A kind of fiber hydrogen sensor and its preparation method

Abstract

This invention proposes a tapered fiber optic hydrogen sensor and its fabrication method, belonging to the field of hydrogen sensors. The sensor includes a tapered section in the middle of an optical fiber; a sensing element tightly fitted around the tapered section; a light source inputting an optical signal into the optical fiber; a spectrometer measuring the position of characteristic peaks in the optical fiber's spectrum; and a three-layer thin-film structure comprising the sensing element from the inside out: an excitation layer that excites the optical fiber surface to generate a plasmon resonance effect; a reaction layer made of a gas-sensitive material that reacts with hydrogen; and a catalytic layer that catalyzes the reaction between the gas-sensitive material and hydrogen. This invention employs a tapering method to fabricate the fiber optic sensor, significantly improving its sensitivity. Using tungsten oxide and gold co-sputtering material as the gas-sensitive material greatly improves the response and recovery times compared to using only tungsten oxide.

Description

Technical Field

[0001] This invention relates to the field of hydrogen sensor technology, and in particular to a tapered fiber hydrogen sensor and its preparation method. Background Technology

[0002] Hydrogen is one of the characteristic gases produced during battery thermal runaway, and its large-scale production in a battery may indicate the onset of thermal runaway. Therefore, detecting the hydrogen produced by a battery is a feasible method for early warning of battery thermal runaway. Currently, the types of fiber optic hydrogen sensors under research include fiber grating type, interferometric type, evanescent field type, and surface plasmon resonance type.

[0003] However, these types of sensors still have sensitivity issues. For example, the sensitivity of fiber optic and interferometric sensors is typically in the range of hundreds of picometers to nanometers per percent of hydrogen concentration, while the sensitivity of surface plasmon resonance sensors can typically reach a few nanometers per percent of hydrogen concentration, but the sensitivity is still relatively low. Summary of the Invention

[0004] In view of this, the present invention proposes a tapered fiber hydrogen sensor and its preparation method.

[0005] The technical solution of this invention is implemented as follows: This invention provides a tapered fiber optic hydrogen sensor, including an optical fiber with a tapered section in its middle; a sensing unit tightly fitted around the tapered section; a light source connected to one end of the optical fiber and inputting an optical signal into the optical fiber; and a spectrometer connected to the other end of the optical fiber and measuring the position of characteristic peaks in the spectrum within the optical fiber; wherein, the sensing unit comprises three thin-film structures from the inside out: an excitation layer that excites the surface of the optical fiber to generate a plasma resonance effect; a reaction layer made of a gas-sensitive material that reacts with hydrogen; and a catalytic layer that catalyzes the reaction between the gas-sensitive material and hydrogen.

[0006] Based on the above technical solutions, preferably, the excitation layer is formed by plating with elemental gold; the reaction layer is formed by co-sputtering with tungsten oxide and elemental gold as gas-sensitive materials; and the catalytic layer is formed by plating with elemental platinum.

[0007] More preferably, the thickness of the reaction layer is 15-60 nm.

[0008] Even more preferably, the thickness of the catalyst layer is no more than 1 nm.

[0009] More preferably, the mass percentage of gold in the reaction layer is 9.4% to 45%.

[0010] Based on the above technical solutions, preferably, the diameter of the tapered section is no greater than 5μm.

[0011] Secondly, the present invention also provides a method for preparing a tapered fiber hydrogen sensor, which is used to prepare the above-mentioned tapered fiber hydrogen sensor, including the following steps: Step 1, forming a tapered section on the optical fiber by melting and tapering; Step 2, obtaining an excitation layer, a reaction layer and a catalytic layer by magnetron sputtering from the inside to the outside on the tapered section; Step 3, connecting the two ends of the optical fiber to a light source and a spectrometer respectively.

[0012] Based on the above technical solution, preferably, in step two, a reaction layer is formed by simultaneous magnetron sputtering of a gold target and a tungsten target, wherein the gold deposition rate is [missing information].

[0013] Based on the above technical solutions, preferably, in step two, after the excitation layer is deposited on the surface of the tapered section, the two ends of the optical fiber with only gold film are connected to the light source and the spectrometer respectively, the light source is turned on, and the spectrometer is used to detect and record the spectral information at this time as the reference spectrum.

[0014] Thirdly, the present invention also provides a method for using a tapered fiber hydrogen sensor. The tapered fiber hydrogen sensor, prepared using the above-mentioned method, includes the following steps: Step 1, placing the sensor in the environment to be tested; Step 2, keeping the light source off, using a spectrometer to detect and record the spectral information at this time as the background spectrum; Step 3, turning on the light source switch, using a spectrometer to detect and record the spectral information at this time as the sample spectrum, and calculating the sensor's transmission spectrum by combining the sample spectrum, background spectrum, and reference spectrum.

[0015] The tapered fiber hydrogen sensor and its preparation method of the present invention have the following advantages over the prior art:

[0016] Beneficial effects:

[0017] (1) When the light emitted by the broadband light source of this invention passes through the tapered section of the sensor, the presence of the gold film will generate a surface plasmon resonance effect, causing a characteristic absorption peak to appear in the transmission spectrum of the sensor. The refractive index of the external material can be calculated by converting the position of the characteristic peak, thereby accurately detecting the hydrogen concentration in the environment. This invention uses a tapered method to prepare the fiber optic sensor, which greatly improves the sensitivity of the sensor. The use of tungsten oxide and gold co-sputtering material as the gas-sensitive material greatly improves the response and recovery time compared to using only tungsten oxide as the gas-sensitive material.

[0018] (2) By limiting the thickness of the reaction layer and the catalyst layer, the present invention can adjust the response speed of the sensor to detect hydrogen; by limiting the mass percentage of gold elements in the reaction layer, the present invention can adjust the shift amplitude of the spectral characteristic peak when the sensor detects hydrogen, thereby greatly improving the accuracy and sensitivity of the sensor. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the test examples of the present invention or the prior art, the drawings used in the description of the test examples or the prior art will be briefly introduced below. Obviously, the drawings described below are only some test examples of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the tapered fiber hydrogen sensor of the present invention;

[0021] Figure 2 This is a schematic diagram of the tapered portion of the present invention;

[0022] Figure 3 This is a gas response curve of the tapered fiber hydrogen sensor of the present invention at a hydrogen concentration of 0.3%.

[0023] In the figure: 1. Optical fiber; 11. Tapered section; 2. Sensing section; 21. Excitation layer; 22. Reaction layer; 23. Catalytic layer; 3. Light source; 4. Spectrometer; 5. Gas chamber to be tested; 6. Gas storage tank; 7. Gas mixing mechanism. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, combined with Figure 2 The present invention provides a tapered fiber hydrogen sensor, comprising an optical fiber 1, a sensing unit 2, a light source 3, and a spectrometer 4.

[0026] In this design, optical fiber 1 is a multimode optical fiber with a biconical region, and therefore has a tapered section 11 in its middle. The presence of the tapered section 11 increases the surface area of ​​optical fiber 1, thereby enhancing the interaction between light and surface plasmons and helping to improve the sensitivity of the sensor.

[0027] The sensing unit 2 is tightly fitted around the tapered section 11. The sensing unit 2 comprises a three-layer thin-film structure from the inside out: an excitation layer 21, a reaction layer 22, and a catalyst layer 23. The excitation layer 21 excites the surface of the optical fiber 1 to generate a plasma resonance effect; the reaction layer 22 is made of a gas-sensitive material and reacts with hydrogen; the catalyst layer 23 catalyzes the reaction between the gas-sensitive material and hydrogen.

[0028] Light source 3 is a broadband light source, specifically a laser emitter or a photoelectric converter, which is connected to one end of optical fiber 1 and inputs optical signals into optical fiber 1.

[0029] Spectrometer 4 is connected to the other end of optical fiber 1 and measures the position of characteristic peaks in the spectrum within optical fiber 1. The end of optical fiber 1 is fused to either light source 3 or spectrometer 4.

[0030] The principle of this invention is as follows: When the light emitted by the broadband light source 5 passes through the tapered section 11 of the optical fiber 1, due to the presence of the excitation layer 21, the optical fiber 1 will generate a surface plasmon resonance effect. Therefore, a characteristic absorption peak will appear in the transmission spectrum of the sensor. The position of the characteristic peak is related to the refractive index of the external material, which can be hydrogen gas in the external environment. When the gas-sensitive material of the reaction layer 22 reacts with hydrogen gas under the catalytic action of the catalytic layer 23 and produces a change in refractive index, the position of the characteristic peak will also change accordingly, thereby enabling accurate detection of the concentration and changes of the external ambient gas.

[0031] exist Figure 2 In a preferred experimental example shown, the excitation layer 21 is formed by plating elemental gold; the reaction layer 22 is formed by co-sputtering tungsten oxide and elemental gold as gas-sensitive materials; and the catalyst layer 23 is formed by plating elemental platinum. The excitation layer 21, being a gold film, excites the plasmon resonance effect on the surface of the tapered optical fiber, resulting in a characteristic peak in the sensor's transmission spectrum that can detect changes in the outer refractive index. The reaction layer 22, a co-sputtered layer of tungsten oxide and gold, acts as a gas-sensitive material, reacting with hydrogen to produce a change in refractive index. The catalyst layer 23, a platinum film, allows hydrogen to react with the co-sputtered layer of tungsten oxide and gold only in its presence, thus playing a catalytic role.

[0032] exist Figure 2 In a preferred experimental example shown, the reaction layer 22 has a thickness of 15-60 nm. The thickness of the reaction layer 22 directly affects the reactivity of the gas-sensitive material: an excessively thin reaction layer 22 may not provide enough reaction area, resulting in insufficient contact between the gas and the material, reducing the sensor's sensitivity to hydrogen, and may even lead to incomplete reaction; an excessively thick reaction layer 22 may prevent the gas from diffusing effectively within the reaction layer, causing the reaction to become slow or uneven, affecting the sensor's response time and stability. An appropriate reaction layer 22 thickness can improve the sensor's gas detection sensitivity. Especially in the 15-60 nm range, the reaction layer 22 can minimize the impact of signal noise while responding to changes in gas concentration, thereby improving the sensor's selectivity. Furthermore, this thickness can also optimize the spectral peak position changes during the reaction with hydrogen, allowing changes in gas concentration to be detected accurately and clearly.

[0033] Furthermore, the thickness of the reaction layer 22 needs to be considered in conjunction with the catalyst layer 23 and the excitation layer 21. The catalyst layer 23 helps accelerate the reaction between hydrogen and the reaction layer, while the excitation layer 21 improves the sensor's response sensitivity by providing a surface plasmon resonance (SPR) effect. Therefore, the thickness of the reaction layer 22 can be coordinated with the thicknesses of the other layers to optimize the overall sensor performance and avoid affecting the sensor's efficiency and stability due to layer thickness mismatch.

[0034] exist Figure 2 In a preferred experimental example shown, the thickness of the catalyst layer 23 is no greater than 1 nm. A thin catalyst layer 23 can maintain a high density of catalytic active sites, maximizing the catalytic reaction surface area, thereby more effectively catalyzing the hydrogen reaction. However, an excessively thick catalyst layer 23 would result in unnecessary additional thickness, potentially affecting the transmission of optical signals. Especially in sensors based on surface plasmon resonance (SPR) or other optical principles, an excessively thick catalyst layer 23 can cause changes in the light propagation mode, reducing the sensor's sensitivity and response speed. Therefore, controlling the thickness of the catalyst layer 23 can effectively avoid this unnecessary optical interference.

[0035] exist Figure 2 In one preferred experimental example shown, the mass percentage of gold in the reaction layer 22 is 9.4%–45%. The mass percentage of gold is directly proportional to the gold deposition rate during the reaction layer 22 process.

[0036] exist Figure 2 In a preferred experimental example shown, the diameter of the tapered section 11 is no greater than 5 μm. When the diameter of the tapered section 11 is smaller, the mode field of the fiber 1 changes and concentrates in the surface region of the fiber 1, thus making the interaction between the surface of the fiber 1 and the surrounding gas or liquid medium more significant. For SPR sensors, the propagation of surface plasmon waves and the reflection and transmission effects of the fiber 1 surface directly affect the sensor's performance. A smaller fiber 1 diameter helps to enhance this interaction, thereby improving the sensor's sensitivity and detection accuracy.

[0037] like Figure 1 As shown, combined with Figure 2 The present invention discloses a method for preparing a tapered fiber optic hydrogen sensor, used to prepare a tapered fiber optic hydrogen sensor for any of the above-mentioned experimental examples, comprising the following steps:

[0038] Step 1: A tapered section 11 is fabricated on optical fiber 1 using fused taper. Specifically, 62.5 / 125 multimode optical fiber is used as the raw material, and the tapered section 11 is fabricated on it by fused tapering the middle of optical fiber 1. Before tapering, a 20mm coating layer is removed from optical fiber 1, and it is cleaned with anhydrous ethanol. The stretched length of the fiber after tapering is 17,000 μm, and the waist diameter is 5 μm.

[0039] Step 2: On the tapered section 11, the excitation layer 21, the reaction layer 22 and the catalyst layer 23 are sequentially deposited from the inside to the outside by magnetron sputtering.

[0040] Specifically, firstly, an excitation layer 21 is deposited on the surface of the tapered section 11, which is prepared by DC magnetron sputtering of a gold target. The deposition thickness of the excitation layer 21 is 30 nm. During magnetron sputtering, the technical parameters are set as follows: deposition temperature is 25℃; nitrogen flow rate is 14 sccm; and gold deposition rate is...

[0041] Then, a reaction layer 22 is deposited, which is prepared by simultaneous magnetron sputtering using gold and tungsten targets. Tungsten oxide is sputtered by radio frequency (RF) sputtering, and gold by DC sputtering. The deposition thickness of reaction layer 22 is 30 nm. The magnetron sputtering parameters are set as follows: deposition temperature 25°C; nitrogen flow rate 13 sccm; oxygen flow rate 6.5 sccm; tungsten oxide deposition rate... Gold deposition rate is

[0042] Finally, a catalyst layer 23 was deposited, which was prepared by DC sputtering of a platinum target. The deposition thickness of the catalyst layer 23 was 0.5 nm. The magnetron sputtering parameters were set as follows: deposition temperature 25 °C; nitrogen flow rate 14 sccm; platinum deposition rate...

[0043] Step 3: Connect both ends of optical fiber 1 to light source 3 and spectrometer 4 respectively by fusion splicing.

[0044] exist Figure 2 In one preferred experimental example shown, in step two, a reaction layer 22 is formed by simultaneous magnetron sputtering using a gold target and a tungsten target, wherein the gold deposition rate is... With the deposition rate of tungsten oxide remaining constant, changes in the deposition rate of gold will alter the mass percentage of gold in reaction layer 22, thereby changing the shift of the spectral characteristic peak when the sensor detects hydrogen, thus adjusting the sensor's accuracy and sensitivity.

[0045] exist Figure 2In one preferred experimental example shown, in step two, after the excitation layer 21 is deposited on the surface of the tapered section 11, the two ends of the optical fiber 1, which is only coated with gold film, are connected to the light source 3 and the spectrometer 4 respectively. The light source 3 is turned on, and the spectrometer 4 is used to detect and record the spectral information at this time as a reference spectrum.

[0046] like Figure 1 As shown, combined with Figure 3 The present invention discloses a method for using a tapered fiber optic hydrogen sensor, which is a tapered fiber optic hydrogen sensor prepared using the preparation method of the tapered fiber optic hydrogen sensor described in the above-mentioned experimental example, comprising the following steps:

[0047] Step one: Place the sensor in the test environment. Specifically, a simulation experiment can be conducted. Place the conical section 11 and sensing part 2 of the sensor in a closed test chamber 5, with the light source 3 and spectrometer 4 located in the test chamber 5. Set up multiple gas storage tanks 6, each containing hydrogen, nitrogen, and air respectively. All gas storage tanks 6 are connected to a gas mixing mechanism 7, which in turn is connected to the test chamber 5. The gas mixing mechanism 7 mixes nitrogen and hydrogen in a certain proportion to produce a mixed gas with different hydrogen concentrations. The mixed gas is introduced into the test chamber 5, and the position of the characteristic peak of the sensor spectrum is measured by the spectrometer 4 to detect the hydrogen concentration in the current test chamber 5.

[0048] In addition, during the test, nitrogen gas is first introduced into the test chamber 5 for 10,000 seconds; after the transmission spectrum stabilizes, a nitrogen gas mixture with a concentration of 0.3% is introduced for 1,800 seconds; then air is introduced as the recovery gas for 1,800 seconds.

[0049] Step 2: Keep light source 3 off, and use spectrometer 4 to detect and record the spectral information at this time as the background spectrum.

[0050] Step 3: Turn on the light source 3 switch, and use the spectrometer 4 to detect and record the spectral information at this time as the sample spectrum. Combine the sample spectrum, background spectrum, and reference spectrum to calculate the sensor's transmission spectrum. The formula for calculating the transmission spectrum is: T = (SD) / (LD), where T is the sensor's transmission spectrum, S is the sensor's sample spectrum when the light source is on, D is the sensor's background spectrum, and L is the sensor's reference spectrum.

[0051] This invention designs experimental examples 1 to 10 to simulate the process of a tapered fiber optic hydrogen sensor detecting hydrogen concentration, and uses the above-described detection method to measure the spectral characteristic peak positions and response times of the sensors in each experimental example. Specifically, the experimental examples are as follows:

[0052] Experimental Example 1

[0053] Fiber 1 is a 62.5 / 125 multimode fiber, with a tapered section 11 having a stretch length of 17000μm and a waist diameter of 5μm.

[0054] The deposition thickness of the excitation layer 21 is 30 nm; the technical parameters for magnetron sputtering are set as follows: deposition temperature 25℃; nitrogen flow rate 14 sccm; gold deposition rate... The deposition thickness of the reaction layer 22 is 30 nm; its magnetron sputtering parameters are set as follows: deposition temperature 25℃; nitrogen inlet flow rate 13 sccm; oxygen inlet flow rate 6.5 sccm; tungsten oxide deposition rate... Gold deposition rate is At this point, the mass percentage of gold in reaction layer 22 is 29%. The deposition thickness of catalyst layer 23 is 0.5 nm; its magnetron sputtering parameters are set as follows: deposition temperature is 25℃; nitrogen flow rate is 14 sccm; platinum deposition rate is...

[0055] In the simulation test, the hydrogen concentration in the test chamber 5 was 0.3%.

[0056] The gas response curve of the sensor was obtained as follows: Figure 3 As shown, the sensor produced a 7.6 nm characteristic peak position shift at a hydrogen concentration of 0.3%, with a response time exceeding 174 seconds. It can be observed that in this experimental example, the sensor's spectral characteristic peak is very significant, and the sensor's response time is extremely short.

[0057] Experimental Example 2

[0058] When depositing reactive layer 22, the gold deposition rate is set to... Other parameters remained the same as in Experimental Example 1, resulting in a low-gold-content tungsten oxide and gold co-sputtered reaction layer 22; at this time, the mass percentage of gold in reaction layer 22 was 9.4%.

[0059] Using the same test method as in Example 1, it was found that the sensor produced a 6 nm characteristic peak position shift at a hydrogen concentration of 0.3%, with a response time exceeding 1800 seconds.

[0060] Experimental Example 3

[0061] When depositing reactive layer 22, the gold deposition rate is set to... Other parameters remained the same as in Experiment 1, resulting in a high gold content tungsten oxide and gold co-sputtered reaction layer 22; at this time, the mass percentage of gold in reaction layer 22 was 49%.

[0062] Using the same test method as in Test Example 1, it was found that the sensor produced a 6.9 nm characteristic peak position shift at a hydrogen concentration of 0.3%, with a response time exceeding 1590 seconds.

[0063] By comparing the detection structures of Experimental Examples 2 and 3 with those of Experimental Example 1, it can be seen that if the mass ratio of gold elements in the reaction layer 22 is too high or too low, it will seriously affect the response speed of the sensor.

[0064] Test Example 4

[0065] When depositing the reaction layer 22, the deposition thickness of the reaction layer 22 was set to 15 nm, and other parameters were kept consistent with those in Experimental Example 1, resulting in a low-thickness reaction layer 22 co-sputtered with tungsten oxide and gold.

[0066] Using the same test method as in Example 1, it was found that the sensor produced a 6 nm characteristic peak position shift at a hydrogen concentration of 0.3%, with a response time exceeding 1800 seconds.

[0067] Experimental Example 5

[0068] When depositing the reaction layer 22, the deposition thickness of the reaction layer 22 was set to 60 nm, and other parameters were kept consistent with those in Experimental Example 1, resulting in a high-thickness reaction layer 22 co-sputtered with tungsten oxide and gold.

[0069] Using the same test method as in Example 1, it was found that the sensor produced a 6 nm characteristic peak position shift at a hydrogen concentration of 0.3%, with a response time exceeding 1800 seconds.

[0070] By comparing the detection structures of Experiment 4 and 5 with those of Experiment 1, it can be seen that if the deposition thickness of the reaction layer 22 is too high or too low, it will seriously affect the response speed of the sensor.

[0071] Experimental Example 6

[0072] The catalyst layer 23 is not deposited outside the reaction layer 22, that is, the deposition thickness of the catalyst layer 23 is set to 0 nm, and other parameters are consistent with those in Experimental Example 1.

[0073] Using the same experimental method as in Example 1, it was found that the sensor did not produce a hydrogen response at a hydrogen concentration of 0.3%. This indicates that if a platinum layer is not deposited on the tungsten oxide and gold co-sputtered layer as a catalyst, the tungsten oxide and gold co-sputtered layer will not react with hydrogen, and therefore will not produce spectral characteristic peaks.

[0074] Experimental Example 7

[0075] When depositing the catalyst layer 23, the deposition thickness of the catalyst layer 23 was set to 1 nm, and other parameters were kept consistent with those in Experimental Example 1, resulting in a high-thickness platinum sputtered catalyst layer 23.

[0076] Using the same experimental method as in Example 1, it was found that the sensor produced an 8.6 nm characteristic peak shift at a hydrogen concentration of 0.3%, with a response time exceeding 490 seconds. This indicates that the shift in the characteristic peak is greater than in Example 1, but the improvement in sensor responsivity is relatively small.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tapered fiber optic hydrogen sensor, characterized in that, include: Optical fiber (1), with a tapered section (11) in its middle; The sensing unit (2) is tightly fitted outside the tapered section (11); A light source (3) is connected to one end of the optical fiber (1) and inputs an optical signal into the optical fiber (1); A spectrometer (4) is connected to the other end of the optical fiber (1) and measures the position of the characteristic peaks of the spectrum within the optical fiber (1). Wherein, the diameter of the tapered section (11) is not greater than 5 μm; The sensing unit (2) comprises three thin-film structures from the inside out, namely, Excitation layer (21) is used to excite the surface of the optical fiber (1) to generate a plasma resonance effect. The excitation layer (21) is made of single gold plating. The reaction layer (22) is made of a gas-sensitive material and reacts with hydrogen. The reaction layer (22) is formed by co-sputtering tungsten oxide and elemental gold as gas-sensitive materials. The thickness of the reaction layer (22) is 15-60 nm, and the mass percentage of gold in the reaction layer (22) is 9.4-45%. The catalyst layer (23) catalyzes the reaction of the gas-sensitive material with hydrogen. The catalyst layer (23) is made of elemental platinum and the thickness of the catalyst layer (23) is no more than 1 nm.

2. A method for fabricating a tapered optical fiber hydrogen sensor, characterized in that: The preparation of the tapered fiber hydrogen sensor according to claim 1 includes the following steps: Step 1: A tapered section (11) is formed on the optical fiber (1) by fusion tapering. Step 2: On the tapered section (11), an excitation layer (21), a reaction layer (22) and a catalyst layer (23) are sequentially deposited from the inside to the outside by magnetron sputtering. Step 3: Connect the two ends of the optical fiber (1) to the light source (3) and the spectrometer (4) respectively.

3. The method for preparing a tapered fiber optic hydrogen sensor according to claim 2, characterized in that: In step two, a reaction layer (22) is formed by simultaneous magnetron sputtering of gold and tungsten targets, wherein the gold deposition rate is 0-0.4 Å / sec.

4. The method for preparing a tapered fiber optic hydrogen sensor according to claim 2, characterized in that: In step two, after the excitation layer (21) is deposited on the surface of the tapered section (11), the two ends of the optical fiber (1) with only gold film are connected to the light source (3) and the spectrometer (4) respectively. The light source (3) is turned on, and the spectrometer (4) is used to detect and record the spectral information at this time as a reference spectrum.

5. A method of using a tapered fiber optic hydrogen sensor, characterized in that: A tapered fiber optic hydrogen sensor, fabricated using the method described in claim 4, comprises the following steps: Step 1: Place the sensor in the environment to be tested; Step 2: Keep the light source (3) off, and use the spectrometer (4) to detect and record the spectral information at this time as the background spectrum; Step 3: Turn on the light source (3) switch, use the spectrometer (4) to detect and record the spectral information at this time as the sample spectrum, and calculate the transmission spectrum of the sensor by combining the sample spectrum, background spectrum and reference spectrum.

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