CN-121541324-B - Preparation method of fiber polymer grating temperature sensing unit and sensor system

CN121541324BCN 121541324 BCN121541324 BCN 121541324BCN-121541324-B

Abstract

The application discloses a preparation method of an optical fiber polymer grating temperature sensing unit and a sensor system, and relates to the technical field of optical fiber sensing, wherein the method comprises the steps of providing a double-opening capillary, alternately pumping a curable polymer precursor and air into the capillary to form a periodic arrangement structure of the polymer precursor and an air section in the capillary; the method comprises the steps of inserting transmission optical fibers from openings at two ends of a capillary tube, enabling the ends of the transmission optical fibers to extend into the capillary tube and optically couple with the periodic arrangement structure, solidifying the polymer precursors to form solidified polymer segments, forming an optical fiber polymer grating structure together with the air segments, and fixing the relative positions of the transmission optical fibers and the capillary tube to obtain the optical fiber sensing unit. The application has the advantages of simple process, low cost and capability of effectively inhibiting stress-strain cross sensitivity.

Inventors

LIN WEI
HUANG JIANWEI
LIU BO
Duan Shaoxiang
LIU HAIFENG
ZHANG HAO
JIA FAN

Assignees

南开大学

Dates

Publication Date: 20260508
Application Date: 20260120

Claims (10)

1. The preparation method of the optical fiber polymer grating temperature sensing unit is characterized by comprising the following steps of: S110, providing a capillary tube (10) with double openings, and alternately pumping a curable polymer precursor (9) and air (14) into the capillary tube (10) to form a periodic arrangement structure of the polymer precursor (9) and air (14) sections inside the capillary tube (10); s120, inserting a transmission optical fiber (5) from two end openings of the capillary tube (10), enabling the end of the transmission optical fiber (5) to extend into the capillary tube (10) and be optically coupled with the periodic arrangement structure; S130, curing the polymer precursor (9) to form a cured polymer segment (13), wherein the polymer segment (13) and the air (14) segment jointly form an optical fiber polymer grating structure; And S140, fixing the relative positions of the transmission optical fiber (5) and the capillary tube (10) to prepare the optical fiber sensing unit (6).
2. The method of manufacturing a fiber optic polymer grating temperature sensing unit according to claim 1, wherein the method pumps the polymer precursor (9) and air (14) into the capillary tube (10) via a peristaltic pump (12) and a silicone tube (11) to form the periodic arrangement.
3. The method for manufacturing the optical fiber polymer grating temperature sensing unit according to claim 1, wherein the polymer precursor (9) is a polydimethylsiloxane precursor, the pumping volume ratio of the polymer precursor (9) to air (14) is 1 to 1, and the thermal expansion coefficient of the cured polymer segment (13) is smaller than that of the air (14).
4. The method of manufacturing a fiber optic polymer grating temperature sensing unit according to claim 1, characterized in that curing the polymer precursor (9) comprises heat curing the transmission fiber (5) and the capillary (10) in an environment of 60 ℃ such that the polymer precursor (9) forms a cured polymer segment (13).
5. The method for preparing the optical fiber polymer grating temperature sensing unit according to claim 1, wherein fixing the relative positions of the transmission optical fiber (5) and the capillary tube (10) comprises coating ultraviolet glue (7) at the joint of the opening of the capillary tube (10) and the transmission optical fiber (5) for encapsulation, and irradiating for 5-10min by ultraviolet light to realize the fixed connection of the transmission optical fiber (5) and the capillary tube (10).
6. The method for manufacturing the fiber polymer grating temperature sensing unit according to claim 1, wherein the capillary tube (10) with double openings is any one of a quartz capillary tube, a stainless steel capillary tube or a polytetrafluoroethylene capillary tube.
7. A fiber polymer grating temperature sensor system is characterized in that, the fiber optic polymer grating temperature sensor system comprises: a light source module (3) for generating an incident light signal (15); The optical fiber sensing unit (6), wherein the optical fiber sensing unit (6) is prepared by adopting the preparation method of the optical fiber polymer grating temperature sensing unit according to any one of claims 1-6; -a fiber optic circulator (4), the fiber optic circulator (4) comprising a first port, a second port and a third port, the first port being connected to the light source module (3), the second port being connected to the fiber optic sensing unit (6) for guiding the incident light signal (15) to the fiber optic sensing unit (6) and for guiding the reflected light signal (16) from the fiber optic sensing unit (6) out of the third port; a signal acquisition and processing module (2) connected to the third port for receiving and demodulating the reflected light signal (16) to obtain reflected spectrum data; The polymer section (13) in the optical fiber sensing unit (6) has thermal expansibility, the grating period formed by the polymer section (13) and the air (14) section is changed along with the temperature change, the drift of characteristic wavelength in the reflection spectrum data is caused, and the temperature sensing is realized by detecting the drift amount of the drift.
8. The fiber optic polymer grating temperature sensor system of claim 7, wherein the signal acquisition and processing module (2) comprises a spectrum analyzer, the system further comprising a computer module (1), the computer module (1) being communicatively coupled to the signal acquisition and processing module (2) for receiving the reflectance spectrum data and extracting characteristic wavelengths of the reflectance spectrum data, and for calculating and outputting a temperature value based on a pre-stored wavelength-temperature calibration relationship.
9. The fiber polymer grating temperature sensor system of claim 7, wherein the transmission fiber (5) is a germanium doped quartz single mode fiber having a germanium content of less than 5%, the core refractive index of the transmission fiber (5) being matched to the refractive index of the polymer segment (13) after curing.
10. The fiber polymer grating temperature sensor system according to claim 7, characterized in that the system comprises a plurality of fiber sensing units (6) with different grating periods, wherein the fiber sensing units (6) are connected to the same light source module (3) and the signal acquisition and processing module (2) in a fiber coupler or cascade mode to form a quasi-distributed temperature sensing network.

Description

Preparation method of fiber polymer grating temperature sensing unit and sensor system Technical Field The application relates to the technical field of optical fiber sensing, in particular to a preparation method of an optical fiber polymer grating temperature sensing unit and a sensor system. Background The optical fiber sensing technology has the advantages of strong anti-interference capability, capability of realizing remote real-time monitoring and the like, and is widely applied to the fields of industry, scientific research, environmental monitoring and the like. Among them, temperature is a key physical quantity, and the optical fiber sensing technology is particularly focused. The conventional optical fiber temperature sensor mainly comprises an optical fiber grating temperature sensor, an optical fiber fluorescence temperature sensor, an optical fiber interferometer temperature sensor and an optical fiber distributed temperature sensor. Various types of optical fiber temperature sensors have the limitations in the preparation process that the optical fiber fluorescence temperature sensor is complex to prepare, part of materials have biotoxicity and have limited service life, the optical fiber interferometer temperature sensor has extremely high requirements on the manufacturing process and is difficult to produce in batches, and the optical fiber distribution type temperature sensor has high system cost and limited spatial resolution although being put into practical use. The fiber bragg grating temperature sensor realizes sensing by utilizing the principle that the temperature causes the wavelength drift of grating reflection, has good stability and repeatability, and is the fiber bragg grating temperature sensor most hopefully industrialized at present. However, the preparation of the fiber grating mainly depends on precise processes such as laser etching, equipment is expensive, the preparation cost is high, and the prepared fiber grating is easily interfered by mechanical factors such as stress and strain, so that obvious cross sensitivity problems exist, and the accuracy and the reliability of temperature detection are affected. Therefore, there is a need for a fiber bragg grating temperature sensor and a preparation method thereof, which have simple preparation process and low cost, and can effectively inhibit stress-strain cross sensitivity. Disclosure of Invention The application aims to provide a preparation method of an optical fiber polymer grating temperature sensing unit and a sensor system, which are used for solving the problems of high preparation cost and cross sensitivity of the optical fiber grating temperature sensor. In order to achieve the above object, the present application provides the following solutions: The application provides a preparation method of an optical fiber polymer grating temperature sensing unit, which comprises the steps of providing a double-opening capillary, alternately pumping a curable polymer precursor and air into the capillary to form a periodic arrangement structure of the polymer precursor and an air section in the capillary, inserting a transmission optical fiber from two end openings of the capillary, enabling the end of the transmission optical fiber to extend into the capillary to be optically coupled with the periodic arrangement structure, curing the polymer precursor to form a cured polymer section, and fixing the relative positions of the transmission optical fiber and the capillary to obtain the optical fiber polymer grating structure, wherein the S110 is used for fixing the relative positions of the transmission optical fiber and the capillary. Illustratively, the method pumps the polymer precursor and air into the capillary tube via peristaltic pump and silicone tube to form the periodic arrangement. Illustratively, the polymer precursor is a polydimethylsiloxane precursor, the polymer to air pumping volume ratio is 1 to 1, and the polymer segments have a coefficient of thermal expansion less than air. Illustratively, curing the polymer precursor includes heat curing the transmission fiber and the capillary in an environment at 60 ℃ to form a cured polymer segment from the polymer precursor. The fixing of the relative position of the transmission optical fiber and the capillary tube comprises the steps of coating ultraviolet glue at the joint of the opening of the capillary tube and the transmission optical fiber for packaging, and irradiating for 5-10min through ultraviolet light to realize the fixed connection of the transmission optical fiber and the capillary tube. Illustratively, the double-opening capillary is any one of a quartz capillary, a stainless steel capillary, or a polytetrafluoroethylene capillary. In a second aspect, the application further provides a fiber polymer grating temperature sensor system, which comprises a light source module, a fiber sensing unit and a fiber circulator, wherein the light source module is