High sensitivity vibration sensing system and method employing a step light source

Abstract

The application discloses a high-sensitivity vibration sensing system and method using a step-by-step light source, step-by-step continuous light is reflected multiple times after passing through a fiber grating, different sensitization multiples of interference light have corresponding frequency difference values by controlling the distance between the fiber gratings and the parameters of the step-by-step light source, the center frequency and the bandwidth of a band-pass filter are controlled to reserve the interference light of a specific sensitization multiple and filter unnecessary light waves, a balanced detection module is used to significantly reduce common-mode noise in an optical path and amplify useful signals, the system uses high-order reflected detection light in a fiber Fabry-Perot resonant cavity to interfere with first-order reflected reference light to improve the sensitivity and the signal-to-noise ratio of the system. The high-sensitivity vibration sensing system and method using the step-by-step light source provided by the application use the frequency conversion characteristics of step-by-step continuous light and the wavelength characteristics of the fiber grating to realize step-by-step light heterodyne interference dynamic signal modulation and demodulation with high sensitivity and high signal-to-noise ratio.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology, specifically relating to a high-sensitivity vibration sensing system and method using a stepper light source. Background Technology

[0002] Fiber optic sensors offer numerous unique advantages over traditional sensors, such as extreme sensitivity to sound, stress, and temperature, low signal transmission loss, and the ability to operate stably and sustainably in harsh environments. Therefore, fiber optic sensing plays a crucial role in modern measurement technology. Currently, fiber optic sensing systems are widely used in various practical applications, including health monitoring of large structures and infrastructure, medical applications, geological disaster monitoring, and pipeline safety monitoring. With the deepening of research in fields such as well logging, seismic waves, and aerospace, the miniaturization and high-sensitivity detection of vibration sensors have become increasingly urgent needs. In structural health monitoring, smaller sensors are easier to embed into structures. In applications such as seismic exploration, only sensors of a certain size can achieve the desired measurement results. In recent years, miniaturizing sensors and improving their sensitivity and resolution have become research hotspots in the field of fiber optic sensing.

[0003] Interferometric fiber optic sensing technology has matured over decades of development, primarily encompassing Fabry-Perot interferometers, Mach-Zehnder interferometers, Sagnac interferometers, Michelson interferometers, and phase-sensitive optical time-domain reflectometers (OTDRs). These are widely used to demodulate the output spectrum of fiber optic sensors. Currently, high-sensitivity, high-resolution fiber optic sensing systems mainly utilize traditional interferometer structures. However, the sensitivity of traditional interferometers is directly proportional to the actual length of the sensing fiber. Therefore, although fiber optic sensing systems using traditional interferometers achieve high measurement accuracy, the trade-off between size and sensitivity limits performance improvement. Phase-sensitive OTDs, on the other hand, utilize the interference effect of backscattered Rayleigh light generated when highly coherent light pulses propagate through weakly reflective fiber gratings or optical fibers. They offer high positioning accuracy and small sensor size, but suffer from issues such as insufficient signal demodulation resolution, low sensitivity, and poor real-time performance.

[0004] Existing fiber optic vibration sensing systems and methods struggle to simultaneously achieve high sensitivity, resolution, and small size. Therefore, it is necessary to develop a system and demodulation method that combines these characteristics to improve the dynamic signal demodulation capability of fiber optic sensing systems. Summary of the Invention

[0005] This invention provides a high-sensitivity vibration sensing system and method using a stepping light source to solve the aforementioned technical problems, specifically employing the following technical solution:

[0006] A high-sensitivity vibration sensing system employing a stepper light source, characterized in that it comprises:

[0007] Stepper light source module, used to emit step-frequency continuous light;

[0008] A first circulator is connected to the stepper light source module and is used to receive the light signal emitted by the stepper light source module;

[0009] A fiber Bragg grating pair is connected to the first circulator, the first circulator outputs an optical signal to the fiber Bragg grating pair, the fiber Bragg grating pair is used to reflect sensing and reference optical signals, and the fiber Bragg gratings in the fiber Bragg grating pair have the same bandwidth and center wavelength;

[0010] The first coupler is connected to the first circulator. The reflected signal from the fiber optic grating enters the first coupler after passing through the first circulator. The first coupler is used to split the stepped-frequency continuous light containing sensing and reference signals into two optical signals. The light containing the sensing signal is used as the probe light and passes through the probe path, while the other optical signal is used as the reference light and passes through the reference path.

[0011] The second coupler, connected to the first coupler, is used to perform heterodyne interference on the reflected light from the probe path and the reference path, and output two beams of 180-degree anti-phase interference light signals.

[0012] The balanced light detection module, connected to the second coupler, is used to detect the beat frequency signal of the interference signals of the detection path and the reference path. At the same time, two photodetectors with the same response coefficient are used to detect the two beams of light. The common-mode signal is suppressed by differential amplification and the differential-mode signal is amplified to achieve balanced detection and output an electrical signal.

[0013] A bandpass filter is connected to the balanced light detection module to receive its output electrical signal. The bandpass filter is used to filter the frequency shift signal in the electrical signal and extract the radio frequency signal carrying the sensing phase shift information.

[0014] The real-time data acquisition and processing module is connected to the bandpass filter to receive the radio frequency signal transmitted by it. The real-time data acquisition and processing module is used to acquire and process the radio frequency signal in real time, demodulate the interference signal, and obtain the detection result of the high-sensitivity heterodyne interference signal of the stepper light source.

[0015] Furthermore, the linewidth of the step-frequency continuous light emitted by the step-light module is smaller than the bandwidth of the fiber Bragg grating pair, and both the start frequency and the end frequency of the step-light are within the bandwidth of the fiber Bragg grating pair.

[0016] Further, the fiber grating pair includes a first fiber grating and a second fiber grating located on the same optical fiber. The first fiber grating and the second fiber grating have the same central wavelength and the same bandwidth. The light wave carrying the reference signal is reflected by the first fiber grating, and the light wave carrying the sensing signal is reflected multiple times by the first fiber grating and the second fiber grating.

[0017] Further, the first coupler and the second coupler form a Mach-Zehnder interferometer, and the two arms of the Mach-Zehnder interferometer are of equal length. The time interval for one frequency conversion of the stepped-frequency continuous light is t0, the propagation speed of the light wave in the optical fiber is v, the sensitization multiple is n, and when i is a positive integer and i < n, the length L between the first fiber grating and the second fiber grating satisfies 2nL = ivt0.

[0018] Further, the second coupler is a 2×2 coupler with two-port outputs of 180-degree inverted interference optical signals.

[0019] Further, the balanced optical detection module includes two photodetectors with the same response coefficient for detecting the two beams of light output by the second coupler. By means of differential amplification, the common-mode signal is suppressed and the differential-mode signal is amplified and output to achieve balanced detection.

[0020] Further, when the starting frequency of the stepped light source is f and the stepped frequency interval is f0, the central frequency of the band-pass filter is if0, where i is a positive integer and n is the sensitization multiple, i < n, and the bandwidth Δf < f0, and only the interference light with nth-order sensitization is allowed to pass through while filtering the light waves of other orders.

[0021] A high-sensitivity vibration sensing method using a stepped light source is applied to the aforementioned high-sensitivity vibration sensing system using a stepped light source;

[0022] The high-sensitivity vibration sensing method using a stepped light source includes:

[0023] The stepped light source module emits stepped-frequency continuous light. The light wave passes through the first port of the first circulator, and is reflected by the fiber grating pair when exiting from the second port of the first circulator. The light wave exits from the third port of the first circulator and is divided into two optical signals by the first coupler. One optical signal serves as the detection light and passes through the detection path, and the other optical signal serves as the reference light and passes through the reference path;

[0024] The second coupler performs heterodyne interference on the reflected light of the detection path and the reference path, and outputs two 180-degree inverted interference optical signals;

[0025] The output interference signal is sequentially amplified differentially, suppressed for common-mode noise, and detected for beat frequency interference signal by the balanced light detection module, and the bandpass filter filters the frequency shift signal in the electrical signal to extract the radio frequency signal carrying the sensing phase shift information.

[0026] The real-time data acquisition and processing module acquires and processes radio frequency signals, demodulates interference signals, and obtains the detection results of high-sensitivity heterodyne interference signals from the stepper light source.

[0027] Furthermore, the fiber Bragg grating pair includes a first fiber Bragg grating and a second fiber Bragg grating located on the same optical fiber. The light wave carrying the reference signal is reflected by the first fiber Bragg grating and passes through the first coupler, and then is transmitted to the second coupler. The light wave carrying the sensing signal is reflected multiple times by the first fiber Bragg grating and the second fiber Bragg grating and passes through the first coupler, and then is transmitted to the second coupler.

[0028] The advantages of this invention lie in the high-sensitivity vibration sensing system and method using a stepper light source. Utilizing the frequency conversion characteristics of stepper continuous light and the wavelength characteristics of fiber optic gratings, it achieves high-sensitivity, high-signal-to-noise ratio stepper light heterodyne interference dynamic signal modulation and demodulation. Specifically, the stepper continuous light is reflected multiple times after passing through a fiber optic grating. By controlling the distance between fiber optic gratings and the parameters of the stepper light source, interference lights with different enhancement factors have corresponding frequency differences. The center frequency and bandwidth of the bandpass filter are controlled to retain interference light with specific enhancement factors and filter out unwanted light waves. Simultaneously, a balanced detection module significantly reduces common-mode noise in the optical path and amplifies the useful signal. The system utilizes the interference between the higher-order reflected probe light and the first-order reflected reference light in the fiber optic Fabry-Perot resonator to improve system sensitivity and signal-to-noise ratio.

[0029] The advantages of this invention also lie in the fact that the high-sensitivity vibration sensing system and method using a stepping light source provided solves the problems of incompatibility between high sensitivity and small size in the application of interferometric sensing systems. Furthermore, while improving the sensitivity of the fiber optic sensing system, it also suppresses the common-mode noise of the system and improves the equivalent resolution of the system.

[0030] The advantages of this invention also lie in the high-sensitivity vibration sensing system and method provided by the stepping light source. It innovatively uses a stepping light source and a Fabry-Perot interferometer, and utilizes the frequency change of the stepping light source and the characteristics of multiple reflections of light waves in the Fabry-Perot interferometer. By using a bandpass filter to filter interference light of a specific sensitization order, it is possible to achieve dynamic sensing measurement with small volume sensitive elements and high sensitivity.

[0031] The advantages of this invention also lie in the high-sensitivity vibration sensing system and method using a stepping light source. By employing a 2×2 coupler, a balanced detector module, and signal processing techniques, differential amplification and common-mode noise elimination methods are used to reduce the multi-order optical noise introduced by multiple reflections in the Fabry-Perot interferometer. This improves both the sensitivity and the signal-to-noise ratio and equivalent resolution of the system. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a high-sensitivity vibration sensing system using a stepper light source according to the present invention;

[0034] Figure 2 This is a schematic diagram of the frequency difference diagram of the interference between the sensitized light wave and the reference light wave of the present invention.

[0035] Stepper light source module 1, first circulator 2, fiber optic grating pair 3, first fiber optic grating 301, second fiber optic grating 301, first coupler 4, second coupler 5, balanced light detection module 6, bandpass filter 7, real-time data acquisition and processing module 8. Detailed Implementation

[0036] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0037] like Figure 1 The image shows a high-sensitivity vibration sensing system using a stepper light source according to this application, comprising: a stepper light source module 1, a first circulator 2, a fiber optic grating pair 3, a first coupler 4, a second coupler 5, a balanced light detection module 6, a bandpass filter 7, and a real-time data acquisition and processing module 8.

[0038] The stepper light source module 1 is used to emit step-frequency continuous light. The first circulator 2 is connected to the stepper light source module 1. The first circulator 2 is used to receive the light signal emitted by the stepper light source module 1.

[0039] Fiber Bragg grating pair 3 is connected to first circulator 2, which outputs an optical signal to fiber Bragg grating pair 3. Fiber Bragg grating pair 3 is used to reflect sensing and reference optical signals, and the fiber gratings in pair 3 have the same bandwidth and center wavelength. Specifically, fiber Bragg grating pair 3 includes a first fiber grating 301 and a second fiber grating 301 located on the same optical fiber. The first fiber grating 301 and the second fiber grating 301 have the same center wavelength and the same bandwidth. The light wave carrying the reference signal is reflected by the first fiber grating 301, and the light wave carrying the sensing signal is reflected multiple times by both the first and second fiber gratings 301.

[0040] The first coupler 4 is connected to the first circulator 2. The reflected signal from the fiber optic grating pair 3 enters the first coupler 4 after passing through the first circulator 2. The first coupler 4 is used to split the stepped-frequency continuous light containing sensing and reference signals into two optical signals. The light containing the sensing signal is used as the probe light and passes through the probe path, while the other optical signal is used as the reference light and passes through the reference path.

[0041] The second coupler 5 is connected to the first coupler 4 and is used to perform heterodyne interference on the reflected light from the probe path and the reference path, outputting two beams of 180-degree anti-phase interference light signals. The balanced light detection module 6 is connected to the second coupler 5. The balanced light detection module 6 is used to detect the beat frequency signal of the interference signals from the probe path and the reference path. Simultaneously, it uses two photodetectors with the same response coefficient to detect these two beams of light. Through differential amplification, the common-mode signal is suppressed, and the differential-mode signal is amplified to achieve balanced detection, and an electrical signal is output. In the embodiment of this application, the second coupler 5 is a 2×2 coupler with a two-port output of 180-degree anti-phase interference light signals. The balanced light detection module 6 includes two photodetectors with the same response coefficient for detecting the two beams of light output from the second coupler 5. Through differential amplification, the common-mode signal is suppressed, and the differential-mode signal is amplified to achieve balanced detection.

[0042] The bandpass filter 7 is connected to the balanced light detection module 6 to receive its output electrical signal. The bandpass filter 7 is used to filter the frequency-shifted signal in the electrical signal and extract the radio frequency signal carrying the sensing phase shift information.

[0043] The real-time data acquisition and processing module 8 is connected to the bandpass filter 7. The real-time data acquisition and processing module 8 receives the radio frequency signal transmitted by the bandpass filter 7. The real-time data acquisition and processing module 8 is used to acquire and process the radio frequency signal in real time, demodulate the interference signal, and obtain the detection result of the high-sensitivity heterodyne interference signal of the stepper light source.

[0044] This application also discloses a high-sensitivity vibration sensing method using a stepping light source, which is applied to the aforementioned high-sensitivity vibration sensing system using a stepping light source.

[0045] Specifically, the high-sensitivity vibration sensing method using a stepped light source includes:

[0046] The stepped light source module 1 emits stepped-frequency continuous light. The light wave passes through the first port of the first circulator 2, and is emitted from the second port of the first circulator 2 and reflected by the fiber Bragg grating pair 3. It is emitted from the third port of the first circulator 2 and divided into two optical signals after passing through the first coupler 4. One optical signal serves as the detection light and passes through the detection path, and the other optical signal serves as the reference light and passes through the reference path.

[0047] The light wave carrying the reference signal is reflected by the first fiber Bragg grating 301 and then passes through the first coupler 4, and then is transmitted to the second coupler 5.

[0048] The light wave carrying the sensing signal is reflected multiple times by the first fiber Bragg grating 301 and the second fiber Bragg grating 301 and then passes through the first coupler 4, and then is transmitted to the second coupler 5.

[0049] The second coupler 5 performs heterodyne interference on the reflected light of the detection path and the reference path, and outputs two 180-degree anti-phase interference optical signals.

[0050] The output interference signal sequentially passes through the balanced optical detection module 6 for differential amplification, common-mode noise suppression and beat-frequency interference signal detection, and the band-pass filter 7 filters the frequency-shifted signal in the electrical signal to extract the radio frequency signal carrying the sensing phase shift information.

[0051] The real-time data acquisition and processing module 8 acquires and processes the radio frequency signal, demodulates the interference signal, and obtains the detection result of the high-sensitivity heterodyne interference signal of the stepped light source.

[0052] In the embodiment of the present application, when the two arms of the Mach-Zehnder interferometer formed by the first coupler 4 and the second coupler 5 are of equal length, the time interval for one frequency conversion of the stepped-frequency continuous light is t0, the propagation speed of the light wave in the optical fiber is v, the sensitivity enhancement multiple is n, and i is a positive integer (i < n), the length L between the first fiber Bragg grating 301 and the second fiber Bragg grating 301 satisfies 2nL = ivt0.

[0053] Assuming that the system sensitivity increases by n times, the starting frequency of the stepped light source is f, and the stepped frequency interval is f0, then the center frequency of the band-pass filter 7 is if0, i is a positive integer, n is the sensitivity enhancement multiple (i < n), and the bandwidth Δf < f0, only allowing the interference light of the nth-order sensitivity enhancement to pass through, and filtering the light waves of the remaining orders at the same time.

[0054] The process and principle of implementing the high-sensitivity Fabry-Perot vibration sensing method using a stepped light source in this embodiment are specifically as follows:

[0055] The stepped-frequency continuous light wave is reflected by the first fiber Bragg grating 301 to obtain a reference optical signal, and the reference optical signal can be expressed as E = Aej[2πf+φ(t)] , where A is the amplitude corresponding to the transmitted optical signal. For the convenience of calculation, f is defined as the starting frequency of the stepped light source. In reality, f can be any frequency of the stepped continuous light, φ(t) is the initial phase, and j represents the imaginary unit.

[0056] The stepped-frequency continuous optical wave passes through the first fiber grating 301 and the second fiber grating 301, and multiple reflections occur. At this time, the phase change of the nth-order reflected light due to vibration is Δφ = 2njβl FBG-FP . In the formula, Δφ is the sensing phase change, n is the sensitivity enhancement factor, j represents the imaginary unit, β is the propagation constant, and l FBG-FP is the length of the fiber Fabry-Perot resonator cavity. At this time, the sensed optical signal after frequency shift due to the time delay of the fiber Fabry-Perot resonator cavity length is expressed as E = A'e j[2π[(f+iΔf)]+φ(t)] , where A' is the amplitude corresponding to the reference optical signal, Δf is the frequency shift amount of the stepped optical wave after passing through the cavity length, j represents the imaginary unit, f is defined as the starting frequency of the stepped light source, φ(t) is the initial phase, and i is a positive integer (i < n).

[0057] The sensing and reference optical waves interfere after passing through the Mach-Zehnder interferometer composed of the first coupler 4 and the second coupler 5. Since the two arms of the interferometer are of equal length, after interference, the frequency difference between the sensing and reference optical waves is iΔf. When i takes 1, the frequency change is for reference Figure 2 .

[0058] In this embodiment, by designing the center frequency and bandwidth of the band-pass filter 7, when the center frequency is the frequency difference iΔf between the sensing and reference optical waves and the bandwidth is less than the frequency interval f0 of one frequency conversion of the stepped light, only the interference light with a sensitivity enhancement of n times can be detected, and the rest of the light beams will be filtered. According to the formula 2nL = ivt0, the time interval for one frequency conversion of the stepped-frequency continuous light is t0, the propagation speed of the optical wave in the optical fiber is v, the sensitivity enhancement factor is n, and when the positive integer is i (i < n), the length between the first fiber grating 301 and the second fiber grating 301 is L. By changing the length L between the grating arrays and the time interval t0 of the stepped continuous light, the sensitivity improvement multiple of the sensing system can be changed.

[0059] Finally, the interference optical signal can be expressed as: I = (E + E')(E + E') * = A' 2 + A” 2+2A'A”cos[2πΔft+φ(t)+Δφ], where Δf is the frequency shift of the stepping light wave after the cavity length delay, t is the time domain independent variable, φ(t) is the initial phase, and Δφ is the sensing phase change. Using a 2×2 coupler and a balanced photodetector module, the common-mode signals A' and A” can be suppressed, while the useful AC term 2A'A”cos[2πΔft+φ(t)+Δφ] is amplified by a factor of 2, effectively improving the signal-to-noise ratio and resolution of the sensing system. After passing through the balanced photodetector module 6 and the bandpass filter 7, the electrical signal can be represented as y=Bcos[2πΔft+φ(t)+Δφ], where B is the amplitude of the AC term. After signal demodulation processing, vibration signal information can be obtained from this electrical signal.

[0060] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A high-sensitivity vibration sensing system employing a stepper light source, characterized in that, include: Stepper light source module, used to emit step-frequency continuous light; A first circulator is connected to the stepper light source module and is used to receive the light signal emitted by the stepper light source module; A fiber Bragg grating pair is connected to the first circulator, the first circulator outputs an optical signal to the fiber Bragg grating pair, the fiber Bragg grating pair is used to reflect sensing and reference optical signals, the fiber Bragg gratings in the fiber Bragg grating pair have the same bandwidth and center wavelength; the fiber Bragg grating pair includes a first fiber Bragg grating and a second fiber Bragg grating located on the same optical fiber. The first coupler is connected to the first circulator. The reflected signal from the fiber optic grating enters the first coupler after passing through the first circulator. The first coupler is used to split the stepped-frequency continuous light containing sensing and reference signals into two optical signals. The light containing the sensing signal is used as the probe light and passes through the probe path, while the other optical signal is used as the reference light and passes through the reference path. The second coupler, connected to the first coupler, is used to perform heterodyne interference on the reflected light from the probe path and the reference path, and output two beams of 180-degree anti-phase interference light signals. The balanced light detection module, connected to the second coupler, is used to detect the beat frequency signal of the interference signals of the detection path and the reference path. At the same time, two photodetectors with the same response coefficient are used to detect the two beams of light. The common-mode signal is suppressed by differential amplification and the differential-mode signal is amplified to achieve balanced detection and output an electrical signal. A bandpass filter is connected to the balanced light detection module to receive its output electrical signal. The bandpass filter is used to filter the frequency shift signal in the electrical signal and extract the radio frequency signal carrying the sensing phase shift information. A real-time data acquisition and processing module is connected to the bandpass filter to receive the radio frequency signal transmitted therefrom. The real-time data acquisition and processing module is used to acquire and process the radio frequency signal in real time, demodulate the interference signal, and obtain the detection result of the high-sensitivity heterodyne interference signal of the stepper light source. The first coupler and the second coupler form a Mach-Zehnder interferometer, and the two arms of the Mach-Zehnder interferometer are of equal length. The time interval for one-time frequency conversion of the stepped-frequency continuous light is , when the propagation speed of light waves in the optical fiber is v, the gain multiple is n, and i is a positive integer with i < n, the length L between the first fiber grating and the second fiber grating satisfies ; The starting frequency of the stepper light source is The step frequency interval is When the center frequency of the bandpass filter is , Where i is a positive integer, n is the amplification factor, and i < n, is the bandwidth. This allows only the nth-order sensitized interference light to pass through, while filtering out light waves of other orders.

2. The high-sensitivity vibration sensing system using a stepper light source according to claim 1, characterized in that, The linewidth of the step-frequency continuous light emitted by the step-light module is smaller than the bandwidth of the fiber grating pair, and the start and end frequencies of the step-light are both within the bandwidth of the fiber grating pair.

3. The high-sensitivity vibration sensing system using a stepper light source according to claim 1, characterized in that, The first fiber grating and the second fiber grating have the same center wavelength and the same bandwidth. The light wave carrying the reference signal is reflected by the first fiber grating, and the light wave carrying the sensing signal is reflected multiple times by the first fiber grating and the second fiber grating.

4. The high-sensitivity vibration sensing system using a stepper light source according to claim 1, characterized in that, The second coupler is a 2×2 coupler with two-port outputs of 180-degree anti-phase interference optical signals.

5. The high-sensitivity vibration sensing system using a stepping light source according to claim 4, characterized in that, The balanced light detection module includes two photodetectors with the same response coefficient to detect the two beams of light output from the second coupler. By differential amplification, the common-mode signal is suppressed and the differential-mode signal is amplified to achieve balanced detection.

6. A high-sensitivity vibration sensing method using a stepping light source, characterized in that, Applied to the high-sensitivity vibration sensing system using a stepper light source as described in any one of claims 1-5; The high-sensitivity vibration sensing method using a stepping light source includes: The step light source module emits step-frequency continuous light. The light wave passes through the first port of the first circulator and is reflected by the fiber grating at the second port of the first circulator. It then exits from the third port of the first circulator and is split into two optical signals after passing through the first coupler. One optical signal is used as a probe light and passes through the probe path, while the other optical signal is used as a reference light and passes through the reference path. The second coupler performs heterodyne interference on the reflected light from the probe path and the reference path, and outputs two 180-degree anti-phase interference light signals; The output interference signal is sequentially amplified differentially, suppressed for common-mode noise, and detected for beat frequency interference signal by the balanced light detection module, and the bandpass filter filters the frequency shift signal in the electrical signal to extract the radio frequency signal carrying the sensing phase shift information. The real-time data acquisition and processing module acquires and processes radio frequency signals, demodulates interference signals, and obtains the detection results of high-sensitivity heterodyne interference signals from the stepper light source.

7. The high-sensitivity vibration sensing method using a stepping light source according to claim 6, characterized in that, The fiber Bragg grating pair includes a first fiber Bragg grating and a second fiber Bragg grating located on the same optical fiber. The light wave carrying the reference signal is reflected by the first fiber Bragg grating and passes through the first coupler, and then is transmitted to the second coupler. The light wave carrying the sensing signal is reflected multiple times by the first fiber Bragg grating and the second fiber Bragg grating and passes through the first coupler, and then is transmitted to the second coupler.

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