Method for manufacturing PDMS modified optical fiber end face microsphere fabry-perot temperature sensor

Abstract

The application belongs to the technical field of optical fiber application, and particularly relates to a PDMS modified optical fiber end face microsphere Fabry-Perot temperature sensor manufacturing method. 1. An optical fiber fusion splicer is used to heat and fuse the end faces of two sections of optical fiber into spherical end faces. 2. The spherical end faces of the optical fiber are dipped in glycerol, and then the fiber cores are aligned. 3. The spherical end faces of the two sections of optical fiber are fused together, and a micro bubble is formed at the fused end face. 4. Discharge is continuously performed, and an axial tension is continuously applied, so that a conical bubble is formed at the discharge center, and the axial tension is continuously applied until the single-mode optical fiber is broken at the fused end face. 5. Discharge is continuously performed, so that the volume of the micro bubble ball at the end face of the discharge center gradually increases, until the radial diameter of the micro bubble ball is greater than the diameter of the single-mode optical fiber cladding. 6. A point-by-point dipping method is used for several times to coat a PDMS thin film layer on the surface of the micro bubble ball of the optical fiber. The prepared sensor realizes the significant improvement of the sensitivity of temperature measurement under the same structural strength.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber application technology, specifically relating to a method for fabricating a Fabry-Perot temperature sensor with PDMS-modified fiber end face microspheres. Background Technology

[0002] Fiber optic sensing technology, as an important branch of modern sensing technology, has greatly promoted the vigorous development of the sensing field. Compared with traditional electronic sensors, fiber optic sensors have advantages such as compact structure, light weight, and resistance to electromagnetic interference, and have been widely used in fields such as petroleum exploration, human health monitoring, and biochemical pharmaceuticals. Compared with other types of fiber optic sensors, fiber optic sensors based on Fabry-Perot interferometers (FPI) have advantages such as high sensitivity, linear response, compact structure, and strong spatial resolution. Among them, breaking through the traditional photothermal limitations through materials engineering to realize the fabrication and application of temperature sensors has become a research hotspot. PDMS material has excellent properties such as high negative thermo-optic coefficient, good biocompatibility, and chemical stability, and has been widely used in the fabrication of fiber optic temperature sensors. In recent years, in order to achieve high-sensitivity temperature detection, a lot of research has focused on precision packaging technology. The aim is to make the sensor produce more obvious refractive index changes or other characteristic responses at different temperatures. However, the complex packaging process significantly increases the difficulty of sensor fabrication. For example, the method of splicing a high thermo-optic coefficient sensitizing medium with a special optical fiber structure can improve sensitivity, but it reduces the repeatability and consistency of sensor fabrication. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention proposes a PDMS-modified fiber end-face microsphere Fabry-Perot interferometer temperature sensor and its fabrication method. The fabricated sensor utilizes the material properties of PDMS at different temperature states to modulate the optical path difference, significantly improving the sensitivity of temperature measurement while maintaining the same structural strength.

[0004] The technical solution adopted in this invention is: a method for fabricating a PDMS-modified fiber end-face microsphere Fabry-Perot temperature sensor, the method comprising the following steps:

[0005] Step 1: Place the two single-mode optical fibers, after the coating has been removed and the end faces have been flattened, into the clamps of the left and right motors of the fiber optic fusion splicer, respectively. Use the fiber optic fusion splicer to heat-fuse the end faces of the two single-mode optical fibers into a spherical end face.

[0006] Step 2: After dipping the spherical end faces of the two processed single-mode optical fibers in glycerin, place them back into the optical fiber fusion splicer and operate the stepper motor of the fusion splicer to align the cores of the two single-mode optical fibers (align them within the operating plane).

[0007] Step 3: Operate the stepper motor of the fiber optic fusion splicer to bring the spherical end faces of the two single-mode optical fibers into contact. The spherical end faces of the two single-mode optical fibers are fused together by arc discharge. After several discharges, tiny bubbles are formed at the end faces of the two single-mode optical fibers after fusion.

[0008] Step 4: Operate the fiber optic fusion splicer to continuously discharge the microbubble area while applying axial tension, so that a cone-shaped bubble forms at the discharge center. Continue to apply axial tension until the single-mode fiber is broken at the splice end.

[0009] Step 5: Continue to discharge the broken end face of the single-mode fiber, so that the volume of the microbubble sphere at the discharge center end face gradually increases until the radial diameter of the microbubble sphere is greater than the diameter of the single-mode fiber cladding. The microbubble sphere is ellipsoidal, with an axial diameter of 76.76-86.76 micrometers and a radial diameter of 122.09-132.09 micrometers.

[0010] Step 6: Prepare PDMS material according to the mass ratio of PDMS main agent to PDMS curing agent of 10:1. Apply PDMS thin film layer to the surface of microbubble spheres of single-mode optical fiber by multiple spot dipping methods. The thickness of PDMS thin film layer is 77.1-83.1 micrometers.

[0011] Furthermore, the axial diameter of the microbubble spheres is 76.76 micrometers, the radial diameter is 122.09 micrometers, and the thickness of the PDMS film layer is 77.1 micrometers.

[0012] Furthermore, the axial diameter of the microbubble spheres is 81.76 micrometers, the radial diameter is 127.09 micrometers, and the thickness of the PDMS thin film layer is 80.1 micrometers.

[0013] Furthermore, the axial diameter of the bubble sphere is 86.76 micrometers, the radial diameter is 132.09 micrometers, and the thickness of the PDMS film layer is 83.1 micrometers.

[0014] The beneficial effects of this invention are as follows: A PDMS-modified fiber end-face microsphere Fabry-Perot interferometer temperature sensor and its fabrication method are proposed. The reflected light beam inside the fabricated sensor is reflected sequentially through an air cavity, a silicon cavity, and a polymer cavity before returning to the fiber core. By utilizing the material properties of PDMS at different temperature states to control the optical path difference, the sensitivity of temperature measurement is significantly improved while maintaining the same structural strength. Its main advantages are:

[0015] (1) The sensor process is simple, requiring only conventional single-mode optical fiber and a commercial optical fiber fusion splicer, which significantly reduces the manufacturing cost.

[0016] (2) The sensor has high temperature sensitivity. By utilizing the high negative thermo-optic coefficient of PDMS, the optical path difference is controlled through photothermal effect and thermal expansion effect, thereby achieving high-sensitivity temperature measurement.

[0017] (3) The sensor has a compact structure. It consists only of microspheres on the end face of optical fiber and PDMS film. It is small in size and easy to integrate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of step one in the fabrication of the temperature sensor in Example 1.

[0019] Figure 2 This is a schematic diagram of step two in the fabrication of the temperature sensor in Example 1.

[0020] Figure 3 This is a schematic diagram of step three in the fabrication of the temperature sensor in Example 1.

[0021] Figure 4 This is a schematic diagram of step four in the fabrication of the temperature sensor in Example 1.

[0022] Figure 5 This is a schematic diagram of step five in the fabrication of the temperature sensor in Example 1.

[0023] Figure 6 This is a schematic diagram of step six in the fabrication of the temperature sensor in Example 1.

[0024] Figure 7 This is the interference curve spectrum of the temperature sensor in Example 1.

[0025] Figure 8 This is a graph showing the relationship between the wavelength change of the temperature sensor and the temperature in Example 1.

[0026] Reference numerals: 1. Fiber optic fusion splicer; 2. Spherical end face; 3. Glycerin; 4. Microbubble; 5. Conical bubble; 6. Microbubble sphere; 7. PDMS thin film layer. Detailed Implementation

[0027] Example 1

[0028] The fabrication method of a PDMS (polydimethylsiloxane) modified fiber end-face microsphere Fabry-Perot temperature sensor includes the following steps:

[0029] Step 1: Place the two single-mode optical fibers (after removing the coating and cutting the end faces flat) into the clamps of the left and right motors of the fiber optic fusion splicer 1, respectively. Use the fiber optic fusion splicer to thermally fuse the end faces of the two single-mode optical fibers into a spherical end face 2, as shown. Figure 1 As shown.

[0030] Step 2: After applying glycerin 3 to the spherical end faces of the two processed single-mode fiber segments, place them back into the fiber fusion splicer. Operate the stepper motor of the splicer to align the cores of the two single-mode fiber segments (align them within the operating plane). Figure 2 As shown;

[0031] Step 3: Operate the stepper motor of the fiber optic fusion splicer to bring the spherical end faces of the two single-mode fiber segments into contact. The spherical end faces of the two single-mode fiber segments are fused together through arc discharge. After several discharges, tiny bubbles 4 are formed at the fused end faces of the two single-mode fiber segments. Figure 3 As shown.

[0032] Step 4: Operate the fiber optic fusion splicer to continuously discharge into the microbubble region while simultaneously applying axial tension, causing a cone-shaped bubble 5 to form at the discharge center. Continue applying axial tension until the single-mode fiber is broken at the splice end. Figure 4 As shown.

[0033] Step 5: Continue discharging the broken end face of the single-mode fiber, causing the volume of the microbubble sphere 6 at the discharge center to gradually increase until the radial diameter of the microbubble sphere is larger than the diameter of the single-mode fiber cladding. The microbubble sphere is ellipsoidal, with an axial diameter of 81.76 micrometers (the axial diameter is the minor axis along the fiber's central axis) and a radial diameter of 127.09 micrometers (the radial diameter is the major axis perpendicular to the fiber's central axis). Figure 5 As shown.

[0034] Step Six: Prepare PDMS material according to a PDMS main agent and PDMS curing agent mass ratio of 10:1. The main agent and curing agent are Dow Corning 184 silicone rubber. Using a dot-dip method, coat the surface of the microbubble spheres of the single-mode optical fiber with a PDMS thin film layer. The thickness of the PDMS thin film layer is 77.1-83.1 micrometers. Using the same dot-dip method, coat the surface of the microbubble spheres of the single-mode optical fiber with a PDMS thin film layer 7, forming a Fabry-Perot interferometer. The thickness of the PDMS thin film layer is 80.1 micrometers. Figure 6 As shown.

[0035] like Figure 7 As shown, the interference spectrum of the sensor prepared in this embodiment changes with temperature within the temperature range of 30℃-80℃, and the test was conducted using a water bath heating method. By monitoring the drift of the interference trough wavelength, the temperature sensitivity of the sensor was measured to be 7.04 pm / ℃.

[0036] like Figure 8As shown, this embodiment also tested the wavelength variation and temperature response characteristics of fiber end-face microsphere Fabry-Perot interferometers with different PDMS film thicknesses in the temperature range of 30℃-80℃. Through water bath heating experiments, it was found that when the PDMS film thickness was 0μm (i.e., no PDMS coating), the sensor sensitivity was 1.77 pm / ℃, and R... 2 = 90.69%; the sensor sensitivity is 7.0 pm / ℃ when the PDMS film thickness is 80.1 μm, R 2 = 99.99%. The results show that the introduction of the PDMS film layer significantly improved the temperature sensitivity and linearity of the sensor.

[0037] Example 2

[0038] In the fabrication method of the temperature sensor in Example 1, the axial diameter of the microbubble spheres is 76.76 micrometers and the radial diameter is 122.09 micrometers; the thickness of the PDMS thin film layer is 77.1 micrometers.

[0039] Example 3

[0040] In the fabrication method of the temperature sensor in Example 1, the axial diameter of the microbubble spheres is 86.76 micrometers and the radial diameter is 132.09 micrometers; the thickness of the PDMS thin film layer is 83.1 micrometers.

[0041] The reflected light beam inside the aforementioned temperature sensor is reflected sequentially through the air cavity, silicon cavity, and polymer cavity before returning to the fiber core. By utilizing the material properties of PDMS at different temperature states to adjust the optical path difference, the sensitivity of temperature measurement is significantly improved under the same structural strength.

Claims

1. A method for fabricating a PDMS-modified fiber end-face microsphere Fabry-Perot temperature sensor, characterized in that: The production method includes the following steps: Step 1: Place the two single-mode optical fibers, after the coating has been removed and the end faces have been flattened, into the clamps of the left and right motors of the fiber optic fusion splicer, respectively. Use the fiber optic fusion splicer to heat-fuse the end faces of the two single-mode optical fibers into a spherical end face. Step 2: After dipping the spherical end faces of the two processed single-mode optical fibers in glycerin, place them back into the optical fiber fusion splicer and operate the stepper motor of the fusion splicer to align the cores of the two single-mode optical fibers. Step 3: Operate the stepper motor of the fiber optic fusion splicer to bring the spherical end faces of the two single-mode optical fibers into contact. The spherical end faces of the two single-mode optical fibers are fused together by arc discharge. After several discharges, tiny bubbles are formed at the end faces of the two single-mode optical fibers after fusion. Step 4: Operate the fiber optic fusion splicer to continuously discharge the microbubble area while applying axial tension, so that a cone-shaped bubble is formed at the discharge center. Continue to apply axial tension until the single-mode fiber is broken at the splice end. Step 5: Continue to discharge the broken end face of the single-mode fiber, so that the volume of the microbubble sphere at the discharge center end face gradually increases until the radial diameter of the microbubble sphere is greater than the diameter of the single-mode fiber cladding. The microbubble sphere is an ellipsoidal microbubble sphere with an axial diameter of 81.76 micrometers and a radial diameter of 127.09 micrometers. Step 6: Prepare PDMS material according to the mass ratio of PDMS main agent to PDMS curing agent of 10:

1. Apply a PDMS thin film layer to the surface of the microbubble spheres of single-mode optical fiber by multiple spot dipping methods. The thickness of the PDMS thin film layer is 80.1 micrometers.

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