Transmitting end time delay compensation method, receiving end time delay compensation method and device

Abstract

The invention provides a transmitting end time delay compensation method and device, and a receiving end time delay compensation method and device, and the method comprises the steps: sequentially setting the transmitting end time delay compensation of a digital signal processor as a plurality of first scanning values, and setting a plurality of second scanning values after each first scanning value is set; two paths of orthogonal sinusoidal voltage signals are output through a digital-to-analog converter in the digital signal processor, a first processing result of an optical signal output by the modulator through a photodiode and a trans-impedance amplifier is obtained, and a sum frequency voltage amplitude and a difference frequency voltage amplitude are extracted from the first processing result; according to the sum frequency voltage amplitude and the difference frequency voltage amplitude, calculating to obtain an optical power difference value between the sum frequency optical power and the difference frequency optical power; and comparing the optical power difference values corresponding to different first scanning values, and setting the sending end time delay compensation of the digital signal processor as the first scanning value corresponding to the minimum optical power difference value. According to the method and the device, the optimal compensation amount of the sending end time delay can be quickly and accurately determined without an external instrument.

Description

Technical Field

[0001] This application relates to the technical field of optical communication devices, and particularly to a method and device for compensating the transmit - end delay and a method and device for compensating the receive - end delay. Background Art

[0002] With the rapid development of technologies such as 5G, big data, Internet of Things, cloud computing, and AI, the demand for service bandwidth and data traffic has increased sharply. 5G drives the continuous development of the rate and market scale of optical modules on the telecom side. While 5G mobile communication networks provide higher transmission rates and lower latencies, the optical port rates between optical transmission nodes at all levels have increased significantly, requiring optical modules to be able to carry higher rates.

[0003] Coherent optical communication has entered an era of development from 100G to 400G and even 800G. The main challenge brought by high speed is the use of high - frequency bandwidth in the channel. The high - bit - rate transmission standard has evolved from the traditional non - return - to - zero (NRZ) coding to the more spectrally efficient four - level pulse amplitude modulation (PAM4). 56G PAM4 has been used in 400G coherent optical transmission devices, and 112G PAM4 is required for 800G. Due to the doubling of the Nyquist frequency, the channel loss of the 112G system far exceeds that of the 56G system, and it is more sensitive to factors such as noise, crosstalk, and skew.

[0004] In the actual design and application of coherent optical devices and modules, the delay between the two signals in a group of differential inputs is inevitable, and the higher the signal frequency, the more obvious the delay effect. In the application of 800G, the tolerance for delay is much smaller than that of 400G, and even a slight difference will cause signal degradation. Through the delay compensation interface on the digital signal processor (DSP), the delay can be compensated, but the premise is that the best compensation amount needs to be known. However, the existing technology relies on a constellation diagram instrument for blind tuning to determine the best compensation amount. In the initial debugging stage of the module or device, if the transmit - end performance is unstable or too poor, the constellation diagram instrument cannot solve the constellation diagram, and it is impossible to quickly and accurately determine the best compensation amount of the transmit - end delay. Summary of the Invention

[0005] This application provides a method and device for compensating the transmit - end delay and a method and device for compensating the receive - end delay, which can solve the technical problem in the existing technology that the best compensation amount of the transmit - end delay cannot be quickly and accurately determined.

[0006] In a first aspect, an embodiment of this application provides a method for compensating the transmit - end delay, which is applied to a coherent optical communication system. The method for compensating the transmit - end delay includes:

[0007] Set the transmit - end delay compensation of the digital signal processor to multiple first scan values in sequence. After setting each first scan value, perform a first preset operation. The first preset operation includes: output two orthogonal sinusoidal voltage signals through the digital - to - analog converter inside the digital signal processor, obtain the first processing result of the optical signal output by the modulator passing through the photodiode and the trans - impedance amplifier, extract the sum - frequency voltage amplitude and the difference - frequency voltage amplitude from the first processing result, and calculate the optical power difference between the sum - frequency optical power and the difference - frequency optical power based on the sum - frequency voltage amplitude and the difference - frequency voltage amplitude;

[0008] Compare the optical power differences corresponding to different first scan values, and set the transmit - end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference.

[0009] Further, in one embodiment, the step of setting the transmit - end delay compensation of the digital signal processor to multiple first scan values in sequence and performing the first preset operation after setting each first scan value includes:

[0010] Set the transmit - end delay compensation of the digital signal processing to the first preset lower limit and perform the first first preset operation;

[0011] After performing the m - th first preset operation, if the transmit - end delay compensation is less than the first preset upper limit, increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the (m + 1)-th first preset operation, where m≥1.

[0012] Further, in one embodiment, the step of setting the transmit - end delay compensation of the digital signal processor to multiple first scan values in sequence and performing the first preset operation after setting each first scan value includes:

[0013] Set the transmit - end delay compensation of the digital signal processing to the first preset lower limit and perform the first first preset operation;

[0014] Increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the second first preset operation;

[0015] Increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the third first preset operation;

[0016] After performing the n - th first preset operation, if ΔP n-2 and ΔP n either one is less than or equal to ΔP n-1 , then increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the (n + 1)-th first preset operation, where n≥3, ΔP n-2 、ΔP n-1 and ΔP nrespectively represent the optical power differences obtained by the (n - 2)-th, (n - 1)-th, and n-th first preset operations;

[0017] The step of comparing the optical power differences corresponding to different first scan values and setting the transmit end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference includes:

[0018] Set the transmit end delay compensation of the digital signal processor to the first scan value corresponding to the penultimate first preset operation.

[0019] Further, in one embodiment, the step of obtaining the first processing result of the optical signal output by the modulator after passing through the photodiode and the transimpedance amplifier includes:

[0020] Obtain the first processing result of the optical signal output by the modulator after passing through the photodiode and the transimpedance amplifier through other analog-to-digital converters external to the digital signal processor.

[0021] Further, in one embodiment, the step of extracting the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result includes:

[0022] Extract the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result by the quadrature digital phase-locked method.

[0023] Further, in one embodiment, the step of calculating the optical power difference between the sum-frequency optical power and the difference-frequency optical power based on the sum-frequency voltage amplitude and the difference-frequency voltage amplitude includes:

[0024] Perform a log operation on the sum-frequency voltage amplitude to obtain the sum-frequency optical power;

[0025] Perform a log operation on the difference-frequency voltage amplitude to obtain the difference-frequency optical power;

[0026] Subtract the difference-frequency optical power from the sum-frequency optical power to obtain the optical power difference.

[0027] In a second aspect, an embodiment of the present application further provides a receive end delay compensation method, which is applied to a coherent optical communication system. The receive end delay compensation method includes:

[0028] Sequentially set the transmit end delay compensation of the digital signal processor to multiple first scan values. After each setting of a first scan value, perform a first preset operation. The first preset operation includes: outputting two orthogonal sine voltage signals through the digital-to-analog converter inside the digital signal processor, obtaining the first processing result of the optical signal output by the modulator after passing through the photodiode and the transimpedance amplifier, extracting the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result, and calculating the optical power difference between the sum-frequency optical power and the difference-frequency optical power based on the sum-frequency voltage amplitude and the difference-frequency voltage amplitude;

[0029] Compare the optical power differences corresponding to different first scan values, and set the transmit - end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference;

[0030] Set the receive - end delay compensation of the digital signal processor to a second scan value, and perform a second preset operation. The second preset operation includes: outputting two orthogonal sine voltage signals through the digital - to - analog converter inside the digital signal processor, obtaining the second processing result of the optical signal output by the modulator passing through the coherent receiver through the analog - to - digital converter inside the digital signal processor, extracting a first photocurrent value and a second photocurrent value from the second processing result, and calculating the photocurrent ratio of the first photocurrent value and the second photocurrent value, where the first photocurrent value and the second photocurrent value are the photocurrent values corresponding to one of the sine voltage signals when the photocurrent value corresponding to the other sine voltage signal is zero;

[0031] If the absolute value of the difference between the photocurrent ratio corresponding to the current second scan value and 1 is outside the error tolerance range, update the second scan value, and return to execute the step of setting the receive - end delay compensation of the digital signal processor to the second scan value and performing the second preset operation.

[0032] Further, in one embodiment, the initial second scan value is the second preset lower limit;

[0033] The step of updating the second scan value includes:

[0034] Increase the second scan value by a second preset step size.

[0035] In a third aspect, an embodiment of the present application further provides a transmit - end delay compensation device applied to a coherent optical communication system. The transmit - end delay compensation device includes:

[0036] A transmit - end scanning module, configured to sequentially set the transmit - end delay compensation of the digital signal processor to a plurality of first scan values. After each first scan value is set, perform a first preset operation. The first preset operation includes: outputting two orthogonal sine voltage signals through the digital - to - analog converter inside the digital signal processor, obtaining the first processing result of the optical signal output by the modulator passing through the photodiode and the transimpedance amplifier, extracting the sum - frequency voltage amplitude and the difference - frequency voltage amplitude from the first processing result, and calculating the optical power difference between the sum - frequency optical power and the difference - frequency optical power according to the sum - frequency voltage amplitude and the difference - frequency voltage amplitude;

[0037] A transmit - end decision module, configured to compare the optical power differences corresponding to different first scan values, and set the transmit - end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference.

[0038] In a fourth aspect, an embodiment of the present application further provides a receive - end delay compensation device applied to a coherent optical communication system. The receive - end delay compensation device includes:

[0039] The transmitting - end scanning module is used to sequentially set the transmitting - end delay compensation of the digital signal processor to a plurality of first scanning values. After each first scanning value is set, a first preset operation is performed. The first preset operation includes: outputting two orthogonal sine voltage signals through the digital - to - analog converter inside the digital signal processor, obtaining the first processing result of the optical signal output by the modulator passing through the photodiode and the transimpedance amplifier, extracting the sum - frequency voltage amplitude and the difference - frequency voltage amplitude from the first processing result, and calculating the optical - power difference between the sum - frequency optical power and the difference - frequency optical power according to the sum - frequency voltage amplitude and the difference - frequency voltage amplitude;

[0040] The transmitting - end decision - making module is used to compare the optical - power differences corresponding to different first scanning values, and set the transmitting - end delay compensation of the digital signal processor to the first scanning value corresponding to the minimum optical - power difference;

[0041] The receiving - end scanning module is used to set the receiving - end delay compensation of the digital signal processor to a second scanning value and perform a second preset operation. The second preset operation includes: outputting two orthogonal sine voltage signals through the digital - to - analog converter inside the digital signal processor, obtaining the second processing result of the optical signal output by the modulator passing through the coherent receiver through the analog - to - digital converter inside the digital signal processor, extracting the first photocurrent value and the second photocurrent value from the second processing result, and calculating the photocurrent ratio of the first photocurrent value and the second photocurrent value, where the first photocurrent value and the second photocurrent value are the photocurrent values corresponding to the other sine voltage signal when the photocurrent value corresponding to one of the sine voltage signals is zero;

[0042] The receiving - end decision - making module is used to update the second scanning value if the absolute value of the difference between the photocurrent ratio corresponding to the current second scanning value and 1 is outside the error - tolerance range, and return to execute the step of setting the receiving - end delay compensation of the digital signal processor to the second scanning value and performing the second preset operation.

[0043] In this application, by utilizing the orthogonal characteristics of the coherent optical communication system, different compensation amounts are set for the transmitting - end delay of the digital signal processor, so that the orthogonal sine signals output by the digital signal processor are modulated with the carrier signal at the transmitting end of the coherent optical system. The optimal compensation amount of the transmitting - end delay is determined by the optical - power difference between the sum - frequency optical power and the difference - frequency optical power of the sine signal and the carrier signal. Through this application, the optimal compensation amount of the transmitting - end delay can be quickly and accurately determined without relying on external instruments. In the R & D stage, the debugging cycle can be shortened and the debugging difficulty can be reduced. In the mass - production stage, the calibration rate can be improved and the instrument cost can be saved. In the engineering stage, problems can be quickly located online without being restricted by the environment and instruments. Description of the Drawings

[0044] Figure 1Schematic diagram of the transmission - end delay compensation method in an embodiment of the present application;

[0045] Figure 2 Schematic diagram of the device required for the transmission - end delay compensation method in an embodiment of the present application;

[0046] Figure 3 Schematic diagram of the reception - end delay compensation method in an embodiment of the present application;

[0047] Figure 4 Schematic diagram of the device required for the reception - end delay compensation method in an embodiment of the present application. Detailed implementation manners

[0048] In order to enable those skilled in the art of the present technology to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0049] To make the purpose, technical solution and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the drawings.

[0050] In a first aspect, an embodiment of the present application provides a transmission - end delay compensation method, which is applied to a coherent optical communication system.

[0051] Figure 1 The schematic diagram of the transmission - end delay compensation method in an embodiment of the present application is shown.

[0052] Referring to Figure 1 , in one embodiment, the transmission - end delay compensation method includes the following steps:

[0053] S11. Sequentially set the transmission - end delay compensation of the digital signal processor to a plurality of first scan values. After each setting of a first scan value, perform a first preset operation. The first preset operation includes: outputting two orthogonal sine voltage signals through the digital - to - analog converter inside the digital signal processor, obtaining the first processing result of the optical signal output by the modulator passing through the photodiode and the trans - impedance amplifier, extracting the sum - frequency voltage amplitude and the difference - frequency voltage amplitude from the first processing result, and calculating the optical power difference between the sum - frequency optical power and the difference - frequency optical power according to the sum - frequency voltage amplitude and the difference - frequency voltage amplitude;

[0054] S12. Compare the optical power differences corresponding to different first scan values, and set the transmission - end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference.

[0055] Specifically, the digital signal processor has a transmitting end delay compensation interface. Through the transmitting end delay compensation interface, the way of the output signal of the digital-to-analog converter inside the digital signal processor can be adjusted to achieve the compensation of the transmitting end delay.

[0056] Figure 2 FIG. shows a schematic diagram of the device required for the transmitting end delay compensation method in an embodiment of the present application.

[0057] Referring to Figure 2 , the Laser (laser) provides a carrier signal, the DSP-DAC (digital-to-analog converter inside the digital signal processor) provides an analog voltage signal, the Driver (driver) amplifies the analog voltage signal, and the Modulator (modulator) modulates the analog voltage signal onto the carrier signal. The photodiode and TIA (transimpedance amplifier) convert the optical signal output by the Modulator into an electrical signal, which is sent to the inside of the MCU (microprocessor) for processing after passing through the ADC (analog-to-digital converter).

[0058] The I channel is divided into two differential inputs, P and N, and the Q channel is divided into two differential inputs, P and N. During the transmission process from the DSP-DAC to the Driver, transmit end delays will occur between the two paths of P and N in the I channel and the two paths of P and N in the Q channel. In this embodiment, the two orthogonal sine voltage signals output by the digital-to-analog converter inside the digital signal processor respectively correspond to a set of differential inputs of the I channel or the Q channel.

[0059] Exemplarily, during the transmit end delay compensation process, the Laser needs to ensure that the output optical power and wavelength are stable without frequency deviation to ensure that the scanning result is accurate and available. The light source frequency point ω l remains unchanged, and there is no requirement for its magnitude. The DSP-DAC outputs two orthogonal sine voltage signals respectively, where the voltage frequency ω d remains unchanged, and its value is determined by the maximum supported baud rate of the DSP. ω d ≠ω l . The MZIs of the Modulator are all at the NULL point, and the Phases are all at 90 degrees.

[0060] The theoretical basis for the transmit end delay compensation is as follows:

[0061] Assume that V P =cos(ω d t) and V N =sin(ω d t + θ) are modulated onto the carrier signal, where θ is the transmit end delay, and the modulated signal is obtained:

[0062] P P =cos(ω d t)cos(ω l t)=[cos(ωd t + ω l t) + cos(ω d t - ω l t)] / 2;

[0063] P N = sin(ω d t + θ)sin(ω l t) = -[cos(ω d t + ω l t + θ) + cos(ω d t - ω l t + θ)] / 2;

[0064] The output optical power P = (1 - cosθ)·cos(ω d t + ω l t) + sinθ·sin(ω d t + ω l t) + (1 + cosθ)·cos(ω d t - ω l t) - sinθ·sin(ω d t - ω l t);

[0065] From the above formula, the optical power of the sum frequency P(ω d t + ω l t) = 1 - cosθ, and the optical power of the difference frequency P(ω d t - ω l t) = 1 + cosθ. If the transmission - end time delay is 0, then the optical power of the sum frequency is 0, and the optical power of the difference frequency is 2. At this time, the difference ΔP between the two is the smallest, which is - 2.

[0066] Specifically in this embodiment, after setting the transmission - end time - delay compensation to different first scan values, the smaller the measured optical - power difference, the closer the compensated transmission - end time delay is to 0, and the better the compensation effect. Therefore, the first scan value corresponding to the smallest optical - power difference is the optimal compensation amount of the transmission - end time delay.

[0067] It can be understood that the wider the coverage range of multiple first scan values and the smaller the adjacent interval, the closer the finally determined optimal compensation amount is to the ideal value.

[0068] Through this embodiment, without relying on external instruments, the optimal compensation amount of the transmission - end time delay can be quickly and accurately determined. In the R & D stage, the debugging cycle can be shortened and the debugging difficulty can be reduced. In the mass - production stage, the calibration rate can be improved and the instrument cost can be saved. In the engineering stage, problems can be quickly located online, and it is not restricted by the environment and instruments.

[0069] Further, in one embodiment, the step of sequentially setting the transmit - end delay compensation of the digital signal processor to a plurality of first scan values and performing a first preset operation after each setting of a first scan value includes:

[0070] Set the transmit - end delay compensation of the digital signal processing to the first preset lower limit and perform the first first preset operation;

[0071] After performing the m - th first preset operation, if the transmit - end delay compensation is less than the first preset upper limit, increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the (m + 1)-th first preset operation, where m≥1.

[0072] In this embodiment, the transmit - end delay compensation is gradually increased from the first preset lower limit to the first preset upper limit according to the first preset step size, so as to achieve fast and uniform transmit - end delay scanning.

[0073] Further, in one embodiment, the step of sequentially setting the transmit - end delay compensation of the digital signal processor to a plurality of first scan values and performing a first preset operation after each setting of a first scan value includes:

[0074] Set the transmit - end delay compensation of the digital signal processing to the first preset lower limit and perform the first first preset operation;

[0075] Increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the second first preset operation;

[0076] Increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the third first preset operation;

[0077] After performing the n - th first preset operation, if either ΔPn - 2 or ΔPn is less than or equal to ΔPn - 1, increase the transmit - end delay compensation of the digital signal processing by the first preset step size and perform the (n + 1)-th first preset operation, where n≥3, and ΔPn - 2, ΔPn - 1, and ΔPn respectively represent the optical power differences obtained from the (n - 2)-th, (n - 1)-th, and n - th first preset operations;

[0078] The step of comparing the optical power differences corresponding to different first scan values and setting the transmit - end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference includes:

[0079] Set the transmit - end delay compensation of the digital signal processor to the first scan value corresponding to the penultimate first preset operation.

[0080] In this embodiment, the transmit end delay compensation is gradually increased from the first preset lower limit in accordance with the first preset step size. During the process of scanning the transmit end delay, the change trend of the optical power difference is observed. When the trend shows a situation of first decreasing and then increasing, that is, both ΔPn-2 and ΔPn are greater than ΔPn-1, it indicates that the minimum value ΔPn-1 has been scanned, and the scanning can be stopped and the optimal compensation amount of the transmit end delay can be directly determined. Through this embodiment, when the first preset step size is set to be relatively small, the scanning can be ended in advance to improve the scanning efficiency. When the first preset step size is set to be relatively large, the scanning range can be expanded to improve the reliability of the optimal compensation amount.

[0081] Further, in one embodiment, the step of obtaining the first processing result of the optical signal output by the modulator through the photodiode and the transimpedance amplifier includes:

[0082] Obtain the first processing result of the optical signal output by the modulator through the photodiode and the transimpedance amplifier by means of other analog-to-digital converters external to the digital signal processor.

[0083] In this embodiment, the transmit end delay compensation does not rely on the analog-to-digital converter inside the digital signal processor. Data sampling is performed by other analog-to-digital converters external to the digital signal processor, so that the transmit and receive delay compensations in the same coherent optical communication device can be independently performed, avoiding mutual influence.

[0084] Exemplarily, the step of extracting the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result includes:

[0085] Extract the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result by means of the quadrature digital phase-locked method.

[0086] Exemplarily, the step of calculating the optical power difference between the sum-frequency optical power and the difference-frequency optical power according to the sum-frequency voltage amplitude and the difference-frequency voltage amplitude includes:

[0087] Perform a log operation on the sum-frequency voltage amplitude to obtain the sum-frequency optical power;

[0088] Perform a log operation on the difference-frequency voltage amplitude to obtain the difference-frequency optical power;

[0089] Subtract the difference-frequency optical power from the sum-frequency optical power to obtain the optical power difference.

[0090] In a second aspect, an embodiment of the present application provides a receive end delay compensation method, which is applied to a coherent optical communication system.

[0091] Figure 3 The flowchart of the receive end delay compensation method in an embodiment of the present application is shown.

[0092] Referring to Figure 3 , in one embodiment, the receive end delay compensation method includes the following steps:

[0093] S21. Sequentially set the transmit end delay compensation of the digital signal processor to multiple first scan values. After each setting of a first scan value, perform a first preset operation. The first preset operation includes: outputting two orthogonal sine voltage signals through the digital-to-analog converter inside the digital signal processor, obtaining the first processing result of the optical signal output by the modulator after passing through the photodiode and the transimpedance amplifier, extracting the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result, and calculating the optical power difference between the sum-frequency optical power and the difference-frequency optical power based on the sum-frequency voltage amplitude and the difference-frequency voltage amplitude;

[0094] S22. Compare the optical power differences corresponding to different first scan values, and set the transmit end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference;

[0095] S23. Set the receive end delay compensation of the digital signal processor to a second scan value, and perform a second preset operation. The second preset operation includes: outputting two orthogonal sine voltage signals through the digital-to-analog converter inside the digital signal processor, obtaining the second processing result of the optical signal output by the modulator after passing through the coherent receiver through the analog-to-digital converter inside the digital signal processor, extracting the first photocurrent value and the second photocurrent value from the second processing result, and calculating the photocurrent ratio between the first photocurrent value and the second photocurrent value, where the first photocurrent value and the second photocurrent value are the photocurrent values corresponding to the other sine voltage signal when the photocurrent value corresponding to one of the sine voltage signals is zero;

[0096] S24. If the absolute value of the difference between the photocurrent ratio corresponding to the current second scan value and 1 is outside the error tolerance range, update the second scan value, and return to execute the step of setting the receive end delay compensation of the digital signal processor to the second scan value and performing the second preset operation.

[0097] Specifically, the digital signal processor has a receive end delay compensation interface. Through the receive end delay compensation interface, the way of receiving signals by the analog-to-digital converter inside the digital signal processor can be adjusted to achieve the compensation of the receive end delay. In the same coherent optical communication device, during the normal working process, the transmit end sends optical signals to the receive end of other coherent optical communication devices, and the receive end receives optical signals from other coherent optical communication devices.

[0098] In this embodiment, the delay compensation is first performed on the transmit end. Through the compensated transmit end, an almost ideal optical signal is provided to the receive end of the same coherent optical communication device, so as to control variables during the receive end delay compensation process to improve the accuracy. Steps S21 and S22 refer to steps S11 and S12 above and will not be elaborated here.

[0099] Figure 4The figure shows a schematic diagram of the device required for the receiving-end delay compensation method in an embodiment of the present application.

[0100] Referring to Figure 4 , the Laser provides a carrier signal, the DSP-DAC (digital-to-analog converter inside the digital signal processor) provides an analog voltage signal, the Driver amplifies the analog voltage signal, the Modulator modulates the analog voltage signal onto the carrier signal, and the ICR (coherent receiver) converts the optical signal output by the Modulator into an electrical signal, which is sent to the inside of the MCU (microprocessor) for processing after passing through the DSP-ADC (analog-to-digital converter inside the digital signal processor). During the transmission process from the ICR to the DSP-ADC, receiving-end delays will occur between the P and N channels of the I channel and between the P and N channels of the Q channel.

[0101] Exemplarily, during the receiving-end delay compensation process, the Laser needs to ensure that the output optical power and wavelength are stable without frequency offset to ensure that the scanning results are accurate and available, and the light source frequency point ω l remains unchanged, and there is no requirement for its magnitude. The DSP-DAC outputs two orthogonal sinusoidal voltage signals respectively. Among them, the voltage frequency ω d remains unchanged, and its value is determined by the maximum supported baud rate of the DSP. The MZIs of the Modulator are all at the NULL point, and the Phases are all at 90 degrees.

[0102] The theoretical basis for the receiving-end delay compensation is as follows:

[0103] Assume that the transmitting-end delay has been compensated to 0, and V P =cos(ω d t) and V N =sin(ω d t) are modulated onto the carrier signal. The ICR PD photocurrent expression:

[0104]

[0105] Among them, I P is the photocurrent corresponding to V P , I N is the photocurrent corresponding to V N , R is the transresistance value, P S is the signal optical power, P lo is the local oscillator optical power, φ s is the signal phase, and φ lo is the local oscillator phase.

[0106] If the receiving-end delay is 0, then when I P =0, it is denoted as the first photocurrent value. When I N =0, It is denoted as the second photocurrent value, and the ratio of the first photocurrent value to the second photocurrent value is 1.

[0107] Specifically in this embodiment, after setting the receiving - end delay compensation to different second scan values, the closer the measured photocurrent ratio is to 1, the closer the receiving - end delay after compensation is to 0, and the better the compensation effect. Therefore, when the absolute value of the difference between the photocurrent ratio corresponding to the current second scan value and 1 is within the error tolerance range, it is considered that the optimal compensation amount of the receiving - end delay is found, and there is no need to update the second scan value. Otherwise, the second scan value needs to be updated and the photocurrent ratio needs to be re - tested.

[0108] Through this embodiment, without relying on external instruments, the optimal compensation amount of the receiving - end delay can be determined quickly and accurately. In the R & D stage, the debugging cycle can be shortened and the debugging difficulty can be reduced. In the mass - production stage, the calibration rate can be improved and the instrument cost can be saved. In the engineering stage, problems can be quickly located online without being restricted by the environment and instruments.

[0109] Further, in one embodiment, the initial second scan value is the second preset lower limit;

[0110] The step of updating the second scan value includes:

[0111] Increasing the second scan value by a second preset step size.

[0112] In this embodiment, the receiving - end delay compensation starts from the second preset lower limit and gradually increases according to the first preset step size, so as to realize fast and uniform receiving - end delay scanning.

[0113] In a third aspect, an embodiment of the present application further provides a transmitting - end delay compensation device applied to a coherent optical communication system.

[0114] In one embodiment, the transmitting - end delay compensation device includes:

[0115] A transmitting - end scanning module, configured to sequentially set the transmitting - end delay compensation of a digital signal processor to a plurality of first scan values. After each first scan value is set, a first preset operation is performed. The first preset operation includes: outputting two orthogonal sine voltage signals through a digital - to - analog converter inside the digital signal processor, obtaining a first processing result of the optical signal output by the modulator passing through a photodiode and a transimpedance amplifier, extracting the sum - frequency voltage amplitude and the difference - frequency voltage amplitude from the first processing result, and calculating the optical power difference between the sum - frequency optical power and the difference - frequency optical power according to the sum - frequency voltage amplitude and the difference - frequency voltage amplitude;

[0116] A transmitting - end decision module, configured to compare the optical power differences corresponding to different first scan values and set the transmitting - end delay compensation of the digital signal processor to the first scan value corresponding to the minimum optical power difference.

[0117] Further, in one embodiment, the transmitting end scanning module is configured to:

[0118] Set the transmitting end delay compensation of digital signal processing to the first preset lower limit, and perform the first first preset operation;

[0119] After performing the m-th first preset operation, if the transmitting end delay compensation is less than the first preset upper limit, increase the transmitting end delay compensation of digital signal processing by the first preset step length, and perform the (m + 1)-th first preset operation, where m ≥ 1.

[0120] Further, in one embodiment, the transmitting end scanning module is configured to:

[0121] Set the transmitting end delay compensation of digital signal processing to the first preset lower limit, and perform the first first preset operation;

[0122] Increase the transmitting end delay compensation of digital signal processing by the first preset step length, and perform the second first preset operation;

[0123] Increase the transmitting end delay compensation of digital signal processing by the first preset step length, and perform the third first preset operation;

[0124] After performing the n-th first preset operation, if ΔP n-2 and ΔP n Any one of them is less than or equal to ΔP n-1 , increase the transmitting end delay compensation of digital signal processing by the first preset step length, and perform the (n + 1)-th first preset operation, where n ≥ 3, ΔP n-2 , ΔP n-1 and ΔP n respectively represent the optical power differences obtained from the (n - 2)-th, (n - 1)-th, and n-th first preset operations;

[0125] The transmitting end decision module is configured to:

[0126] Set the transmitting end delay compensation of the digital signal processor to the first scan value corresponding to the penultimate first preset operation.

[0127] Further, in one embodiment, the transmitting end scanning module is configured to:

[0128] Obtain the first processing result of the optical signal output by the modulator passing through the photodiode and the transimpedance amplifier through another analog-to-digital converter external to the digital signal processor.

[0129] Further, in one embodiment, the transmitting end scanning module is configured to:

[0130] Extract the sum-frequency voltage amplitude and the difference-frequency voltage amplitude from the first processing result by the quadrature digital phase-locked method.

[0131] Further, in one embodiment, the transmitting - end scanning module is configured to:

[0132] Perform a log operation on the sum - frequency voltage amplitude to obtain the sum - frequency optical power;

[0133] Perform a log operation on the difference - frequency voltage amplitude to obtain the difference - frequency optical power;

[0134] Subtract the difference - frequency optical power from the sum - frequency optical power to obtain the optical - power difference.

[0135] Among them, the function implementation of each module in the above - mentioned transmitting - end delay compensation device corresponds to each step in the above - mentioned embodiment of the transmitting - end delay compensation method, and its function and implementation process will not be elaborated here one by one.

[0136] Fourthly, an embodiment of the present application further provides a receiving - end delay compensation device, which is applied to a coherent optical communication system.

[0137] In one embodiment, the receiving - end delay compensation device includes:

[0138] A transmitting - end scanning module, configured to sequentially set the transmitting - end delay compensation of the digital signal processor to a plurality of first scanning values. After each first scanning value is set, a first preset operation is performed. The first preset operation includes: outputting two orthogonal sine voltage signals through a digital - to - analog converter inside the digital signal processor, obtaining a first processing result of the optical signal output by the modulator passing through a photodiode and a transimpedance amplifier, extracting the sum - frequency voltage amplitude and the difference - frequency voltage amplitude from the first processing result, and calculating the optical - power difference of the sum - frequency optical power and the difference - frequency optical power according to the sum - frequency voltage amplitude and the difference - frequency voltage amplitude;

[0139] A transmitting - end decision - making module, configured to compare the optical - power differences corresponding to different first scanning values, and set the transmitting - end delay compensation of the digital signal processor to the first scanning value corresponding to the minimum optical - power difference;

[0140] A receiving - end scanning module, configured to set the receiving - end delay compensation of the digital signal processor to a second scanning value, and perform a second preset operation. The second preset operation includes: outputting two orthogonal sine voltage signals through a digital - to - analog converter inside the digital signal processor, obtaining a second processing result of the optical signal output by the modulator passing through a coherent receiver through an analog - to - digital converter inside the digital signal processor, extracting a first photocurrent value and a second photocurrent value from the second processing result, and calculating the photocurrent ratio of the first photocurrent value and the second photocurrent value, where the first photocurrent value and the second photocurrent value are the photocurrent values corresponding to the other sine voltage signal when the photocurrent value corresponding to one of the sine voltage signals is zero;

[0141] The receiving - end decision module is used to update the second scan value if the absolute value of the difference between the photocurrent ratio corresponding to the current second scan value and 1 is outside the error - tolerance range, and then return to execute the step of setting the receiving - end delay compensation of the digital signal processor to the second scan value and performing the second preset operation.

[0142] Further, in one embodiment, the initial second scan value is the second preset lower limit;

[0143] The receiving - end decision module is used for:

[0144] Increasing the second scan value by a second preset step size.

[0145] Among them, the function implementation of each module in the above - mentioned receiving - end delay compensation device corresponds to each step in the embodiment of the above - mentioned receiving - end delay compensation method, and its function and implementation process will not be elaborated here one by one.

[0146] It should be noted that the serial numbers of the above - mentioned embodiments of the present application are only for description and do not represent the superiority or inferiority of the embodiments.

[0147] The terms "including" and "having" and any variations thereof in the specification, claims and drawings of the present application are intended to cover non - exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices. The descriptions of the terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit that "first", "second" and "third" are of different types.

[0148] In the description of the embodiments of the present application, terms such as "exemplary", "for example" or "for instance" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary", "for example" or "for instance" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of terms such as "exemplary", "for example" or "for instance" is intended to present relevant concepts in a specific manner.

[0149] In the description of the embodiments of the present application, unless otherwise specified, " / " means "or". For example, A / B can represent A or B; the "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present application, "a plurality of" means two or more than two.

[0150] In some processes described in the embodiments of the present application, multiple operations or steps appear in a specific order. However, it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or may be executed in parallel. The serial numbers of the operations are only used to distinguish different operations, and the serial numbers themselves do not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0151] Through the description of the above embodiments, those skilled in the art can clearly understand that the above embodiment methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above and includes several instructions for causing a terminal device to execute the methods described in the various embodiments of the present application.

[0152] The above are only the preferred embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A method for compensating a transmission delay applied to a coherent optical communication system, characterized in that: The transmitting end delay compensation method comprises: The transmitting end delay compensation of the digital signal processor is sequentially set to a plurality of first scanning values. After each first scanning value is set, a first preset operation is performed. The first preset operation includes: outputting two orthogonal sinusoidal voltage signals through a digital-to-analog converter inside the digital signal processor, obtaining a first processing result of an optical signal output by a modulator through a photodiode and a transimpedance amplifier, extracting a sum frequency voltage amplitude and a difference frequency voltage amplitude from the first processing result, and calculating an optical power difference between the sum frequency optical power and the difference frequency optical power according to the sum frequency voltage amplitude and the difference frequency voltage amplitude; The optical power differences corresponding to different first scanning values ​​are compared, and the transmitting end delay compensation of the digital signal processor is set to the first scanning value corresponding to the minimum optical power difference.

2. The method for compensating the transmission delay as claimed in claim 1, characterized in that: The step of sequentially setting the transmitting end delay compensation of the digital signal processor to a plurality of first scanning values, and performing a first preset operation after each first scanning value is set, comprises: Setting the transmitting end delay compensation of the digital signal processing to a first preset lower limit, and performing a first first preset operation; After performing the mth first preset operation, if the transmitting end delay compensation is less than the first preset upper limit, the transmitting end delay compensation of the digital signal processing is increased by a first preset step size, and the m+1th first preset operation is performed, where m≥1.

3. The method for compensating the transmission delay as claimed in claim 1, characterized in that: The step of sequentially setting the transmitting end delay compensation of the digital signal processor to a plurality of first scanning values, and performing a first preset operation after each first scanning value is set, comprises: Setting the transmitting end delay compensation of the digital signal processing to a first preset lower limit, and performing a first first preset operation; Increasing the sending end delay compensation of the digital signal processing by a first preset step length, and performing the first preset operation for a second time; Increasing the sending end delay compensation of the digital signal processing by a first preset step length, and performing the first preset operation for a third time; After executing the first preset operation for the nth time, if ΔP n-2 and ΔP n Any one is less than or equal to ΔP n-1 , the delay compensation of the transmitting end of the digital signal processing is increased by a first preset step size, and the first preset operation is performed for the n+1th time, where n≥3, ΔP n-2 , ΔP n-1 and ΔP n Respectively represent the optical power differences obtained by the n-2th, n-1th and nth first preset operations; The step of comparing the optical power differences corresponding to different first scanning values ​​and setting the transmitting end delay compensation of the digital signal processor to the first scanning value corresponding to the minimum optical power difference comprises: The transmitting end delay compensation of the digital signal processor is set to a first scanning value corresponding to the second to last first preset operation.

4. The method for compensating the transmission delay as claimed in claim 1, characterized in that: The step of obtaining a first processing result of the optical signal output by the modulator after passing through a photodiode and a transimpedance amplifier comprises: The first processing result of the optical signal output by the modulator after passing through the photodiode and the transimpedance amplifier is obtained through other analog-to-digital converters outside the digital signal processor.

5. The method for compensating the transmission delay as claimed in claim 1, characterized in that: The step of extracting the sum frequency voltage amplitude and the difference frequency voltage amplitude from the first processing result comprises: The sum frequency voltage amplitude and the difference frequency voltage amplitude are extracted from the first processing result by using an orthogonal digital phase-locked method.

6. The method for compensating the transmission delay as claimed in claim 1, characterized in that: The step of calculating the optical power difference between the sum frequency optical power and the difference frequency optical power according to the sum frequency voltage amplitude and the difference frequency voltage amplitude comprises: Performing logarithm operation on the sum frequency voltage amplitude obtains the sum frequency optical power; Performing logarithm operation on the difference frequency voltage amplitude obtains the difference frequency optical power; Subtract the difference frequency optical power from the sum frequency optical power to obtain the optical power difference.

7. A receiving end delay compensation method, applied to a coherent optical communication system, characterized in that: The receiving end delay compensation method comprises: The transmitting end delay compensation of the digital signal processor is sequentially set to a plurality of first scanning values. After each first scanning value is set, a first preset operation is performed. The first preset operation includes: outputting two orthogonal sinusoidal voltage signals through a digital-to-analog converter inside the digital signal processor, obtaining a first processing result of an optical signal output by a modulator through a photodiode and a transimpedance amplifier, extracting a sum frequency voltage amplitude and a difference frequency voltage amplitude from the first processing result, and calculating an optical power difference between the sum frequency optical power and the difference frequency optical power according to the sum frequency voltage amplitude and the difference frequency voltage amplitude; Comparing optical power differences corresponding to different first scanning values, and setting the transmitting end delay compensation of the digital signal processor to the first scanning value corresponding to the minimum optical power difference; The receiving-end delay compensation of the digital signal processor is set to a second scanning value, and a second preset operation is performed, wherein the second preset operation includes: outputting two orthogonal sinusoidal voltage signals through a digital-to-analog converter inside the digital signal processor, obtaining a second processing result of the optical signal output by the modulator through a coherent receiver through an analog-to-digital converter inside the digital signal processor, extracting a first photocurrent value and a second photocurrent value from the second processing result, and calculating a photocurrent ratio of the first photocurrent value and the second photocurrent value, wherein the first photocurrent value and the second photocurrent value are respectively photocurrent values ​​corresponding to one sinusoidal voltage signal when the photocurrent value corresponding to the other sinusoidal voltage signal is zero; If the absolute value of the difference between the photocurrent ratio corresponding to the current second scanning value and 1 is outside the allowable error range, the second scanning value is updated, and the process returns to the step of setting the receiving end delay compensation of the digital signal processor to the second scanning value and executing the second preset operation.

8. The receiving end delay compensation method according to claim 4, characterized in that: The initial second scanning value is a second preset lower limit; The step of updating the second scan value comprises: The second scan value is increased by a second preset step size.

9. A transmitting end delay compensation device, applied to a coherent optical communication system, characterized in that: The transmitting end delay compensation device comprises: A transmitting end scanning module is used to sequentially set the transmitting end delay compensation of the digital signal processor to a plurality of first scanning values, and after each first scanning value is set, perform a first preset operation, wherein the first preset operation includes: outputting two orthogonal sinusoidal voltage signals through a digital-to-analog converter inside the digital signal processor, obtaining a first processing result of an optical signal output by a modulator through a photodiode and a transimpedance amplifier, extracting a sum frequency voltage amplitude and a difference frequency voltage amplitude from the first processing result, and calculating an optical power difference between the sum frequency optical power and the difference frequency optical power according to the sum frequency voltage amplitude and the difference frequency voltage amplitude; The transmitting end decision module is used to compare the optical power differences corresponding to different first scanning values, and set the transmitting end delay compensation of the digital signal processor to the first scanning value corresponding to the minimum optical power difference.

10. A receiving end delay compensation device, applied to a coherent optical communication system, characterized in that: The receiving end delay compensation device comprises: A transmitting end scanning module is used to sequentially set the transmitting end delay compensation of the digital signal processor to a plurality of first scanning values, and after each first scanning value is set, perform a first preset operation, wherein the first preset operation includes: outputting two orthogonal sinusoidal voltage signals through a digital-to-analog converter inside the digital signal processor, obtaining a first processing result of an optical signal output by a modulator through a photodiode and a transimpedance amplifier, extracting a sum frequency voltage amplitude and a difference frequency voltage amplitude from the first processing result, and calculating an optical power difference between the sum frequency optical power and the difference frequency optical power according to the sum frequency voltage amplitude and the difference frequency voltage amplitude; A transmitting end decision module, used for comparing optical power differences corresponding to different first scanning values, and setting the transmitting end delay compensation of the digital signal processor to the first scanning value corresponding to the minimum optical power difference; A receiving end scanning module, used for setting the receiving end delay compensation of the digital signal processor to a second scanning value, and performing a second preset operation, wherein the second preset operation includes: outputting two orthogonal sinusoidal voltage signals through a digital-to-analog converter inside the digital signal processor, obtaining a second processing result of an optical signal output by a modulator through a coherent receiver through an analog-to-digital converter inside the digital signal processor, extracting a first photocurrent value and a second photocurrent value from the second processing result, and calculating a photocurrent ratio of the first photocurrent value and the second photocurrent value, wherein the first photocurrent value and the second photocurrent value are respectively photocurrent values ​​corresponding to one sinusoidal voltage signal when the photocurrent value corresponding to the other sinusoidal voltage signal is zero; The receiving end decision module is used to update the second scanning value if the absolute value of the difference between the photocurrent ratio corresponding to the current second scanning value and 1 is outside the allowable error range, and return to execute the step of setting the receiving end delay compensation of the digital signal processor to the second scanning value and executing the second preset operation.

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