) is a graphical representation of output power as a function of modulation current as the wavelength is aligned with the center of the longitudinal mode.
  • Figure 5 is a structural view showing a first embodiment of the light source mode aligning apparatus of the present invention.
  • Figure 6 is a structural view showing a second embodiment of the light source mode aligning device of the present invention.
  • Figure 7 is a structural view showing a third embodiment of the light source mode aligning device of the present invention.
  • Figure 8 is a structural view showing a fourth embodiment of the light source mode aligning device of the present invention.
  • Fig. 9 is a flow chart showing the anti-deadlock of the temperature scanning method in the embodiment of the present invention.
  • FIG. 10 is a flow chart of the power threshold judgment method for preventing deadlock in the embodiment of the present invention.
  • Fig. 11 is a flow chart showing the anti-deadlock by the disturbance interference method in the embodiment of the present invention.
  • Figure 12 is a block diagram showing the first embodiment of the WDM-PON system of the present invention.
  • Figure 13 is a block diagram showing a second embodiment of the WDM-PON system of the present invention.
  • Figure 3 shows the variation of output optical power with temperature in the case where the wavelength of the injected light is constant:
  • the longitudinal mode moves toward the long wavelength, and the output optical power changes with the profile of the longitudinal mode.
  • a small periodic change is introduced to the temperature of the laser, if the injected light is not aligned with the center of the longitudinal mode, the wavelength variation caused by a small temperature change will cause a large power fluctuation due to the steep edge of the longitudinal mode.
  • the temperature adjustment direction can be judged based on the power fluctuation and the phase relationship of the temperature modulation signal.
  • the change in optical power is in phase with the temperature modulated signal, as shown in Figure 4 (a).
  • the negative voltage will correspond to the negative voltage of the modulated signal
  • the positive voltage corresponds to the positive voltage of the modulated signal, but the integral IPM of their product is greater than zero.
  • the temperature should be adjusted in a high direction, that is, the bias voltage is increased.
  • the injection light can be accurately aligned with the center of the longitudinal mode.
  • Adjusting the bias voltage can be done in a variety of ways, such as linear adjustment methods and PID (Proportional-Integral-Differential) control methods.
  • the voltage can be adjusted to the exact value as quickly as possible. This will be described in detail below.
  • IPM is the integral value of the product of the power signal and the modulated signal after the second amplification
  • c is a constant
  • t is the adjustment time (divide by t to avoid causing the algorithm to oscillate).
  • A, B, and C are constants.
  • the modulation signal applied to the temperature control voltage is a small low frequency signal, and the amplitude is selected according to the line width of the FP-LD longitudinal mode.
  • the temperature adjustment range is small to basic. It does not cause a change in optical power.
  • the low frequency is used to avoid interference with high frequency digital signals. In general, the lower the response frequency, the cheaper the PD is, and the higher the sensitivity.
  • existing FP-LD lasers include FP-LD chips, MPD (or PD), TEC, thermistor (negative temperature coefficient), and amplifier (including transimpedance amplifier) components, which can provide ATC. (Automatic Temperature Control) function and APC (Automatic Power Control) function. Therefore, in order to realize the closed-loop control function of the injection light alignment longitudinal mode, the light source alignment device of the embodiment of the present invention introduces a signal processing function and a feedback control function in the existing FP-LD laser.
  • MPD refers to a laser backlight photodetector
  • PD refers to a photodetector external to the laser, unless otherwise specified.
  • the light source mode aligning device of the embodiment of the invention converts the injected light into a current signal by a laser, the current signal is amplified by a transimpedance amplifier and converted into a voltage signal; generated by a signal processing unit Modulating the signal; and adjusting the bias voltage of the temperature control unit by the voltage signal and the modulation signal.
  • the temperature control unit includes a thermoelectric controller, a thermistor, and a temperature controlled driver.
  • FIG. 5 a structure diagram of a light source mode alignment device according to a first embodiment of the present invention is shown:
  • the injected light passes through the circulator 51 into the FP-LD 501 in the universal laser module 50, and the FP-LD 501 acts as an optical pump to excite the FP-LD chip to generate laser light, and a part of the laser (most of the energy) is emitted through the front end surface of the FP-LD chip.
  • the output light is formed, and another portion forms the back light of the laser through the rear end surface of the FP-LD chip, and the back light is detected by the MPD 502 and converted into a current signal, which is located across the common laser module 50.
  • the resistance amplifier 503 is amplified to become a voltage signal, which is then transmitted to the signal processing unit 52.
  • the signal processing unit 52 is implemented by an analog circuit, and the specific processing is as follows:
  • the band-pass filter 521 first band-pass filters the voltage signal with the frequency of the temperature-controlled current as a center frequency (the DC component is removed), and filters out each of the voltage signals.
  • the interference signal and the DC component of the optical power variation caused by the factors obtain a voltage signal including the output optical power fluctuation information, and then the amplified voltage signal is dynamically amplified by the amplifier 522 to obtain a voltage having the same amplitude of the output signal and the amplitude of the modulated signal.
  • Signal power-varying voltage signal with consistent amplitude).
  • the modulated signal generator 523 in the signal processing unit 52 produces a modulated signal that is delayed by a delay 524 (to compensate for the time difference between the temperature controlled current and the wavelength response), and the amplified amplitude as previously described.
  • the consistent power varying voltage signals together enter phase detector 525.
  • the phase detector 525 is composed of a multiplier and an integrator, and the integrated value IPM of the two signals (reflecting the phase relationship between the two signals) is output to the bias voltage generator 526 to adjust the bias for temperature control. Voltage, specific adjustment methods can refer to the previous description.
  • the bias voltage outputted by the bias voltage generator 526 and the modulation signal generated by the modulation signal generator 523 are weighted and added to obtain a voltage, which is applied to the TEC 504 of the universal laser module 50 via the temperature control driver 53 to control the FP-LD.
  • the temperature causes the longitudinal mode of the FP-LD to move in the direction of the alignment injection light wavelength, thereby finally achieving the alignment of the injection light with the longitudinal mode center.
  • the circulator in Figure 5 can be replaced by a 1x2 bidirectional coupler if 3dB attenuation is not considered.
  • the adaptive mode alignment light source can be implemented by an analog circuit, and the power value measured by the PD can also be used. In this case, it is implemented by digital signal processing.
  • This embodiment is basically the same as the first embodiment shown in Fig. 5, except that in the present embodiment, the signal processing unit is realized by a digital circuit.
  • the voltage signal output from the universal laser module 50 reflecting the backlight power is sent to the A/D module 61 for sampling to obtain a digitized power signal. Thereafter, the digitized power signal is sent to signal processing unit 62 for digital signal processing.
  • the signal processing unit 62 processes the digitized power signal in accordance with the analog processing shown in Fig. 5, except that all processing is digital processing, and the processing shown in Fig. 5 is analog processing.
  • the processing of the digitized power signal by signal processing unit 62 is as follows:
  • the band pass filter 621 band-pass filters the voltage signal with the frequency of the temperature-controlled current as the center frequency (the DC component is removed), and filters out the optical power variation caused by various factors in the voltage signal.
  • the interference signal and the DC component obtain a voltage signal containing the output optical power fluctuation information, and then the amplifier 622 dynamically amplifies the filtered voltage signal to obtain a voltage signal having the same amplitude of the output signal and the amplitude of the modulated signal (power variation with the same amplitude) Voltage signal).
  • the modulated signal generator 623 in the signal processing unit 62 produces a modulated signal that is delayed by the delay 624 (to compensate for the time difference between the temperature controlled current and the wavelength response), and the amplified amplitude as previously described.
  • the consistent power varying voltage signals together enter phase detector 625.
  • the phase detector 625 is composed of a multiplier and an integrator, and the integrated value IPM of the two signals (reflecting the phase relationship between the two signals) is output to the bias voltage generator 626 to adjust the bias for temperature control. Voltage, specific adjustment methods can refer to the previous description.
  • the bias voltage output from the bias voltage generator 626 and the modulation signal generated by the modulation signal generator 623 are weighted and added to obtain a voltage, which is converted into an analog signal by the D/A module 63, and enters the temperature control driver 53.
  • the temperature control driver 53 is applied to the TEC 504 of the universal laser module 50 to control the temperature of the FP-LD so that the longitudinal mode of the FP-LD moves toward the direction of the aligned injection light wavelength, thereby finally achieving the alignment of the injection light with the longitudinal mode center. .
  • the light source mode aligning device of the embodiment of the invention can also output the light from the laser by the photodetector Converting an optical signal into a current signal, the current signal being amplified by a transimpedance amplifier and converted into a voltage signal; generating a modulation signal by the signal processing unit; the voltage signal and the modulation signal jointly adjusting a bias of the temperature control unit Voltage.
  • the temperature control unit includes a thermoelectric controller, a thermistor, and a temperature controlled driver.
  • the injected light in this embodiment does not enter through the circulator.
  • the FP-LD enters the FP-LD through the coupler 71.
  • the injected light is introduced into the FP-LD at a certain ratio (e.g., 50%), and on the other hand, the output light of the FP-LD is derived at a certain ratio for output optical power detection.
  • the PD externally placed on the laser is used.
  • the derivation light of the coupler 71 is detected by the PD 72.
  • the PD 72 converts the optical power derived by the coupler 71 into a current signal, which is supplied to an amplifier 73 connected thereto, and the transimpedance amplifier in the amplifier 73 amplifies and converts the current signal into a voltage signal.
  • This voltage signal is output to the signal processing unit 52.
  • the processing of the voltage signal by the signal processing unit 52 is the same as that in the embodiment shown in FIG. 5, and details are not described herein again.
  • the injected light in this embodiment does not enter through the circulator.
  • the FP-LD enters the FP-LD through the coupler 71.
  • the injected light is introduced into the FP-LD at a certain ratio (e.g., 50%), and on the other hand, the output light of the FP-LD is derived at a certain ratio for output optical power detection.
  • the PD external to the laser is used.
  • the derivation light of the coupler 71 is detected by the PD 72.
  • the PD 72 converts the optical power derived from the coupler 71 into a current signal, which is sampled by the A/D module 61 to obtain a digitized power signal. Thereafter, the digitized power signal is sent to signal processing unit 62 for digital signal processing.
  • the subsequent processing is the same as the processing of the embodiment shown in FIG. 6, and details are not described herein again.
  • Embodiments of the present invention achieve automatic alignment of wavelengths with longitudinal modes of the laser (without manual calibration) at low cost (which can be used with conventional AWGs, and not limited to athermal AWGs) to compensate for the effects of temperature variations. Moreover, the present invention still suffers from interference of optical power drift and wavelength drift caused by various factors. Mode alignment can be achieved because the phase information of the signal is used and it has strong anti-interference ability.
  • the embodiment of the present invention uses the standard components of the existing semiconductor laser module: LD, TEC, MPD or PD, without increasing the cost, the signal processing uses the commonly used functional modules, so the cost of the entire device will be compared with the existing light emission. The module is similar.
  • the apparatus of the embodiment of the present invention can automatically find the position of the main longitudinal mode corresponding to the injection wavelength, a common temperature-sensitive AWG can be used, and the AWG does not require temperature control, and the cost of the AWG will be cheaper than the existing products.
  • the apparatus of the embodiment of the present invention can automatically align the mode, the injected optical power threshold is reduced, that is, the power requirement of the wide-spectrum light source as the injection source is lowered, thereby reducing the cost of the broad-spectrum light source.
  • IPM is equal to 0
  • the above algorithm will lock at the bottom of the valley, forming a deadlock.
  • the embodiment of the present invention can select three methods to avoid deadlock.
  • the first is temperature scanning. Before performing the adaptive adjustment, the temperature of the LD is scanned extensively, and the temperature corresponding to the maximum output power is selected as the starting temperature. After adjusting the initial temperature, the temperature modulation method can be used to ensure alignment of the longitudinal mode with the implantation wavelength during the entire operation of the LD.
  • Step 901 Scan the temperature of the FP-LD laser to obtain the temperature T 0 at the maximum power of the laser;
  • Step 902 Set the driving voltage corresponding to T Q to be the temperature-controlled starting bias voltage;
  • Step 903 Start the adaptive mode alignment process.
  • the second method is the power threshold method. Referring to Figure 10, when the injection wavelength corresponds to the bottom of the valley, the output power is significantly lower than when the longitudinal mode is aligned. If the output power is lower than a certain threshold, it is determined that the injection wavelength corresponds to the vicinity of the valley bottom, and the temperature is adjusted so that the output power is higher than the threshold value, so that the injection wavelength corresponds to the vicinity of the longitudinal mode center, and the adaptive mode alignment process is started. You can avoid deadlocks at the bottom.
  • Step 101 Determine whether the optical power output by the FP-LD laser is greater than a set threshold; if yes, execute 102; otherwise, perform step 103;
  • Step 102 Start an adaptive mode alignment process
  • Step 103 Adjust the temperature in one direction (increment or decrement).
  • the third method is the perturbation method. Please refer to Figure 11, if the adaptive mode alignment process begins, The IPM value is 0, then a small temperature deviation is added randomly so that the IPM value is not 0, so that the feedback process can be adjusted to the mode center.
  • Step 111 Determine whether the IPM value is 0; if yes, execute 112; otherwise, perform step 113; Step 112: change the temperature of the FP-LD laser (randomly take a smaller temperature deviation); Step 113: Start adaptive Mode alignment process.
  • the light source mode aligning device of the embodiment of the present invention can be applied to a WDM-PON system, and the light source mode aligning device is used as an OLT (Optical Line Terminal) and/or an ONU (Optical Network Unit) of the WDM-PON system.
  • the light source in the optical network unit can ensure the stability of the output power of the light source, so that the WDM-PON system can operate reliably.
  • FIG. 12 there is shown a block diagram of a first embodiment of a DM-PON system using the present invention: the system is based on a wavelength division multiplexing/demultiplexer, as shown in Figure 12, the OLT 121 is based on a second wavelength division
  • the passive optical distribution network of multiplexer/demultiplexer 122 performs data interaction with ONU 123.
  • the optical transceiver array 101 at the OLT 121 modulates the downlink data to the wide-spectrum light source 102 through the optical signal sent from the first wavelength division multiplexing/demultiplexing unit 103 of the OLT 121, and passes the first wave splitting.
  • the modulated downlink data optical signal is transmitted to the ONU 123 by the demultiplexer 103 and the passive optical distribution network.
  • the ONU 123 receives the downlink data through the optical receiver 105 in the optical transceiver 104.
  • the ONU 123 modulates the uplink data onto the upstream optical signal by the automatic mode alignment source 106, and transmits the optical data to the OLT 121 through the passive optical distribution network; the optical transceiver array 101 in the OLT 121 will pass the first wavelength division multiplexing.
  • the uplink data optical signal received by the demultiplexer 103 is converted into an uplink data electrical signal and transmitted to the clock recovery and MAC module 107 located at the OLT 121.
  • the system uses the basic characteristics of the same wavelength in the uplink and downlink directions, it can be divided into two basic situations: 1) the uplink uses a different wavelength from the downlink, and the wide-spectrum light source 102 provides the downlink optical signal to the transceiver array 101.
  • the optical signal of the upstream wavelength is also provided to the ONU 123 through the passive optical distribution network; 2) the downstream wavelength is used, and the wide spectrum light source 102 only provides the optical signal to the transceiver array 101.
  • the coupler 108 in the ONU 123 uses a WDM coupler (i.e., a splitter). Therefore, in the downstream direction, the optical receiver 105 in the optical transceiver 104 of the ONU 123 passes through The over-wavelength filter extracts the downlink data optical signal using the downlink wavelength modulation, and converts it into a downlink data electrical signal, and transmits it to the clock recovery and MAC module 109 for clock recovery and further protocol processing; in the uplink direction, the optical transceiver 104 of the ONU 123
  • the automatic mode alignment light source 106 passes through the 1:2 optical splitter 110 (corresponding to the third and fourth embodiments of the light source mode aligning device of the present invention) or the second circulator 120 (corresponding to the first embodiment of the light source mode aligning device of the present invention) And the second embodiment) receiving the upstream wavelength optical signal from the splitter, and modulating the uplink data received from the clock recovery and MAC module 109 to the upstream wave to the OLT 121.
  • the coupler 108 of the ONU 123 uses a bidirectional optical power coupler (ie, a 1:2 optical splitter), and the processing of the downlink optical signal is the same as in the first aspect described above, and the uplink direction
  • the optical signal processing procedure is similar to that of the first aspect described above, and the main difference is that the uplink data is modulated on the same optical signal as the downstream wavelength.
  • optical transceiver array 101 in the OLT 121 can also use the automatic mode alignment light source in the embodiment of the present invention, and the principle and process of modulating data and receiving data are the same as the automatic mode alignment light source 106 in the ONU 123, and will not be described again. .
  • FIG. 13 there is shown a block diagram of a second embodiment of a DM-PON system using the present invention:
  • the system is based on a wavelength division multiplexing/demultiplexer, as shown in Figure 12, the OLT 121 is based on an optical splitter.
  • the passive optical distribution network of 132 performs data interaction with the ONU 133.
  • This embodiment is basically the same as the first embodiment shown in FIG. 12, except that the optical splitter-based passive optical distribution network is used, so that it is necessary to add an allocation for the specific optical network unit in the ONU 133.
  • the process of data interaction between the OLT 121 and the ONU 133 through the passive optical distribution network based on the optical splitter 132 is similar to the embodiment shown in FIG. 12 and will not be described again.

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Description

光源模式对准装置及方法、 无源光网络系统
本申请要求于 2006 年 8 月 10 日提交中国专利局、 申请号为 200610062091.7、 发明名称为 "光源自适应模式对准装置及对准方法"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
本发明涉及光通信领域， 尤其是涉及一种光源模式对准装置及方法、无源 光网络系统。
背景技术
目前视频业务的迅猛发展使得用户对带宽的需求越来越高， DSL ( Digital Subscriber Line, 数字用户线） 的 2Mbps带宽能应付目前的数据传输业务， 但 很难满足视频业务。 EPON ( Ethernet Passive Optical Network , 以太网无源光 网络）、 GPON ( Gigabit Passive Optical Network , 千兆以太网无源光网络）等 新的宽带接入网进一步提升了接入网的带宽，但由于釆用了时分复用和突发模 式技术， 使得系统的成本居高不下， 而且所有用户共享带宽， 单用户的带宽并 没有增加很多。 视频业务的发展， 特别是高清晰度视频业务的需求， 促使人们 开发更大带宽的接入网。 WDM-PON( Wave Division Multiplexer Passive Optical Network,基于波分复用的无源光网络）继承了 WDM网络的带宽特性， 又具备 PON ( Passive Optical Network,无源光网络）的低成本特性， 引起了很多公司、 标准组织和研究机构的注意， 不少公司已经研制出了样机， 标准的制定也在日 程之中。 但总体来说， WDM-PON还不是很成熟， 还有很多需要完善的方面， 比如无色（Colorless )光源、 温度补偿、 网络升级等等。 釆用无色光源主要是 为了降低网络的维护成本并简化网络的管理。 目前， 无色光源主要有注入锁定 法布里 -珀罗激光二极管 （ FP-LD, Fabry Perot Laser Diode )、 反射式半导体 光放大器 RSOA ( Reflecting Semiconductor Optical Amplifier )、超辐射发光二极 管 SLED ( Superluminescent LED ), 这三种光源中注入锁定的 FP-LD的成本是 最低的， 最具有推广的可能性。 但 FP-LD具有多个纵模， 如果注入波长不能和 其中的一个纵模对准， 那么注入光的阔值将提高， FP-LD的输出光功率将显著 低于对准时候的功率。 而且随着外界温度的变化， 模式也会随着变化， 从而使 输出光功率发生幅度较大的变化。 图 1为一现有的注入锁定 FP-LD技术方案。 宽谱光源 10发出的宽谱光经过 环形器 11之后进入波分解复用器（DMUX ) 12, 宽谱光的频谱被 DMUX12分割 成很多窄谱光，从 DMUX12的每个通道输出不同波长的窄谱光，并注入相应的 FP-LD激光器 13。 FP-LD13将会输出与注入光相同波长的光， 而抑制其他波长 的光。 通过对 FP-LD13的驱动电流进行调制可以将信号加载到 FP-LD13的输出 光里。 所有 FP-LD的 13光经过波分复用器（MUX, 与 DMUX为同一个器件） ， 合并在一起成为多通道 WDM信号， 经过环形器 11输出。
如图 2所示， 现有的普通 FP-LD激光器组件的结构包括一个 FP-LD芯片 21、 一个 MPD ( Monitor Photo Detector, 监测光电探测器） 22、 一个放大器 23 (可 选的）。 为了保证输出功率恒定， FP-LD芯片的后端面不是理想的全反射， 而 是有一定的损耗，使得 FP-LD芯片发送的一部分激光能量通过该端面入射到位 于该端面后面的 MPD中。 由于 MPD实际上就是一个光电二极管， 能够将入射 激光转化为电流输出， 经过放大器放大后，作为激光器驱动器芯片的一个反馈 输入， 从而保证 FP-LD激光器输出恒定的光功率。 此外， 温度变化对激光器的 输出功率和波长影响较大， 为了进一步保证功率和波长的稳定， 激光器组件通 常还包括热电控制器（TEC, Thermal Electric Control )和热敏电阻 24 (负温度 系数）。 根据热敏电阻测得的 LD ( Laser Diode, 激光二极管）的温度调整温控 电流， 实现闭环负反馈， 使得 LD保持在一个恒定的温度上， 从而保证功率和 波长的稳定。
FP-LD是一种多纵模激光器，通常边模抑制比 (主要模式的功率和邻近的 模式的功率的比）都比较低， 当注入光的波长对应于主模的中心和对应于模式 之间的低谷时， 输出光功率将有显著的差别。 因为 AWG ( Array Wave Guide, 阵列波导光栅）通道和 FP-LD温度的漂移以及 FP-LD纵模的不一致性， 使得 FP-LD的输出功率具有随机性， 而且注入光对准纵模低谷时， 注入锁定的阔值 也将提高。 为了减小模式对不准引起的这些问题， 通常的方法是在 FP-LD的 前端面镀抗反射膜， 弱化 FP-LD的模式， 但是会引入比较大的功率罚 （power penalty 在现有技术方案中， 若将前端面的反射率降低为 1 % , 弱化 FP-LD 的模式。 由于- 0.2nm 和 +0.07nm 的模式失配将引起 3dB 的功率罚 （power penalty )。 此外， 发明人在实际过程中发现， 如果不对每个 FP-LD做特定的波 长校准， 那么模式失配的范围会更大， 引起的 ONU ( Optical Network Unit, 光网络单元）之间的差异将影响系统的可靠运行。 而对每个 FP-LD做波长校 准， 会大大增加器件成本以及维护成本。 如果 AWG 不是釆用高成本的无热 AWG, 那么 AWG通道的漂移将使得通常的 FP-LD波长控制方法不再可行。 发明内容
本发明实施例提供一种光源模式对准装置及方法，以实现波长与激光器纵 模的自动对准， 保证激光器输出功率的稳定性。
本发明实施例还提供一种无源光网络系统，以使无源光网络系统中的光源 输出稳定的功率， 保证无源光网络系统的可靠运行。
本发明实施例提供一种光源模式对准装置，包括相连的激光器和温度控制 单元， 还包括信号处理单元， 所述激光器将注入光转换成电流信号， 所述电流 信号经放大并转换成电压信号，与所述信号处理单元生成的调制信号共同调节 所述温度控制单元的偏置电压。
本发明实施例还提供一种光源模式对准装置，包括相连的激光器和温度控 制单元，还包括光电探测器及信号处理单元， 所述光电探测器将输出光中的一 路光信号转换成电流信号， 所述电流信号经放大并转换成电压信号， 与所述信 号处理单元生成的调制信号共同调节所述温度控制单元的偏置电压。
本发明实施例还提供一种光源模式对准方法， 包括：
分别生成激光器的注入光功率波动信号和温度调制信号；
获取所述注入光功率波动信号和所述调制信号的相位关系；
才艮据所述相位关系调节所述激光器的偏置电压。
本发明实施例还提供一种无源光网络系统， 包括： 光线路终端， 光分配网 络， 光网络单元， 在光线路终端和 /或光网络单元中包括自适应模式对准光源； 所述自适应模式对准光源包括： 相连的激光器和温度控制单元，还包括信 号处理单元， 所述激光器将注入光转换成电流信号， 所述电流信号经放大并转 换成电压信号，与所述信号处理单元生成的调制信号共同调节所述温度控制单 元的偏置电压。
本发明实施例还提供一种无源光网络系统， 包括： 光线路终端， 光分配网 络， 光网络单元， 在光线路终端和 /或光网络单元中包括自适应模式对准光源； 所述自适应模式对准光源包括： 相连的激光器和温度控制单元，还包括光 电探测器及信号处理单元，所述光电探测器将输出光中的一路光信号转换成电 流信号， 所述电流信号经放大并转换成电压信号， 与所述信号处理单元生成的 调制信号共同调节所述温度控制单元的偏置电压。
本发明实施例以低成本（可以使用普通的 AWG, 而不限定于无热 AWG ) 实现波长与激光器纵模的自动对准 (不需要人工校准 ) , 补偿温度变化带来的 影响。 而且， 在各种因素引起的光功率漂移和波长漂移的干扰下， 本发明实施 例的光源模式对准装置仍然可以实现模式对准， 因为釆用的是信号的相位信 息， 具有很强的抗干扰能力。将该光源模式对准装置作为无源光网络系统的光 线路终端和 /或光网络单元中的光源， 可以输出稳定的功率， 保证无源光网络 系统的可靠运行。
附图说明
图 1是现有注入锁定 FP-LD方案的示意图。
图 2是现有的普通激光器的结构示意图。
图 3是输出光功率随 LD温度变化的示意图。
图 4 ( a )是在波长对准纵模上升沿时输出功率随调制电流变化的示意图。 图 4 ( b )是在波长对准纵模下降沿时输出功率随调制电流变化的示意图。 图 4 ( c )是在波长对准纵模中心时输出功率随调制电流变化的示意图。 图 5是本发明光源模式对准装置第一实施例的结构图。
图 6是本发明光源模式对准装置第二实施例的结构图。
图 7是本发明光源模式对准装置第三实施例的结构图。
图 8是本发明光源模式对准装置第四实施例的结构图。
图 9是本发明实施例中温度扫描法防死锁的流程图。
图 10是本发明实施例中功率阔值判断法防死锁的流程图。
图 11是本发明实施例中扰动干扰法防死锁的流程图。
图 12是本发明 WDM-PON系统第一实施例的结构图。
图 13是本发明 WDM-PON系统第二实施例的结构图。
具体实施方式
以下结合附图对本发明进行详细描述。 首先， 参照图 3至图 4说明现有 FP-LD激光器输出光功率与温度变化的关 系。
参照图 3 , 图 3示出了注入光波长不变的情况下，输出光功率随温度的变化 情况：
当温度逐渐升高的时候， 纵模向长波长方向移动， 输出光功率也就随着纵 模的轮廓变化。 当给激光器的温度引入一个小幅的周期性变化时，如果注入光 没有对准纵模中心， 由于纵模的边沿很陡， 小幅的温度变化带来的波长变化将 会引起很大的功率波动。如注入光的波长位于纵模中心的左侧， 即注入光波长 小于纵模中心波长，即使很小的温度增加也会带来较大的输出功率的增强性变 化； 反之， 当注入光的波长位于纵模中心的右侧， 即注入光波长大于纵模中心 波长， 则即使很小的温度增加也会带来较大的输出功率的减小性变化。 因此， 可以根据功率波动和温度调制信号的相位关系来判断温度调节方向。
如果注入光对准了纵模（图 3所示的轮廓实际上与纵模的轮廓一致） 的上 升沿， 那么光功率的变化与温度的调制信号是同相位的， 如图 4 ( a )所示， 此 时， 如果将功率波动进行带通滤波处理， 负电压将对应着调制信号的负电压， 而正电压则对应着调制信号的正电压， 但它们的乘积的积分 IPM大于零， 这时 候应该将温度向高的方向调整， 也就是增大偏置电压。 反之， 如果注入光对准 了图 3的下降沿， 那么光功率的变化和温度的调制信号的相位是相反的， 如图 4 ( b ) 所示， 此时的功率波动经过带通滤波处理之后， 乘积积分 IPM小于零， 这时候应该将温度向低的方向调，也就是减小偏置电压。 注入光就对准了纵模 的中心时， 由于纵模的对称性， 乘积积分值 IPM必然等于零， 如图 4 ( c )所示。
根据上述原理， 通过监测 IPM的变化， 同时根据 IPM的极性依据下面的方 法调节温度调制信号电压 （或称偏置电压）， 则可以准确将注入光对准纵模的 中心。
1 ) IPM为正时， 增大温度调制信号电压；
2 ) IPM为负时， 减小温度调制信号电压；
3 ) IPM为 0时， 不调节温度调制信号。
调节偏置电压， 可以有多种方法， 如釆用线性调节方法和 PID ( Proportional-Integral-Differential , 比例-积分 -微分）控制方法， 均可使得偏置 电压能尽快的调整到确切的值。 下面对此进行详细说明。
1 ) 线性调节方法
如式（1 ) 所示， 电压调整量 与 IPM成正比：
AV = ^ ( 1 )
c - t
其中， 为偏置电压的调整量； IPM为二次放大后功率信号与调制信号 的乘积的积分值； c为常数； t为调整时间 （除以 t是为了避免引起算法振荡） 。
通常，调整时间 t越长， 电压的增减量越小。 当调节到 近似为零的时候， t重置为 1 , 以应付下一次较大的波长失配。
2 ) PID控制方法
PID控制方法时 (偏置电压调整量）与 IPM不再是简单的线性比例关系， 而是满足式（2 ) 的关系：
AV = Α · ΙΡΜ + Β .— (IPM) + C - jlPMdt (2)
dt
其中， A、 B、 C均为常数。
值得注意的是， 加在温控电压上的调制信号为小幅低频信号， 其幅度的选 择与 FP-LD纵模的线宽有关， 当注入光处于纵模中心位置时， 温度调节幅度小 到基本上不会引起光功率的变化。 釆用低频是为了避免对高频数字信号的干 扰。 通常， 响应频率越低， PD的成本越便宜， 而且灵敏度也较高。
如图 2所示，现有 FP-LD激光器中包含了 FP-LD芯片、 MPD (或 PD )、 TEC、 热敏电阻（负温度系数） 、 放大器 （含跨阻放大器）等组件， 能够提供 ATC ( Automatic Temperature Control,自动温度控制）功能和 APC( Automatic Power Control, 自动功率控制）功能。 因此， 为了实现注入光对准纵模的闭环控制功 能， 本发明实施例的光源对准装置在现有的 FP-LD激光器中引入了信号处理功 能和反馈控制功能。
下面分别描述本发明实施例的光源模式对准装置， 为了叙述方便， 在没有 特别说明时， MPD指的是激光器背光光电检测器， 而 PD则指的是激光器外部 的光电探测器。
本发明实施例的光源模式对准装置， 通过激光器将注入光转换成电流信 号， 所述电流信号经跨阻放大器放大并转换成电压信号； 由信号处理单元生成 调制信号；并由所述电压信号和所述调制信号共同调节温度控制单元的偏置电 压。 所述温度控制单元包括热电控制器、 热敏电阻以及温控驱动器。
1 )第一实施例： 釆用模拟信号处理单元和激光器内部的 MPD
参照图 5所示本发明第一实施例的光源模式对准装置结构图：
注入光经过环形器 51进入通用激光模块 50中的 FP-LD501 , FP-LD501作为 光泵激发 FP-LD芯片产生激光， 所述激光一部分（能量的大部分）通过 FP-LD 芯片的前端面出射形成输出光， 另一部分通过所述 FP-LD芯片的后端面形成激 光器的背向光， 所述的背向光被 MPD502探测并转换为电流信号， 该电流信号 被位于通用激光器模块 50中的跨阻放大器 503放大变成电压信号， 然后， 该电 压信号被传送到信号处理单元 52。在该实施例中，信号处理单元 52由模拟电路 实现， 具体处理过程如下：
在信号处理单元 52中， 首先由带通滤波器 521以温控电流的调制信号的频 率为中心频率对该电压信号进行带通滤波（去掉了直流分量）， 滤除所述电压 信号中的各种因素引起的光功率变化的干扰信号和直流分量得到包含输出光 功率波动信息的电压信号， 然后由放大器 522对滤波后的电压信号进行动态放 大，得到输出信号幅度和调制信号的幅度一样的电压信号（幅度一致的功率变 化电压信号） 。
信号处理单元 52中的调制信号发生器 523产生调制信号， 该调制信号经过 延时器 524延时 （为了弥补温控电流与波长响应之间的时间差）后， 与前面所 述的放大后的幅度一致的功率变化电压信号一起进入鉴相器 525。 鉴相器 525 由乘法器和积分器构成， 两个信号相乘的积分值 IPM (反映了两个信号之间的 相位关系）输出到偏置电压发生器 526 , 调节用于温控的偏置电压， 具体的调 节方法可参照前面的描述。
偏置电压发生器 526输出的偏置电压与调制信号发生器 523产生的调制信 号经过加权的加法运算得到一个电压，经过温控驱动器 53加到通用激光器模块 50的 TEC504上， 控制 FP-LD的温度，使得 FP-LD的纵模向对准注入光波长的方 向移动， 从而最终实现注入光与纵模中心对准。
此外，如果不考虑 3dB的衰减， 图 5中的环行器可以由 1x2双向耦合器代替。 该自适应模式对准光源可以用模拟电路实现， 也可以将 PD测得的功率值 釆样， 用数字信号处理方法实现。
2 )第二实施例： 釆用数字信号处理单元和 MPD
参照图 6所示的本发明第二实施例的光源模式对准装置结构图：
本实施例与图 5所示的第一实施例基本相同， 所不同是在本实施例中信号 处理单元由数字电路实现。
如图 6所示， 通用激光器模块 50输出的反映背光功率的电压信号被送到 A/D模块 61进行釆样， 得到数字化的功率信号。 之后， 该数字化功率信号被送 到信号处理单元 62进行数字信号处理。信号处理单元 62对该数字化的功率信号 的处理过程与图 5所示的模拟处理过程一致， 所不同的是所有的处理均是数字 化处理， 而图 5所示的处理均是模拟处理。
信号处理单元 62对该数字化的功率信号的处理过程如下：
首先由带通滤波器 621以温控电流的调制信号的频率为中心频率对该电压 信号进行带通滤波（去掉了直流分量）， 滤除所述电压信号中的各种因素引起 的光功率变化的干扰信号和直流分量得到包含输出光功率波动信息的电压信 号， 然后由放大器 622对滤波后的电压信号进行动态放大， 得到输出信号幅度 和调制信号的幅度一样的电压信号 （幅度一致的功率变化电压信号） 。
信号处理单元 62中的调制信号发生器 623产生调制信号， 该调制信号经过 延时器 624延时 （为了弥补温控电流与波长响应之间的时间差）后， 与前面所 述的放大后的幅度一致的功率变化电压信号一起进入鉴相器 625。 鉴相器 625 由乘法器和积分器构成， 两个信号相乘的积分值 IPM (反映了两个信号之间的 相位关系）输出到偏置电压发生器 626 , 调节用于温控的偏置电压， 具体的调 节方法可参照前面的描述。
偏置电压发生器 626输出的偏置电压与调制信号发生器 623产生的调制信 号经过加权的加法运算得到一个电压， 经 D/A模块 63转换后变成模拟信号， 进 入温控驱动器 53。 经过温控驱动器 53加到通用激光器模块 50的 TEC504上， 控 制 FP-LD的温度， 使得 FP-LD的纵模向对准注入光波长的方向移动， 从而最终 实现注入光与纵模中心对准。
此外，如果不考虑 3dB的衰减， 图 6中的环行器可以由 1x2双向耦合器代替。 本发明实施例的光源模式对准装置，还可以由光电探测器将激光器输出光 中的一路光信号转换成电流信号，所述电流信号经跨阻放大器放大并转换成电 压信号； 由信号处理单元生成调制信号； 所述电压信号与所述调制信号共同调 节温度控制单元的偏置电压。 所述温度控制单元包括热电控制器、热敏电阻以 及温控驱动器。
3 )第三实施例： 釆用模拟信号处理单元和 PD
参照图 7所示的本发明第三实施例的光源模式对准装置结构图：
与图 5所示的实施例不同， 本实施例中的注入光不是通过环行器进入
FP-LD, 而是通过耦合器 71进入 FP-LD。 耦合器 71—方面将注入光以一定比例 (如 50% )导入 FP-LD, 另一方面将 FP-LD的输出光按照一定比例导出供输出 光功率检测。
本实施例中釆用了外置于激光器的 PD, 如图 7所示， 耦合器 71的导出光由 PD72进行光功率的探测。 PD72将耦合器 71导出的光功率转换为电流信号， 送 到与之相连的放大器 73 ,放大器 73内的跨阻放大器将该电流信号进行放大并转 换成电压信号。该电压信号输出到信号处理单元 52。信号处理单元 52对该电压 信号的处理过程与图 5所示实施例中相同， 在此不再赘述。
4 )第四实施例： 釆用数字信号处理单元和 PD
参照图 8所示的本发明第四实施例的光源模式对准装置结构图：
与图 6所示的实施例不同， 本实施例中的注入光不是通过环行器进入
FP-LD, 而是通过耦合器 71进入 FP-LD。 耦合器 71—方面将注入光以一定比例 (如 50% )导入 FP-LD, 另一方面将 FP-LD的输出光按照一定比例导出供输出 光功率检测。
本实施例中釆用了外置于激光器的 PD, 如图 8所示， 耦合器 71的导出光由 PD72进行光功率的探测。 PD72将耦合器 71导出的光功率转换为电流信号， 由 A/D模块 61对该电流信号进行釆样， 得到数字化的功率信号。 之后， 该数字化 功率信号被送到信号处理单元 62进行数字信号处理。 之后的处理过程与图 6所 示实施例的处理过程一致， 在此不再赘述。
本发明实施例以低成本（可以使用普通的 AWG, 而不限定于无热 AWG ) 实现波长与激光器纵模的自动对准（不需要人工校准）， 补偿温度变化带来的 影响。 而且， 在各种因素引起的光功率漂移和波长漂移的干扰下， 本发明仍然 可以实现模式对准， 因为釆用的是信号的相位信息， 具有很强的抗干扰能力。 本发明实施例釆用了现有半导体激光器模块的标准组件： LD、 TEC、 MPD 或 PD, 没有增加成本， 信号处理釆用了常用的功能模块， 所以整个装置的成 本将与现有的光发射模块差不多。
由于本发明实施例的装置可以自动寻找对应注入波长的主纵模的位置，所 以使用普通的温度敏感的 AWG即可， 而且 AWG不需要温控， AWG的成本将比 现有的产品更加便宜。
由于本发明实施例的装置能自动对准模式， 降低了注入光功率阔值，也就 是降低了作为注入光源的宽谱光源的功率要求， 从而降低了宽谱光源的成本。
如果一开始注入波长就对准了纵模之间的谷底， IPM等于 0, 上述算法将 锁定在谷底， 形成死锁。 本发明实施例可以选用三种方法来避免死锁。
第一种是温度扫描。 在进行该自适应调节之前先大范围地扫描一下 LD的 温度， 选取最大输出功率对应的温度作为起始温度。 调整好起始温度之后， 使 用温度调制方法就可以在 LD的整个工作期间保证纵模与注入波长的对准。
参照图 9所示， 具体包括以下步骤：
步骤 901 : 扫描 FP-LD激光器的温度， 得到激光器最大功率时的温度 T0; 步骤 902: 设置 TQ对应的驱动电压为温控的起始偏置电压；
步骤 903: 启动自适应模式对准过程。
第二种方法是功率阔值判断法。请参照图 10所示， 当注入波长对应谷底的 时候，输出功率明显的比对准纵模时候的低。如果输出功率低于某个阔值的时 候， 判定注入波长对应与谷底附近， 调节温度， 使得输出功率高于阔值， 这样 注入波长就对应于纵模中心附近， 启动自适应模式对准过程， 就可避免死锁在 谷底。
参照图 10所示， 具体包括以下步骤：
步骤 101 : 判断 FP-LD激光器输出的光功率是否大于设定的阔值； 如果是， 则执行 102; 否则， 执行步骤 103;
步骤 102: 启动自适应模式对准过程；
步骤 103: 往一个方向 （递增或递减）调节温度。
第三种方法是扰动法。请参照图 11所示，如果自适应模式对准过程一开始， IPM值就为 0, 那么随机加一个较小的温度偏差， 使得 IPM值不为 0, 这样， 反 馈过程就可以向模式中心调节。
参照图 11所示， 具体包括以下步骤：
步骤 111 : 判断 IPM值是否为 0; 如果是， 则执行 112; 否则， 执行步骤 113; 步骤 112: 改变 FP-LD激光器的温度（随机取一个较小的温度偏差） ； 步骤 113: 启动自适应模式对准过程。
可以将本发明实施例的光源模式对准装置应用于 WDM-PON系统， 将该 光源模式对准装置作为 WDM-PON系统的 OLT ( Optical Line Terminal, 光线 路终端）和 /或 ONU ( Optical Network Unit, 光网络单元） 中的光源， 可以保 证该光源输出功率的稳定性， 从而使 WDM-PON系统能够可靠运行。
参照图 12, 图 12示出了使用本发明 DM-PON系统第一实施例的结构图： 该系统基于波分复用 /解复用器， 如图 12所示， OLT121通过基于第二波 分复用 /解复用器 122的无源光分配网络完成与 ONU123的数据交互。
下行方向，位于 OLT121的光收发器阵列 101将下行数据调制到宽谱光源 102通过位于 OLT121的第一波分复用 /解复用器 103送来的光信号上，并通过 第一波分复用 /解复用器 103 以及所述无源光分配网络将调制的下行数据光信 号传送到 ONU123。 ONU123通过光收发器 104中的光接收器 105接收下行数 据。
上行方向， ONU123通过自动模式对准光源 106将上行数据调制在上行波 长光信号上， 通过所述无源光分配网络传送到 OLT121 ; OLT121 中的光收发 器阵列 101将通过第一波分复用 /解复用器 103接收到的上行数据光信号转换 为上行数据电信号， 传送到位于 OLT121的时钟恢复和 MAC模块 107。
根据系统是否在上、 下行方向使用同一波长的基本特性， 可以区分为两种 基本情况： 1 )上行使用不同于下行的波长， 宽谱光源 102为收发器阵列 101 提供下行波长光信号的同时， 也通过所述无源光分配网络为 ONU123 提供上 行波长的光信号； 2 )上行使用下行波长， 宽谱光源 102仅仅为收发器阵列 101 提供光信号。
针对上述第 1 )种情况， ONU123中的耦合器 108釆用 WDM耦合器（即 分波器）。 因此， 在下行方向， ONU123的光收发器 104中的光接收器 105通 过分波器提取使用下行波长调制的下行数据光信号， 并转换为下行数据电信 号， 传送给时钟恢复和 MAC模块 109进行时钟恢复和进一步的协议处理； 在 上行方向， ONU123的光收发器 104中的自动模式对准光源 106通过 1 :2光分 路器 110 (对应本发明光源模式对准装置第三和第四实施例）或者第二环行器 120 (对应本发明光源模式对准装置第一和第二实施例）从分波器接收上行波 长光信号， 并将从时钟恢复和 MAC模块 109接收到的上行数据调制到上行波 到 OLT121。
针对上述第 2 )种情况， ONU123的耦合器 108釆用双向光功率耦合器（即 1 :2光分路器） ， 而且下行方向光信号的处理过程与上述第 1 )种情况相同， 上行方向的光信号处理过程与上述第 1 )种情况类似， 主要区别在于上行数据 调制在与下行波长相同的光信号上。
此外， OLT121中光收发器阵列 101也可以釆用本发明实施例中的自动模 式对准光源， 其调制数据和接收数据的原理和过程与 ONU123 中的自动模式 对准光源 106相同， 不再赘述。
参照图 13 , 图 13示出了使用本发明 DM-PON系统第二实施例的结构图： 该系统基于波分复用 /解复用器， 如图 12所示， OLT121通过基于光分路 器 132的无源光分配网络完成与 ONU133的数据交互。
本实施例与图 12所示的第一实施例基本相同， 所不同的是因为釆用基于 光分路器的无源光分配网络， 从而需要在 ONU133 中增加用于提取分配给特 定光网络单元的上下行波长光信号的光滤波器 134。
OLT121通过基于光分路器 132的无源光分配网络与 ONU133进行数据交 互的过程与图 12所示实施例类似， 不再赘述。
以上所述仅为本发明的较佳实施例而已， 并不用以限制本发明， 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

权 利 要 求
1、 一种光源模式对准装置， 包括相连的激光器和温度控制单元， 其特征 在于： 还包括信号处理单元， 所述激光器将注入光转换成电流信号， 所述电流 信号经放大并转换成电压信号，与所述信号处理单元生成的调制信号共同调节 所述温度控制单元的偏置电压。
2、 根据权利要求 1所述的光源模式对准装置， 其特征在于： 所述激光器 是 FP-LD激光器。
3、 根据权利要求 2所述的光源模式对准装置， 其特征在于： 所述激光器 内设置有将注入光转换成电流信号的光电探测器。
4、 根据权利要求 1所述的光源模式对准装置， 其特征在于： 所述信号处 理单元包括放大器和滤波器，所述电压信号由所述放大器进行动态放大后传送 至所述滤波器进行带通滤波。
5、 根据权利要求 4所述的光源模式对准装置， 其特征在于： 所述信号处 理单元还包括鉴相器、调制信号发生器及延时器， 经滤波处理后的信号与由所 述调制信号发生器生成并经所述延时器延时的调制信号一起进入到所述鉴相 器调节所述温度控制单元的偏置电压，所述偏置电压与所述调制信号经加权的 加法运算生成控制电压， 并施加到所述温度控制单元。
6、 根据权利要求 1所述的光源模式对准装置， 其特征在于： 所述温度控 制单元包括热电控制器、 热敏电阻以及温控驱动器， 所述控制电压通过所述温 控驱动器施加到所述热电控制器； 所述电压信号由模拟 /数字转换器 A/D转换 成数字信号， 经数字信号处理后由数字 /模拟转换器 D/A转换成模拟信号， 并 传输到所述温度控制单元。
7、 一种光源模式对准装置， 包括相连的激光器和温度控制单元， 其特征 在于： 还包括光电探测器及信号处理单元， 所述光电探测器将输出光中的一路 光信号转换成电流信号， 所述电流信号经放大并转换成电压信号， 与所述信号 处理单元生成的调制信号共同调节所述温度控制单元的偏置电压。
8、 根据权利要求 7所述的光源模式对准装置， 其特征在于： 所述激光器 是 FP-LD激光器； 所述信号处理单元包括放大器和滤波器， 所述电压信号由 所述放大器进行动态放大后传送至所述滤波器进行带通滤波。
9、 根据权利要求 8所述的光源模式对准装置， 其特征在于： 所述信号处 理单元还包括鉴相器、调制信号发生器及延时器， 经滤波处理后的信号与由所 述调制信号发生器生成并经所述延时器延时的调制信号一起进入到所述鉴相 器调节所述温度控制单元的偏置电压，所述偏置电压与所述调制信号经加权的 加法运算生成控制电压， 并施加到所述温度控制单元。
10、 根据权利要求 7所述的光源模式对准装置， 其特征在于： 所述温度控 制单元包括热电控制器、 热敏电阻以及温控驱动器， 所述控制电压通过所述温 控驱动器施加到所述热电控制器； 所述电压信号由模拟 /数字转换器 A/D转换 成数字信号， 经数字信号处理后由数字 /模拟转换器 D/A转换成模拟信号， 并 传输到所述温度控制单元。
11、 一种光源模式对准方法， 其特征在于， 包括：
分别生成激光器注入光的功率波动信号和温度调制信号；
获取所述功率波动信号和所述调制信号的相位关系；
才艮据所述相位关系调节所述激光器的偏置电压。
12、根据权利要求 11所述的模式对准方法，其特征在于：所述方法还包括： 由所述偏置电压与所述温度调制信号生成控制电压，并施加到所述激光器 的温度控制单元。
13、 根据权利要求 11所述的模式对准方法， 其特征在于： 所述生成激光器 注入光的功率波动信号的步骤包括：
将所述注入光转换成电压信号， 并对其进行带通滤波；
将滤波后的电压信号进行动态放大， 生成所述功率波动信号。
14、 根据权利要求 13所述的模式对准方法， 其特征在于： 所述放大后的电 压信号幅度与所述调制信号的幅度一致。
15、 根据权利要求 11所述的模式对准方法， 其特征在于： 所述生成调制信 号的步骤包括：
由调制信号发生器生成调制信号；
对所述调制信号经延时器延时。
16、 根据权利要求 11所述的模式对准方法， 其特征在于： 所述获取所述功 率波动信号和所述调制信号的相位关系的步骤包括：由鉴相器对所述功率波动 信号和所述调制信号进行相乘和积分， 获得相乘的积分值， 所述积分值反映二 信号的相位关系。
17、 根据权利要求 16所述的模式对准方法， 其特征在于： 所述根据所述相 位关系调节所述激光器的偏置电压的步骤包括：
如果所述积分值大于零， 则增大所述偏置电压；
如果所述积分值小于零， 则减小所述偏置电压。
18、 根据权利要求 17所述的模式对准方法， 其特征在于： 所述增大或减小 所述偏置电压的调整量根据以下公式来确定：
AV = ^ - , 其中， 表示偏置电压的调整量， IPM表示第二次放大后的 c - t
功率信号与调制信号的乘积的积分值， C表示一个常数， t表示时间； 或者
所述增大或减小所述偏置电压的调整量根据以下公式来确定：
AV = Α · ΙΡΜ + Β ·— (IPM) + C - \lPMdt , 其中， 表示偏置电压的调整量，
IPM表示第二次放大后的功率信号与调制信号的乘积的积分值， t表示时间， A、 B、 C为常数。
19、 根据权利要求 11所述的模式对准方法， 其特征在于： 在所述分别生成 激光器注入光的功率波动信号和所述调制信号的步骤之前还包括：
扫描激光器温度， 选取所述激光器最大输出功率对应的温度作为起始温 度； 或者
调节激光器温度， 使其输出功率高于设定的阔值； 或者
给激光器随机施加一个温度偏差，使所述注入光的波长对应于所述激光器 的纵模中心附近。
20、 一种无源光网络系统， 包括： 光线路终端， 光分配网络， 光网络单元， 其特征在于， 在光线路终端和 /或光网络单元中包括自适应模式对准光源； 所述自适应模式对准光源包括： 相连的激光器和温度控制单元，还包括信 号处理单元， 所述激光器将注入光转换成电流信号， 所述电流信号经放大并转 换成电压信号，与所述信号处理单元生成的调制信号共同调节所述温度控制单 元的偏置电压。
21、 一种无源光网络系统， 包括： 光线路终端， 光分配网络， 光网络单元， 其特征在于， 在光线路终端和 /或光网络单元中包括自适应模式对准光源； 所述自适应模式对准光源包括： 相连的激光器和温度控制单元，还包括光 电探测器及信号处理单元，所述光电探测器将输出光中的一路光信号转换成电 流信号， 所述电流信号经放大并转换成电压信号， 与所述信号处理单元生成的 调制信号共同调节所述温度控制单元的偏置电压。
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107562087A (zh) * 2016-06-30 2018-01-09 南京中兴软件有限责任公司 基于加热器的温度控制方法及装置、光模块

Families Citing this family (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100558012C (zh) * 2006-08-10 2009-11-04 华为技术有限公司 光源自适应模式对准装置及对准方法
US8364043B2 (en) * 2008-12-12 2013-01-29 Electronics And Telecommunications Research Institute Method and apparatus for controlling reflective semiconductor optical amplifier (RSOA)
JP5388913B2 (ja) * 2010-03-15 2014-01-15 三菱電機株式会社 画像表示装置
CN103516434B (zh) * 2012-06-19 2016-08-31 上海贝尔股份有限公司 光发射机
CN103001123B (zh) * 2012-12-18 2014-11-05 上海交通大学 一种半导体激光器宽带锁频方法及其锁频装置
EP3044888B1 (en) 2013-10-14 2018-09-19 Huawei Technologies Co., Ltd. Wavelength stabilizer for twdm-pon burst mode dbr laser
CN105223654B (zh) * 2014-06-11 2019-02-01 上海诺基亚贝尔股份有限公司 用于热可调谐滤波器的波长跳跃的方法和装置
CN104536721B (zh) * 2014-12-08 2018-04-17 北京大学 基于超亮发光二极管的多路真随机数序列发生方法及装置
JP6508956B2 (ja) * 2015-01-28 2019-05-08 富士通株式会社 変調光源
US10880013B2 (en) 2016-04-12 2020-12-29 Cable Television Laboratories, Inc Network communications systems and methods
US10623104B2 (en) * 2016-04-12 2020-04-14 Cable Television Laboratories, Inc Fiber communication systems and methods
US10601513B2 (en) 2016-04-12 2020-03-24 Cable Television Laboratories, Inc. Network communications systems and methods
US11996893B2 (en) 2016-04-12 2024-05-28 Cable Television Laboratories, Inc. Communication systems and methods
US11115126B2 (en) * 2016-04-12 2021-09-07 Cable Television Laboratories, Inc. Fiber communication systems and methods
CN108768514B (zh) * 2017-04-19 2020-05-22 中兴通讯股份有限公司 光网络系统、装置及方法
CN107171176B (zh) * 2017-07-05 2019-08-23 辽宁优迅科技有限公司 一种fp滤波器的光器件光路耦合方法
US10965393B2 (en) * 2018-06-26 2021-03-30 Cable Television Laboratories, Inc. Systems and methods for dual-band modulation and injection-locking for coherent PON
CN112073123B (zh) * 2019-06-11 2022-01-11 青岛海信宽带多媒体技术有限公司 一种电光调制器工作点自动偏压控制的装置及方法
CN110572216A (zh) * 2019-09-17 2019-12-13 成都芯瑞科技股份有限公司 一种光模块apc控制的软件实现方法
CN115576372A (zh) * 2022-10-09 2023-01-06 国网江苏省电力有限公司电力科学研究院 提高半导体光源输出稳定性的双闭环控制装置及方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2143075A (en) * 1983-05-06 1985-01-30 Coherent Inc Lasers
JPH03222486A (ja) * 1990-01-29 1991-10-01 Nec Corp 空冷アルゴンレーザ装置
CN1280310A (zh) * 1999-07-13 2001-01-17 朗迅科技公司 用于波长稳定激光器的主动数值温度补偿的方法及装置
CN1300123A (zh) * 1999-12-16 2001-06-20 朗迅科技公司 稳定激光波长的方法和装置
CN1444349A (zh) * 2002-03-08 2003-09-24 华为技术有限公司 数字调节光接收模块及其调节方法
CN1554139A (zh) * 2000-10-10 2004-12-08 光谱传感器公司 利用可调标准具在密集波分复用器中锁定激光器的传输波长的方法和系统
CN1909419A (zh) * 2006-08-10 2007-02-07 华为技术有限公司 光源自适应模式对准装置及对准方法
CN101026417A (zh) * 2006-02-20 2007-08-29 华为技术有限公司 激光调制器数字自动偏置电压控制设备

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3222486B2 (ja) 1991-05-21 2001-10-29 日鍛バルブ株式会社 油圧式ラッシュアジャスタ

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2143075A (en) * 1983-05-06 1985-01-30 Coherent Inc Lasers
JPH03222486A (ja) * 1990-01-29 1991-10-01 Nec Corp 空冷アルゴンレーザ装置
CN1280310A (zh) * 1999-07-13 2001-01-17 朗迅科技公司 用于波长稳定激光器的主动数值温度补偿的方法及装置
CN1300123A (zh) * 1999-12-16 2001-06-20 朗迅科技公司 稳定激光波长的方法和装置
CN1554139A (zh) * 2000-10-10 2004-12-08 光谱传感器公司 利用可调标准具在密集波分复用器中锁定激光器的传输波长的方法和系统
CN1444349A (zh) * 2002-03-08 2003-09-24 华为技术有限公司 数字调节光接收模块及其调节方法
CN101026417A (zh) * 2006-02-20 2007-08-29 华为技术有限公司 激光调制器数字自动偏置电压控制设备
CN1909419A (zh) * 2006-08-10 2007-02-07 华为技术有限公司 光源自适应模式对准装置及对准方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107562087A (zh) * 2016-06-30 2018-01-09 南京中兴软件有限责任公司 基于加热器的温度控制方法及装置、光模块
CN107562087B (zh) * 2016-06-30 2024-04-02 中兴通讯股份有限公司 基于加热器的温度控制方法及装置、光模块

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