Single-end phi-OTDR disturbance detection system and method based on far-end pumping erbium-doped relay

Abstract

The invention discloses a single-ended phi-OTDR (Optical Time Domain Reflectometer) disturbance detection system and method based on a far-end pumping erbium-doped optical fiber relay. The system is used for long-distance single-ended phi-OTDR distributed disturbance detection based on the far-end pumping erbium-doped optical fiber relay and a pumping energy bypass unit. Comprising a transmitting-end coherent light source and pulse generation link, a signal and pump multiplexing single-end transceiving link, a plurality of EDF relay and PPBU pump distribution links arranged along the line, and a receiving and digital signal processing link. PPBU pumping allocation links are introduced among the multiple EDF sections, and residual pumping of the previous EDF section is bypassed to the next EDF section in proportion through a high-power 1 * 2 low-insertion-loss coupler and a high-isolation WDM (Wavelength Division Multiplexing), which is the bypass proportion of the kth PPBU. According to the method, the PPBU (pump energy bypass unit) is used for carrying out interpretable, computable and online correctable bypass distribution and constraint optimization on the pump energy of the multi-section EDF, and unification of high SNR (signal to noise ratio), low nonlinear risk and robust engineering implementability is realized from the system level.

Description

Technical Field

[0001] This invention relates to the field of distributed optical fiber sensing and optical fiber amplification technology, and in particular to a single-ended φ-OTDR disturbance detection system and method based on a remotely pumped erbium-doped relay. Background Technology

[0002] φ-OTDR (phase-sensitive optical time-domain reflectometry) recovers the location and type of disturbances along the fiber by periodically injecting narrow pulses into a single-mode fiber and collecting the subtle fluctuations in Rayleigh backscattering (RBS) over time, thus establishing a time-space mapping relationship. However, when the range extends to the hundreds of kilometers, the intrinsic link loss and various nonlinear effects (stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and self-phase modulation (SPM)) significantly limit the pulse peak value and the effective signal-to-noise ratio (SNR).

[0003] While traditional dual-end pumping or remote active power supply solutions can improve detection performance to some extent, they often introduce problems such as on-site power supply, dual-end coordination, and complex maintenance in engineering implementation. Summary of the Invention

[0004] This invention provides a single-ended φ-OTDR perturbation detection system and method based on a remotely pumped erbium-doped fiber repeater. To achieve end-point detectability comparable to that of a double-ended system under single-ended, passive boundary conditions, this invention proposes a deep integration of a remotely pumped erbium-doped fiber passive repeater with φ-OTDR. This is achieved by establishing population inversion in stages within the EDF (erbium-doped fiber) and providing stimulated gain for subsequent narrow measurement pulses. Simultaneously, a PPBU (pump energy bypass unit) is used to perform interpretable, calculable, and online-correctable bypass allocation and constraint optimization of the pump energy across multiple EDF segments. This achieves a system-level balance of "high SNR, low nonlinear risk, and robust engineering feasibility," as detailed below.

[0005] A single-ended φ-OTDR disturbance detection system based on a remote-pumped erbium-doped fiber optic relay, wherein the system is based on long-distance single-ended φ-OTDR distributed disturbance detection using a remote-pumped erbium-doped fiber optic relay and a pump energy bypass unit.

[0006] The system includes: a coherent light source and pulse generation link at the transmitting end, a single-ended transceiver link for signal and pump multiplexing, multiple EDF relays and PPBU pump distribution links set along the line, and a receiving and digital signal processing link.

[0007] A PPBU pump distribution link is introduced between multiple EDF segments. The residual pump from the previous EDF segment is distributed proportionally via a high-power 1×2 low-insertion-loss coupler and a high-isolation WDM. Take a detour to the next section. Let be the bypass ratio of the k-th PPBU.

[0008] The equivalent form of the link's equivalent path efficiency is:

[0009]

[0010] in, To determine the equivalent path efficiency up to the k-th segment, Let i be the bypass ratio of the i-th PPBU. For the overall path efficiency of the pump transfer in the i-th segment, The pump power is input to the k-th segment of the EDF. This is the pump power output of the first EDF stage.

[0011] The method also includes: constructing a bypass ratio set. Multi-objective optimization model;

[0012] The model is as follows:

[0013]

[0014] in, To optimize the objective function for multiple objectives, The weights are the objective function weights. To measure the uniformity of RBS along the route, For the first The nonlinear cost term of the segment; online control uses a first-order update approximated by the projected gradient. , Let t be the bypass ratio of PPBU in the t-th update. Update the step size for gradient.

[0015] A single-ended φ-OTDR perturbation detection method based on a remotely pumped erbium-doped relay, the method comprising:

[0016] Based on the detection distance and spatial resolution, the detection pulse parameters are set, and a transmitting pulse generation link, signal and pump multiplexing, and single-ended transceiver link are established. Multiple EDF repeaters are set along the sensing fiber, and PPBUs are connected between each segment. The bypass ratio of each segment is given. Overall path efficiency The initial values ​​are used to obtain the available pump and end-to-end gain budgets for each segment based on the pump friction loss and the recursive relationship between the multi-segment EDF pump. Simultaneously, the nonlinear constraint boundaries of SBS, SRS, and SPM are determined. A multi-objective function is constructed with end-to-end gain, RBS uniformity, and nonlinear cost as objectives. The first-order projection method is used to determine the bypass ratio for each segment. Small-step online updates, with limits applied to the change amount in each cycle; based on the updated bypass ratio of each segment. Recalculate each segment , and nonlinear indices, forcibly satisfying , , If violated, the step size will be reversed. Alternatively, adjust the boundary strategy to form a closed loop of "optimization-verification-rollback";

[0017] by With the echo uniformity index along the route as the target, for each section and Perform joint tuning;

[0018] Set trigger conditions so that when the SNR, OSNR, reflection monitoring quantity or temperature drift related indicators exceed the limits, the adaptive update process is started; otherwise, steady-state operation is maintained.

[0019] The output includes event results such as location, amplitude, frequency band, and confidence level, and records key parameters, constraint margins, and DSP parameters to ensure experimental and engineering traceability.

[0020] The beneficial effects of the technical solution provided by this invention are:

[0021] 1. This invention addresses the problem of extending the detection capability of phase-sensitive optical time-domain reflectometry in ultra-long-distance, single-end, passive deployment scenarios. It proposes an overall architecture that injects a remote pump at the beginning of the system and sets up erbium-doped fiber (EDF) passive repeaters at the far end of the sensing fiber or along the path.

[0022] 2. This invention introduces a Pump Power Bypass Unit (PPBU) to perform segmented allocation and recursive optimization of residual pumping in multiple EDF segments, enabling single-end disturbance detection over a distance of hundreds of kilometers without relying on relay power supply and dual-end coordination. This system forms a complete set of engineering-feasible methods and implementation paths in terms of material and device parameters, link power budget, nonlinear threshold, security control, and signal processing. Attached Figure Description

[0023] Figure 1 This is a structural block diagram of the system.

[0024] Figure 2 This is a schematic diagram of a remote pump;

[0025] Figure 3 This is a schematic diagram of the structure of a remote pumped EDF detection system;

[0026] Figure 4 This is a schematic diagram of the pump energy bypass unit (PPBU).

[0027] Figure 5 A schematic diagram of a parallel 1480 pump cascaded with multiple EDFs for amplification;

[0028] Figure 6 This is a timing diagram of the three-stage narrow pulse amplification process from RP (remote pumping) to EDF;

[0029] Figure 7 A schematic diagram of the topology for energy distribution between a multi-stage EDF cascade and a PPBU pump;

[0030] Figure 8 for A diagram illustrating optimization and constraints;

[0031] Figure 9 This is a schematic diagram of the design window for SNR budget and nonlinear constraints. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0033] Example 1

[0034] A single-ended φ-OTDR disturbance detection system based on a remotely pumped erbium-doped relay, see [link to relevant documentation]. Figure 1 The system includes: implementation using the system as a carrier, and the formation of corresponding methodological processes on top of the system. The system is a long-distance single-ended φ-OTDR distributed disturbance detection system based on a remotely pumped erbium-doped fiber repeater (RP-EDF) and a pump energy bypass unit (PPBU).

[0035] The system consists of a coherent light source and pulse generation link at the transmitting end, a single-ended transceiver link for signal and pump multiplexing, multiple EDF relays and PPBU pump distribution links set along the line, and a receiving and digital signal processing link.

[0036] The system operates at a signal wavelength of 1550 nm and a pump wavelength of 1480 or 1490 nm. Structurally, the transmitting end sequentially includes a narrow-linewidth laser source, an electro-optical modulator (EOM), and a preamplifier (Pre-EDFA). After out-of-band filtering and a circulator link, the signal is injected into the front-end single-mode sensing fiber (SSMF). At least one EDF repeater is installed along the sensing fiber or at a distant end, and multiple EDFs can be cascaded to form segmented gain compensation. The pump link is powered by the pump laser and pump controller at the beginning, coupled into the sensing fiber via a wavelength division multiplexer (WDM) and a low-loss coupler, and transmitted in the same direction to the distant EDF region. In the case of multiple cascaded EDFs, a power-saving buffer (PPBU) is used to achieve graded bypass distribution of pump energy, ensuring that the remaining pump power from the previous EDF is distributed proportionally. Traffic is redirected to the next EDF segment, while considering path efficiency. The impact on pump delivery is investigated, thereby maximizing end-to-end available gain and echo signal-to-noise ratio while satisfying nonlinear constraints and safe power limits.

[0037] In terms of signal path, the 1550nm pulse is injected into the SSMF at the transmitting end and propagates forward along the link. After being amplified by the RP-EDF, it continues to propagate. The Rayleigh backscatter (RBS) generated along the line returns to the transmitting end in the opposite direction. After being separated by the circulator, it enters the photoelectric detection and digital processing module at the receiving end to complete I / Q construction, phase demodulation and event detection.

[0038] In terms of pump direction, the 1480 / 1490nm pump is injected from the beginning and propagates forward along the link to the EDF region, providing population inversion to support RP-EDF gain; in the case of multiple EDF segments, the pump is bypassed in stages via PPBU, so that each EDF segment obtains a matching pump share and maintains the uniformity of the link echo.

[0039] To ensure spatial resolution while avoiding overlap of round-trip delays, pulse width... With repetition frequency It must simultaneously satisfy the speed of light Core refractive index With the maximum range The two spatiotemporal constraints determined are as follows, where the spatial resolution is written as The upper limit of repetition frequency is written as Regarding the nonlinear threshold, the laser linewidth is broadened by applying moderate linewidth dithering to the light source. It can significantly raise the threshold of stimulated Brillouin scattering; if the effective modulus area is used... Brillouin gain coefficient Effective length Brillouin gain spectral width Characterizing the medium and link, the engineering approximation of the stimulated Brillouin threshold is:

[0040] The remote pump is injected from the beginning of the fiber and transmitted to the EDF position via the front-end SSMF. If P0 is taken as the input pump power at the beginning of the sensing fiber, (Unit: dB / km) represents the attenuation coefficient of the pump light in the sensing fiber, approximately 0.26 dB / km, and L is the length of the first segment of the sensing fiber. Therefore, the pump power at the erbium fiber tip satisfies... .

[0041] In order to form a stable usable inversion and maintain a steady-state period before the detection narrow pulse reaches the EDF position, the following should be satisfied: ,and Much larger .in, The pulse repetition period is the time interval between two adjacent detection pulses, measured in seconds. The pulse repetition frequency is the number of pulses emitted per second, measured in Hz. The equivalent lifetime of the energy level on the EDF is expressed in seconds.

[0042] When solving differential equations and performing numerical simulations, the following is often used:

[0043]

[0044] The logarithmic loss was converted to linear coefficients to maintain consistency in units and dimensions of the model. Among these, is the pump light power attenuation factor in SSMF, in dB / km; To convert dB / km into a linear exponential decay coefficient; Let z be the pump power at position z; Here, z represents the pump input power at z=0; z is the distance coordinate along the fiber, in km. This embodiment of the invention employs a two-level equivalent model and a mode overlap factor. and To provide a unified description of pump and signal power and the number of particles in the upper energy level The coupled evolution, with its energy level occupation rate equation and power propagation equation, are as follows:

[0045]

[0046]

[0047]

[0048] in, The number of particles in the upper energy level of the EDF. The total number of particles, For signal optical power, Let be Planck's constant. For the pump optical frequency, For signal optical frequency, The mode overlap factor between the pump and erbium-doped regions. The mode overlap factor between the signal and the erbium-doped region. The absorption cross-sectional area at the pump wavelength. Let be the stimulated radiation cross-section at the pump wavelength. This represents the absorption cross-section at the signal wavelength. Let be the stimulated radiation cross-section at the signal wavelength. This is the intrinsic loss coefficient of the EDF at the signal wavelength. Let be the intrinsic loss coefficient at the pump wavelength. For narrow pulse amplification time windows, a quasi-steady-state approximation can be used. Seeking Algebraic solution:

[0049]

[0050] Substituting this into the signal propagation equation yields the position-dependent gain coefficient:

[0051]

[0052] Under the approximation of small spatial fluctuations in the above equation, the small-signal segment gain and pulse saturation model can be expressed as follows:

[0053]

[0054]

[0055] in, For small signal gain, The length of the EDF. For saturation power, To account for the gain after saturation, Characterize the effect of pulse peak value on gain compression. For the peak power of the signal pulse, empirical factor While increasing the gain at the far end to improve the downstream RBS, it is necessary to budget the receiver noise and end-to-end SNR; if... Represents the Rayleigh divergence coefficient, in terms of Representing spatial discrete units, with and Indicates the backhaul link loss and one-way distance, in Let z represent the signal power at position z. Then, the average power of the RBS reaching the receiver can be approximated as:

[0056]

[0057] Photoresponsivity With electrical bandwidth The unified expression for single-point SNR is:

[0058]

[0059] in, The echo power at the receiving end, For relative intensity noise, To amplify spontaneous emission noise, Thermal noise, This is shot noise.

[0060] The engineering representation of the main noise components is as follows:

[0061]

[0062] in, For electron charge, The photocurrent generated by the signal light. Background current generated by background light, Boltzmann's constant, Absolute temperature For load resistance, To amplify the optical gain of the link, Spontaneous emission factor, It refers to the optical frequency.

[0063] At the end-to-end scale, with Given the gain density, the total gain can be written. and introduce A unified measure of the effective action length of a nonlinear gain process, while using Verify the stimulated Raman threshold, and in addition... Characterizing the phase matching condition of four-wave mixing (FWM), in order to Nonlinear integrals constrained by self-phase modulation.

[0064] in, The equivalent cumulative length of multiple EDF segments. The linear loss coefficient is... For SRS threshold power, The Raman gain coefficient is... This is due to phase mismatch in four-wave mixing. Let be the propagation constant. To participate in the various wave angle frequencies of FWM, For Kerr's nonlinear coefficients, It is a self-phase modulated nonlinear integral.

[0065] This invention introduces a PPBU between multiple EDF segments, and uses a high-power 1×2 low insertion loss coupler and a high-isolation WDM to proportionally distribute the residual pump of the previous EDF segment. Take a detour to the next section. Let this be the bypass ratio of the k-th PPBU. Consider the efficiency of the k-th coupler segment. Efficiency of the k-th optical path and the overall path efficiency of the k-th segment. The unified relationship between multi-stage recursion and end-to-end gain can be written as:

[0066]

[0067] in, The first EDF input pump power, The length of the first SSMF segment. The output pump power of the k-th EDF segment, The pump power is input to the k-th segment of the EDF. Let be the equivalent function of the k-th segment of EDF for the pump. The pump power is input to the (k+1)th segment of the EDF. For EDF segment number, The gain provided by the k-th segment of EDF to the signal.

[0068] Furthermore, an equivalent form that is easier to implement in engineering can be obtained:

[0069]

[0070] in, To determine the equivalent path efficiency up to the k-th segment, Let i be the bypass ratio of the i-th PPBU. For the overall path efficiency of the pump transfer in the i-th segment, This is the pump power output of the first EDF stage.

[0071] To achieve the optimal end-to-end trade-off between nonlinear boundaries and end-to-end detectability, embodiments of the present invention construct a bypass ratio set. Multi-objective optimization model:

[0072]

[0073] in, To optimize the objective function for multiple objectives, The weights are the objective function weights. To measure the uniformity of RBS along the route, For the first The nonlinear cost term of the segment; online control uses a first-order update approximated by the projected gradient. , Let t be the bypass ratio of PPBU in the t-th update. The step size is updated using gradient. A gradual increase is adopted on the pump source side to mitigate transient reflections and nonlinear impacts; its time-domain curve is as follows. , For the maximum pump power, Let be the pump-on ramp time constant. In the signal processing link, the downstream RBS energy boost and homogenization caused by far-end amplification, combined with the I / Q component construction and phase demodulation-unwrapping of adjacent pulse intensities, can recover the equivalent phase at position z at time t. High-fidelity distribution is obtained, and spatial-spectral analysis is performed within a sliding time window to extract narrow-band or broadband features of the perturbation; spatial discretization consistent with time-domain sampling is typically employed. space bin number Ensure resampling and positioning accuracy.

[0074] Regarding component selection, to ensure compatibility with the aforementioned model, the narrow-linewidth laser source must meet the center wavelength requirement. Line width Relative intensity noise and output power Pulse modulators need to have rise / fall times. Extinction ratio and Voltage Recommended gain range for pre-EDFA Maximum output With noise figure The filter / loop link needs to have a passband. Insertion loss With isolation Regarding reception, photoelectric responsivity bandwidth effective number of sampling ADCs Sampling rate .

[0075] PPBU splitters require low insertion loss and high load capacity; insertion loss Rated power handling capacity Return loss WDM should meet the pump light wavelength requirement. Signal light wavelength , Typical length of multi-segment EDF The end face, front / rear section SSMF is G.652D level and meets the requirements. .

[0076] Pump source meets output power Output power stability The controller satisfies It is also equipped with reflection monitoring, amplitude limiting and interlocking, and optical isolators. Together with temperature / health monitoring, they form a closed loop of safety and reliability.

[0077] Therefore, the embodiments of the present invention form a complete closed loop in seven levels: structure, equations, constraints, optimization, control, processing, and parameter solidification. The structure level uses the physical topology of RP-EDF relay and PPBU bypass as the carrier; the equation level provides a computable physical baseline; the constraint level characterizes nonlinearity and threshold boundaries; the optimization level defines the recursion and objective of bypass allocation; the control level embodies the safety strategy of gradual power-on; and the processing level links SNR and spatial sampling.

[0078] Example 2

[0079] A single-ended φ-OTDR perturbation detection method based on a remotely pumped erbium-doped relay, the method comprising the following steps:

[0080] Step 1: Ensure parameter consistency and unit uniformity;

[0081] Unified units of length and units of loss: if attenuation If dB / km is used, then distance z is expressed in km; if the differential equation uses a linear attenuation coefficient, then a conversion is performed. and used in subsequent propagation equations .

[0082] Step 2: Spatiotemporal constraints and pulse parameter settings;

[0083] Based on target spatial resolution and maximum range and ,satisfy , , .

[0084] Step 3: Signal link setup and port direction verification;

[0085] Connect the optical path according to “Laser→EOM→Pre-EDFA→Filter / Circulator→SSMF→RP-EDF / EDF stages→SSMF→Receiver”, verify the circulator port direction and echo separation path, and ensure that the RBS echo enters the receiver port and does not backfeed the light source / amplifier.

[0086] Step 4: Pump link setup and WDM multiplexing / splitting check;

[0087] Connect the pump link by following the steps "Pump Laser→Pump Controller→WDM→SSMF→EDF / RP-EDF area". Check the isolation and insertion loss of the WDM port to ensure that the pump enters the EDF area and that the 1550nm signal is not mistakenly injected into the pump end.

[0088] Step 5: PPBU topology access and adjustable parameter initialization;

[0089] Connect PPBU at multiple EDF cascade locations and initialize bypass ratio and path efficiency parameters. , And establish a calculation interface for the pump energy distribution recursive relationship (for online optimization and initial value generation).

[0090] Step 6: Pump friction loss and achievable pump budget;

[0091] The achievable pump power at EDF is estimated based on the pump attenuation at SSMF, and the following is adopted: This yields the pump budget range for the EDF region, providing boundary conditions for subsequent RP-EDF gain and nonlinear constraint evaluation.

[0092] Step 7: EDF level modeling;

[0093] The rate equation and propagation equation are adopted as follows:

[0094] , .

[0095] Step 8: Quasi-steady-state approximation and initial value calculation;

[0096] A quasi-steady-state approximation is used within the narrow pulse amplification time window. calculate The algebraic initial values ​​are used for subsequent numerical iteration initialization of gain, saturation, and pump depletion.

[0097] Step 9: Solidify the three-stage timing control parameters of RP-EDF;

[0098] The three-stage timing parameters of the solidified RP-EDF (P1 pre-charge, P2 narrow pulse amplification, P3 residual dissipation) are configured, and pump ramp-up and steady-state maintenance strategies are set to ensure that each... The gain variation within the range is controllable and consistent with the quasi-steady-state assumption.

[0099] Step 10: Calculation of nonlinear threshold and design window constraints;

[0100] A joint safety boundary is established for stimulated Brillouin scattering (SBS), stimulated Raman scattering (SRS), and self-phase modulation (SPM). Each threshold is calculated, and design allowances are set. The SBS threshold is approximately... The SRS threshold is approximately... Self-phase modulation constrained by B-integral .

[0101] Step 11: Multi-stage EDF cascaded pump distribution recursion;

[0102] A pump recursive update formula is established for multiple EDF segments to calculate the available pump and achievable gain for each segment:

[0103] , .in Losses are synthesized from couplers / WDM / connectors, etc. Assign variables to PPBU.

[0104] Step 12: Interlock between gradual pump power-up and reflection monitoring;

[0105] The pump is gradually powered on, and the reflection monitoring value is read in real time to constrain the return power and avoid device damage; when the reflection is abnormal or the power exceeds the constraint boundary, automatic derating or shutdown is triggered.

[0106] Step 13: Transmit pulse calibration and receive window synchronization;

[0107] For EOM pulse width The amplitude and Pre-EDFA gain are calibrated, and the ADC sampling rate and receiving window are set so that the receiving window covers the maximum range. Corresponding round-trip time and synchronous.

[0108] Step 14: RBS echo power budget and baseline SNR estimation;

[0109] A budget model for return power and link loss is established, and the baseline SNR is estimated based on noise components, using a unified form. .

[0110] Step 15: I / Q construction and phase demodulation link solidification;

[0111] Complete photoelectric detection, down-conversion or digital quadrature demodulation, construct I / Q and extract the phase sequence ϕ(z,t), and implement compensation strategies for carrier frequency offset and phase drift.

[0112] Step 16: Phase difference and perturbation feature construction;

[0113] Phase difference or coherence difference features are calculated based on spatial channels and time series to form an event detection input feature sequence.

[0114] Step 17: Time-Frequency Analysis: STFT Implementation;

[0115] STFT is performed on the time series of the selected spatial channel, using

[0116]

[0117] The output time spectrum is used to distinguish between environmental noise and event disturbances and to support subsequent threshold decisions. It is a discrete time series. For sequence The short-time Fourier transform results, This refers to the time window number. For frequency bin, For frame shift, For the length of the window, For window functions, The number of FFT points.

[0118] Step 18: Matched filtering and processing gain fixing;

[0119] To improve detection performance, matched filtering is applied to the emitted pulse template, for example... .in, To achieve the signal-to-noise ratio after matched filtering. To match the signal-to-noise ratio before filtering. For signal template energy, For noise power spectral density, This is the equivalent noise bandwidth.

[0120] Step 19: Event Decision and Multi-Scale Consistency Constraints;

[0121] Set minimum detectable threshold Minimum duration With minimum number of continuous points in space To achieve consistent decision-making across time, space, and frequency domains, thereby reducing false alarms.

[0122] Step 20: Online optimization loop for bypass ratio;

[0123] Construct a multi-objective function with end-to-end gain, RBS uniformity, and nonlinear cost as objectives. The first-order projection method is used to determine the bypass ratio of each segment. Xiaobuzhang is updating online: .in For interval projection operators, This refers to the step size; in engineering, a limit is added to the change in each cycle. To ensure convergence stability and operational safety.

[0124] Step 21: Constraint closed loop: SBS / SRS / B-integral joint verification;

[0125] Each update Then, recalculate each segment. , and nonlinear indices, forcibly satisfying , , If violated, the step size will be reversed. Alternatively, adjust the boundary strategy to form a closed loop of "optimization-verification-rollback".

[0126] Step 22: Multi-segment gain equalization and echo uniformity tuning;

[0127] by With the echo uniformity index along the route as the target, for each section and Perform joint tuning to avoid nonlinearity caused by local over-amplification or local undergain leading to far-end blind zone.

[0128] Step 23: Runtime monitoring and adaptive update of trigger conditions;

[0129] Set trigger conditions: When the SNR, OSNR (optical signal-to-noise ratio), reflection monitoring quantity, or temperature drift-related indicators exceed the limits, initiate the adaptive update process (online optimization or parameter retuning); otherwise, maintain steady-state operation.

[0130] Step 24: Output generation: location, amplitude, frequency band, confidence level;

[0131] Output event results ,in For positioning, Amplitude, frequency band characteristics Derived from STFT, confidence level It stems from consistent decision-making and threshold margin.

[0132] Step 25: Data recording and reproducibility solidification;

[0133] Record key parameters: , , , , , Constraint margins (SBS, SRS, B-integral), and DSP parameters , , This ensures the reproducibility of experiments and traceability in engineering.

[0134] Step 26: Shutdown and State Recovery.

[0135] Perform controlled shutdown: Derated the pump to 0, shut down the amplification link, release the optimization state, save the final parameters and alarm logs, and complete the system reset.

[0136] Unless otherwise specified, the model numbers of the various devices in this embodiment of the invention are not limited, and any device that can perform the above functions is acceptable.

[0137] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A single-ended φ-OTDR disturbance detection system based on a remotely pumped erbium-doped relay, characterized in that, The system is based on long-distance single-ended φ-OTDR distributed disturbance detection using a remote-pumped erbium-doped fiber repeater and a pump energy bypass unit. The system includes: a coherent light source and pulse generation link at the transmitting end, a single-ended transceiver link for signal and pump multiplexing, multiple EDF relays and PPBU pump distribution links set along the line, and a receiving and digital signal processing link. A PPBU pump distribution link is introduced between multiple EDF segments. The residual pump from the previous EDF segment is distributed proportionally via a high-power 1×2 low-insertion-loss coupler and a high-isolation WDM. Take a detour to the next section. Let be the bypass ratio of the k-th PPBU.

2. The single-ended φ-OTDR disturbance detection system based on remote-pumped erbium-doped relay according to claim 1, characterized in that, The equivalent form of the link's equivalent path efficiency is: in, To determine the equivalent path efficiency up to the k-th segment, Let i be the bypass ratio of the i-th PPBU. For the overall path efficiency of the pump transfer in the i-th segment, The pump power is input to the k-th segment of the EDF. This is the pump power output of the first EDF stage.

3. The single-ended φ-OTDR disturbance detection system based on a remotely pumped erbium-doped relay as described in claim 1, characterized in that, The method further includes: constructing a bypass ratio set. Multi-objective optimization model; The model is as follows: in, To optimize the objective function for multiple objectives, The weights are the objective function weights. To measure the uniformity of RBS along the route, For the first The nonlinear cost term of the segment; online control uses a first-order update approximated by the projected gradient. , Let t be the bypass ratio of PPBU in the t-th update. Update the step size for gradient.

4. A single-ended φ-OTDR disturbance detection method based on a remotely pumped erbium-doped relay, characterized in that, The method includes: Based on the detection distance and spatial resolution, the detection pulse parameters are set, and a transmitting pulse generation link, signal and pump multiplexing, and single-ended transceiver link are established. Multiple EDF repeaters are set along the sensing fiber, and PPBUs are connected between each segment. The bypass ratio of each segment is given. Overall path efficiency The initial values ​​are used to obtain the available pump and end-to-end gain budgets for each segment based on the pump friction loss and the recursive relationship between the multi-segment EDF pump. Simultaneously, the nonlinear constraint boundaries of SBS, SRS, and SPM are determined. A multi-objective function is constructed with end-to-end gain, RBS uniformity, and nonlinear cost as objectives. The first-order projection method is used to determine the bypass ratio for each segment. Small-step online updates, with limits applied to the change amount in each cycle; based on the updated bypass ratio of each segment. Recalculate each segment , and nonlinear indices, forcibly satisfying , , If violated, the step size will be reversed. Alternatively, adjust the boundary strategy to form a closed loop of "optimization-verification-rollback"; by With the echo uniformity index along the route as the target, for each section and Perform joint tuning; Set trigger conditions so that when the SNR, OSNR, reflection monitoring quantity or temperature drift related indicators exceed the limit, the adaptive update process is started; otherwise, the steady-state operation is maintained. The output includes event results such as location, amplitude, frequency band, and confidence level, and records key parameters, constraint margins, and DSP parameters to ensure experimental and engineering traceability.

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