CN-121978060-A - Optical fiber twin controllable cursor hydrogen sensor and detection method

CN121978060ACN 121978060 ACN121978060 ACN 121978060ACN-121978060-A

Abstract

The invention discloses an optical fiber twin controllable vernier hydrogen sensor and a detection method, which belong to the technical field of optical fiber sensing and comprise a single-mode optical fiber, a femtosecond laser direct-write grating, a Fabry-Perot interferometer and a Pd/WO 3 hydrogen sensitive film, wherein the single-mode optical fiber comprises an optical fiber core and an optical fiber cladding, the femtosecond laser direct-write grating is prepared inside the optical fiber core, the Fabry-Perot interferometer is composed of a reflecting surface 1 and a reflecting surface 2 which are relatively arranged in parallel, the Pd/WO 3 hydrogen sensitive film is coated on the inner side of the reflecting surface 2, the femtosecond laser direct-write grating and the Fabry-Perot interferometer are arranged in series, the optical path of the Fabry-Perot interferometer is modulated through the interaction of the Pd/WO 3 hydrogen sensitive film and hydrogen, the interference spectrum wavelength drift is induced, and the temperature response of the femtosecond laser direct-write grating is combined to realize temperature compensation, so that hydrogen concentration sensing is completed. The invention is suitable for hydrogen leakage detection in industrial environment, energy equipment and other scenes.

Inventors

ZHAO YONG
FAN YIXUAN
LI CHAOFAN
WEN CHAOYAN
YAN YINUO
ZHOU LIMING
YANG JINGHAN
LIU YINXI
ZHAO YUTING
LIU YINGXUAN

Assignees

东北大学秦皇岛分校

Dates

Publication Date: 20260505
Application Date: 20260318

Claims (5)

1. The optical fiber twin controllable vernier hydrogen sensor is characterized by comprising a single-mode fiber, a femtosecond laser direct-write grating, a Fabry-Perot interferometer, a polydimethylsiloxane PDMS layer and a Pd/WO 3 hydrogen sensitive film, wherein the single-mode fiber comprises an optical fiber core and an optical fiber cladding, the femtosecond laser direct-write grating is prepared inside the optical fiber core, the Fabry-Perot interferometer is composed of a reflecting surface 1 and a reflecting surface 2 which are relatively arranged in parallel, the Pd/WO 3 hydrogen sensitive film is coated on the inner side of the reflecting surface 2, the femtosecond laser direct-write grating and the Fabry-Perot interferometer are arranged in series, the PDMS layer is used for packaging an interference cavity and fixing the Pd/WO 3 hydrogen sensitive film, the PDMS layer is used for modulating an optical path of the Fabry-Perot interferometer through interaction of the Pd/WO 3 hydrogen sensitive film and hydrogen, interference spectrum wavelength drift is caused, temperature compensation is realized by combining temperature response of the femtosecond laser direct-write grating, and then hydrogen concentration sensing is completed.
2. The optical fiber twin controllable vernier hydrogen sensor according to claim 1, wherein the femtosecond laser direct writing grating is prepared by a femtosecond laser point-by-point scanning writing technology and is positioned at one side of an input end of a fabry-perot interferometer.
3. The optical fiber twin controllable vernier hydrogen sensor according to claim 1, wherein the reflecting surface 1 is an end surface of a single mode optical fiber, the reflecting surface 2 is an end surface of a PDMS-Pd/WO 3 hydrogen sensitive film coated, and a sealed interference cavity is formed between the two reflecting surfaces.
4. The optical fiber twin controllable vernier hydrogen sensor according to claim 1, wherein the femtosecond laser direct writing grating is not responsive to hydrogen and is only sensitive to temperature, and the peak wavelength offset is used as a temperature compensation signal to offset the temperature cross interference of the fabry-perot interferometer.
5. The optical fiber twin controllable vernier hydrogen sensor according to any one of claims 1-4, wherein the hydrogen detection method is an optical fiber twin controllable vernier detection method, and specifically comprises the steps of: S1, a Fabry-Perot interferometer at the tail end of a hydrogen sensor is used as a hydrogen sensing unit, when the hydrogen sensor is exposed to a hydrogen environment, a Pd/WO 3 sensitive film at the tail end of a cavity triggers dual response, namely, palladium Pd absorbs hydrogen and then undergoes lattice expansion, the cavity length of the Fabry-Perot interferometer is changed through a PDMS supporting layer, meanwhile, the reduction reaction of tungsten trioxide WO 3 and hydrogen changes the optical refractive index of the hydrogen sensitive film, the two factors together cause wavelength drift of interference fringes, and the output spectrum of the hydrogen sensor is used as an original interference spectrum; S2, converting an original interference spectrum containing the cavity length and the optical refractive index change information of the Fabry-Perot interferometer into a frequency domain through Fourier transform filtering, and filtering out high-frequency noise and a spurious interference mode to obtain a pure trigonometric function standard spectrum; S3, after the trigonometric function standard spectrum is obtained, establishing a mathematical expression of the original interference spectrum through sine fitting, accurately extracting the period, amplitude and phase of the original interference spectrum, and providing a quantitative basis for constructing a twin periodic function; S4, designing a twin periodic function with controllable deviation based on the original period, and carrying out twin superposition on the twin periodic function and the original interference spectrum to generate a twin interference spectrum; s5, forming a controllable vernier spectrum by twinning the superimposed signals, separating a low-frequency envelope curve from the signals through an envelope extraction algorithm, wherein the movement amount of the envelope directly corresponds to the wavelength drift of an original interference peak, and the movement amount is obviously amplified due to a vernier effect, so that the detection difficulty is reduced; S6, reversely deducing the wavelength drift amount of the interference peak of the original Fabry-Perot interferometer through the envelope movement amount, and demodulating the hydrogen concentration in the environment by combining the cavity length-wavelength response model of the hydrogen sensing unit.

Description

Optical fiber twin controllable cursor hydrogen sensor and detection method Technical Field The invention relates to the technical field of optical fiber sensing, in particular to an optical fiber twin controllable cursor hydrogen sensor and a detection method. Background Hydrogen is used as a clean and efficient energy carrier and is widely applied to the fields of new energy, aerospace, chemical industry and the like, but the inflammable and explosive property of the hydrogen brings extremely high requirements for real-time accurate detection of the concentration of the hydrogen in the environment, and particularly for early warning detection of ultra-trace hydrogen. The optical fiber sensor is intrinsically safe, electromagnetic interference resistant, high in response speed and easy to remotely network, and becomes a main technical scheme in the field of hydrogen detection, and common types include an optical fiber grating (FBG), a Fabry-Perot interferometer (FPI), a spectral absorption type optical fiber sensor, a Surface Plasmon Resonance (SPR) optical fiber sensor and the like. Although various optical fiber hydrogen sensors have been studied and applied to a certain extent, two general problems exist, namely, firstly, the temperature and humidity interference resistance is weak, a special temperature and humidity interference compensation mechanism is not arranged in the prior art, environmental temperature fluctuation and humidity change are easy to cross-couple with hydrogen concentration signals, measurement deviation is obvious, the complex working condition is difficult to adapt to, secondly, the detection sensitivity is low, the vernier regulation flexibility is insufficient, the traditional sensing mechanism is limited by a hardware structure, the ultra-trace detection of hydrogen cannot be realized, and the adaptation to different detection scenes through flexible regulation of vernier parameters is difficult to meet the actual requirements of early warning. For example, the fiber bragg grating hydrogen sensor is easily affected by temperature-strain intersection, temperature-humidity compensation is not achieved, temperature-humidity environment fluctuation can directly interfere with detection results, the traditional FPI and SPR fiber bragg grating hydrogen sensor is high in response speed, sensitivity can only meet constant or micro detection, humidity change easily causes performance attenuation of a sensing interface, and meanwhile a flexible vernier regulation means is lacking, so that detection applicability is further limited. At present, in the existing optical fiber sensing technology, a technical scheme capable of combining temperature and humidity interference resistance, ultra-trace detection and flexible adaptability is lacking, and the actual requirement of hydrogen safety monitoring in a complex environment is difficult to meet. Chinese patent CN119827461B proposes a tapered optical fiber hydrogen sensor and a method for preparing the same, but lacks a temperature-humidity compensation unit, and has weak temperature-humidity interference resistance. Chinese patent CN111999265B proposes an inclined fiber grating hydrogen sensor based on UIO-66-NH-2, but the hydrogen measurement sensitivity is lower. Disclosure of Invention The invention aims to provide an optical fiber twin controllable vernier hydrogen sensor and a detection method, which are used for fusing a compensation temperature and humidity sensitive unit, a twin model and a software controllable vernier to form a synergistically optimized sensing mechanism and solving three problems of temperature and humidity interference, low sensitivity and regulation and control stiffness. The invention provides an optical fiber twin controllable vernier hydrogen sensor, which comprises a single-mode optical fiber, a femtosecond laser direct-write grating, a Fabry-Perot interferometer, a polydimethylsiloxane PDMS layer and a Pd/WO 3 hydrogen sensitive film, wherein the single-mode optical fiber comprises an optical fiber core and an optical fiber cladding, the femtosecond laser direct-write grating is prepared inside the optical fiber core, the Fabry-Perot interferometer is composed of a reflecting surface 1 and a reflecting surface 2 which are relatively arranged in parallel, the Pd/WO 3 hydrogen sensitive film is coated on the inner side of the reflecting surface 2, the femtosecond laser direct-write grating and the Fabry-Perot interferometer are arranged in series, the PDMS layer is used for packaging an interference cavity and fixing the Pd/WO 3 hydrogen sensitive film, the PDMS layer is used for modulating the optical path of the Fabry-Perot interferometer through the interaction of the Pd/WO 3 hydrogen sensitive film and hydrogen, the interference spectrum wavelength drift is induced, and the temperature compensation is realized by combining the temperature response of the femtosecond laser direct-write grating, so that the