Vanadium dioxide-based micro-nano fiber temperature sensor and preparation method thereof
By depositing vanadium dioxide thin films on micro- and nano-fibers and combining fused tapering and hydrofluoric acid etching methods, a highly sensitive micro- and nano-fiber temperature sensor was fabricated. This solved the problems of difficult-to-control fabrication and high harm to human health in existing technologies, and enabled efficient and low-cost sensor fabrication and application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUAZHONG UNIV OF SCI & TECH
- Filing Date
- 2022-10-11
- Publication Date
- 2026-06-02
AI Technical Summary
Existing methods for fabricating micro- and nano-fibers suffer from problems such as difficulty in control, significant harm to the human body, poor repeatability, and insufficient sensor sensitivity and responsiveness.
By employing specific stretching speeds and hydrogen flow rates, and under suitable sputtering power and annealing temperatures, vanadium dioxide thin films are deposited on micro/nano optical fibers. Pure M-phase vanadium dioxide thin films are prepared through magnetron sputtering and annealing. Combined with fused taper method and hydrofluoric acid etching method, a highly sensitive micro/nano optical fiber temperature sensor is fabricated.
The controllable preparation of vanadium dioxide thin films has been achieved, which improves the sensitivity and responsiveness of the sensor. The sensor is small in size, has strong anti-electromagnetic interference ability, adapts to complex environments, has low cost, and the preparation process is less harmful to the human body and has high repeatability.
Smart Images
Figure CN115711686B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of micro-nano optical fiber fabrication, and more specifically, relates to a vanadium dioxide-based micro-nano optical fiber temperature sensor and its fabrication method. Background Technology
[0002] Optical fiber, short for optical waveguide fiber, is a type of light transmission tool made by drawing glass or plastic into a thinner strand, allowing light to be transmitted through total internal reflection. The concept of optical fiber was first proposed by Kao Kuen in 1966. In 1970, the first optical fiber with a transmission loss of 20 dB / km was manufactured by Corning Incorporated in the United States, thus ushering in the era of optical fiber communication. When light propagates in an optical fiber, it is affected by external factors such as stress, temperature, and humidity, causing changes in optical parameters such as amplitude, phase, and polarization state. Fiber optic sensing technology detects these changes in optical variables to reflect the corresponding physical quantities. Compared to traditional thermally excited semiconductor sensors, fiber optic sensors are characterized by their small size, flexibility, strong resistance to electromagnetic interference, ease of miniaturization, and low cost, enabling them to adapt to signal detection in various complex environments. Fiber optic sensors have a wide range of measurement applications, demonstrating excellent performance in common areas such as stress-strain, temperature, and gas sensing.
[0003] Micro- and nano-fibers refer to optical fibers with diameters in the micrometer or even nanometer range. In these fibers, the proportion of evanescent fields is greatly increased, which can effectively improve the sensitivity and responsivity of fiber optic sensors. In 2003, Tong et al. first reported a method for fabricating subwavelength low-loss micro- and nano-fibers, bringing micro- and nano-fibers to the forefront of research and making them a hot topic. There are many methods for fabricating micro / nano optical fibers, among which the most common are fused biconical taper (FBT), hydrofluoric acid etching (HB), and mechanical polishing. FBT is the most mature method, producing fibers with atomically smooth surfaces and the smallest diameter micro / nano fibers. HB is the simplest method, using different concentrations of HB or HB buffer solutions to etch the silica that makes up the fiber. However, the size of the micro / nano fibers fabricated using this method is difficult to control. Changes in the concentration of HB during etching affect the etching rate and the surrounding environment. Furthermore, the use of HB poses a significant safety hazard to humans. Mechanical polishing is the least used method, involving mechanical grinding with a polishing wheel. This method is generally used to fabricate special fibers such as D-type fibers, but it is time-consuming, has low repeatability, and is currently some distance from commercialization.
[0004] Vanadium dioxide (VDC), as a photoelectric material, has attracted widespread attention due to its typical insulator-metal phase transition characteristics near room temperature (68°C). During the phase transition, VDC transforms from a monoclinic phase with insulating properties to a tetragonal rutile phase with metallic properties, accompanied by dramatic changes in optical, electrical, thermal, and magnetic properties. The electrical resistance changes by four orders of magnitude before and after the phase transition, and the infrared absorption rate changes by 60%. VDC exhibits reversible, rapid, and multi-stimulus-responsive phase transition characteristics; its crystallographic transformation from a monoclinic to a tetragonal phase can be triggered by various stimuli, including optical, electrical, thermal, electrochemical, mechanical, and magnetic disturbances. Therefore, high-performance intelligent devices based on VDC have been rapidly developed, such as photoelectric switches, memory, photodetectors, actuators, smart windows, passive radiators, resonators, sensors, field-effect transistors, magnetic refrigeration, and oscillators. Its excellent properties give VDC ample potential in sensing regions such as temperature, gas, and stress-strain. Summary of the Invention
[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a vanadium dioxide-based micro / nano fiber optic temperature sensor and its fabrication method. The method successfully deposits a vanadium dioxide thin film on a micro / nano fiber using a specific stretching speed and hydrogen flow rate, at a suitable sputtering power and annealing temperature. Variable-temperature Raman spectroscopy and XRD methods confirm that the vanadium dioxide is a pure M-phase. Finally, relevant temperature sensing experiments were completed using a 1550nm infrared light source and an optical power detector.
[0006] To achieve the above objectives, according to one aspect of the present invention, a method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor is provided, the method mainly comprising the following steps:
[0007] (1) After removing part of the coating layer on the surface of the single-mode fiber, the fiber cladding in the area where the coating layer has been removed is etched or the area where the coating layer has been removed is heated and stretched by the melt stretching method to obtain micro-nano fiber.
[0008] (2) Vanadium metal is deposited onto the etched or stretched region of a micro / nano optical fiber by magnetron sputtering to obtain a vanadium metal film with a nanoscale thickness.
[0009] (3) The coated micro-nano optical fiber is annealed in an inert atmosphere to transform the metal vanadium film into an M-phase vanadium dioxide film, thereby obtaining a micro-nano optical fiber temperature sensor.
[0010] Furthermore, the coating layer of the single-mode fiber to be stretched is peeled off using Miller clamps, and then the fiber is symmetrically placed on a vacuum stage. After the fiber is firmly fixed, it is heated by hydrogen ignition. During the heating process, the stepper motors at both ends stretch the fiber at a preset speed to obtain micro-nano fiber.
[0011] Furthermore, the length of the coating peeled off is 1 cm; the hydrogen flow rate is 165 sccm; and the temperature of the outer flame is 1300℃.
[0012] Furthermore, the stretching length is 2.6 cm, the stretching speed is 145 μm / s, and the diameter of the fiber waist region after stretching is 1.4 μm.
[0013] Furthermore, a portion of the coating layer on the surface of the single-mode fiber is removed by mechanical stripping, and then the fiber cladding is etched by a chemical reaction with 40% hydrofluoric acid.
[0014] Furthermore, the magnetron sputtering power was 144W, and the deposition rate of the vanadium metal film was... The final deposition thickness of the vanadium metal film is 60 nm.
[0015] Furthermore, the coated micro / nano optical fiber is annealed in a tube furnace or a ceramic head local heating device to obtain a vanadium dioxide film.
[0016] Furthermore, the tube furnace annealing temperature is 450℃, the heating time is 20min, the holding time is 2h, and the gas used during annealing is an argon-oxygen mixture.
[0017] According to another aspect of the present invention, a vanadium dioxide-based micro / nano fiber optic temperature sensor is provided, wherein the temperature sensor is prepared by the method described above for preparing a vanadium dioxide-based micro / nano fiber optic temperature sensor.
[0018] In summary, compared with the prior art, the vanadium dioxide-based micro / nano fiber optic temperature sensor and its fabrication method provided by this invention have the following advantages:
[0019] 1. Vanadium dioxide thin films are obtained by magnetron sputtering of metal films followed by tube furnace annealing. The advantage of this method is that vanadium dioxide thin films can be prepared in a controllable manner. After determining the parameters, pure vanadium dioxide M-phase thin films can be prepared stably and repeatedly. Moreover, the thickness of the film can be selected independently. At the same time, the surface roughness and porosity of the film can be controlled by controlling the ion sputtering rate and power.
[0020] 2. Using argon as a protective gas can effectively protect the material from external environmental interference during the annealing process, ensuring that the transformation of metallic vanadium into vanadium dioxide is the only possible pathway, and improving the purity of the vanadium dioxide film.
[0021] 3. The micro-nano optical fibers and vanadium dioxide thin film materials under the architecture of this invention are obtained using conventional industrial methods and can be mass-produced in a short time, which has the advantages of high efficiency and suitability for industrial applications.
[0022] 4. Compared to traditional thermally excited semiconductor sensors, fiber optic sensors are smaller, more compact, have stronger resistance to electromagnetic interference, are easier to miniaturize, and are lower in cost, making them suitable for signal detection in various complex environments. Fiber optic sensors can measure a wide range of objects, demonstrating excellent performance in common areas such as stress-strain, temperature, and gas sensing.
[0023] 5. The fused taper method is used as a fabrication method for micro- and nano-fibers. The fiber fabricated by the fused taper method has an atomically smooth surface, the stretching diameter of the micro- and nano-fibers is controllable, the harm to the human body during the entire stretching process is very small, and the fabrication of micro- and nano-fibers has high repeatability.
[0024] 6. Compared with other types of fiber optic sensors, micro / nano fiber has a large evanescent field ratio, which can be well utilized for power-type fiber optic sensing. The evanescent field ratio of micro / nano fiber stretched to 1.4μm is 70%, and that of micro / nano fiber stretched to 3μm is 30%. After stretching, the sensing area of micro / nano fiber will be longer, and the sensing sensitivity can be increased. Attached Figure Description
[0025] Figure 1 This is a flowchart of a method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor provided by the present invention.
[0026] Figure 2 This is a schematic diagram of an optical microscope showing the micro / nano optical fiber fabricated according to the present invention;
[0027] Figure 3 (a) and (b) are optical microscope images of vanadium film deposited on optical fiber and vanadium dioxide formed by annealing, respectively. (c)-(e) are SEM images of vanadium dioxide on optical fiber from low magnification to high magnification.
[0028] Figure 4 This is a Raman characterization image of vanadium dioxide on an optical fiber;
[0029] Figure 5 The Raman curves of vanadium dioxide on optical fiber at different temperatures are shown.
[0030] Figure 6a , Figure 6b , Figure 6c The electrodes were prepared on the surface of vanadium dioxide thin films, and the resistance curves as a function of temperature were measured using a semiconductor probe station.
[0031] Figure 7 The power curve of the fabricated vanadium dioxide micro / nano fiber optic temperature sensor switching between room temperature and 70°C shows that the power change before and after the phase transition is approximately 40%. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0033] Please see Figure 1 and Figure 2 This invention provides a method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor, mainly comprising the following steps:
[0034] S1 involves mechanically stripping away a portion of the coating layer on the surface of the single-mode optical fiber, followed by etching the fiber cladding using a 40% concentration of hydrofluoric acid, or by a melt-stretching method. The melt-stretching method involves heating the portion of the fiber where the coating has been removed using a high-temperature heating source (above 1000°C), while stepper motors are used at both ends to stretch the fiber, elongating and thinning it to obtain optical fibers with diameters in the micrometer or even nanometer range.
[0035] In this embodiment, the coating layer of the single-mode optical fiber to be stretched was peeled off using Miller clamps, and then the fiber was symmetrically placed on a vacuum stage. After the fiber was firmly fixed, it was heated using hydrogen ignition. During the heating process, the stepper motors at both ends stretched the fiber at a preset speed to prepare a slender micro / nano fiber. The length of the coating layer peeled off was 1 cm. After removing the coating layer, the fiber was cleaned with alcohol and acetone. The hydrogen flow rate was 165 sccm, and the temperature of the outer flame was approximately 1300℃. The stretching length was 2.6 cm, the stretching speed was 145 μm / s, and the diameter of the fiber waist region after stretching was 1.4 μm. During the scanning heating stretching, the scanning length was 2000 μm, and the scanning speed was 2000 μm / s. The entire stretching process was observed under an optical microscope.
[0036] The single-mode optical fiber is manufactured by Corning Incorporated in the United States, with a core diameter of 9 μm, a cladding thickness of 125 μm, and a coating thickness of 250 μm.
[0037] S2. After obtaining the micro-nano fiber, nano-sized vanadium metal is deposited onto the etched or stretched area of the fiber using magnetron sputtering.
[0038] In this embodiment, the fabricated micro / nano optical fiber is encapsulated in a quartz tank using UV-curable adhesive. The quartz tank is then inverted onto a magnetron sputtering platform using double-sided copper tape, and metallic vanadium is sputtered onto the surface of the micro / nano optical fiber. The magnetron sputtering power is 144 W, and the deposition rate of the metallic vanadium film is [missing information]. The final deposition thickness of the vanadium metal film is 60 nm. The target material used for magnetron sputtering is a vanadium metal target with a purity of 99.99% (imported material) and a size of φ76.2*6 mm.
[0039] S3. After coating, the micro / nano fiber is placed in a tube furnace and annealed with an inert gas to obtain a pure M-phase vanadium dioxide thin film-coated micro / nano fiber, which is then used to obtain a micro / nano fiber temperature sensor.
[0040] In this embodiment, vanadium-sputtered optical fibers are annealed in a tube furnace to obtain vanadium dioxide, and finally, temperature sensing tests are performed. The tube furnace annealing temperature is 450°C, the heating time is 20 min, the holding time is 2 h, and the gas used for annealing is an argon-oxygen mixture with an argon concentration of 99.999% and an oxygen concentration of 0.001%, and a total flow rate of 50 sccm.
[0041] S4. After protecting the micro-nano fiber optic temperature sensor with heat shrink tubing, it was placed in a self-prepared electrolyte environment for temperature detection. Because the encapsulated heat shrink tubing has a certain heat insulation effect, the phase transition temperature is delayed to around 70°C, and a sudden change in the optical signal is detected near this temperature.
[0042] The present invention also provides a vanadium dioxide-based micro / nano fiber optic temperature sensor prepared by the method described above for preparing a vanadium dioxide-based micro / nano fiber optic temperature sensor.
[0043] The present invention will be further described in detail below with reference to several specific embodiments.
[0044] Example 1
[0045] Single-mode optical fiber was used as the raw material for fabricating micro / nano optical fibers, and micro / nano optical fibers with a waist diameter of 3 μm were prepared by fused taper method.
[0046] Specifically, single-mode optical fiber manufactured by Corning Incorporated was used. This type of fiber has a core diameter of 9 μm, a cladding diameter of 125 μm, and a coating diameter of 250 μm. The single-mode optical fiber was connected to the optical receiver of a fused tapered fiber machine, enabling the machine to receive the optical signals transmitted inside the single-mode optical fiber. The coating, which is 2.4 cm long in the middle of the single-mode optical fiber, was removed using wire strippers. Then, the area where the coating was removed was carefully wiped with anhydrous ethanol until no obvious dust particles could be observed under an optical microscope.
[0047] After the above preparations were completed, the single-mode optical fiber was fixed on a vacuum adsorption stage. Between the two adsorption stages was a hydrogen torch capable of generating a high temperature of 1300℃, used for the melting and stretching of the fiber. The adsorption stage itself had a stepper motor function, allowing it to move left and right. By moving the hydrogen torch to the center point of the area where the coating was stripped, the two adsorption stages slowly moved left and right as heating progressed. The hydrogen flow rate was 165 sccm, and the stage moving speed was 145 μm / s. Stretching was stopped when the overall stretching length reached 1.8 cm. After stretching, the waist diameter of the micro / nano fiber was 3 μm. The optical microscope image of the micro / nano fiber area after stretching is shown below. Figure 2 As shown.
[0048] The micro / nano fiber prepared in the previous step was placed into a magnetron sputtering cavity, and vanadium ions were sputtered onto the fiber using DC magnetron sputtering to form a vanadium film. The sputtering power was 144 W, and the deposition rate of the vanadium film was [missing information]. The final deposition thickness of the vanadium metal film was 60 nm. The target used for magnetron sputtering was a vanadium metal target with a purity of 99.99% (imported material) and dimensions of φ76.2*6 mm. Throughout the sputtering process, the gas pressure in the sputtering chamber was 3 mtorr. The sputtered micro / nano fiber was as follows... Figure 3 As shown.
[0049] The micro / nano optical fiber coated with a vanadium film obtained from the previous sputtering step was placed in a tube furnace for annealing. Vanadium can be annealed into M-phase vanadium dioxide in an oxygen-containing atmosphere at 400℃-450℃. After multiple experimental parameter adjustments, we determined the optimal annealing temperature for the tube furnace to be 450℃, the heating time to be 20 min, and the holding time to be 2 h. The annealing gas used was an argon-oxygen mixture with an argon concentration of 99.999% and an oxygen concentration of 0.001%, with a total flow rate of 50 sccm. After annealing, the optical fiber was allowed to cool with the furnace until it reached room temperature, at which point it was removed. Figure 3 As shown in (b), under an optical microscope, only a color change was observed compared to before annealing; the sensitive material on the surface remained undamaged. Figure 3 (c)-(e) in the figure confirms, through SEM characterization from low to high magnification, that vanadium dioxide is indeed formed on the optical fiber, and that it has good density, high degree of crystallinity, and is uniformly distributed on the surface of the micro-nano optical fiber.
[0050] To confirm that the sensitive material film obtained by the method of this invention is indeed vanadium dioxide of the M phase, we performed Raman characterization on the annealed sensitive material film. The Raman laser wavelength was 532 nm and the laser power was 3 nW. The entire characterization process was conducted in air at room temperature. The characteristic peaks exhibited by the sensitive material are as follows: Figure 4As shown, the three characteristic peaks at 198, 229, and 617 are characteristic peaks of standard M-phase vanadium dioxide, confirming that the synthesized sensitive material is M-phase vanadium dioxide. Subsequently, variable-temperature Raman spectroscopy was performed on the sample, as shown... Figure 5 As shown, by analyzing the Raman characterization curves of vanadium dioxide from 25℃ to 80℃, it can be found that at around 56℃, the three characteristic peaks of vanadium dioxide, 198, 229, and 617, completely disappear. That is, at this temperature, the vanadium dioxide film synthesized in this invention completely transforms into tetragonal vanadium dioxide of the rutile phase, which is biased towards metallic properties.
[0051] like Figure 6a , Figure 6b , Figure 6c As shown, to study the change curve of the resistivity of vanadium dioxide before and after the phase transition, a metal electrode was fabricated on the surface of vanadium dioxide using a mask method. The electrode composition consisted of 10 nm of Ti metal and 50 nm of Cr metal. An optical microscope image of the completed electrode is shown below. Figure 6b As shown, the resistivity of the device was tested using a low-temperature probe station. The temperature control range of the low-temperature probe station is from 150K to 500K, which meets the requirements of this test. The experimental test showed that the resistance change before and after the phase transition reached nearly three orders of magnitude.
[0052] The vanadium dioxide-coated micro / nano optical fiber is protected with heat-shrink tubing to prevent oxidation of the vanadium dioxide material and fiber breakage after annealing. A transmission optical path is constructed using a 1550nm infrared laser source, a multi-band absorption optical power meter, an optical fiber adapter, and the fabricated vanadium dioxide-coated micro / nano optical fiber. After assembly, the fiber encapsulated in a heating sleeve is placed in a glass container filled with water. The aqueous solution is heated using a heating stage. The advantage of using an aqueous solution for temperature detection is its uniform temperature distribution, allowing for constant temperature monitoring. After heating, the temperature of the aqueous solution is approximately 70°C, which is within the typical alarm temperature range for battery thermal runaway. The temperature sensor data for the micro / nano optical fiber in this embodiment is as follows: Figure 7 As shown, the optical power changed by about 40% during the change from room temperature to 70°C, and the overall response time was on the order of seconds. After the temperature sensor was removed from the high-temperature aqueous solution, the optical power gradually recovered to its original value, with a recovery time of less than 10 seconds. After repeated experiments, the power that changed with the temperature phase transition remained stable at the same value each time, indicating that the sensor has high stability. In addition, the device can still work stably after one month.
[0053] Example 2
[0054] The fabrication method of the micro / nano fiber optic temperature sensor based on vanadium dioxide thin film provided in Embodiment 2 of the present invention is basically the same as the fabrication method of the micro / nano fiber optic temperature sensor based on vanadium dioxide thin film provided in Embodiment 1. The difference is that the tube furnace used for annealing heating is replaced with a ceramic head local heating device.
[0055] Because the coating of optical fibers is not resistant to high temperatures, using a tubular atmosphere furnace to heat the area too large will damage the coating. By using a local heating device, the heating temperature can be controlled within 2cm, which will not damage the unpeeled coating and enhance the stability and strength of the micro-nano optical fiber sensor. The temperature of the entire local heating device is controlled by a voltage source and can be heated up to 500℃. The temperature is stable and adjustable.
[0056] Example 3
[0057] The fabrication method of the micro / nano fiber optic temperature sensor based on vanadium dioxide thin film provided in Embodiment 3 of the present invention is basically the same as the fabrication method of the micro / nano fiber optic temperature sensor based on vanadium dioxide thin film provided in Embodiment 2, except that the melt tapering method is changed to the hydrofluoric acid etching method.
[0058] Both fused ablation and hydrofluoric acid etching are methods for fabricating micro / nano optical fibers. Fused ablation offers advantages such as high surface smoothness, good repeatability of the drawn fibers, and finer diameters, but it requires specialized production equipment, resulting in high costs if mass production is not considered. Hydrofluoric acid etching is convenient to operate and has lower costs, but its disadvantages include low sample repeatability and the significant health risks associated with hydrofluoric acid. This example provides a low-cost hydrofluoric acid etching method for small-scale production of micro / nano optical fibers.
[0059] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a vanadium dioxide-based micro-nano fiber temperature sensor, characterized in that, The method includes the following steps: (1) After removing part of the coating layer on the surface of the single-mode fiber, the fiber cladding in the area where the coating layer has been removed is etched or the area where the coating layer has been removed is heated and stretched by the melt stretching method to obtain micro-nano fiber. (2) Vanadium metal is deposited onto the etched or stretched region of a micro / nano optical fiber by magnetron sputtering to obtain a vanadium metal film with a nanoscale thickness. (3) The coated micro-nano optical fiber is annealed in an inert atmosphere to transform the metal vanadium film into an M-phase vanadium dioxide film, thereby obtaining a micro-nano optical fiber temperature sensor.
2. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in claim 1, characterized in that: The coating layer of the single-mode optical fiber to be stretched is peeled off using Miller clamps, and then the fiber is symmetrically placed on a vacuum stage. After the fiber is firmly fixed, it is heated by hydrogen ignition. During the heating process, the stepper motors at both ends stretch the fiber at a preset speed to obtain micro-nano optical fibers.
3. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in claim 2, characterized in that: The length of the coating peeled off is 1 cm; the hydrogen flow rate is 165 sccm; and the temperature of the outer flame is 1300℃.
4. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in claim 2, characterized in that: The stretching length was 2.6 cm, the stretching speed was 145 μm / s, and the diameter of the fiber waist region after stretching was 1.4 μm.
5. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in claim 1, characterized in that: A portion of the coating layer on the surface of the single-mode fiber is removed by mechanical stripping, and then the fiber cladding is etched by a chemical reaction with 40% hydrofluoric acid.
6. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in claim 1, characterized in that: The magnetron sputtering power was 144W, and the deposition rate of the vanadium metal film was... The final deposition thickness of the vanadium metal film is 60 nm.
7. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in any one of claims 1-6, characterized in that: Vanadium dioxide film is obtained by annealing the coated micro / nano optical fiber in a tube furnace or a local heating device for ceramic head.
8. The method for fabricating a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in claim 1, characterized in that: The tube furnace annealing temperature is 450℃, the heating time is 20min, the holding time is 2h, and the gas used for annealing is an argon-oxygen mixture.
9. A micro / nano fiber optic temperature sensor based on vanadium dioxide, characterized in that: The temperature sensor is prepared using the method for preparing a vanadium dioxide-based micro / nano fiber optic temperature sensor as described in any one of claims 1-8.