CN-121977623-A - Time domain optical fiber sensing system and method based on adiabatic dynamic tuning inflection point

CN121977623ACN 121977623 ACN121977623 ACN 121977623ACN-121977623-A

Abstract

The invention relates to the technical field of optical fiber sensing and spectrum detection, and discloses a time domain optical fiber sensing system and a method based on an adiabatic dynamic tuning inflection point, wherein the time domain optical fiber sensing system comprises the steps of applying dynamic current drive to a light source to complete wavelength tuning under an adiabatic condition, and forming at least one adiabatic dynamic tuning inflection point in the tuning process; analyzing the time change rule of the time domain features to obtain sensing parameter information, constructing a specific pulse current waveform by a driving circuit to form an adiabatic dynamic tuning inflection point, and combining time division multiplexing to realize multi-point optical fiber sensing measurement. The method actively constructs the stable time domain reference feature points without passive feature devices, simplifies the demodulation process, improves the stability and applicability of the sensing system in a complex environment, reduces the system cost, and is beneficial to engineering and large-scale application of the optical fiber sensing technology.

Inventors

YANG JIAHUA
CUI ZIMENG
Lv Yunxin

Assignees

杭州电子科技大学

Dates

Publication Date: 20260505
Application Date: 20260403

Claims (9)

1. A time domain optical fiber sensing system based on adiabatic dynamic tuning inflection point is characterized by comprising: The driving circuit is electrically connected with the semiconductor laser and is used for outputting a dynamic current driving signal meeting the requirements of forming adiabatic dynamic tuning inflection points to the semiconductor laser; The temperature control system is connected with the semiconductor laser and used for stably controlling the working temperature of the semiconductor laser; A semiconductor laser having an optical output connected to the first input of the coupler; The first output end of the coupler is connected with the reflector, and the second output end of the coupler is connected with one end of the delay optical fiber; The reflector is used for providing a signal acquisition trigger signal; The other end of the delay optical fiber is connected with the optical fiber sensor; The optical input end of the photoelectric detector is connected with the second input end of the coupler, and the electric output end of the photoelectric detector is electrically connected with the signal acquisition system; And the signal acquisition system is used for acquiring, storing and processing the electric signals.
2. The time domain optical fiber sensing system based on adiabatic dynamic tuning inflection point of claim 1, wherein the driving circuit comprises a voltage stabilizing circuit, a logic control circuit, a signal generating circuit, a pulse generating circuit, a waveform shaping circuit and a high-frequency switch driving circuit, wherein the voltage stabilizing circuit is used for providing stable power supply, the signal generating circuit and the pulse generating circuit are matched to generate a basic pulse signal, the waveform shaping circuit is used for shaping the basic pulse signal to enable an output current waveform to meet the requirement that an extreme point exists in a current amplitude, the logic control circuit is used for achieving start-stop control and modulation mode switching of a tuning process, and the high-frequency switch driving circuit is used for converting a voltage signal into a high-current signal meeting the driving requirement of the semiconductor laser.
3. The time domain optical fiber sensing system based on the adiabatic dynamic tuning inflection point of claim 1, wherein the temperature control system is a temperature controller or an incubator, the temperature controller is controlled by an upper computer by combining a PID algorithm, a voltage driving circuit and a resistance detection circuit are integrated, and when the semiconductor laser is integrated with a laser chip, a thermoelectric cooler and a thermistor, the temperature controller monitors the temperature through the thermistor, and the output voltage adjusts the thermoelectric cooler to realize temperature control.
4. The time domain optical fiber sensing system based on the adiabatic dynamic tuning inflection point of claim 1, wherein the semiconductor laser is one of a DFB laser, a VCSEL laser or an FP laser, the communication optical fiber low-loss transmission band with the center wavelength of 0.8-1.8 μm is adopted, the coupler is an optical fiber coupler, the reflector is a Faraday reflector or an optical fiber end surface reflecting structure, the signal acquisition system is an oscilloscope or an acquisition card, and the photoelectric detector is a PIN photodiode.
5. The time domain optical fiber sensing system based on adiabatic dynamic tuning inflection point of claim 1, wherein the time domain optical fiber sensing system is a multi-point optical fiber sensing measurement system and comprises a plurality of sections of delay optical fibers and a plurality of optical fiber sensors, the sections of delay optical fibers are connected with the second output end of the coupler in parallel through optical fiber splitters, each section of delay optical fiber is correspondingly connected with one optical fiber sensor, or the sections of delay optical fibers are sequentially cascaded with the couplers, the second output end of each coupler is connected with one optical fiber sensor, and the length difference of the sections of delay optical fibers is larger than the optical fiber transmission length converted by pulse width time.
6. A sensing method of a time domain fiber optic sensing system based on an adiabatic dynamic tuning inflection point according to any of claims 1-5, comprising the steps of: Step one, dynamic current driving is applied to a semiconductor laser, so that the semiconductor laser completes a wavelength tuning process under an adiabatic condition; controlling the waveform characteristics of the dynamic current drive to form at least one adiabatic dynamic tuning inflection point in the wavelength tuning process, wherein the adiabatic dynamic tuning inflection point corresponds to the moment when the instantaneous scanning rate in the wavelength scanning process of the semiconductor laser tends to zero; Collecting output signals of an optical fiber sensing system by taking an adiabatic dynamic tuning inflection point as a time domain reference characteristic, and determining the time domain characteristic position related to the adiabatic dynamic tuning inflection point in the output signals; And fourthly, analyzing the change rule of the time domain characteristic position along with time, and mapping the change rule into the change of the measured physical quantity to obtain corresponding sensing parameter information.
7. The method of claim 6, wherein the waveform of the dynamic current driving in the first step satisfies that an extreme point exists in the current amplitude, and turns to monotonic decrease after the current monotonically increases for a period of time, and the dynamic current driving is implemented in any one of continuous waveform driving generated by an analog circuit, modulation driving of pulse current in a single pulse, sine-like modulation driving of a monostable circuit combined with a filter network, direct current and alternating current signal superposition driving implemented by a radio frequency bias device, triangular wave/sawtooth wave/nonlinear waveform driving output by a signal generator, and arbitrary waveform driving implemented by a digital circuit or programmable logic.
8. The method of claim 6, wherein the dynamic current driving in the first step is a pulse current driving with a pulse width of at least 10ns and a pulse repetition frequency of at least 1kHz, the pulse current is greater than a threshold current for normal continuous operation of the semiconductor laser, and the injection current is changed in a single pulse time window by setting the pulse width to form a transition section from a rising section to a falling section, wherein the transition section is a formation section of the adiabatic dynamic tuning inflection point.
9. The method for time domain optical fiber sensing based on adiabatic dynamic tuning inflection point of claim 6, wherein the implementation of driving adiabatic dynamic tuning inflection point in the second step comprises the following steps: S11, generating a dynamic tuning time window, namely adopting a timer chip to form a square wave generating circuit, and generating a square wave signal by adjusting a peripheral timing resistor and a capacitor to serve as the dynamic tuning time window to realize the control of pulse repetition frequency and pulse width; s12, timing sequence shaping of a tuning signal, namely inputting a square wave signal into a pulse generating unit formed by a high-speed bistable trigger circuit to generate monostable pulses with controllable width, limiting an effective time interval of dynamic tuning of a light source and ensuring the repeatability of the tuning pulse in each period; S13, enabling and selecting a tuning process, namely adopting a logic chip to form a logic selection unit, and performing gating and enabling control on monostable pulse to realize starting and stopping of the tuning process and switching of a modulation mode; s14, the structure of injection current waveform is that a pulse signal output by a logic selection unit is input into a voltage-to-current driving unit formed by a power device, a voltage control signal is converted into a large current signal, and the injection current is enabled to show waveform characteristics of monotonously rising of a first half section and monotonously falling of a second half section in a pulse window by designing the amplitude and the phase of an alternating current modulation signal; And S15, forming an adiabatic dynamic inflection point, namely injecting the pulse current with the waveform characteristics into a semiconductor laser, and finishing wavelength tuning of the laser under an adiabatic condition, wherein a turning section of current change corresponds to the moment when the instantaneous speed of wavelength scanning is close to zero, so as to form a stable and repeatable adiabatic dynamic tuning inflection point.

Description

Time domain optical fiber sensing system and method based on adiabatic dynamic tuning inflection point Technical Field The invention relates to a time domain optical fiber sensing system and a method based on an adiabatic dynamic tuning inflection point, and belongs to the technical field of optical fiber sensing and spectrum detection. Background The optical fiber sensing technology has been widely used in the fields of industrial monitoring, environmental detection, aerospace, biomedical and the like by virtue of the advantages of electromagnetic interference resistance, long transmission distance, high sensitivity, small volume and the like. Wavelength scanning and spectrum demodulation are key links of an optical fiber sensing system, the links generally depend on a continuous scanning light source or a tunable filter in the prior art, and the core is to finish measurement and analysis of a sensing signal in a wavelength domain. However, the existing wavelength domain scanning demodulation method has a plurality of technical defects and becomes a key factor for limiting the engineering and large-scale application of the optical fiber sensing technology. 1. The characteristic points which are stable and can be directly calibrated are lacking, namely the reference characteristic points which are not actively constructed in the existing method have the problems of periodicity and multiple values of a sensing signal in the interference type sensor detection or dense spectrum detection scene, so that the spectrum characteristics can not be uniquely judged, and demodulation results are easy to be ambiguous; 2. The demodulation algorithm is complex, the environmental adaptability is poor, for single-peak spectral feature devices such as fiber Bragg gratings and the like, simple demodulation can be realized by constructing feature wavelengths, but for interference sensors such as Fabry-Perot interferometers, michelson interferometers, mach-Zehnder interferometers and the like, and sensing objects with periodicity or multimodal characteristics such as gas absorption spectra and the like, the traditional frequency sweeping method needs to rely on a complex real-time tracking algorithm, and under the condition of wide-range wavelength scanning or multicycle spectrum, the algorithm is easy to lose lock, and the demodulation stability is greatly reduced; 3. The system has high cost and large realization complexity, and in order to solve the problem of the lack of characteristic points, the prior art generally needs to introduce special passive characteristic devices such as fiber Bragg gratings and the like, or adopts a high-precision tunable module, thereby not only increasing the hardware cost of the system, but also improving the difficulty of light path construction and circuit debugging, and reducing the integration level and reliability of the system. Therefore, developing an optical fiber sensing method and system capable of actively constructing stable and calibratable feature points, realizing mapping of spectrum information to a time domain, and needing no complex algorithm and special passive devices becomes a technical problem to be solved in the field. Disclosure of Invention In order to overcome the defects of the prior optical fiber sensing technology that wavelength scanning demodulation lacks stable and calibratable characteristic points, complex algorithm is needed for demodulating periodic/multimodal spectrum signals, system cost is high and realization is complex, the invention provides a time domain optical fiber sensing system and a method based on adiabatic dynamic tuning inflection points, which actively constructs repeatable and calibratable adiabatic dynamic tuning inflection points through dynamic control of a light source tuning process, solves the problem of lacking stable characteristic points in wavelength domain demodulation, the method has the advantages that the mapping of spectrum information to time domain characteristics is realized, the demodulation of sensing signals in a time domain is completed, the dependence on accurate wavelength calibration and a complex real-time tracking algorithm is reduced, the use of special passive characteristic devices and high-precision tunable modules is abandoned, the system structure is simplified, the system cost and the realization complexity are reduced, the stability and the applicability of an interference type optical fiber sensor and dense spectrum detection under complex environments and large-scale scanning conditions are improved, and the engineering and large-scale application of an optical fiber sensing technology are promoted. A time domain fiber optic sensing system based on an adiabatic dynamic tuning inflection point, comprising: the driving circuit is electrically connected with the semiconductor laser, and is internally integrated with the voltage stabilizing circuit, the logic control circuit, the signal generating circuit,