Optimization method of long distance high signal-to-noise ratio optical path in incoherent DVS system

Abstract

The application belongs to the technical field of optical path optimization, and specifically relates to a long-distance high signal-to-noise ratio optical path optimization method in a non-coherent DVS system, which comprises the following steps: formulating optical path optimization parameters, building a three-stage serial optical path architecture to collect and detect pulse data, and processing the pulse data to obtain low-noise amplification data. The pulse base suppression method is used to analyze the coherence characteristics of the light source and the noise characteristics of the amplification link to obtain parameter calibration data, the optical path optimization parameters are calibrated to obtain target optimization parameters, and it is judged whether the low-noise amplification data meets a preset signal-to-noise ratio threshold value. If yes, a qualified optical path optimization result is output, and if not, the noise defect position and type are marked. The correlation between the noise defect position and type and the optical path optimization parameters is analyzed to obtain optical path correction data, and the target optimization parameters are adjusted to obtain accurate optimization parameters. The application can realize the unification of long distance and high signal-to-noise ratio, extend the effective detection distance, greatly improve the fault diagnosis efficiency, and adapt to diversified application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of optical path optimization technology, specifically a method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems. Background Technology

[0002] Coherent distributed fiber optic vibration sensing (DVS) systems are widely used in long-distance security monitoring scenarios such as oil and gas pipelines, rail transit, and tunnel engineering due to their advantages of anti-coherent interference, strong stability, and adaptability to long-distance deployment. However, current incoherent DVS optical path optimization technology still faces many technical bottlenecks, severely restricting the system's long-distance high-precision detection performance. First, link loss accumulates continuously during long-distance fiber optic transmission. Traditional optical paths lack targeted noise suppression mechanisms, and pulse substrate leakage light and amplified link ASE noise are amplified by the superposition of transmission distance, resulting in a sharp attenuation of the signal-to-noise ratio of weak vibration signals from backscattered Rayleigh at the far end, significantly reducing long-distance detection accuracy. Second, the existing optical path signal amplification mode is relatively coarse, unable to accurately control the peak power of the detection pulse, making it difficult to effectively compensate for long-distance link transmission loss. The effective signal power is insufficient and easily submerged by substrate noise, resulting in poor signal fidelity.

[0003] Meanwhile, existing optical path optimization schemes mostly adopt fixed static parameter configurations, relying solely on initial debugging to complete a single parameter calibration, lacking dynamic correction and iterative optimization mechanisms. Long-term operation of optoelectronic devices can lead to operational deviations such as drift in light source coherence characteristics and dynamic changes in link noise characteristics. Traditional fixed parameters cannot adapt to the real-time operating status of the devices, making it difficult to adaptively adjust optical path parameters based on noise defects and link conditions, resulting in noise degradation and performance decline after long-term system operation.

[0004] In summary, existing technologies suffer from drawbacks such as low signal-to-noise ratio for long-distance detection, insufficient effective signal power, and inability to adaptively and dynamically correct optical path parameters. These shortcomings make it difficult to meet the requirements of long-distance, high-stability, and high signal-to-noise ratio detection in engineering scenarios. Therefore, it is urgent to propose a long-distance high signal-to-noise ratio optical path optimization method in incoherent DVS systems to solve the above problems. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention proposes a long-distance, high signal-to-noise ratio optical path optimization method for incoherent DVS systems. This invention primarily addresses the problems of poor signal-to-noise ratio during long-distance detection, insufficient signal power, and the inability of optical path optimization to adaptively correct for changes in device state.

[0006] The technical solution adopted by this invention to solve its technical problem is: the method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems provided by this invention, comprising: The optical path defect type and link loss data of the incoherent DVS system were determined. Optical path optimization parameters were formulated in combination with the target requirements of long-distance detection and high signal-to-noise ratio. A three-level serial optical path architecture was built to collect detection pulse data. The detection pulse data was processed using the synchronous gating amplification method to obtain low-noise amplified data.

[0007] The pulsed substrate suppression method was used to analyze the coherence characteristics of the light source and the noise characteristics of the amplification link to obtain parameter calibration data. Based on the parameter calibration data, the optical path optimization parameters were calibrated to obtain the target optimization parameters.

[0008] Based on the target optimization parameters, determine whether the low-noise amplified data meets the preset signal-to-noise ratio threshold. If yes, output the qualified optical path optimization result; otherwise, mark the location and type of noise defects.

[0009] By analyzing the correlation between the location and type of noise defects and the optical path optimization parameters, optical path correction data is obtained. The target optimization parameters are then iteratively adjusted to obtain precise optimization parameters.

[0010] The method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems provided by this invention includes the following steps for determining optical path optimization parameters: According to the direction of optical signal flow, the incoherent DVS optical path is divided into multiple independent segments. Based on the working principle of incoherent DVS, the location, phenomenon and severity of optical path defects are investigated segment by segment, and the types of optical path defects are classified.

[0011] Segment-by-segment loss tests were performed on the forward transmission light and the back echo light of the incoherent DVS, and the total loss summary and loss distribution curve were used as link loss data.

[0012] Long-distance detection indicators and high signal-to-noise ratio indicators are defined as quantitative targets, and optimization priorities are determined based on the impact of optical path defect types on system performance.

[0013] Based on optimization priorities, combined with optical path defect types, quantification targets, and link loss data, parameters are determined according to optical path functions, and the basis for setting these parameters is labeled to obtain optical path optimization parameters.

[0014] The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system provided by this invention includes the following steps for acquiring probe pulse data: A three-stage serial optical path architecture consisting of a narrow-linewidth distributed feedback laser, an electro-optic intensity modulator, and a semiconductor optical amplifier was constructed.

[0015] Multiple sets of time-domain waveform data, including the pulse conduction region, the turn-off base region, and the edge region, are captured using an oscilloscope, and the corresponding data and acquisition information are recorded simultaneously to obtain the probe pulse data.

[0016] The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system provided by this invention includes the following steps for processing low-noise amplified data: The semiconductor optical amplifier is configured to operate in pulse gating amplification mode, so that the semiconductor optical amplifier is synchronized with the electrical drive pulse of the electro-optic intensity modulator. During the duration of the probe pulse, the semiconductor optical amplifier is kept in a high gain state, so that the peak power of the optical pulse is amplified to not less than 100mW.

[0017] Continuous probe pulse data is output from a DFB laser, and pulse chopping is performed based on an EO intensity modulator to remove leaked light and obtain purified pulse data. Combined with timing matching, the purified pulse data is amplified based on a configured semiconductor optical amplifier to obtain low-noise amplified data.

[0018] The present invention provides a method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems, including a pulse substrate suppression method.

[0019] A narrow-linewidth distributed feedback laser with a working wavelength of 1550.12nm ± 0.02nm and a spectral linewidth of less than 3kHz was selected as the system light source, outputting 10–20mW of continuous seed light. The continuous seed light was modulated using an electro-optic intensity modulator with an extinction ratio of not less than 50dB to obtain optical pulses.

[0020] The method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems provided by this invention includes the following steps for analyzing and obtaining parameter calibration data: The center wavelength, spectral linewidth, and output optical power of the DFB laser were detected in the optical pulse working mode and compared with the preset standard thresholds to obtain the characteristic deviation. The influence on the pulse substrate was analyzed to obtain the coherence deviation of the light source.

[0021] Read the optical power in the conduction zone and the leakage power in the off zone under pulse working mode, calculate the measured extinction ratio, and compare it with the preset extinction ratio to determine the leakage light deviation.

[0022] The time difference between the signals from the electro-optic modulator and the amplifier unit is detected, and the amplification link noise deviation is obtained by summarizing the ASE noise, gain fluctuation and leakage light deviation.

[0023] Based on the deviation combination scenarios of light source coherence deviation and amplification link noise deviation, for each deviation, the optical path optimization parameters are identified, the parameters to be calibrated and the adjustment direction are determined, and a safe adjustable range is set for each parameter to be calibrated in combination with the device hardware parameters.

[0024] Establish the correspondence between parameter changes and index improvements, and calculate the calibration range for each calibration parameter by combining the measured deviation values. Verify the calibration range according to the safe adjustable range and generate parameter calibration data.

[0025] The method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems provided by this invention includes the following steps for obtaining the target optimization parameters: Based on a three-level cascaded optical path architecture, optical path optimization parameters are loaded, parameter calibration data is verified, and adjustment priorities and safe adjustable ranges are determined.

[0026] According to the transmission order and adjustment priority of the three-level serial optical path architecture, the parameters of each module in the optical path architecture are adjusted one by one based on the parameter calibration data, and the corresponding device status and index changes are recorded.

[0027] Based on changes in equipment status and indicators, retest the indicators and observe the pulse waveform to verify whether the adjustment effect meets the preset requirements. If so, save the current parameters as the target optimization parameters; otherwise, readjust the parameters of each module.

[0028] The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system provided by this invention includes the following steps for determining whether low-noise amplified data meets a preset signal-to-noise ratio threshold: For each segment of the optical path and the corresponding sensing link, the average power of the effective pulse signal and the average power of the noise in the pulse off interval are read. The real-time signal-to-noise ratio of each segment is calculated and compared with the preset threshold of the corresponding position, and the comparison results are recorded.

[0029] When all parameters meet the preset signal-to-noise ratio threshold, the pulse waveform, power, and noise status of the entire link are reviewed. The current target optimization parameters, low-noise amplification data, and comparison results are integrated to form a qualified optical path optimization result.

[0030] When the preset signal-to-noise ratio threshold is not reached, the location and type of noise defects are determined by combining optical path segmentation and sensor link area localization.

[0031] The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system provided by this invention includes the following steps for obtaining optical path correction data: Based on the location and type of noise defects, the adjustable parameter set corresponding to the region is determined. By combining the working principle of the device, the range of the adjustable parameter set is narrowed to obtain the highly correlated parameters.

[0032] The single-variable method was used to test highly correlated parameters. The changes in noise amplitude and signal-to-noise ratio before and after adjustment were compared to analyze the influence of the current parameters on defects and obtain parameter sensitivity.

[0033] Based on parameter sensitivity, the direction of parameter adjustment is determined. Combined with the current signal-to-noise ratio deviation and noise overshoot, the defect elimination adjustment amount is calculated to obtain optical path correction data.

[0034] The method for optimizing long-distance, high signal-to-noise ratio optical paths in incoherent DVS systems provided by this invention includes the following steps for obtaining accurate optimization parameters: The target optimization parameters are mapped one-to-one with the optical path correction data to establish a two-way mapping relationship. The scene correction data is obtained by filtering based on the current optical path link loss, deployment distance and noise defect type.

[0035] Correction priorities are determined based on adjustment priorities and parameter sensitivity, and the adjustment parameter values ​​corresponding to the correction priorities are calculated based on scenario correction data.

[0036] Based on the rated operating range of optical devices and the nonlinear threshold of the system, a parameter conflict coordination strategy is formulated, and the target optimization parameters are adjusted according to the adjusted parameter values ​​to obtain the precise optimization parameters.

[0037] The beneficial effects of this invention are as follows: This invention significantly reduces the noise floor in the pulse turn-off region and improves the overall signal-to-noise ratio by combining pulse floor suppression and synchronous gating amplification. The three-stage cascaded architecture increases the pulse peak power to ≥100 mW, effectively compensating for long-distance link losses and extending the effective detection range. A safe adjustable range verification and parameter conflict coordination strategy is introduced to ensure that parameter adjustments are made within the device's rated operating range and the system's nonlinear threshold, preventing over-adjustment damage. Precise attribution of noise defect location and type is achieved, decomposing substandard signal-to-noise ratio problems to specific optical path segments and device levels, significantly improving fault diagnosis efficiency. By combining parameter calibration data and scene correction data, the optimization method can adapt to diverse application scenarios with different link losses, deployment distances, and defect types. Attached Figure Description

[0038] The invention will now be further described with reference to the accompanying drawings.

[0039] Figure 1 This is a schematic diagram of the module of the long-distance high signal-to-noise ratio optical path optimization method in the non-coherent DVS system provided in the embodiments of the present invention; Figure 2 This is a schematic diagram of the process for obtaining clinical mechanical characterization data in the long-distance high signal-to-noise ratio optical path optimization method in the incoherent DVS system provided in this embodiment of the invention; Figure 3 This is a flowchart illustrating a method for testing the firing force of a linear electric cutting stapler according to an embodiment of the present invention. Detailed Implementation

[0040] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0041] like Figures 1 to 3 As shown in the embodiment of the present invention, the method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system includes: The optical path defect type and link loss data of the incoherent DVS system are determined. Optical path optimization parameters are formulated in combination with the target requirements of long-distance detection and high signal-to-noise ratio. A three-level serial optical path architecture is built to collect detection pulse data. The detection pulse data is processed using a synchronous gating amplification method to obtain low-noise amplified data.

[0042] The steps for determining the optical path optimization parameters include: According to the direction of optical signal flow, the incoherent DVS optical path is divided into multiple independent segments. Based on the working principle of incoherent DVS, the location, phenomenon and severity of optical path defects are investigated segment by segment, and the types of optical path defects are obtained by classification.

[0043] The incoherent DVS optical path can be divided into 7 independent segments: S1: light source output segment, S2: pulse modulation segment, S3: pre-amplifier segment, S4: passive device segment of optical circulator / isolator, S5: long-distance sensing fiber backbone segment, S6: Raman pumping and combining segment, and S7: receiving filter and photodetector segment.

[0044] Optical path defects are mainly classified into six categories: noise, signal distortion, polarization, nonlinearity, device degradation, and environmental coupling.

[0045] If a light source spectrum is collected using a spectrometer, the spectral linewidth and center wavelength are detected: if the linewidth is greater than 3kHz, the center wavelength deviates from 1550.12nm, or stray peaks appear in the spectrum, it is determined to be an abnormal defect in the light source spectrum; The relative intensity noise of the light source is tested using a RIN noise tester: if RIN > -150dB / Hz, it is determined to be a defect where the inherent noise of the light source exceeds the standard. Continuously monitor the output power of the light source using an optical power meter (duration 10 min): if the power fluctuation is > ±2%, it is determined to be a power drift defect of the light source.

[0046] Segment-by-segment loss tests were performed on the forward transmission light and the back echo light of the incoherent DVS, and the total loss summary and loss distribution curve were used as the link loss data. Incoherent DVS is a back Rayleigh scattering detector. The light is divided into forward propagation light and back echo light, and the two types of loss need to be tested separately.

[0047] The inherent insertion loss of each segment from S1 to S7 was tested segment by segment using the cascade test method. The entire optical fiber was scanned using an optical time domain reflectometer to obtain the average attenuation coefficient of the fiber. All local high-loss points on the OTDR curve were marked, and the loss location and additional loss value were recorded. The total length of the optical fiber was counted, and the total inherent loss of the optical fiber itself was calculated.

[0048] Forward loss: The total loss of the test light as it travels from the laser, through modulation, amplification, and circulator, to the farthest point of the optical fiber. Backward return loss: The total loss of Rayleigh scattered light from the far end of the optical fiber, which is transmitted in reverse from the end of the optical fiber, through the circulator and filter, to the detector. The polarization-dependent loss (PDL) of each segment was tested, and the maximum loss difference under different polarization states was recorded. The dispersion tester was used to test chromatic dispersion and polarization mode dispersion (PMD). The effective signal loss caused by pulse broadening was calculated in combination with the pulse width.

[0049] The total loss is obtained by summing the losses of all segments. A loss distribution curve is plotted with fiber distance on the horizontal axis and loss value on the vertical axis.

[0050] Long-distance detection indicators and high signal-to-noise ratio indicators are defined as quantitative targets, and optimization priorities are determined based on the impact of the optical path defect types on system performance. Defining long-range detection metrics may include the maximum effective sensing distance: clarifying system design objectives; Spatial resolution: This parameter is set according to application requirements and directly determines the optical pulse width. Full coverage requirement: No signal dead zones or intermittent disconnections along the entire sensing fiber; Positioning accuracy: Spatial positioning error threshold for vibration events.

[0051] High signal-to-noise ratio (SNR) indicators include: minimum SNR threshold: set the overall SNR ≥ 30dB and the SNR at the farthest point of the fiber optic cable ≥ 28dB; Noise tolerance: limits the maximum value of the pulse noise floor and the upper limit of the ASE noise floor; Signal fidelity: pulse distortion rate, waveform distortion allowable threshold; Dynamic range: The maximum / minimum vibration signal amplitude that the system can normally recognize.

[0052] Optimization priorities may include: highest priority: insufficient pulse extinction ratio, pulse floor noise, and ASE noise; Medium priority: polarization drift, gain ripple, and localized high fiber loss; Low priority: minor power drift and slight temperature drift.

[0053] Based on the optimization priority, combined with the optical path defect type, the quantization target and the link loss data, the parameters are determined according to the optical path function, and the setting basis is marked to obtain the optical path optimization parameters.

[0054] Optimization parameters may include the operating center wavelength, spectral linewidth, continuous light output power, and extinction ratio of the light source module.

[0055] The steps for acquiring the detection pulse data include: The three-stage cascaded optical path architecture consisting of a narrow-linewidth distributed feedback (DFB) laser, an electro-optic (EO) intensity modulator, and a semiconductor optical amplifier (SOA) was constructed. The detection pulse data is obtained by capturing multiple sets of time-domain waveform data, including the pulse conduction region, the turn-off base region, and the edge region, using an oscilloscope, and simultaneously recording the accompanying data and acquisition information.

[0056] When the three-stage optical path, drive circuit, and timing system are all working properly, the system runs continuously for 5 to 10 minutes to allow all components to reach thermal equilibrium and become completely stable.

[0057] Capture the complete pulse waveform using an oscilloscope, including the pulse conduction region, the turn-off base region, and the edge region, and record the time-domain waveform data.

[0058] Synchronously record the accompanying data, including: optical power value at the measurement point, spectral curve, real-time timing error, and device operating current and voltage.

[0059] Mark the information collected in this group: collection time, optical path condition, and equipment number.

[0060] For multiple data acquisitions, each acquisition should be spaced 1-2 minutes apart; each data set should be independently named and numbered; and no optical, electrical, or instrument parameters should be altered during the acquisition process.

[0061] The steps for processing the low-noise amplified data include: The semiconductor optical amplifier is configured to operate in pulse gating amplification mode, so that the semiconductor optical amplifier is synchronized with the electrical drive pulse of the electro-optic intensity modulator, and the semiconductor optical amplifier is in a high gain state during the duration of the detection pulse, so that the peak power of the optical pulse is amplified to not less than 100mW. Continuous probe pulse data is output from a DFB laser, and pulse chopping is performed based on an EO intensity modulator to remove leakage light and obtain purified pulse data. The purified pulse data is then amplified using a time-matched semiconductor optical amplifier to obtain low-noise amplified data.

[0062] The pulsed substrate suppression method is used to analyze the coherence characteristics of the light source and the noise characteristics of the amplification link to obtain parameter calibration data. Based on the parameter calibration data, the optical path optimization parameters are calibrated to obtain the target optimization parameters. The pulse base suppression method includes: A narrow-linewidth distributed feedback laser with a working wavelength of 1550.12nm±0.02nm and a spectral linewidth of less than 3kHz was selected as the system light source to output 10–20mW of continuous seed light. The continuous seed light was modulated by an electro-optic intensity modulator with an extinction ratio of not less than 50dB to obtain optical pulses.

[0063] The steps for analyzing and obtaining the parameter calibration data include: In the working mode of the optical pulse, the center wavelength, spectral linewidth and output optical power of the DFB laser are detected and compared with the preset standard threshold to obtain the characteristic deviation, and the influence on the pulse substrate is analyzed to obtain the coherence deviation of the light source. Use a spectrometer to read the measured center wavelength of the light source: if the measured wavelength exceeds the range of 1550.12nm±0.02nm, it is determined to be a wavelength offset deviation, and the offset value and offset direction are recorded; Analysis of the impact: Wavelength shift will indirectly change the response characteristics of optical path filtering and amplification modules, raising the noise floor.

[0064] If the measured linewidth is ≥3kHz, it is determined to be a deviation of the spectral linewidth exceeding the standard, and the linewidth excess amount is recorded. Analysis of the impact: Excessive linewidth will exacerbate coherent noise, which is an important source of pulse-based noise.

[0065] If the measured power is not within the 10-20mW range, it is determined to be an abnormal deviation in output power, and the power difference is recorded; at the same time, short-term power fluctuations are observed, and if the fluctuations are obvious, the power drift deviation is additionally marked. Analysis of the impact: Too low power will lead to insufficient signal-to-noise ratio, while too high power will easily induce nonlinear noise, both of which will degrade the pulse substrate.

[0066] By summarizing the above test results, we can clarify the deviation type, measured value, standard value, deviation amount, and deviation level, and indicate the degree of influence of each type of deviation on the pulse floor noise to obtain the light source coherence deviation.

[0067] Read the optical power in the conduction zone and the leakage power in the off zone under pulse working mode, calculate the measured extinction ratio, and compare it with the preset extinction ratio to determine the leakage light deviation; The formula for calculating the measured extinction ratio is expressed as:

[0068] In the formula, It is the measured extinction ratio. It is the optical power in the conduction region. It is the power of light leakage in the off-zone.

[0069] If the measured extinction ratio is <50dB, it is determined to be an insufficient extinction ratio deviation, and the difference from the standard value is recorded. The average amplitude of the leakage light during the quantized pulse off-peak interval is used to determine whether the leakage light exceeds the standard deviation.

[0070] The time difference between the signals from the electro-optic modulator and the amplifier unit is detected, and the amplification link noise deviation is obtained by summing up the ASE noise, gain fluctuation and the leakage light deviation. Use a timing analyzer to detect the time difference between the electro-optic modulator drive signal and the amplifier unit gating drive signal: if the timing of the two signals is misaligned, it is determined to be a timing mismatch deviation, and the time error value is recorded; Analysis of the impact: The amplification unit's early turn-on / delayed turn-off will continuously amplify the noise during the turn-off period, significantly deteriorating the pulse substrate.

[0071] If the amplified spontaneous emission (ASE) noise floor is too high and significantly covers the edge of the pulse signal, it is determined to be an ASE noise deviation exceeding the standard, and the power difference between the noise floor and the effective signal is recorded. The output power of the amplifier unit is continuously sampled for 5 minutes. If the power fluctuates significantly, it is determined to be a gain fluctuation deviation.

[0072] Based on the light source coherence deviation and the amplification link noise deviation, the deviation combination scenario is divided. For each deviation, the optical path optimization parameter is corresponding to the optical path optimization parameter. The parameter to be calibrated and the adjustment direction are determined. Combined with the device hardware parameters, a safe adjustable range is set for each parameter to be calibrated. Deviation combinations may include: Scenario 1: Only the coherence characteristics of the light source are substandard, while the amplification link indicators are qualified; the calibration focus is on laser-related parameters. Scenario 2: The light source performance is acceptable, but the amplification link noise is substandard; the calibration focus is on the modulator, amplification unit, and timing parameters. Scenario 3: Multiple deviations exist simultaneously in the light source and amplification link; synchronous calibration is performed based on noise weights, prioritizing the main and secondary components.

[0073] Parameter Adjustment Direction Table:

[0074] Establish the correspondence between parameter changes and index improvements, and calculate the calibration range for each calibration parameter by combining the measured deviation values. Verify the calibration range according to the safe adjustable range to generate parameter calibration data.

[0075] The relationship between parameter changes and index improvements can include: for every 0.5°C change in laser temperature, the spectral linewidth changes by 0.2 kHz; For every 0.1V change in modulator bias voltage, the extinction ratio increases by 1dB; For every 1ns adjustment to the timing delay parameter, the timing error decreases by 1ns.

[0076] Based on the measured deviation values ​​and their corresponding relationships, the calibration amplitude of each parameter is calculated one by one; if it is a multi-deviation coupled scenario, the total improvement target is split according to the noise weight, and the basic adjustment amount of the light source and amplification link side parameters is calculated separately.

[0077] Compare the calculated actual calibration amplitude with the safe adjustable range: within the range: retain the calibration amplitude; Exceeding the interval: truncate to the limit of the interval.

[0078] The steps to obtain the target optimization parameters include: Based on the three-level serial optical path architecture, the optical path optimization parameters are loaded, the parameter calibration data is checked, and the adjustment priority and safe adjustable range are determined. According to the transmission order and adjustment priority of the three-level serial optical path architecture, the parameters of each module in the optical path architecture are adjusted one by one based on the parameter calibration data, and the corresponding device status and index changes are recorded. Based on the changes in equipment status and indicators, the indicators are retested and pulse waveforms are observed to verify whether the adjustment effect meets the preset requirements. If so, the current parameters are saved as the target optimization parameters; otherwise, the parameters of each module are readjusted.

[0079] FB laser module parameter calibration: mainly calibrating the center wavelength, spectral linewidth, and output optical power to ensure that the light source meets the requirements of 1550.12nm±0.02nm, linewidth<3kHz, and output power10~20mW.

[0080] Electro-optic intensity modulator module parameter calibration: calibrate the static bias voltage to increase the extinction ratio to over 50dB and suppress leakage light and substrate noise in the pulse turn-off interval.

[0081] Semiconductor Optical Amplifier (SOA) module parameter calibration: calibrate the operating mode, basic gain, and output power to ensure that the SOA operates stably in pulse gating amplification mode, while controlling ASE noise and gain fluctuations.

[0082] The retesting of indicators includes: re-testing the core indicators of the module, such as light source wavelength, linewidth, power, modulator extinction ratio, SOA noise and timing error, to confirm that the indicators are close to the standard threshold.

[0083] Pulse waveform observation includes: using an oscilloscope to view the overall shape of the pulse, focusing on checking the floor noise in the off-section, confirming that the noise is suppressed and there are no problems such as waveform distortion, pulse loss, or sudden power changes.

[0084] Based on the target optimization parameters, determine whether the low-noise amplified data meets the preset signal-to-noise ratio threshold. If yes, output the qualified optical path optimization result; otherwise, mark the location and type of noise defects. The steps for determining whether the low-noise amplified data meets the preset signal-to-noise ratio threshold include: For each segment of the optical path and the corresponding sensor link, the average power of the effective pulse signal and the average power of the noise in the pulse off interval are read, the real-time signal-to-noise ratio of each segment is calculated, and the results are compared with the preset threshold of the corresponding position and the comparison results are recorded. The formula for calculating the real-time signal-to-noise ratio at each segment position is expressed as follows:

[0085] In the formula, It is the real-time signal-to-noise ratio at the segment location. It is the average power of the effective pulse signal. It is the average power of noise during the pulse off interval.

[0086] When all preset signal-to-noise ratio thresholds are met, the full-link pulse waveform, power and noise status are reviewed, and the current target optimization parameters, low-noise amplification data and comparison results are integrated to form the qualified optical path optimization results. When the preset signal-to-noise ratio threshold is not reached, the location and type of noise defects are determined by combining optical path segmentation and sensor link area localization.

[0087] By combining the optical path segmentation, signal attenuation characteristics, and noise distribution characteristics of the data anomalies, the physical location of noise defects with substandard signal-to-noise ratios can be accurately pinpointed, clarifying whether the defect occurs in the light source segment, pulse modulation segment, amplification link segment, passive device segment, or long-distance sensing fiber segment. Simultaneously, by combining pulse waveforms, spectral curves, and power variation patterns, the type of noise defect can be distinguished: based on characteristics, it is determined to be pulse floor noise, amplified spontaneous emission (ASE) noise, timing mismatch noise, light source coherence noise, fiber nonlinear distortion noise, polarization-dependent loss noise, etc.

[0088] The optical path correction data is obtained by analyzing the correlation between the location and type of the noise defect and the optical path optimization parameters, and the target optimization parameters are iteratively adjusted to obtain the precise optimization parameters.

[0089] The steps for obtaining the optical path correction data include: Based on the location and type of the noise defect, determine the adjustable parameter group corresponding to the region, and narrow the range of the adjustable parameter group by combining the working principle of the device to obtain the highly correlated parameter; The defects are located in the light source section and include excessive spectral linewidth, wavelength shift, and inherent coherent noise of the light source. The key is to match the relevant parameters of the DFB laser, including operating temperature, drive current, output power, wavelength locking parameters, etc. If the defect is located in the modulation section, or if the defect is due to insufficient extinction ratio, excessive leakage light, or pulse floor noise, the focus should be on matching the electro-optic intensity modulator parameters, mainly the static bias voltage and the amplitude of the drive signal. If the defect is located in the amplification section, or if the defect is high ASE noise, gain fluctuation, or abnormal peak power: focus on matching SOA parameters, including operating gain, gating mode, and operating current; If the defect is noise rise caused by timing mismatch: focus on matching timing parameters such as the synchronization delay and clock skew between the modulator and SOA; If the defect occurs in a long-distance sensing fiber optic link and manifests as nonlinear distortion or abnormal loss, matching should be carried out by combining the input power parameters and Raman pump parameters.

[0090] For the identified noise type, the parameter range is further narrowed down by combining the device's operating principle, and irrelevant parameters are eliminated. For example, when excessive ASE noise is detected, the focus is directly on SOA gain and quiescent operating point, excluding unrelated parameters such as light source wavelength and modulator bias; when timing noise is detected, only timing synchronization parameters are retained.

[0091] The highly correlated parameters were tested using a single variable method. The changes in noise amplitude and signal-to-noise ratio before and after adjustment were compared, and the influence of the current parameters on the defects was analyzed to obtain the parameter sensitivity. The single-variable method was used, fine-tuning only one related parameter at a time, keeping the adjustment range within the device's safe range, avoiding large-scale changes, and keeping all other parameters completely unchanged. After parameter adjustment, the device was allowed to stabilize before data such as pulse waveform, noise power, and signal-to-noise ratio were reacquired.

[0092] By comparing the changes in noise amplitude and signal-to-noise ratio before and after parameter adjustment, the impact of the parameter on the current defect can be quantified. The larger the change, the higher the sensitivity of the parameter; if the indicator hardly changes after parameter adjustment, it is judged as a low-correlation parameter and temporarily shelved.

[0093] Based on the sensitivity results, highly correlated parameters are divided into high-sensitivity core parameters and low-sensitivity auxiliary parameters. For cases where multiple types of noise are superimposed at the same location, the core parameters corresponding to each type of noise are statistically analyzed to elucidate the coupling effects of multiple parameters.

[0094] Based on the parameter sensitivity, the parameter adjustment direction is determined. Combined with the current signal-to-noise ratio deviation value and the noise over-limit value, the defect elimination adjustment amount is calculated to obtain the optical path correction data.

[0095] Parameter adjustment directions may include: insufficient modulator extinction ratio and high floor noise, requiring fine-tuning of the bias voltage to increase the extinction ratio; excessive ASE noise, requiring appropriate reduction of SOA static gain; and noise caused by timing misalignment, requiring adjustment of delay parameters to reduce timing errors.

[0096] Optical path correction data may include the location and type of noise defects, the name of highly correlated parameters, the current value of the parameters, the direction of parameter adjustment, and the amount of adjustment to eliminate defects.

[0097] The steps to obtain the precise optimization parameters include: The target optimization parameters are mapped one-to-one with the optical path correction data to establish a bidirectional mapping relationship, and the scene correction data is obtained by filtering according to the current optical path link loss, deployment distance and noise defect type. Based on the magnitude of link loss: high-loss links are prioritized for power compensation and gain optimization correction data, while low-loss adaptation fine-tuning data are removed; Based on deployment distance: For long-distance applications, retain corrected data that suppresses transmission noise, resists attenuation, and resists nonlinearity, and remove local optimization data for short-distance applications; Based on the type of residual noise defect, the corresponding noise reduction and correction strategy is precisely matched. For example, the modulator bias correction data is preserved for the basis noise, and the SOA gain correction data is preserved for the ASE noise.

[0098] Based on the adjustment priority and the parameter sensitivity, a correction priority is determined, and the adjustment parameter value corresponding to the correction priority is calculated according to the scenario correction data. Based on the selected scenario correction data, a linear fitting relationship between parameter adjustment and signal-to-noise ratio improvement is established. Combined with the current system signal-to-noise ratio deficit, the required parameter correction magnitude is matched.

[0099] The adjustment values ​​for each parameter are calculated hierarchically, from highest to lowest correction priority, and each parameter is quantified one by one: High-priority core parameters: Accurately calculate full correction adjustment values ​​to completely eliminate major noise defects; Low-to-medium priority auxiliary parameters: Calculate small fine-tuning values, only to optimize performance, without interfering with the core optical path operation; A parameter conflict coordination strategy is formulated based on the rated operating range of optical devices and the nonlinear threshold of the system. The target optimization parameters are then adjusted according to the adjusted parameter values ​​to obtain the precise optimization parameters.

[0100] Rated operating range of devices: The safe operating range specified by each optical device manufacturer, including laser temperature, drive current, modulator bias voltage, SOA operating current and timing delay limits. Parameters must not exceed this range to avoid device damage and instability.

[0101] System nonlinear threshold: The critical input power threshold that triggers nonlinear effects such as stimulated Brillouin scattering and self-phase modulation in long-distance fiber transmission. After parameter adjustment, the power must not exceed this threshold to prevent pulse distortion and signal-to-noise ratio degradation.

[0102] Parameter conflict coordination strategy: When the theoretically adjusted parameter value exceeds the safe range or triggers the nonlinear threshold, a trade-off optimization rule is used to balance device safety, no nonlinear distortion, and optimal noise reduction, thereby avoiding parameter conflicts.

[0103] In summary, the long-distance high signal-to-noise ratio (SNR) optical path optimization method for incoherent DVS systems provided in this embodiment significantly reduces noise and improves the overall SNR through multi-stage noise reduction design involving light source parameter control, high extinction ratio modulation, and synchronous gating amplification. This effectively addresses the common problem of high near-end SNR and a sharp drop in far-end SNR in long-distance DVS systems, effectively extending the maximum effective sensing distance of incoherent DVS systems to meet long-distance detection requirements and improve signal integrity. The establishment of a bidirectional mapping mechanism between parameters and defects / operating conditions allows for flexible data filtering and correction based on on-site link loss, sensing distance, and noise type. This adapts to different on-site deployment conditions and different noise fault types in incoherent DVS optical paths, enhancing the versatility and engineering feasibility of the solution and improving system stability and environmental adaptability.

[0104] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system, characterized in that, include: The optical path defect type and link loss data of the incoherent DVS system are determined. Optical path optimization parameters are formulated in combination with the target requirements of long-distance detection and high signal-to-noise ratio. A three-level serial optical path architecture is built to collect detection pulse data. The detection pulse data is processed using a synchronous gating amplification method to obtain low-noise amplified data. The pulsed substrate suppression method is used to analyze the coherence characteristics of the light source and the noise characteristics of the amplification link to obtain parameter calibration data. Based on the parameter calibration data, the optical path optimization parameters are calibrated to obtain the target optimization parameters. Based on the target optimization parameters, determine whether the low-noise amplified data meets the preset signal-to-noise ratio threshold. If yes, output the qualified optical path optimization result; otherwise, mark the location and type of noise defects. The step of determining whether the low-noise amplified data meets the preset signal-to-noise ratio threshold includes: According to the direction of optical signal flow, the incoherent DVS optical path is divided into multiple independent segments. For the measurement points of each segment of the optical path and the corresponding sensor links at different positions, the average power of the effective pulse signal and the average power of the noise in the pulse off interval are read respectively. The real-time signal-to-noise ratio of each segment position is calculated and compared with the preset threshold of the corresponding position one by one, and the comparison results are recorded. When all preset signal-to-noise ratio thresholds are met, the full-link pulse waveform, power and noise status are reviewed, and the current target optimization parameters, low-noise amplification data and comparison results are integrated to form the qualified optical path optimization results. When the preset signal-to-noise ratio threshold is not reached, the location and type of noise defects are determined by combining optical path segmentation and sensor link area. The optical path correction data is obtained by analyzing the correlation between the location and type of the noise defect and the optical path optimization parameters, and the target optimization parameters are iteratively adjusted to obtain the precise optimization parameters.

2. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 1, characterized in that: The steps for determining the optical path optimization parameters include: Based on the working principle of incoherent DVS, the location, phenomenon and severity of optical path defects are investigated segment by segment, and the types of optical path defects are obtained by classification; Segment-by-segment loss tests were performed on the forward transmission light and the back echo light of the incoherent DVS, and the total loss summary and loss distribution curve were used as the link loss data. Long-distance detection indicators and high signal-to-noise ratio indicators are defined as quantitative targets, and optimization priorities are determined based on the impact of the optical path defect types on system performance. Based on the optimization priority, combined with the optical path defect type, the quantization target and the link loss data, the parameters are determined according to the optical path function, and the setting basis is marked to obtain the optical path optimization parameters.

3. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 1, characterized in that: The steps for acquiring the detection pulse data include: A three-stage serial optical path architecture consisting of a narrow-linewidth distributed feedback laser, an electro-optic intensity modulator, and a semiconductor optical amplifier was constructed. The detection pulse data is obtained by capturing multiple sets of time-domain waveform data, including the pulse conduction region, the turn-off base region, and the edge region, using an oscilloscope, and simultaneously recording the accompanying data and acquisition information.

4. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 3, characterized in that: The steps for processing the low-noise amplified data include: The semiconductor optical amplifier is configured to operate in pulse gating amplification mode, so that the semiconductor optical amplifier is synchronized with the electrical drive pulse of the electro-optic intensity modulator, and the semiconductor optical amplifier is in a high gain state during the duration of the detection pulse, so that the peak power of the optical pulse is amplified to not less than 100mW. Continuous probe pulse data is output from a DFB laser, and pulse chopping is performed based on an EO intensity modulator to remove leakage light and obtain purified pulse data. The purified pulse data is then amplified using a time-matched semiconductor optical amplifier to obtain low-noise amplified data.

5. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 2, characterized in that: The pulse base suppression method includes: A narrow-linewidth distributed feedback laser with a working wavelength of 1550.12nm±0.02nm and a spectral linewidth of less than 3kHz was selected as the system light source to output 10–20mW of continuous seed light. The continuous seed light was modulated by an electro-optic intensity modulator with an extinction ratio of not less than 50dB to obtain optical pulses.

6. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 5, characterized in that: The steps for analyzing and obtaining the parameter calibration data include: In the working mode of the optical pulse, the center wavelength, spectral linewidth and output optical power of the DFB laser are detected and compared with the preset standard threshold to obtain the characteristic deviation, and the influence on the pulse substrate is analyzed to obtain the coherence deviation of the light source. Read the optical power in the conduction zone and the leakage power in the off zone under pulse working mode, calculate the measured extinction ratio, and compare it with the preset extinction ratio to determine the leakage light deviation; The time difference between the signals from the electro-optic modulator and the amplifier unit is detected, and the amplification link noise deviation is obtained by summing up the ASE noise, gain fluctuation and the leakage light deviation. Based on the light source coherence deviation and the amplification link noise deviation, the deviation combination scenario is divided. For each deviation, the optical path optimization parameter is corresponding to the optical path optimization parameter. The parameter to be calibrated and the adjustment direction are determined. Combined with the device hardware parameters, a safe adjustable range is set for each parameter to be calibrated. Establish the correspondence between parameter changes and index improvements, and calculate the calibration range for each calibration parameter by combining the measured deviation values. Verify the calibration range according to the safe adjustable range to generate parameter calibration data.

7. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 1, characterized in that: The steps to obtain the target optimization parameters include: Based on the three-level serial optical path architecture, the optical path optimization parameters are loaded, the parameter calibration data is checked, and the adjustment priority and safe adjustable range are determined. According to the transmission order and adjustment priority of the three-level serial optical path architecture, the parameters of each module in the optical path architecture are adjusted one by one based on the parameter calibration data, and the corresponding device status and index changes are recorded. Based on the changes in equipment status and indicators, the indicators are retested and pulse waveforms are observed to verify whether the adjustment effect meets the preset requirements. If so, the current parameters are saved as the target optimization parameters; otherwise, the parameters of each module are readjusted.

8. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 1, characterized in that: The steps for obtaining the optical path correction data include: Based on the location and type of the noise defect, determine the adjustable parameter group corresponding to the region, and narrow the range of the adjustable parameter group by combining the working principle of the device to obtain the highly correlated parameter; The highly correlated parameters were tested using a single variable method. The changes in noise amplitude and signal-to-noise ratio before and after adjustment were compared, and the influence of the current parameters on the defects was analyzed to obtain the parameter sensitivity. Based on the parameter sensitivity, the parameter adjustment direction is determined. Combined with the current signal-to-noise ratio deviation value and the noise over-limit value, the defect elimination adjustment amount is calculated to obtain the optical path correction data.

9. The method for optimizing long-distance, high signal-to-noise ratio optical paths in an incoherent DVS system according to claim 8, characterized in that: The steps to obtain the precise optimization parameters include: The target optimization parameters are mapped one-to-one with the optical path correction data to establish a bidirectional mapping relationship, and the scene correction data is obtained by filtering according to the current optical path link loss, deployment distance and noise defect type. Based on the adjustment priority and the parameter sensitivity, a correction priority is determined, and the adjustment parameter value corresponding to the correction priority is calculated according to the scenario correction data. A parameter conflict coordination strategy is formulated based on the rated operating range of optical devices and the nonlinear threshold of the system. The target optimization parameters are then adjusted according to the adjusted parameter values ​​to obtain the precise optimization parameters.

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