CN-121977651-A - Double-parameter measurement optical fiber sensor and manufacturing method thereof

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a double-parameter measurement optical fiber sensor and a manufacturing method thereof. The double-parameter measurement optical fiber sensor comprises an optical fiber and a sensing unit arranged at one end of the optical fiber, wherein the sensing unit is formed by sequentially arranging a Bragg reflector and a noble metal nano film, the noble metal nano film is provided with nano structure units which are arranged in an array, and the sensing unit can excite two resonance modes, so that the refractive index variation and the temperature variation of an external medium cause the resonance wavelength movement of the two resonance modes, and the simultaneous measurement of the refractive index and the temperature of the external medium is realized. According to the invention, the metal nano film is improved to excite two resonant modes, so that the detection sensitivity is improved, meanwhile, the processing difficulty is simplified, the structural stability is improved, and the accurate decoupling measurement of the refractive index and the temperature is realized.

Inventors

• DU BOBO
• ZHOU JINGMIN
• LU JINXIAN
• ZHANG CHAOYANG
• YANG RUISHENG
• ZHANG YANPENG
• ZHANG LEI

Assignees

• 西安交通大学

Dates

Publication Date

20260505

Application Date

20260311

Claims (10)

1. 1. A double-parameter measurement optical fiber sensor comprises an optical fiber and a sensing unit arranged at one end of the optical fiber, and is characterized in that the sensing unit is formed by sequentially arranging a Bragg reflector and a noble metal nano film, the noble metal nano film is provided with nano structure units which are arranged in an array, and the sensing unit can excite two resonance modes, so that the refractive index variation and the temperature variation of an external medium can induce the resonance wavelength movement of the two resonance modes, and the simultaneous measurement of the refractive index and the temperature of the external medium is realized.
2. 2. The dual-parameter measurement optical fiber sensor according to claim 1, wherein the noble metal nano-film is a gold nano-film or a silver nano-film, and the thickness of the noble metal nano-film is 50 nm-100 nm.
3. 3. The dual-parameter measurement optical fiber sensor according to claim 1, wherein the period of the nanostructure unit on the noble metal nano-film is 400 nm-700 nm to satisfy the resonance mode excitation of the target operating band.
4. 4. The dual-parameter measurement optical fiber sensor according to claim 1, wherein the array configuration of the nanostructure units on the noble metal nano film is one-dimensional periodic distribution or two-dimensional periodic distribution, the nanostructure units distributed in one-dimensional periodic distribution are nano strips, and the width of the nano strips is 100 nm-400 nm; The two-dimensional periodically distributed nanostructure units are holes, and the aperture is 100 nm-400 nm.
5. 5. The dual-parameter measurement optical fiber sensor according to claim 1, wherein the bragg reflector is formed by alternately arranging a first material and a second material along a thickness direction, the number of periods of the alternate arrangement is 5-10, and the refractive index of the first material is larger than that of the second material.
6. 6. The dual parameter measurement fiber optic sensor of claim 5 wherein the first material is tantalum pentoxide, titanium dioxide or hafnium dioxide and the second material is silicon dioxide.
7. 7. The dual-parameter measurement fiber optic sensor of claim 1, wherein the optical fiber is a multimode fiber having a core diameter of 50 μm to 1000 μm and a cladding diameter of 125 μm to 1100 μm.
8. 8. A method of making a dual-parameter measurement fiber optic sensor according to claim 1, comprising: and depositing a Bragg reflector on the end face of the optical fiber by a vacuum coating technology, and then transferring the noble metal nano film to the end face of the optical fiber by a metal sacrificial layer etching transfer method to obtain the double-parameter measurement optical fiber sensor.
9. 9. The method of manufacturing a dual-parameter measurement fiber optic sensor of claim 8, wherein the method comprises the steps of: depositing a Bragg reflector on the end face of the optical fiber by utilizing a vacuum coating technology to obtain a combined optical fiber; Depositing a metal sacrificial layer and a noble metal nano film on the surface of a substrate respectively by a vacuum coating technology to obtain a substrate containing the noble metal nano film, wherein the substrate is provided with nano structure units arranged in an array; immersing the substrate containing the noble metal nano film into a metal etching solution to remove the metal sacrificial layer and release the noble metal nano film; And after evaporating to remove the residual water on the end face of the combined optical fiber, cutting and shaping the noble metal nano film to obtain the double-parameter measuring optical fiber sensor.
10. 10. The manufacturing method of the dual-parameter measurement optical fiber sensor according to claim 9, wherein the metal sacrificial layer is made of copper, the thickness of the metal sacrificial layer is 30-50 nm, the metal corrosive liquid is copper corrosive liquid, and the area of the noble metal nano film is larger than the area of the end face of the combined optical fiber.

Description

Double-parameter measurement optical fiber sensor and manufacturing method thereof Technical Field The invention relates to the technical field of optical fiber sensing, in particular to a double-parameter measurement optical fiber sensor and a manufacturing method thereof. Background In many fields of modern industrial production, environmental monitoring, biomedical treatment and the like, the precise and real-time measurement of two key physical parameters of refractive index and temperature is of great importance. The optical fiber sensor has been widely focused and applied in the field of parameter measurement by virtue of the advantages of electromagnetic interference resistance, small volume, light weight, long-distance transmission and the like. In the aspect of refractive index measurement, the traditional optical fiber refractive index sensor is mainly based on the principles of Mach-Zehnder interference, michelson interference, fabry-Perot interference and the like, or based on a sensing mechanism of an optical fiber grating, for example, patent applications CN121431445A and CN121113953A each construct an interference type optical fiber sensor around the mode mismatch principle, so that biochemical detection based on refractive index measurement is realized. However, the two types of optical fiber refractive index sensors focus on a single refractive index sensing target, so that the problem of sensitivity to temperature exists due to the fact that the temperature change in an actual application scene has significant influence on an optical fiber sensing system, and the refractive index measurement result is significantly disturbed due to the temperature change in the measurement process, so that the measurement accuracy is reduced and even the function is disabled. In order to solve the cross-sensitivity problem in multi-parameter measurement, researchers have proposed a dual-parameter measurement scheme. Typically, sensors of different sensing mechanisms are combined, and dual parameter measurements are achieved by measuring signals corresponding to different parameters separately. However, such a scheme often has the problems of complex structure, large volume and inconvenient data analysis. The tower plasmon (TPP) acts as a localized electromagnetic mode of the metal film to Distributed Bragg Reflector (DBR) interface. Compared with the traditional optical mechanism, the TPP can be directly excited at the end face of the optical fiber without a complex coupling structure, has simple structure, obvious local field enhancement effect, narrow resonance peak line and strong interference resistance, and provides a new high-quality solution for optical fiber sensing. However, the electromagnetic field of the conventional TPP mode is localized inside the structure, and thus it is difficult to perceive the refractive index change of the external environment. For this reason, in the prior art, a microcavity spacer layer is introduced into the multilayer film structure of the TPP, for example, the characteristics of patent applications CN117309812a and CN117990658A both around the TPP theoretically show refractive index measurement, and patent application CN118425100a, which uses the environmental refractive index and temperature change in the microcavity spacer layer to affect different levels of TPP, also theoretically shows refractive index and temperature double-parameter sensing. However, the sensing unit of such sensors remains essentially a TPP mode and separates the integrated TPP structure into three parts, a distributed bragg mirror layer, an open microcavity spacer layer and a metal layer. The introduction of the open microcavity spacer layer separates the distributed Bragg reflector from the metal film, and the separation structure is equivalent to the combined use of two independent elements, which is difficult to process and difficult to operate in practice. In addition, the thickness of the open microcavity spacer layer is critical to the mode spectrum and the sensing performance of the TPP, usually between tens of nanometers and hundreds of nanometers, the thickness and uniformity of the microcavity spacer layer in actual processing are extremely difficult to control, the key obstacle affecting the practical application of the scheme is that the electromagnetic field energy ratio in the microcavity spacer layer is very low, so that the interaction strength of the electromagnetic field and the environment is low, and the refractive index sensitivity and the temperature sensitivity are relatively low. Disclosure of Invention The invention provides a double-parameter measuring optical fiber sensor with high sensitivity, high reliability, low cost and easy preparation and a manufacturing method thereof, which aim to solve the problems that the refractive index sensitivity and the temperature sensitivity of the existing optical fiber temperature refractive index sensor introduced into a micr