WO2022000338A1 - Circuit de traitement, module optique et procédé de détection de chirp - Google Patents

Circuit de traitement, module optique et procédé de détection de chirp Download PDF

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Publication number
WO2022000338A1
WO2022000338A1 PCT/CN2020/099569 CN2020099569W WO2022000338A1 WO 2022000338 A1 WO2022000338 A1 WO 2022000338A1 CN 2020099569 W CN2020099569 W CN 2020099569W WO 2022000338 A1 WO2022000338 A1 WO 2022000338A1
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Prior art keywords
optical
signal
chirp
module
output
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PCT/CN2020/099569
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English (en)
Chinese (zh)
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汪若虚
满江伟
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华为技术有限公司
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Priority to CN202080101810.XA priority Critical patent/CN115698658A/zh
Priority to PCT/CN2020/099569 priority patent/WO2022000338A1/fr
Publication of WO2022000338A1 publication Critical patent/WO2022000338A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J11/00—Measuring the characteristics of individual optical pulses or of optical pulse trains
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements

Definitions

  • the embodiments of the present application relate to the field of optical communications, and in particular, to a processing circuit, an optical module, and a chirp detection method.
  • the transmitting end may be provided with an optical module, which can generate and transmit optical signals required for optical communication.
  • a laser provided in the optical module can generate an optical signal according to a control signal sent by a processor provided in the optical module, and the information to be sent is loaded into the optical signal for transmission by means of intensity modulation.
  • the chirp effect that is, in the process of intensity modulation, due to the dispersion of the laser itself, when it modulates the optical signal, it will produce spectrum broadening at the front and rear edges of the optical signal pulse
  • the existence of the optical signal will affect the signal quality of the obtained optical signal.
  • the transmission power of the laser With the improvement of communication performance requirements in short- and medium-distance optical communication, the transmission power of the laser will inevitably increase, which will also lead to more obvious chirp effect.
  • the magnitude of the chirp effect can be identified by the chirp coefficient, and the larger the chirp coefficient, the greater the influence of the chirp effect on the optical signal. Conversely, the smaller the chirp coefficient is, the less the chirp effect has on the optical signal.
  • the embodiments of the present application provide a processing circuit, an optical module, and a chirp detection method, which can quickly and accurately determine the chirp coefficient of the laser, and then control the optical signal generated by the laser to be affected by the chirp effect, so that the optical communication Signal quality is improved.
  • a first aspect provides a processing circuit, applied to an optical module, the optical module further includes a chirp detection circuit and an optical emission module, wherein the processing circuit includes: a first optical coupler, an optical delay line, an optical filter and second optocoupler.
  • the first optical coupler is used for receiving an optical signal from the optical transmitting module, and performing branch processing on the optical signal to obtain a first output signal and a second output signal.
  • the optical delay line is used for delaying the first output signal to obtain a delayed signal.
  • the optical filter is used for filtering the second output signal to obtain a filtered signal.
  • the second optical coupler is used for combining the delayed signal and the filtered signal to obtain an output detection signal, and sending the output detection signal to the chirp detection circuit, so that the chirp detection circuit can detect according to the output signal, and calculate the chirp coefficient of the light emitting module.
  • the processing circuit can determine the chirp coefficient of the corresponding optical emitting module (such as a laser) according to the output detection signal obtained after processing by the optical delay line and the optical filter. Since the size of the optical delay line and the optical filter is very small, the integration can be better achieved, and further, the optical delay line and the optical filter can be arranged in the optical circuit, thereby reducing the detection cost. In addition, since the optical signal used for input may be the full amount of the optical signal generated by the laser, or may be a part of the optical signal generated by the laser, in some implementations, the chirping can be performed without affecting the optical communication. Coefficient detection.
  • a high degree of integration between the chirp detection circuit and the optical circuit can be achieved, so that the chirp coefficient can be detected in real time, thereby enabling fast and effective adjustment of the optical signal, so as to apply the chirp effect to the optical signal. It is possible to control the impact within a reasonable range.
  • the center wavelength of the rising or falling edge of the transmission spectrum of the optical filter is aligned with the center wavelength of the second output signal.
  • the optical filter can effectively filter out the spectrum signals other than the spectrum near the center frequency when filtering the optical signal input to the corresponding channel, so as to obtain the filtered signal that meets the calculation requirements of the chirp coefficient. It should be understood that, in other implementation manners, even if the center wavelength of the rising edge or the falling edge of the transmission spectrum of the optical filter is not aligned with the center wavelength of the second output signal, the processing circuit provided by the embodiments of the present application The detection of the chirp coefficient can still be achieved. It's just that the accuracy may be slightly lower than that of the solution in this possible design.
  • the processing circuit also includes a micro-heater.
  • the micro heater is used to adjust the transmission spectrum of the optical filter by adjusting the temperature of the optical filter. Based on the solution, a method for actively adjusting the transmission spectrum of the optical filter is provided, that is, the temperature of the optical filter is adjusted by a micro heater. Therefore, when the center wavelength of the optical filter needs to be aligned with the center wavelength of the second output signal, the second output signal does not need to be adjusted, and the alignment can be achieved by adjusting the optical filter. This makes it unnecessary to adjust the emission parameters of the laser during chirp detection.
  • the micro-heater is arranged around the optical filter, and the distance from the optical filter does not exceed a preset distance. Based on this solution, a possible solution for adjusting the temperature of the optical filter through the micro-heater is provided, that is, the micro-heater is set close to the optical filter (for example, the micro-heater is set at a position of 1 to 2um around the optical filter) , thereby achieving the purpose of adjusting the temperature of the optical filter through the micro-heater.
  • the time domain distribution of the delayed signal and the time domain distribution of the filtered signal do not coincide with each other. Based on this solution, the delayed signal processed by the optical delay line does not overlap with the filtered signal in the time domain, thereby facilitating the subsequent combining of the two signals.
  • the chirp detection circuit detects the time domain distribution of the corresponding spectrum of the output signal, the peak spectrum, the slope of the transmission spectrum of the optical filter, and the The time delay of the optical delay line is calculated to obtain the chirp coefficient of the optical transmitter module. Based on the solution, a possible method for determining the chirp coefficient by the chirp detection circuit according to the output detection signal is provided.
  • the chirp detection circuit obtains the chirp coefficient of the light emitting module according to the following formula:
  • ⁇ is the chirp coefficient of the light emission module
  • t1 is the time of the previous pulse in the output detection signal
  • t2 is the time of the next pulse in the output detection signal
  • P1 is the time of the previous pulse in the output detection signal.
  • Peak power P2 is the peak power of the next pulse in the output detection signal
  • S is the slope of the optical filter
  • D is the time delay of the optical delay line
  • C is a constant.
  • the processing circuit also includes a photodetector.
  • the photodetector is used to convert the output detection signal into a corresponding analog electrical signal, and the output detection signal is the analog electrical signal.
  • the delayed optical signal and the filtered optical signal can be combined into one spectrum, so as to calculate and obtain the chirp coefficient according to the parameters of the spectrum.
  • the optical signal can be converted into an electrical signal by the photodetector, so as to be processed and calculated by the operation module.
  • the processing circuit also includes a photodetector and an analog-to-digital converter.
  • the photodetector is used to convert the output detection signal into a corresponding analog electrical signal and transmit it to the analog-to-digital converter.
  • the analog-to-digital converter is used for converting the analog electrical signal into a digital electrical signal, and the output detection signal is the digital electrical signal.
  • the splitting ratio of the first optical coupler is 1:1 or 1:2. Based on this solution, a possible characteristic of the first optical coupler is provided, that is, the input detection signal can be divided into an upper arm optical signal and a lower arm optical signal with an optical power of 1:1 or 1:2.
  • an optical module which includes a first optical coupler, an optical delay line, an optical filter, a second optical coupler, a first optical emission module, and a chirp detection circuit.
  • the optical communication branch provided with the first optical transmission module may be referred to as the first branch.
  • the first light emitting module is used for generating a first optical signal and transmitting the first optical signal to the first optical coupler.
  • the first optical coupler is configured to perform branch processing according to the first optical signal to obtain a first output signal and a second output signal.
  • the optical delay line is used for delaying the first output signal to obtain a first delay signal.
  • the optical filter is used for filtering the second output signal to obtain the first filtering signal.
  • the second optical coupler is used for combining the first delayed signal and the first filtered signal to obtain a first output detection signal, and sending the first output detection signal to the chirp detection circuit.
  • the chirp detection circuit is used for calculating the chirp coefficient of the first light emitting module according to the first output detection signal.
  • the optical module may also include other branches, and the other branches can work while the first branch works, so as to Generate optical signals with the same or different center wavelengths. Its specific working mechanism is similar to that of the first branch, which will not be repeated here.
  • the optical signal received by the first optical coupler may be the full signal of the first optical signal.
  • the signal received by the first optical coupler may be a part of the first optical signal.
  • a third optical coupler may be set on the first branch, and the third optical coupler may be used to perform branch processing on the first optical signal, and one of the obtained two optical signals is used for inputting to the The first optical coupler is used to detect the chirp coefficient, and the other can be directly transmitted to a transmission medium such as an optical fiber that communicates with the outside world for optical communication. Take real-time measurements.
  • the center wavelength of the rising or falling edge of the transmission spectrum of the optical filter is aligned with the center wavelength of the second output signal.
  • the optical filter can effectively filter out the spectrum signals other than the spectrum near the center frequency when filtering the optical signal input to the corresponding channel, so as to obtain the filtered signal that meets the calculation requirements of the chirp coefficient. It should be understood that, in other implementation manners, even if the center wavelength of the rising edge or the falling edge of the transmission spectrum of the optical filter is not aligned with the center wavelength of the second output signal, the processing circuit provided by the embodiments of the present application The detection of the chirp coefficient can still be achieved. It's just that the accuracy may be slightly lower than that of the solution in this possible design.
  • the optical module also includes a micro-heater.
  • the micro heater is used to adjust the transmission spectrum of the optical filter by adjusting the temperature of the optical filter.
  • a method for actively adjusting the transmission spectrum of the optical filter is provided, that is, the temperature of the optical filter is adjusted by a micro heater. Therefore, when the center wavelength of the optical filter needs to be aligned with the center wavelength of the second output signal, the second output signal does not need to be adjusted, and the alignment can be achieved by adjusting the optical filter. This makes it unnecessary to adjust the emission parameters of the laser during chirp detection.
  • the micro-heater is arranged around the optical filter, and the distance from the optical filter does not exceed a preset distance. Based on this solution, a possible solution for adjusting the temperature of the optical filter through the micro-heater is provided, that is, the micro-heater is set close to the optical filter (for example, the micro-heater is set at a position of 1 to 2um around the optical filter) , thereby achieving the purpose of adjusting the temperature of the optical filter through the micro-heater.
  • the time domain distribution of the delayed first delayed signal and the time domain distribution of the first filtered signal do not coincide with each other. Based on this solution, the first delayed signal after being delayed and processed by the optical delay line does not overlap with the first filtered signal in the time domain, thereby facilitating subsequent combining of the two signals.
  • the chirp detection circuit detects the time domain distribution of the spectrum corresponding to the first output signal, the peak value of the spectrum, and the transmission spectrum of the optical filter. The slope, and the time delay of the optical delay line are calculated to obtain the chirp coefficient of the first optical emitting module. Based on the solution, a possible method for determining the chirp coefficient by the chirp detection circuit according to the output detection signal is provided.
  • the chirp detection circuit obtains the chirp coefficient of the first light emitting module according to the following formula:
  • ⁇ is the chirp coefficient of the first light emission module
  • t1 is the time of the previous pulse in the first output detection signal
  • t2 is the time of the next pulse in the first output detection signal
  • P1 is the first output detection signal.
  • P2 is the peak power of the next pulse in the first output detection signal
  • S is the slope of the optical filter
  • D is the delay of the optical delay line
  • C is a constant.
  • the optical module further includes an adjustment module.
  • the chirp detection circuit is also used for instructing the adjustment module to adjust the chirp effect in the first light emitting module according to the chirp coefficient of the first light emitting module.
  • the optical module adjusts the chirp effect of the first optical emitting module according to the chirp detection result obtained in real time (eg, the chirp coefficient of the first optical emitting module).
  • the optical module can actively manage the chirp effect, thereby ensuring the signal quality in the optical communication process.
  • the chirp detection circuit is further configured to determine that the chirp coefficient of the first light emitting module is greater than a preset threshold, and send the signal to the adjustment module according to the chirp coefficient of the first light emitting module an adjustment signal, the adjustment module is used for adjusting the chirp effect in the first light emitting module according to the adjustment signal.
  • a specific method for actively managing the chirp effect of an optical module is provided. That is, by judging the magnitude relationship between the chirp coefficient obtained by detection and the preset threshold, it is determined whether the chirp effect needs to be adjusted, and then the chirp effect can be controlled through the adjustment module.
  • the adjustment signal includes a bias voltage/bias current adjustment signal, and/or a temperature adjustment signal. Based on the solution, a specific method for controlling the chirp effect is provided, that is, the chirp effect of the light emitting module is adjusted by the bias voltage/bias current adjustment signal and/or the temperature adjustment signal.
  • the optical module further includes a second branch, and the second branch includes a second light emitting module, and the second light emitting module is configured to generate a second optical signal and transmit the second light
  • the signal is transmitted to the first optocoupler.
  • the first optical coupler is further configured to perform branch processing according to the second optical signal to obtain a third output signal and a fourth output signal.
  • the optical delay line is also used for delaying the third output signal to obtain a second delay signal.
  • the optical filter is also used for filtering the fourth output signal to obtain a second filtering signal.
  • the second optical coupler is also used for combining the second delayed signal and the second filtered signal to obtain a second output detection signal, and sending the second output detection signal to the chirp detection circuit.
  • the chirp detection circuit is used for calculating the chirp coefficient of the second light emitting module according to the second output detection signal.
  • an extension structure of an optical module is provided.
  • the optical module may include a second branch similar to the first branch provided in the second aspect, and the optical module may manage the chirp effect of other optical emitting modules in the optical module through the second branch.
  • more of the second branches may also be included.
  • the optical module may include a first branch and a plurality of second branches, so that the optical module can manage the chirp effect of all lasers working at the same time.
  • more lasers can be set in the optical module in addition to the first branch and the second branch, thereby expanding the working capability of the optical module (for example, it can provide more lasers with different centers at the same time).
  • the chirp detection results of the first branch and the second branch can be used to realize the control of the chirp effect of the optical signal sent by the entire optical module.
  • an optical coupler may also be provided in the second branch to perform branch processing on the second optical signal, so as to While not affecting the normal communication of the second optical signal, chirp detection is performed on the branch.
  • the optical module also includes a photodetector.
  • the photodetector is used for converting the first output detection signal into a corresponding analog electrical signal, and the output detection signal is the analog electrical signal.
  • the delayed optical signal and the filtered optical signal can be combined into one spectrum, so as to calculate and obtain the chirp coefficient according to the parameters of the spectrum.
  • the optical signal can be converted into an electrical signal by the photodetector, so as to be processed and calculated by the operation module.
  • the optical module further includes a photodetector and an analog-to-digital converter.
  • the photodetector is used to convert the output detection signal into a corresponding analog electrical signal and transmit it to the analog-to-digital converter.
  • the analog-to-digital converter is used for converting the analog electrical signal into a digital electrical signal, and the output detection signal is the digital electrical signal.
  • the splitting ratio of the first optical coupler is 1:1 or 1:2. Based on this solution, a possible characteristic of the first optical coupler is provided, that is, the input detection signal can be divided into an upper arm optical signal and a lower arm optical signal with an optical power of 1:1 or 1:2.
  • a chirp detection method is provided, the method is applied to an optical module, and the optical module includes a first optical coupler, an optical delay line, an optical filter, a second optical coupler, and a first optical emission module, Chirp detection circuit.
  • the method includes: the first optical emitting module generates a first optical signal, and transmits the first optical signal to the first optical coupler.
  • the first optical coupler performs branch processing according to the first optical signal to obtain a first output signal and a second output signal.
  • the optical delay line performs delay processing on the first output signal to obtain a first delayed signal.
  • the optical filter performs filtering processing on the second output signal to obtain a first filtered signal.
  • the second optical coupler combines the first delayed signal and the first filtered signal to obtain a first output detection signal, and sends the first output detection signal to the chirp detection circuit.
  • the chirp detection circuit calculates the chirp coefficient of the first light emitting module according to the first output detection signal.
  • the center wavelength of the rising or falling edge of the transmission spectrum of the optical filter is aligned with the center wavelength of the second output signal.
  • the optical module also includes a micro-heater.
  • the method further includes: adjusting the temperature of the optical filter by the micro heater to adjust the transmission spectrum of the optical filter.
  • the micro-heater is arranged around the optical filter, and the distance from the optical filter does not exceed a preset distance.
  • the time domain distribution of the delayed first delayed signal and the time domain distribution of the first filtered signal do not coincide with each other.
  • the chirp detection circuit detects the time domain distribution of the spectrum corresponding to the first output signal, the peak value of the spectrum, and the transmission spectrum of the optical filter. The slope, and the time delay of the optical delay line are calculated to obtain the chirp coefficient of the first optical emitting module.
  • the chirp detection circuit obtains the chirp coefficient of the first light emitting module according to the following formula:
  • ⁇ is the chirp coefficient of the first light emission module
  • t1 is the time of the previous pulse in the first output detection signal
  • t2 is the time of the next pulse in the first output detection signal
  • P1 is the first output detection signal.
  • P2 is the peak power of the next pulse in the first output detection signal
  • S is the slope of the optical filter
  • D is the delay of the optical delay line
  • C is a constant.
  • the optical module further includes an adjustment module.
  • the method further includes: the chirp detection circuit instructs the adjustment module to adjust the chirp effect in the first light emission module according to the chirp coefficient of the first light emission module.
  • the method further includes: the chirp detection circuit determines that the chirp coefficient of the first light emitting module is greater than a preset threshold, and according to the chirp coefficient of the first light emitting module, to the adjustment The module sends an adjustment signal, and the adjustment module is used for adjusting the chirp effect in the first light emitting module according to the adjustment signal.
  • the adjustment signal includes a bias voltage/bias current adjustment signal, and/or a temperature adjustment signal.
  • the optical module further includes a second branch, and the second branch includes a second light emitting module.
  • the method further includes: the second optical emitting module generates a second optical signal, and transmits the second optical signal to the first optical coupler.
  • the first optical coupler performs branch processing according to the second optical signal to obtain a third output signal and a fourth output signal.
  • the optical delay line performs delay processing on the third output signal to obtain a second delayed signal.
  • the optical filter performs filtering processing on the fourth output signal to obtain a second filtered signal.
  • the second optical coupler combines the second delayed signal and the second filtered signal to obtain a second output detection signal, and sends the second output detection signal to the chirp detection circuit.
  • the chirp detection circuit calculates the chirp coefficient of the second light emitting module according to the second output detection signal.
  • the optical module also includes a photodetector.
  • the method further includes: converting the first output detection signal into a corresponding analog electrical signal by the photodetector, where the output detection signal is the analog electrical signal.
  • the optical module further includes a photodetector and an analog-to-digital converter.
  • the method also includes: converting the output detection signal into a corresponding analog electrical signal by the photodetector, and transmitting the signal to the analog-to-digital converter.
  • the analog-to-digital converter converts the analog electrical signal into a digital electrical signal, and the output detection signal is the digital electrical signal.
  • the splitting ratio of the first optical coupler is 1:1 or 1:2.
  • Fig. 1 is a kind of schematic diagram of determining chirp coefficient
  • Fig. 2 is another kind of schematic diagram of determining chirp coefficient
  • Fig. 3 is another kind of schematic diagram of determining chirp coefficient
  • FIG. 4 is a schematic diagram of the composition of a processing circuit provided by an embodiment of the present application.
  • FIG. 5 is a schematic diagram of processing an upper arm optical signal by an optical delay line according to an embodiment of the present application
  • FIG. 6 is a schematic diagram of processing a lower arm optical signal by an optical filter according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of the composition of another processing circuit provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram of an optical signal obtained after processing by a second optical coupler according to an embodiment of the present application.
  • FIG. 9 is a schematic diagram of the composition of a chirp detection circuit provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of the composition of another chirp detection circuit provided by an embodiment of the application.
  • FIG. 11 is a schematic diagram of the composition of another processing circuit provided by an embodiment of the present application.
  • FIG. 12 is a schematic diagram of the composition of an optical module according to an embodiment of the present application.
  • FIG. 13 is a schematic diagram of the composition of another optical module provided by an embodiment of the present application.
  • FIG. 14 is a schematic diagram of the composition of an adjustment module provided by an embodiment of the present application.
  • 15 is a schematic flowchart of a chirp detection method provided by an embodiment of the application.
  • 16 is a schematic flowchart of another chirp detection method provided by an embodiment of the present application.
  • FIG. 17 is a schematic diagram of the composition of another optical module provided by an embodiment of the present application.
  • FIG. 18 is a schematic diagram of the composition of another optical module provided by an embodiment of the present application.
  • FIG. 19 is a schematic diagram of the composition of another optical module provided by an embodiment of the present application.
  • FIG. 20 is a schematic diagram of the composition of another optical module provided by an embodiment of the present application.
  • medium- and short-distance communication networks such as metropolitan area networks, data centers, or content distribution networks.
  • medium- and short-distance communication networks such as metropolitan area networks, data centers, or content distribution networks.
  • optical module due to its advantages in cost, volume and power consumption, has gradually become a standard component of the transmitting/receiving end in short- and medium-distance optical communication.
  • the transmission rate of optical modules can be improved through parallel optical fiber architecture or wavelength division multiplexing technology during optical signal transmission.
  • the transmission rate of optical modules can be increased from 10 switching bandwidth (Gbps) to 40Gbps, 100Gbps, or even 400Gbps.
  • Gbps switching bandwidth
  • 400Gbps 2km optical module 4 wavelength channels can be selected, the single channel rate is 100Gbps, and the Coarse Wavelength Division Multiplexer (CWDM) technology is used to realize.
  • CWDM Coarse Wavelength Division Multiplexer
  • the transmission rate of optical modules will be further improved. For example, from the current 400Gbps to 800Gbps or higher.
  • two methods can be adopted: one is to increase the number of channels for optical signal transmission, such as from 4 channels to 8 channels.
  • the other is to increase the data communication speed (ie baud rate) of a single channel for optical signal transmission, such as from 100Gbps per channel with a baud rate of 50G Baud PAM4 to 200Gbps per channel with a baud rate of 100G Baud PAM4.
  • the scheme of increasing the baud rate of a single channel is regarded as a low-cost and low-power consumption solution. evolution route.
  • the signal spectrum is further broadened.
  • the problem of ineffective spectrum expansion (or called dispersion cost) caused by the chirp effect will cause problems. It is becoming more and more prominent, which will have a non-negligible impact on the signal quality of the optical signal, and at the same time bring huge challenges to the design of the optical module link budget and the design of the optical port index. Therefore, how to accurately detect the chirp coefficient of the laser in the optical module in the optical communication process, and correct the influence of the chirp effect on the optical signal accordingly, has become the focus of improving the signal quality of the optical communication.
  • the chirp coefficient of the laser can be determined by the following three methods.
  • Method 1 This method can also be called the frequency response method.
  • the method can measure the optical signal generated by the laser through a network analyzer, and take the optical signal as the input and transmit the frequency response spectrum of the output optical signal after passing through a dispersive medium (whose dispersion characteristics are known), and combine the frequency response spectrum.
  • the position of the resonance peak in the line determines the corresponding chirp coefficient of the laser when generating the optical signal.
  • port 1 of the network analyzer is connected to a laser
  • port 2 is connected to an optical signal receiver.
  • the laser is connected to the optical signal receiver through a dispersive medium.
  • the laser transmits the generated optical signal to the network analyzer through port1 on the one hand, and on the other hand, it is amplified by the amplifier in the dispersive medium, and then transmitted through the dispersive medium (such as standard optical fiber) and then transmitted by the optical signal.
  • Receiver receives.
  • the optical signal received by the optical signal receiver can be transmitted from port2 to the network analyzer.
  • the network analyzer can obtain the frequency response spectrum of the optical signal sideband generated by the laser and the optical signal (or called carrier beat frequency) after transmission through a standard optical fiber according to the optical signal input from port1 and the optical signal input to port2. Obtain the frequency response spectrum as shown in (b) in Figure 1.
  • the chirp coefficient corresponding to the laser when generating the optical signal can be calculated and obtained.
  • f ⁇ is the frequency when the frequency response curve has a minimum value
  • L is the length of the fiber
  • c is the speed of light
  • D is the dispersion value of the fiber
  • ⁇ is the center frequency of the optical signal
  • ⁇ is the series, take 0, 1, 2 , 3 and other integers
  • ⁇ chirp is the chirp coefficient of the laser.
  • Method 2 This method can divide the optical signal from the laser with the chirp coefficient to be measured into two channels through the optical coupler, and input the optical fiber with positive dispersion (+D) and the optical fiber with negative dispersion (-D) respectively. to transmit.
  • the dispersion values of the two sections of fiber are opposite and known, and have the same length.
  • the optical signals transmitted through the two optical fibers are respectively transmitted to the two nonlinear detectors, so as to obtain the corresponding two electrical signals. It can be understood that when the two optical signals are transmitted in optical fibers with different dispersions, the pulse width will change due to the existence of the chirp effect. Exemplarily, as shown in FIG.
  • the pulse width of the optical signal after passing through the fiber with positive dispersion (+D) is compressed, and the corresponding pulse width of the optical signal after passing through the fiber with negative dispersion (-D) is broadened. Therefore, the electrical signals converted from optical signals with different pulse widths also have different characteristics.
  • the two signals can be input into the subtractor respectively to obtain the corresponding differential signal, and the chirp coefficient of the laser that emits the optical signal can be obtained by calculating with the following formula (2).
  • V(C, ⁇ ,B 2 ) is the differential voltage signal output by the subtractor
  • E is the average power of the optical signal input to the nonlinear detector
  • C is the chirp coefficient
  • ⁇ is the optical signal input to the nonlinear detector
  • the spectral width of , B 2 is the length of the positive dispersion fiber (or negative dispersion fiber).
  • Method 3 This method may also be called Time-Resolved.
  • the device to be tested ie, the laser with the chirp coefficient to be measured, referred to as DUT for short
  • a band-pass filter BPF
  • a photodetector Photo detector, PD
  • the DUT is controlled to generate an input optical signal 1 whose center wavelength is aligned with the center of the rising edge of the BPF transmission spectrum (as shown in (b) in Figure 3).
  • the PD detects the signal 1 filtered by the BPF, and obtains the power P1 of the signal 1 .
  • the DUT is adjusted to generate an input optical signal 2 whose center wavelength is aligned with the center of the falling edge of the BPF transmission spectrum (as shown in (c) in FIG. 3 ).
  • the PD detects the signal 2 filtered by the BPF, and obtains the power P2 of the signal 2 .
  • the power and waveform of the electrical signal output by the PD can be determined by an oscilloscope (OSC) connected to the PD. According to P1, P2 and the rising and falling slopes of the transmission spectrum of the filter, the chirp coefficient of the DUT can be calculated by combining the following formula (3).
  • ⁇ is the chirp coefficient
  • P0 is the average optical power of the DUT output signal
  • S is the absolute value of the rising edge/falling edge slope in the filter transmission spectrum.
  • the chirp coefficient of the corresponding laser can be obtained by any one of the above three methods, so as to determine the influence degree of the chirp effect on the signal quality of the optical signal during the operation of the optical module, and then it can be compensated.
  • the above three methods all have certain problems:
  • the positive dispersion fiber and the negative dispersion fiber used in the method 2 are also long (generally several kilometers), so the accuracy of chirp detection is not high.
  • the use of two nonlinear photodetectors will also increase the measurement cost.
  • the chirp detection method provided by method 3 needs to lock the rising edge and falling edge of the filter transmission spectrum twice, which requires extremely high accuracy of the wavelength locking function of the laser, and the two locking processes during measurement also require Takes a lot of time.
  • the linearity, uniformity, and free spectral range of the rising and falling edges of the filter's transmission spectrum can introduce errors into the measurement.
  • method 1 and method 2 both require the use of longer optical fibers, so they cannot be integrated into optical modules.
  • Method 3 has relatively high requirements for filters and lasers. Therefore, it is also not suitable for integration in optical modules. This also leads to an increase in the layout cost of chirp detection.
  • the laser needs to generate a corresponding optical signal for chirp detection separately, so chirp detection cannot be performed during the normal operation of the laser. Therefore, it is impossible to adjust the optical signal generated by the laser for the chirp effect in real time.
  • the embodiment of the present application provides a processing circuit, which can quickly and accurately perform chirp detection, and at the same time, due to the simple composition, it can realize the integration in the optical module while ensuring the low cost of chirp detection, Then realize the real-time reporting and adjustment of the chirp effect. It can be understood that since the processing circuit can be used to perform accurate and fast chirp detection, the chirp effect can be corrected according to the chirp detection result (such as the chirp coefficient), so as to achieve the purpose of improving the signal quality of the optical signal.
  • an optical signal can be transmitted to the processing circuit, an output detection signal can be obtained after processing by the processing circuit, and then the chirp coefficient of the corresponding laser can be calculated and determined according to the output detection signal.
  • FIG. 4 is a schematic diagram of the composition of a processing circuit 400 according to an embodiment of the present application.
  • the processing circuit 400 may include a first optical coupler 401 , an optical delay line 402 , an optical filter 403 , and a second optical coupler 404 .
  • FIG. 4 also shows a chirp detection circuit 405 capable of processing the output detection signal output by the processing circuit 400 .
  • the first optical coupler 401 can receive the optical signal (the input detection signal as shown in FIG. 4 ) generated by the laser through its input end (the A1 end as shown in FIG. 4 ).
  • the first output terminal (terminal A2 shown in FIG. 4 ) of the first optical coupler 401 is coupled to the input terminal (terminal B1 shown in FIG. 4 ) of the optical delay line 402 .
  • the second output terminal (terminal A3 shown in FIG. 4 ) of the first optical coupler 401 is coupled to the input terminal (terminal C1 shown in FIG. 4 ) of the optical filter 403 .
  • the output terminal of the optical delay line 402 (terminal B2 shown in FIG. 4 ) is coupled to the first input terminal (terminal D1 shown in FIG.
  • the output terminal of the optical filter 403 (terminal C2 shown in FIG. 4 ) is coupled to the second input terminal (terminal D2 shown in FIG. 4 ) of the second optical coupler 404 .
  • the output terminal of the second optical coupler 404 is coupled to the input terminal of the chirp detection circuit 405 .
  • the processing circuit 400 provided by this embodiment of the present application can obtain the delayed signal corresponding to the detection signal and the filtered signal corresponding to the detection signal on the same time domain spectrum, and can calculate Obtain the chirp coefficient of the laser.
  • the first optical coupler 401 can be used to receive the input detection signal through the A1 terminal.
  • the input detection signal is generated by the laser whose chirp coefficient is to be detected.
  • the input detection signal may be a detection optical signal obtained by inputting the full amount of the optical signal into the first coupler 401 for chirp detection after the laser generates the optical signal.
  • the input detection signal may also be a detection optical signal obtained by dividing the optical signal used for communication by the laser during normal operation (eg, splitting through an optical coupler).
  • the first optical coupler 401 can be used to perform optical splitting (or branching) processing on it. For example, the received input detection signal is split according to the splitting ratio of 1:1 to obtain two optical signals with the same power (such as the upper arm optical signal and the lower arm optical signal).
  • the first optical coupler 401 can be used to transmit the upper arm optical signal to the optical delay line 402 through the A2 terminal for processing.
  • the first optical coupler 401 can also be used to transmit the lower arm optical signal to the optical filter 403 through the A3 terminal for processing.
  • the first optical coupler 401 may also divide the received input detection signal into two optical signals with different powers according to other optical splitting ratios (eg 1:2), and divide the received input detection signal into two optical signals with different powers.
  • the corresponding optical signals are respectively transmitted to the optical delay line 402 through the A2 terminal, and transmitted to the optical filter 403 through the A3 terminal for processing.
  • the optical delay line 402 can receive the upper arm optical signal through the B1 terminal.
  • the optical delay line 402 may be used to adjust the delay of the upper arm optical signal (eg, increase the delay of the upper arm optical signal), so as to achieve the purpose of shifting the spectrum of the upper arm optical signal backward in the time domain.
  • the optical delay line 402 can shift the spectrum of the upper-arm optical signal in the time domain backward by 1 bit to obtain the delayed optical signal (eg, the optical signal) 1). It should be noted that, in the example shown in FIG.
  • the delay adjustment of the upper arm optical signal is realized by the optical delay line 402 , in other embodiments, other devices may also be used to realize the upper arm optical signal
  • the adjustment of the delay is not limited in this embodiment of the present application.
  • the adjustment of the delay of the upper arm optical signal by the optical delay line 402 as shown in FIG. 4 will be described as an example.
  • FIG. 5( a ) and FIG. 5( b ) show a schematic diagram of processing an upper arm optical signal by an optical delay line 402 .
  • the input detection signal is a Gaussian pulse optical signal as an example.
  • the optical delay line 402 can receive the upper-arm optical signal having the spectral distribution shown in (a) in FIG. 5 through the B1 end, and perform delay processing on it. That is, the time-domain delayed optical signal 1 can be obtained.
  • the optical signal 1 may have a spectral distribution as shown in (b) in FIG. 5 .
  • the optical delay line 402 can also be used to transmit the optical signal 1 to the second optical coupler 404 through the B2 terminal.
  • the optical filter 403 can receive the lower arm optical signal through the C1 terminal.
  • the optical filter 403 may be used to filter the lower arm optical signal.
  • the center frequency of the lower arm optical signal is aligned with the center of the rising edge or the center of the falling edge of the transmission spectrum of the optical filter 403, so that the signal obtained after filtering (such as the optical signal 2) Determine the chirp coefficient of the laser.
  • the center frequency of the lower arm optical signal is aligned with the rising edge of the transmission spectrum of the optical filter 403.
  • the instantaneous frequency of the optical signal will increase with time. Therefore, when the center frequency of the lower arm optical signal is aligned with the center of the rising edge of the optical filter 403, since the instantaneous frequency of the rising edge is low, the low frequency part of the transmission spectrum of the optical filter 403 corresponds to the low frequency part of the optical filter 403, so this part of the optical signal will be greatly attenuated. Correspondingly, since the instantaneous frequency of the falling edge is relatively low, it corresponds to the high frequency part of the transmission spectrum of the optical filter 403 , so the attenuation amplitude of this part of the optical signal is relatively small. Therefore, after the lower arm optical signal is processed by the optical filter 403, the output optical signal 2 is attenuated in intensity compared with the lower arm optical signal before processing in the time domain, and at the same time, the pulse peak will appear in the time domain. displacement.
  • FIG. 6(a) and FIG. 6(b) show a schematic diagram of processing the optical signal of the lower arm by an optical filter 403 .
  • the optical signal input to the processing circuit 400 is a Gaussian pulse optical signal
  • the lower arm optical signal is the same as the upper arm optical signal
  • the rising edge of the transmission spectrum of the optical filter 403 is aligned with the center frequency of the optical signal as an example.
  • the optical filter 403 can receive the lower-arm optical signal having the spectral distribution shown in (a) of FIG. 6 through the C1 terminal, and perform filtering processing on the lower-arm optical signal. to obtain the optical signal 2 as shown in (b) of FIG. 6 . It can be seen that after the filtering process, the time domain distribution of the spectrum of the optical signal 2 is still within the time domain distribution range of the spectrum of the lower arm optical signal, but both the amplitude and the peak phase have changed.
  • the optical filter 403 can transmit the optical signal to the second optical coupler 404 through the C2 terminal as shown in FIG. 4 .
  • the rising edge or falling edge of the transmission spectrum of the optical filter 403 involved in the embodiment of the present application needs to be aligned with the center frequency of the optical signal input to the optical filter 403 (the following arm optical signal). It is understandable that the center frequencies of the optical signals generated by the same laser in different usage scenarios are different. When generating different optical signals, the chirp coefficients of the lasers may also be different due to differences in the corresponding optical power and other reasons. Therefore, in order to ensure that the corresponding chirp detection can be covered when the laser works in different scenarios (that is, the laser generates optical signals with different center frequencies), in some implementations of the embodiments of the present application, the optical filter 403 can be adjusted by actively adjusting the chirp detection. The transmission spectrum is aligned to the center frequency of the corresponding input optical signal.
  • FIG. 7 shows a schematic composition diagram of another processing circuit 400 provided by an embodiment of the present application.
  • a micro-heater 406 may be provided near the optical filter 403 .
  • the temperature of the optical filter 403 can be adjusted by setting the micro-heater 406, and the position of the transmission spectrum of the optical filter 403 in the frequency domain can be adjusted, so that the rising edge of the transmission spectrum of the optical filter 403/ The center of the falling edge is aligned with the center frequency of the incoming optical signal.
  • the micro-heater 406 can be placed close to the optical filter 403 so as to be able to control the transmission spectrum of the optical filter 403 more effectively, for example, the micro-heater 406 can be placed at a distance around the optical filter 403 1 to 2 ⁇ m, so that the micro-heater 406 can effectively adjust the optical filter 403 .
  • the optical filter 403 can be flexibly selected according to different cost requirements and selection requirements. For example, when the optical filter 403 needs to be realized through an on-chip structure, it can be realized through a Mach-Zehnder interferometer structure or a micro-ring resonance.
  • the cavity structure is integrated in the processing circuit 400 .
  • the second optical coupler 404 can be used to receive the optical signal 1 obtained after processing from the optical delay line 402 through the D1 end, and can also be used to receive the optical signal 2 obtained after processing from the optical filter 403 through the D2 end.
  • the second optical coupler 404 can also be used for combining and processing the two optical signals received from the D1 end and the D2 end. It can be understood that, since the upper-arm optical signal is subjected to delay processing by the optical delay line 402, its spectral position in the time domain does not overlap with the upper-arm optical signal. Meanwhile, the processing of the lower arm optical signal by the optical filter 403 is only filtering processing, and the spectrum of the optical signal obtained after processing in the time domain will still fall within the time domain range of the spectrum of the lower arm optical signal.
  • the time domain positions of the upper arm optical signal and the lower arm optical signal are the same. Therefore, after the second optical coupler 404 performs combined processing on the optical signal 1 and the optical signal 2, the optical signal 1 and the optical signal 2 can be obtained in the time domain that are complete and do not cross each other.
  • FIG. 8 shows a schematic diagram of an optical signal obtained after processing by the second optical coupler 404 .
  • the optical signal input to the processing circuit 400 is a Gaussian pulse optical signal
  • the lower arm optical signal is the same as the upper arm optical signal
  • the rising edge of the transmission spectrum of the optical filter 403 is aligned with the center frequency of the optical signal as an example.
  • the optical signal input to the second optical coupler 404 may include optical signal 1 as shown in (b) of FIG. 5 , and optical signal 2 as shown in (b) of FIG. 6 .
  • an output detection signal as shown in FIG. 8 can be obtained. It can be seen that the output detection signal shown in FIG. 8 also includes the spectrum of the optical signal 1 obtained after filtering by the optical filter 403 and the spectrum of the optical signal 2 obtained after the delay processing by the optical delay line 402. Two pulses signal spectrum.
  • the output detection signal may include two pulses (for example, the time domain spectrum of the output detection signal may have the characteristics shown in FIG. 8 . distribution shown).
  • the output detection signal may be transmitted to the chirp detection circuit 405 as shown in FIG. 4 or FIG. 7 so that the chirp detection circuit 405 determines the chirp coefficient of the laser generating the input detection signal from the output detection signal.
  • the chirp detection circuit 405 may include a photodetector 901 and an operation module 902 .
  • the input terminal of the photodetector 901 can be used as the input terminal of the chirp detection circuit 405 to receive the output detection signal.
  • the output terminal of the photodetector 901 is coupled to the operation module 902 .
  • the obtained output detection signal is an optical signal, which generally cannot be directly processed and calculated.
  • the photodetector 901 can be used to convert the output detection signal into a corresponding electrical signal for subsequent processing.
  • the operation module 902 since the electrical signal output by the photodetector 901 is generally an analog electrical signal, the operation module 902 needs to be capable of processing analog signals.
  • the analog-to-digital converter 903 may be set before the analog signal is input to the operation module 902.
  • the input end of the analog-to-digital converter 903 is coupled to the output end of the photodetector 901 , and the output end of the analog-to-digital converter 903 is coupled to the operation module 902 .
  • the analog-to-digital converter 903 can be used to perform analog-to-digital conversion on the analog electrical signal output by the photodetector 901 to obtain a corresponding digital electrical signal, so that the operation module 903 can quickly and accurately perform calculation processing.
  • the photodetector 901 and/or the analog-to-digital converter 903 are provided in the chirp detection circuit 405 as an example for description. In other implementations, the photodetector 901 and/or the analog-to-digital converter 903 may also be provided in the processing circuit 400 .
  • FIG. 11 is a schematic diagram of the composition of another processing circuit 400 provided in an embodiment of the present application. As shown in FIG.
  • a photodetector 901 coupled to the output end of the second optical coupler 404 may be provided in the processing circuit, and the output end of the photodetector 901 is coupled to the input end of the analog-to-digital converter 903 Then, the output end of the analog-to-digital converter 903 can be the output end of the processing circuit 400 .
  • the processing circuit shown in FIG. 11 performs chirp detection
  • the signal obtained through its processing ie, the output detection signal
  • the photodetector 901 and/or the analog-to-digital converter 903 may also be arranged on the serial path between the processing circuit 400 and the chirp detection circuit 405 .
  • the operation module 902 may be a component with a computing function.
  • the operation module 902 may implement its corresponding function through a component having a logic operation function such as a field programmable gate array (Field-Programmable Gate Array, FPGA).
  • the operation module 902 can also implement its corresponding function through a component with processing functions such as a processor (Central Processing Unit, CPU) or a Microcontroller Unit (Microcontroller Unit, MCU). In specific implementation, it can be flexibly selected according to product characteristics and related requirements, which is not limited in this embodiment of the present application.
  • the operation module 902 can calculate and obtain the chirp coefficient according to the electrical signal output by the photodetector 901 by comparing the electrical signal with the intensity and time domain difference of the two pulses before and after the output detection signal. It should be noted that the method for calculating and obtaining the chirp coefficient by the operation module 902 is related to the spectrum type of the optical signal generated by the laser. Generally speaking, in the process of optical communication, most of the optical signals generated by the laser conform to the Gaussian pulse distribution. Therefore, the optical signal generated by the laser whose chirp coefficient is to be measured is taken as an example of the Gaussian pulse.
  • the computing module may calculate and obtain the chirp coefficient of the corresponding laser according to the following formula (4).
  • ⁇ is the chirp coefficient
  • t1 is the time of outputting the previous pulse of the double-pulse signal
  • t2 is the time of outputting the next pulse of the double-pulse optical signal
  • P1 is the peak power of the previous pulse of the output double-pulse signal
  • P2 is the output double-pulse signal.
  • S is the slope of the rising edge (or falling edge) spectrum aligned with the center wavelength of the input detection signal
  • D is the time delay of the optical delay line
  • C is a constant. It should be noted that, according to the different models or types of lasers whose chirp coefficients are to be measured, C can take different values. For example, this C can be taken as 0.1.
  • the optical signal generated by the laser can be subjected to light splitting, and the input detection signal can be obtained without affecting the current optical communication.
  • the input detection signal is input into the processing circuit shown in FIG. 4 or FIG. 7 or FIG. 11 to obtain the corresponding output detection signal.
  • the chirp detection circuit can determine the chirp coefficient of the currently working laser. In this way, real-time and fast measurement of the chirp coefficient can be achieved without affecting the optical communication.
  • the involved optical couplers such as the first optical coupler 401 and the second optical coupler 404
  • the optical delay line 402, the optical filter 403, and the micro-heater 406 are all commonly used components in optical communication.
  • the board area of each component is also very small, so the processing circuit can be well integrated in the optical module, which greatly reduces the cost and implementation difficulty of chirp detection.
  • FIG. 12 is a schematic diagram of the composition of an optical module 1200 according to an embodiment of the present application.
  • the optical module 1200 may be provided with the processing circuit 400 described in any one of the above descriptions.
  • the real-time chirp detection can be performed without affecting the normal optical communication, and the optical signal can be adjusted according to the detection result, so as to reduce the influence of the chirp effect on the signal quality of the output optical signal.
  • the processing circuit 1205 has the composition of the processing circuit 400 shown in Fig. 11 as an example.
  • the optical module 1200 may include a processor 1201 , a signal processing module 1202 , a light emission module 1203 , an optical coupler 1204 , a processing circuit 1205 , and an adjustment module 1206 .
  • the light emitting module 1203 may also be referred to as a laser or a modulator.
  • the first output terminal of the processor 1201 (the A1 terminal shown in FIG. 12 ) is coupled to the first receiving terminal (the B1 terminal shown in FIG. 12 ) of the signal processing module 1202 .
  • the first transmitting terminal (terminal B2 shown in FIG. 12 ) of the signal processing module 1202 is coupled to the input terminal (terminal C1 shown in FIG. 12 ) of the light transmitting module 1203 .
  • the output end (the C2 end shown in FIG. 12 ) of the light emitting module 1203 is coupled to the input end (the D1 end shown in FIG. 12 ) of the optical coupler 1204 .
  • the first output terminal (terminal D2 shown in FIG. 12 ) of the optical coupler 1204 is coupled to the input terminal (terminal E1 shown in FIG.
  • the second output terminal of the optical coupler 1204 (terminal D3 shown in FIG. 12 ) is the output terminal of the optical module 1200 .
  • the output terminal of the processing circuit 1205 (the E2 terminal shown in FIG. 12 ) is coupled to the first input terminal (the A2 terminal shown in FIG. 12 ) of the processor 1201 .
  • the second output terminal of the processor 1201 (terminal A3 shown in FIG. 12 ) is coupled to the input terminal (terminal F1 shown in FIG. 12 ) of the adjustment module 1206 , and the output terminal of the adjustment module 1206 (as shown in FIG. 12 )
  • the F2 terminal is coupled to the second input terminal (C3 terminal as shown in FIG. 12 ) of the light emitting module 1203.
  • the processor 1201 is responsible for the generation of control signals and the processing of feedback signals, and is generally implemented by a micro-processing unit (micro control unit, MCU).
  • MCU micro control unit
  • the processor 1201 since the processor 1201 has a computing function, it can be used to implement the function of the operation module 902 in the chirp detection circuit 405 as shown in FIG. 10 .
  • the following description takes the processor as an MCU as an example.
  • the signal processing module 1202 can be used for generating, processing and recovering electrical signals that meet different rate standards and modulation formats.
  • the light emitting module 1203 can be used to generate an optical signal with a specific wavelength according to the received instruction.
  • the light emitting module 1203 may be implemented by components such as a directly modulated semiconductor laser (DML), an electroabsorption modulator (EML), and the like.
  • DML directly modulated semiconductor laser
  • EML electroabsorption modulator
  • the electrical signal generated by the signal processing module 1202 under the control of the MCU 1201 may not be directly recognized by the light emission module 1203 and generate a corresponding optical signal. Therefore, between the signal processing module 1202 and the light emitting module 1203, a driving module can also be provided, so as to send an instruction that can be recognized and applied to the light emitting module 1203 according to the instruction of the signal processing module 1202.
  • FIG. 13 is a schematic diagram of the composition of another optical module 1200 provided in this embodiment of the present application.
  • a driving module 1207 may also be provided between the signal processing module 1202 and the light emitting module 1203 .
  • the input terminal (G1 terminal shown in FIG. 13 ) of the driving module 1207 can be coupled with the B2 terminal of the signal processing module 1202 , and the output terminal (G2 terminal shown in FIG. 13 ) of the driving module 1207 can be connected to the light emitting module
  • the C1 terminal of 1203 is coupled.
  • the driving module 1207 can be used to receive the electrical signal sent by the signal processing module 1202 through the G1 terminal, perform operations such as amplifying/rectifying the electrical signal, obtain the corresponding electrical signal that can be recognized and processed by the light emitting module 1203, and pass the G2 The terminal is transmitted to the light emission module 1203.
  • the adjustment module 1206 may be used to adjust the bias current/voltage and/or the ambient temperature of the light emission module 1203, so as to adjust the chirp size of the optical signal generated when the light emission module 1203 is working.
  • FIG. 14 shows a schematic diagram of the composition of an adjustment module 1206 .
  • the adjustment module 1206 may include a bias voltage/bias current control module 1206-1, and a temperature control module 1206-2.
  • the input terminal of the bias voltage/bias current control module 1206-1 (the F1-1 terminal in Figure 14) and the input terminal of the temperature control module 1206-2 (such as the F1-2 terminal shown in the input 14) can correspond to
  • the F1 end of the adjustment module 1206 as shown in FIG. 12 is used to receive the corresponding control signal from the MCU 1201.
  • the bias voltage/bias current control module 1206-1 can receive an instruction for controlling the bias voltage/bias current from the MCU 1201 from the F1-1 terminal, so as to realize the adjustment of the bias voltage/bias current of the light emission module 1203 by the MCU 1201.
  • the temperature control module 1206-2 can receive an instruction for controlling the temperature from the MCU 1201 through the F1-2 terminal, so as to realize the adjustment of the ambient temperature of the light emission module 1203 by the MCU 1201.
  • the adjustment module 1206 includes both the bias voltage/bias current control module 1206 - 1 and the temperature adjustment module 1206 as an example for description. In other embodiments of the present application, the adjustment module 1206 may also include only one of the bias voltage/bias current control module 1206 - 1 or the temperature adjustment module 1206 .
  • the adjustment module 1206 since the corresponding chirp coefficient when the light emission module 1203 modulates the optical signal will be affected by both the bias voltage/bias current and the temperature, therefore, when the adjustment module 1206 only includes the bias voltage/bias current control module 1206 -1 or one of the temperature adjustment modules 1206, the optical module 1200 can still control the size of the chirp through the MCU 1201, so as to realize the adjustment of the corresponding chirp of the optical signal.
  • the adjustment module 1206 includes both the bias voltage/bias current control module 1206-1 and the temperature adjustment module 1206.
  • the MCU 1201 can be used to send an instruction message 1 to the signal processing module 1202 through the A1 end, and the instruction message 1 can be used to instruct the signal processing module 1202 to generate a corresponding instruction, so as to pass the instruction message 1 to the signal processing module 1202.
  • the instruction controls the optical transmission module 1203 to generate a corresponding optical signal for optical communication.
  • the signal processing module 1202 can generate an instruction (eg, control message 1) corresponding to the instruction message 1 according to the instruction message 1, and send the instruction to the light transmitting module 1203 through the B2 terminal.
  • the optical transmission module 1203 can be configured to generate the corresponding optical signal 1 according to the control message 1, and transmit the optical signal 1 to the optical coupler 1204 through the C2 terminal.
  • the optical coupler 1204 can be used to receive the optical signal 1 through the D1 terminal, and perform branch processing on the optical signal 1 to obtain an output optical signal and an input detection signal for chirp detection.
  • the optical coupler 1204 can also be used to send the output optical signal from the optical module 1200 through the D3 terminal, so as to realize the external communication of the optical module 1200 .
  • the optocoupler 1204 can also be used to transmit the input detection signal to the processing circuit 1205 through the D2 terminal.
  • the processing circuit 1205 can receive the input detection signal through the E1 terminal, process the input detection signal and obtain an output detection signal.
  • the chirp monitoring module can generate an output detection signal having the spectral distribution shown in FIG. 8 .
  • the processing circuit 1205 can transmit the output detection signal to the MCU 1201 through the E2 terminal.
  • the MCU 1201 can receive the output detection signal through the A2 terminal, and calculate and obtain the corresponding chirp coefficient accordingly.
  • the real-time detection of the chirp coefficient is realized without interrupting the optical communication.
  • the optical module 1200 can adjust the optical signal currently being communicated accordingly, so as to control the influence of the chirp effect on the optical signal within a reasonable range.
  • the MCU 1201 can also be used to obtain the output detection signal sent by the processing circuit 1205, in conjunction with the calculation method of the chirp coefficient in the above description. After obtaining the size of the chirp coefficient of the current light emission module 1203, the MCU 1201 can determine whether the current chirp coefficient is within a reasonable range, and if it exceeds the reasonable range, the control adjustment module 1206 (such as the bias voltage/bias current control module 1206- 1 and/or the temperature control module 1206-2) adjust the bias voltage/bias current of the light emitting module 1203 and the ambient temperature in order to realize the adjustment of the chirp.
  • the control adjustment module 1206 such as the bias voltage/bias current control module 1206- 1 and/or the temperature control module 1206-2
  • whether the chirp coefficient needs to be adjusted can be determined by comparing the magnitude relationship between the chirp coefficient obtained by the calculation and the preset threshold.
  • the MCU 1201 may determine that the chirp coefficient needs to be adjusted when it is determined that the current chirp coefficient is greater than the preset threshold. Conversely, the MCU 1201 may determine that the chirp coefficient does not need to be adjusted when it is determined that the current chirp coefficient is less than the preset threshold.
  • the preset threshold may be a threshold in the MCU 1201, or may be flexibly set during chirp detection. This embodiment of the present application does not limit this.
  • FIG. 15 is a schematic flowchart of a chirp detection method provided by an embodiment of the present application.
  • the method can be applied to the optical module 1200 described in any one of the above examples (eg, FIG. 12 or FIG. 13 or FIG. 14 ).
  • the method can be applied to the chirp detection during the normal working process of the optical module, and can also be applied to the chirp detection of the laser during the non-working process.
  • the following is an example of chirp detection applied to a laser in a non-working process.
  • the method may include S1501-S1506.
  • the MCU sends a chirp detection instruction to a signal processing module.
  • the MCU can trigger the optical module to start working by sending a chirp detection command, and generate a corresponding optical signal, so as to perform chirp detection accordingly.
  • the signal processing module generates and sends a chirp detection signal according to the chirp detection instruction.
  • the driving module receives the chirp detection signal, amplifies the chirp detection signal, and sends the processed chirp detection signal to the light emission module.
  • the optical transmitting module receives the chirp detection signal, and generates a corresponding input detection signal according to the chirp detection signal.
  • the light emitting module sends the input detection signal to the processing circuit.
  • the optical transmitting module can transmit the full amount of the optical signal to the processing circuit after generating the optical signal.
  • the optical module 1200 may also not include the optical coupler 1204 . After the light emitting module 1203 generates the light signal, it can input the full amount of the light signal into the processing circuit 1205, so as to perform chirp detection accordingly.
  • the processing circuit acquires the output detection signal according to the input detection signal, and sends the output detection signal to the MCU.
  • the MCU determines the chirp coefficient according to the output detection signal.
  • the processing circuit obtains the output detection signal according to the input detection signal, and the method for the MCU to determine the chirp coefficient according to the output detection signal is similar to the above description, and will not be repeated here.
  • the MCU may also first determine whether the acquired signal strength of the output detection signal meets the preset strength, and only if the signal strength meets the preset strength , execute S1506 again.
  • the MCU can stop executing the above S1506 and adjust the relevant parameters of the processing circuit to obtain the output detection signal with the signal strength satisfying the detection requirements. For example, the MCU can send a wavelength adjustment instruction to the processing circuit for controlling the micro-heater to adjust the center frequency of the rising edge/falling edge of the optical filter, thereby obtaining a light enough output detection signal.
  • the MCU can determine whether the influence of the chirp effect in the current state of the laser on the optical signal is acceptable. If the influence of the chirp effect on the optical signal is too large, targeted correction processing can be performed.
  • the method may further include S1507-S1509.
  • the MCU judges whether the chirp correction needs to be performed.
  • the MCU may determine whether to perform chirp correction according to the magnitude relationship between the acquired chirp coefficient and the preset threshold. For example, when the chirp coefficient is greater than a preset threshold, it is determined that chirp correction is required. Continue to execute S1508. Conversely, when the chirp coefficient is smaller than the preset threshold, chirp correction is not required.
  • the MCU sends an adjustment instruction to the adjustment module.
  • the adjustment module receives the adjustment instruction, and adjusts the chirp coefficient of the light emission module according to the adjustment instruction.
  • the MCU can send corresponding adjustment instructions to the bias voltage/bias current control module and the temperature control module respectively, so that the adjustment module can adjust the Instruct to adjust the bias voltage/bias current and ambient temperature of the light emitting module respectively.
  • the MCU may send an adjustment instruction 1 to the bias voltage/bias current control module, so that the bias voltage/bias current control module adjusts the bias voltage/bias current of the light emitting module according to the adjustment instruction 1.
  • the MCU may send the adjustment instruction 2 to the temperature control module, so that the temperature control module adjusts the ambient temperature of the light emitting module according to the adjustment instruction 2 .
  • the MCU may determine the corresponding adjustment instruction according to the magnitude relationship between the chirp coefficient obtained by detection and the preset threshold.
  • the MCU may store corresponding relationships of adjustment indications corresponding to different chirp coefficients.
  • the MCU can filter and determine the corresponding adjustment instruction according to the corresponding relationship, and send it to the adjustment module, so that the adjustment module can perform accurate chirp adjustment accordingly.
  • the above-mentioned S1501 may be repeatedly performed to detect the adjusted chirp coefficient again until the chirp adjustment is not required.
  • the processing circuit provided by the embodiment of the present application can be conveniently and effectively integrated into the optical module.
  • the optical module has the ability to detect the chirp coefficient in real time without affecting the current communication.
  • an adjustment module is set in the optical module, so that the optical module can adjust the chirp coefficient in real time, so as to control the influence of the chirp effect on the optical signal within a reasonable range, thereby effectively improving the signal quality of optical communication.
  • an optical module is set in a certain node of optical communication, and may need to have the capability of receiving optical signals and transmitting optical signals at the same time.
  • the optical module involved in the above example can effectively adjust the chirp coefficient of the output optical signal to ensure the signal quality of the output optical signal.
  • the embodiments of the present application further provide an optical module capable of simultaneously receiving and processing optical signals.
  • a light receiving module 1208 may also be provided in the light module 1200 .
  • the input terminal of the light receiving module 1208 (the H1 terminal shown in Fig. 17 ) can be used to receive the input optical signal.
  • the output terminal of the light receiving module 1208 (the H2 terminal shown in FIG. 17 ) is coupled to the second input terminal (the B3 terminal shown in FIG. 17 ) of the signal processing module 1202 .
  • the second output terminal (terminal B4 shown in FIG. 17 ) of the signal processing module 1202 is coupled to the MCU.
  • the optical receiving module 1208 can be used to receive the input optical signal through the H1 terminal, convert the input optical signal into a corresponding electrical signal, and transmit it to the signal processing module 1202 through the H2 terminal.
  • the signal processing module 1202 can be used to process the received electrical signal, analyze the electrical signal to obtain corresponding data, and transmit it to the MCU through the B3 terminal. So that the MCU can process the data correspondingly.
  • an optical module is generally capable of simultaneously performing communication of optical signals corresponding to multiple wavelengths.
  • the optical module can simultaneously work at 1270nm, 1290nm, 1310nm, and 1330nm (also known as CWDM 4 wavelengths).
  • the embodiment of the present application further provides an optical module, so that the optical module can effectively perform the optical communication of the optical signals corresponding to multiple wavelengths at the same time.
  • the influence of the chirp effect of the corresponding optical communication on the signal quality of the optical signal is controlled.
  • FIG. 18 is a schematic diagram of the composition of another optical module 1200 provided by an embodiment of the present application.
  • the optical module may include a plurality of light emitting modules (1203-1 to 1203-n as shown in the figure), and optical couplers corresponding to the plurality of light emitting modules one-to-one (as shown in the figure). 1204-1 to 1204-n shown in).
  • one optical transmission module and one optical coupler correspond to an optical signal link of one wavelength.
  • Each optical signal link works under a different operating wavelength.
  • FIG. 18 it is taken as an example that each optical signal link has the composition shown in FIG. 12 .
  • one or more optical signal links in the optical module 1200 may have the composition described in any of FIG. 13 or FIG. 14 or FIG. 17 . This embodiment of the present application does not limit this.
  • the MCU 1201 can control the signal processing module 1202 to send an indication of working under the wavelength 1 to the optical transmission module 1 1203-1, so that the optical transmission module 1 1203-1203-1 An optical signal A having a center wavelength of wavelength 1 is generated.
  • the optical signal A can be processed by the splitter of the optocoupler 1 1204-1 to obtain an output optical signal 1 that is output for optical communication, and an input detection signal 1 that is used for chirp detection.
  • the input detection signal 1 can be input into the processing circuit 1205 to obtain the corresponding output detection signal 1 and transmit the output detection signal 1 to the MCU 1201.
  • the MCU 1201 can determine whether the light emission module 1 1203-1 needs to be chirp adjusted according to the output detection signal 1. If necessary, adjust the chirp coefficient corresponding to the light emission module 1 1203-1 through the adjustment module. Similarly, the MCU 1201 can control the signal processing module 1202 to send an instruction to work under the wavelength n to the light emitting module n 1203-n, so that the light emitting module n 1203-n generates an optical signal N whose center wavelength is the wavelength n.
  • the optical signal N can be processed by the splitter of the optocoupler n 1204-n to obtain an output optical signal n that is output for optical communication, and an input detection signal n that is used for chirp detection.
  • the input detection signal n can be input into the processing circuit 1205 to obtain the corresponding output detection signal n, and transmit the output detection signal n to the MCU 1201.
  • the MCU 1201 can determine whether the light emission module n 1203-n needs to be chirp adjusted according to the output detection signal n. If necessary, adjust the chirp coefficient corresponding to the light emission module n 1203-n by adjusting the module.
  • FIG. 19 shows a schematic diagram of the composition of an optical module 1200 capable of supporting CWDM 4-wavelength optical communication.
  • the light emitting module 1 therein can generate an optical signal with a center wavelength of 1270 nm under the control of the signal processing module.
  • the light emitting module 2 can generate an optical signal with a center wavelength of 1290 nm under the control of the signal processing module.
  • the light emitting module 3 can generate an optical signal with a center wavelength of 1310 nm under the control of the signal processing module.
  • the light emitting module 4 can generate an optical signal with a center wavelength of 1330 nm under the control of the signal processing module.
  • the optical coupler corresponding to the optical transmission module can split the optical signal of the corresponding wavelength into two channels, one channel is emitted outward for optical communication, and the other channel is input to the processing circuit as the chirp detection signal of the corresponding wavelength, so as to perform the corresponding chirp detection. Chirp detection.
  • the MCU After the MCU obtains the chirp coefficient corresponding to the optical transmitter module, it can adjust the chirp according to the method in S1507-S1509 as shown in Figure 16, so as to ensure that the optical signals of different center wavelengths are affected by the chirp effect and can be within the control range.
  • chirp detection and adjustment of the optical emitting modules corresponding to a plurality of different wavelengths in the optical module can be realized.
  • the influence of the chirp effect on the optical signals of different wavelengths is different.
  • the impact of the chirp effect on optical signals with the largest and smallest wavelengths is at the two extremes of bandwidth expansion/compression. Therefore, in some other embodiments of the present application, chirp detection and adjustment may be performed only on the light emitting module that outputs the maximum wavelength and the light emitting module that outputs the minimum wavelength, so as to effectively control the chirp while simplifying the light module.
  • the chirp effect has the greatest impact on the signal quality of the optical signal generated by the optical transmitter module.
  • the optical module 1200 capable of supporting CWDM 4-wavelength optical communication as an example.
  • corresponding optical couplers can be configured for the optical emission module 1 and the optical emission module 4, and the optical emission module 2 for generating the wavelength of 1290 nm and the optical emission module 3 for generating the wavelength of 1310 nm can be configured.
  • the MCU can cooperate with the processing circuit to detect and adjust the chirp of the optical transmitter module 1 and the optical transmitter module 4, so as to ensure that the optical signal output by the CWDM 4 wavelength is controlled within a reasonable range due to the chirp effect.
  • the optical module provided by the embodiment of the present application can realize real-time detection of the chirp coefficient, and when the chirp effect has a great influence on the signal quality of the optical signal, that is, when the chirp coefficient is greater than the preset threshold, then The chirp effect is adjusted by the adjustment module, so as to effectively control the influence of the chirp effect on the quality of the optical signal.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Optics & Photonics (AREA)
  • Optical Communication System (AREA)

Abstract

La présente invention concerne un circuit de traitement, un module optique et un procédé de détection de chirp, qui se rapportent au domaine des communications optiques et peuvent déterminer rapidement et avec précision un coefficient de chirp d'un laser. La solution spécifique implique : un circuit de traitement appliqué à un module optique, le module optique comprenant un circuit de détection de chirp et un module d'émission de lumière, et le circuit de traitement comprenant un premier coupleur optique, une ligne de retard optique, un filtre optique et un second coupleur optique. Le premier coupleur optique reçoit un signal optique provenant du module d'émission de lumière et effectue un traitement de dérivation sur le signal optique pour obtenir un premier signal de sortie et un second signal de sortie. La ligne de retard optique retarde le premier signal de sortie pour obtenir un signal retardé. Le filtre optique filtre le second signal de sortie pour obtenir un signal filtré. Le second coupleur optique combine le signal retardé et le signal filtré pour obtenir un signal de détection de sortie, et envoie le signal de détection de sortie au circuit de détection de chirp, de sorte que le circuit de détection de chirp calcule un coefficient de chirp du module d'émission de lumière en fonction du signal de détection de sortie.
PCT/CN2020/099569 2020-06-30 2020-06-30 Circuit de traitement, module optique et procédé de détection de chirp WO2022000338A1 (fr)

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CN202080101810.XA CN115698658A (zh) 2020-06-30 2020-06-30 一种处理电路、光模块以及啁啾检测方法
PCT/CN2020/099569 WO2022000338A1 (fr) 2020-06-30 2020-06-30 Circuit de traitement, module optique et procédé de détection de chirp

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6958467B2 (en) * 2001-11-02 2005-10-25 Nippon Telegraph And Telephone Corporation Chirp measurement apparatus
US7283572B2 (en) * 2004-01-15 2007-10-16 Ben Gurion University Of The Negey Measurement of wavelength transients in tunable lasers
US20080205884A1 (en) * 2007-02-23 2008-08-28 Agilent Technologies, Inc. Polarization Controlled Interferometric Chirp Characterization
CN104729723A (zh) * 2013-12-20 2015-06-24 中国工程物理研究院激光聚变研究中心 一种线性啁啾脉冲啁啾特性的测量方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6958467B2 (en) * 2001-11-02 2005-10-25 Nippon Telegraph And Telephone Corporation Chirp measurement apparatus
US7283572B2 (en) * 2004-01-15 2007-10-16 Ben Gurion University Of The Negey Measurement of wavelength transients in tunable lasers
US20080205884A1 (en) * 2007-02-23 2008-08-28 Agilent Technologies, Inc. Polarization Controlled Interferometric Chirp Characterization
CN104729723A (zh) * 2013-12-20 2015-06-24 中国工程物理研究院激光聚变研究中心 一种线性啁啾脉冲啁啾特性的测量方法

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