Hydrogen sensor, hydrogen detection system, related method and aircraft

Abstract

The invention relates to a hydrogen sensor, a hydrogen detection system comprising the hydrogen sensor, a method for measuring hydrogen concentration and an aircraft. The hydrogen sensor comprises an optical fiber core part, an optical fiber cladding surrounding the optical fiber core part and a hydrogen-sensitive coating surrounding the optical fiber cladding, and the hydrogen-sensitive coating is configured to be capable of absorbing hydrogen to expand. The optical fiber core part comprises a first half part and a second half part which are divided by a virtual plane extending in the axial direction of the optical fiber core part, and a first Bragg grating and a second Bragg grating with different grating periods are etched in the first half part and the second half part respectively. According to the hydrogen sensor disclosed by the invention, the grating strain variable quantity and the temperature variable quantity at the same spatial position can be simultaneously measured, so that the hydrogen concentration is measured based on the strain variable quantity, the interference of the temperature variable quantity on detection is eliminated, and the sensitivity and the reliability of the hydrogen sensor are improved.

Description

Technical Field

[0001] The present disclosure relates to a hydrogen sensor, a detection system and related methods for detecting hydrogen leakage, and also relates to an aircraft including such a detection system. Background Art

[0002] The content of this section only provides background information related to the present disclosure, which may not constitute prior art.

[0003] Hydrogen is widely sourced, has a high calorific value and no carbon emissions, and is one of the most promising clean energy sources at present. In particular, hydrogen may at least partially replace existing fossil fuels as the energy source for future aircraft. For example, hydrogen may be directly burned as fuel or made into a fuel cell to supply energy to the aircraft. Such a use of hydrogen raises many specific design considerations. Hydrogen is combustible, has a relatively small molecular weight compared to other fuels, and is colorless and odorless. Therefore, special attention needs to be paid to how to store hydrogen sufficiently without leakage and make any leakage detectable. At normal temperature and pressure, combustion may occur when the hydrogen content in the air is between 4.0% and 75%. Therefore, it is necessary to develop a hydrogen sensor with appropriate sensitivity and reliability to quickly and accurately detect hydrogen leakage.

[0004] Optical fiber sensors have the advantages of small size, light weight, low power consumption, corrosion resistance, electromagnetic interference resistance, and suitability for long-distance signal transmission, and can work normally in various complex environments, meeting the technical requirements of hydrogen sensors. Currently, there are hydrogen sensors including fiber Bragg gratings. When light passes through a fiber Bragg grating, light near a specific central wavelength will be reflected by the grating. The central wavelength of the reflected light is related to the grating period and will shift due to the strain and temperature of the grating. Such hydrogen sensors may include a hydrogen-sensitive coating coated on the fiber Bragg grating. The hydrogen-sensitive coating absorbs hydrogen and expands, causing strain on the grating. Therefore, the hydrogen concentration can be established as a function of the strain of the grating. Thus, the strain of the grating can be detected by measuring the shift of the central wavelength of the reflected light, and then the hydrogen concentration can be obtained. However, since both the grating strain and temperature affect the shift of the central wavelength of the reflected light, it is necessary to separate variables to exclude the interference of temperature changes when measuring the grating strain. One current solution is to set two fiber Bragg grating sensors in series or parallel as a control group. However, it is impossible to ensure that two independent gratings at different spatial positions have exactly the same strain or temperature. Therefore, the accuracy of this hydrogen detection scheme is relatively low, especially unable to adapt to applications with extremely high safety standards such as aircraft. In addition, setting multiple fiber Bragg grating sensors in series or parallel at different spatial positions requires a large installation space, increasing the complexity and cost of the hydrogen detection system. Summary of the Invention

[0005] One object of the present disclosure is to provide a hydrogen detection solution with high sensitivity and high reliability. Another object of the present disclosure is to eliminate the influence of the cross-sensitivity of the fiber Bragg grating type hydrogen sensor to strain and temperature on the accuracy of hydrogen detection. Still another object of the present disclosure is to provide a hydrogen detection solution with a simple structure and low cost.

[0006] The first aspect of the present disclosure provides a hydrogen sensor, which includes a fiber core, a fiber cladding surrounding the fiber core, and a hydrogen-sensitive coating surrounding the fiber cladding. The hydrogen-sensitive coating is configured to be able to absorb hydrogen and expand. The fiber core includes a first half and a second half divided by a virtual plane extending in the axial direction of the fiber core. A first Bragg grating and a second Bragg grating with different grating periods are etched in the first half and the second half respectively.

[0007] In some embodiments, the first half and the second half may be symmetric about the central axis of the fiber core.

[0008] In some embodiments, the fiber core may have a circular cross-section, and the first half and the second half may be configured as two semi-circular portions divided along the diameter direction of the fiber core.

[0009] In some embodiments, the hydrogen-sensitive coating may include palladium or a palladium alloy.

[0010] In some embodiments, the axial length of the first Bragg grating may be the same as the axial length of the second Bragg grating.

[0011] The second aspect of the present disclosure provides a hydrogen detection system including the hydrogen sensor of the first aspect.

[0012] In some embodiments, the hydrogen detection system may further include a light source, an optical circulator, a signal processing device, and a pigtail fiber. The light source is connected to the first port of the optical circulator via a first transmission fiber. The second port of the optical circulator is connected to one end of the hydrogen sensor via a second transmission fiber. The opposite end of the hydrogen sensor is connected to the pigtail fiber via a third transmission fiber. The third port of the optical circulator is connected to the signal processing device via a fourth transmission fiber.

[0013] In some embodiments, the signal processing device may include a demodulator configured to convert an optical signal into an electrical signal.

[0014] In some embodiments, the hydrogen detection system may further include a display device connected to the signal processing device for displaying the detection result.

[0015] In some embodiments, the light source may be configured as a broadband laser source.

[0016] The third aspect of the present disclosure provides a method for measuring hydrogen concentration. The method includes: setting a hydrogen sensor according to the first aspect above at a position to be measured; passing the light emitted by a light source through the hydrogen sensor; receiving a first optical signal reflected by a first Bragg grating and a second optical signal reflected by a second Bragg grating; measuring an offset Δλ of the central wavelength of the first optical signal relative to a predetermined initial reflected light central wavelength of the first Bragg grating 1 and an offset Δλ of the central wavelength of the second optical signal relative to a predetermined initial reflected light central wavelength of the second Bragg grating 2 ; based on the offset Δλ of the central wavelength of the first optical signal 1 and the offset Δλ of the central wavelength of the second optical signal 2 calculate a common strain change amount Δε of the first Bragg grating and the second Bragg grating; and calculate the hydrogen concentration at the position to be measured based on the strain change amount Δε.

[0017] In some embodiments, the strain change amount Δε can be calculated by the following formula:

[0018]

[0019] wherein, K ε1 is the strain coefficient of the first Bragg grating, K ε2 is the strain coefficient of the second Bragg grating, K T1 is the temperature coefficient of the first Bragg grating, K T2 is the temperature coefficient of the second Bragg grating.

[0020] In some embodiments, the method may further include calculating a common temperature change amount ΔT of the first Bragg grating and the second Bragg grating based on the offset Δλ of the central wavelength of the first optical signal 1 and the offset Δλ of the central wavelength of the second optical signal 2 The temperature change amount ΔT can be calculated by the following formula:

[0021]

[0022] wherein, K ε1 is the strain coefficient of the first Bragg grating, K ε2 is the strain coefficient of the second Bragg grating, K T1 is the temperature coefficient of the first Bragg grating, K T2 is the temperature coefficient of the second Bragg grating.

[0023] In some embodiments, the method may further include calibrating the hydrogen concentration as a function of the common strain of the first Bragg grating and the second Bragg grating.

[0024] A fourth aspect of the present disclosure provides an aircraft including a hydrogen detection system according to the second aspect.

[0025] In various embodiments of the present disclosure, two Bragg gratings with different grating periods are etched into the same section of optical fiber, whereby two optical signals can be reflected simultaneously, so that the hydrogen concentration and temperature at the same spatial position can be measured simultaneously based on these two optical signals, improving the sensitivity and reliability of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the present disclosure will be described hereinafter only by way of example with reference to the drawings. In the drawings, the same features or components are denoted by the same reference numerals, and the drawings are not necessarily drawn to scale. In the drawings:

[0027] Figure 1 shows a longitudinal sectional view taken along the central axis of a hydrogen sensor according to an embodiment of the present disclosure;

[0028] Figure 2 shows Figure 1 a cross-sectional view taken along a direction perpendicular to the central axis of the hydrogen sensor in

[0029] Figure 3 shows a schematic diagram of a hydrogen detection system according to an embodiment of the present disclosure; and

[0030] Figure 4 shows a schematic diagram of an aircraft according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] The following description is essentially exemplary only and is not intended to limit the present disclosure, its application, and uses. It should be understood that in all these drawings, like reference numerals indicate the same or similar parts and features. Each drawing only schematically shows the concept and principle of the embodiments of the present disclosure, and does not necessarily show the specific dimensions and their ratios of the embodiments of the present disclosure. Specific parts in a specific drawing may be exaggerated to illustrate relevant details or structures of the embodiments of the present disclosure.

[0032] In the description of the embodiments of the present disclosure, the orientation terms related to "upper", "lower", etc. are described based on the upper and lower positions of the views shown in the drawings. In actual applications, the "upper", "lower", etc. position relationships used herein can be defined according to actual situations, and these relationships can be reversed with each other and are not intended to limit the scope of the present disclosure.

[0033] Figure 1 shows a longitudinal sectional view taken along the central axis of a hydrogen sensor 10 according to an embodiment of the present disclosure, Figure 2It is a cross-sectional view of the hydrogen sensor 10 taken along a direction perpendicular to the central axis.

[0034] As Figure 1 and Figure 2 shown, the hydrogen sensor 10 is constructed from a section of optical fiber and may include an optical fiber core 101 and an optical fiber cladding 102 surrounding the optical fiber core 101. The optical fiber core 101 may include a first half 103 and a second half 104 divided by a virtual plane extending along its axial direction. Preferably, the first half 103 and the second half 104 are symmetric about the central axis of the optical fiber core 101. In this embodiment, the optical fiber core 101 has a circular cross-section, so the first half 103 and the second half 104 are configured as two semi-circular portions divided along the diameter direction of the optical fiber core 101. In other embodiments, an optical fiber with a non-circular cross-section, such as a polygonal cross-section, may also be used. A first Bragg grating B1 and a second Bragg grating B2 are respectively etched in the first half 103 and the second half 104. The first Bragg grating B1 has a first grating period Λ 1 , and the second Bragg grating 103 has a second grating period Λ 1 different from the first grating period Λ 2 . The axial length of the first Bragg grating B1 may be substantially the same as the axial length of the second Bragg grating B2. The hydrogen sensor 10 further includes a hydrogen-sensitive coating 105, and the hydrogen-sensitive coating 105 is arranged around the optical fiber core 101 where the first Bragg grating B1 and the second Bragg grating B2 are arranged and the optical fiber cladding 102 on its radial outer side. The hydrogen-sensitive coating 105 is configured to be able to absorb hydrogen and expand, causing axial and radial deformations of the optical fiber core 101 and the optical fiber cladding 102, thereby generating strain in the first Bragg grating B1 and the second Bragg grating B2. The hydrogen-sensitive coating 105 may include, for example, a thin film made of palladium (Pd) or a palladium alloy. The optical fiber cladding 102 disposed between the optical fiber core 101 and the hydrogen-sensitive coating 105 can play a role in protecting the optical fiber core 101 and the gratings therein.

[0035] When manufacturing the hydrogen sensor 10, the second half 104 of the optical fiber core 101 can be masked first and the first Bragg grating B1 can be laser-etched in the first half 103, and then the etched first half 103 can be masked and the second Bragg grating B2 can be laser-etched in the second half 104. Alternatively, the first Bragg grating B1 and the second Bragg grating B2 with high consistency and stability can also be etched by a single exposure with a laser passing through a two-dimensional spatial phase mask with a double periodic structure. After etching the first Bragg grating B1 and the second Bragg grating B2, the hydrogen-sensitive coating 105 can be applied on the outer peripheral surface of the optical fiber cladding 102 around the first Bragg grating B1 and the second Bragg grating B2.

[0036] Figure 3 FIG. 1 shows a schematic diagram of a hydrogen detection system 1 according to an embodiment of the present disclosure. As Figure 3 shown, the hydrogen detection system 1 generally may include the aforementioned hydrogen sensor 10, a light source 20, an optical circulator 30, a signal processing device 40, and a pigtail fiber 50. The hydrogen sensor 10 is arranged at a position to be measured, for example, it may be arranged in a closed or semi-closed gas chamber 60. The arrangement of the gas chamber 60 can prevent dust and the like from affecting the sensing accuracy of the hydrogen sensor 10. The light source 20 may be configured as a broadband laser source (BBS). An optical circulator is a multi-port optical device with non-reciprocal characteristics. In the present embodiment, the optical circulator 30 has three ports. When an optical signal is input from any port, the optical signal will output from the next port with a very small loss, that is, the optical signal input from the first port 301 of the optical circulator 30 can only output from the second port 302, and the optical signal input from the second port 302 can only output from the third port 303, and so on. The light source 20 is connected to the first port 301 of the optical circulator 30 via a first transmission optical fiber 701. One end of the hydrogen sensor 10 is connected to the second port 302 of the optical circulator 30 via a second transmission optical fiber 702, and the opposite end of the hydrogen sensor 10 is connected to the pigtail fiber 50 via a third transmission optical fiber 703. The signal processing device 40 is connected to the third port 303 of the optical circulator 30 via a fourth transmission optical fiber 704. The signal processing device 40 is configured to receive the optical signal output from the third port 303 and calculate the hydrogen concentration accordingly. The signal processing device 40 may include, for example, a demodulator configured to convert the optical signal into an electrical signal. The hydrogen sensor 10 may further include a display device 80 for displaying the detection result, and the display device may be connected to the signal processing device 40. The display device 80 may display data such as the center wavelength of the reflected light, temperature, hydrogen concentration, etc.

[0037] The principle of using the hydrogen detection system 1 to measure the hydrogen concentration is specifically described below. The hydrogen sensor 10 includes two Bragg gratings with different grating periods. A Bragg grating is a narrowband filter with a periodic microstructure, which has a strong reflection effect only on light with a very narrow spectrum near a specific center wavelength (also known as the Bragg wavelength), and the remaining light waves will continue to propagate through the Bragg grating. The center wavelength λ of the reflected light satisfies the Bragg equation:

[0038] λ = 2nΛ

[0039] where n is the refractive index and Λ is the grating period (i.e., the distance between two adjacent grooves in the Bragg grating).

[0040] When the optical fiber with a Bragg grating is stretched or compressed, the grating period Λ of the Bragg grating will change accordingly. In addition, the sensitivity to temperature is another characteristic of the Bragg grating. On the one hand, the thermo-optic effect will cause a change in the refractive index n. On the other hand, the thermal expansion of the grating will cause a change in the grating period Λ. Since the refractive index n and the grating period Λ are affected by the grating strain and the ambient temperature around the grating, the central wavelength of the reflected light reflected by the Bragg grating will also change with the changes in strain and temperature. Therefore, the change in the corresponding physical quantity of the part to be measured can be determined according to the offset of the central wavelength of the reflected light relative to the predetermined initial central wavelength of the reflected light. For example, the central wavelength of the reflected light at a temperature of 0 °C and a grating strain of 0 can be used as the initial central wavelength of the reflected light. The offset Δλ of the central wavelength of the reflected light can be calculated by Equation (1):

[0041] Δλ = K ε *Δε + K T *ΔT (1)

[0042] Where, K ε is the strain coefficient, Δε is the strain change of the Bragg grating, K T is the temperature coefficient, and ΔT is the ambient temperature change.

[0043] The light emitted by the light source 20 is transmitted to the hydrogen sensor 10 via the first transmission optical fiber 701, the first port 301 and the second port 302 of the optical circulator 30, and the second transmission optical fiber 702. At the hydrogen sensor 10, the first Bragg grating B1 and the second Bragg grating B2 will respectively reflect the first optical signal and the second optical signal near the corresponding central wavelengths. These two reflected optical signals are output to the signal processing device 40 via the second transmission optical fiber 702 and the third port 303 of the optical circulator 30. The remaining unreflected light passes through the hydrogen sensor 10 and continues to be transmitted to the pigtail 50 via the third transmission optical fiber 703.

[0044] When the hydrogen-sensitive coating 105 of the hydrogen sensor 10 absorbs hydrogen, it will expand radially and axially, thereby causing strain in the optical fiber core 101 etched with the first Bragg grating B1 and the second Bragg grating B2. Therefore, the central wavelengths of the reflected lights corresponding to the first Bragg grating B1 and the second Bragg grating B2 shift relative to their initial values. Since the first Bragg grating B1 and the second Bragg grating B2 are etched in two halves of the same section of optical fiber, that is, at the same spatial point, the first Bragg grating B1 and the second Bragg grating B2 have substantially the same ambient temperature change amount ΔT, and have substantially the same strain change amount Δε when the optical fiber deforms. Then, the offset Δλ 1 of the central wavelength of the reflected light of the first Bragg grating B1 2 and the offset Δλ

[0045]

[0046] Among them, K ε1 is the strain coefficient of the first Bragg grating B1, K ε2 is the strain coefficient of the second Bragg grating B2, K T1 is the temperature coefficient of the first Bragg grating B1, K T2 is the temperature coefficient of the second Bragg grating B2. These coefficients can be determined, for example, through a calibration test.

[0047] From equation (2), the strain change Δε and the temperature change ΔT can be solved, as shown in equations (3) and (4):

[0048]

[0049]

[0050] Based on the change amounts and initial values of the strain and temperature of the grating, the current strain ε and temperature T of the grating can be determined. Since the strain of the grating is caused by the expansion of the hydrogen-sensitive coating 105 absorbing hydrogen, the hydrogen concentration C H can be calibrated as a function of the strain ε, as shown in equation (5):

[0051] C H = f(ε) (5)

[0052] Therefore, according to the hydrogen detection system 1 of the present disclosure, two variables, namely, the strain change Δε and the temperature change ΔT, can be separated and calculated respectively, so that the hydrogen concentration and temperature at the same spatial position can be accurately measured simultaneously, excluding the interference of the temperature factor in the process of measuring the hydrogen concentration through the offset of the central wavelength of the reflected light.

[0053] In an existing conventional hydrogen detection system using two fiber optic sensors in series or parallel as a control group, the two fiber optic sensors measure the temperature and strain at two different spatial positions. Therefore, it is impossible to completely separate the effects of temperature and strain on the offset of the central wavelength of the detected reflected light. In the hydrogen detection system 1 according to the present disclosure, the two Bragg gratings are etched in the same section of optical fiber, thus enabling simultaneous measurement of the temperature and strain at the same spatial position, accurately eliminating the influence of temperature changes on the measurement result of hydrogen concentration, and improving the detection sensitivity and reliability. If the two Bragg gratings are symmetrically arranged with respect to the central axis in the optical fiber core and have substantially the same axial length, consistent strain of the two Bragg gratings can be ensured in the case of deformation of the optical fiber in any direction, which is beneficial to further improving the detection sensitivity and reliability. In addition, arranging the two Bragg gratings in the same section of optical fiber significantly simplifies the structure of the hydrogen detection system, reduces the space occupied by the hydrogen detection system, and lowers the cost.

[0054] As Figure 4 Schematically shown, the hydrogen sensor 10 according to the present disclosure or the hydrogen detection system 1 including the hydrogen sensor can be applied in the aircraft 2. The aircraft 2 can be an aircraft that directly uses hydrogen as fuel for combustion or uses a hydrogen fuel cell for power supply. The hydrogen sensor 10 can be arranged, for example, near the hydrogen storage tank or the hydrogen fuel cell (not shown) of the aircraft 2. The display device 80 of the hydrogen detection system 1 can be arranged, for example, in the cockpit 202 of the aircraft 2.

[0055] Herein, exemplary embodiments of the hydrogen sensor, hydrogen detection system, aircraft, and related methods according to the present disclosure have been described in detail. However, it should be understood that the present disclosure is not limited to the specific embodiments described and illustrated above in detail. Those skilled in the art can make various modifications and variations to the present disclosure without departing from the gist and scope of the present disclosure. All such modifications and variations fall within the scope of the present disclosure. Moreover, all components described herein can be replaced by other technically equivalent components.

Claims

1. A hydrogen sensor (10), comprising an optical fiber core (101), an optical fiber cladding (102) surrounding the optical fiber core (101), and a hydrogen-sensitive coating (105) surrounding the optical fiber cladding (102), wherein the hydrogen-sensitive coating (105) is configured to absorb hydrogen and expand. It is characterized in that The optical fiber core (101) comprises a first half (103) and a second half (104) divided by a virtual plane extending along the axial direction of the optical fiber core (101), and a first Bragg grating (B1) and a second Bragg grating (B2) having different grating periods are respectively etched in the first half (103) and the second half (104).

2. The hydrogen sensor (10) according to claim 1, It is characterized in that The first half (103) and the second half (104) are symmetrical about the central axis of the optical fiber core (101).

3. The hydrogen sensor (10) according to claim 1 or 2, It is characterized in that The optical fiber core has a circular cross section, and the first half (103) and the second half (104) are constructed as two semicircular parts divided along the diameter direction of the optical fiber core.

4. The hydrogen sensor (10) according to claim 1 or 2, It is characterized in that The hydrogen sensitive coating (105) comprises palladium or a palladium alloy.

5. The hydrogen sensor (10) according to claim 1 or 2, It is characterized in that The axial length of the first Bragg grating (B1) is the same as the axial length of the second Bragg grating (B2).

6. A hydrogen detection system (1), It is characterized in that The hydrogen gas detection system comprises the hydrogen gas sensor (10) according to any one of claims 1 to 5.

7. The hydrogen detection system (1) according to claim 6, It is characterized in that The hydrogen detection system (1) further comprises a light source (20), an optical circulator (30), a signal processing device (40) and a pigtail (50). The light source (20) is connected to the first port (301) of the optical circulator (30) via a first transmission optical fiber (701), the second port (302) of the optical circulator (30) is connected to one end of the hydrogen sensor (10) via a second transmission optical fiber (702), the opposite end of the hydrogen sensor (10) is connected to the pigtail (50) via a third transmission optical fiber (703), and the third port (303) of the optical circulator (30) is connected to the signal processing device (40) via a fourth transmission optical fiber (704).

8. The hydrogen detection system (1) according to claim 7, It is characterized in that The signal processing device (40) includes a demodulator configured to convert an optical signal into an electrical signal.

9. The hydrogen detection system (1) according to claim 7, It is characterized in that The hydrogen detection system (1) further comprises a display device (80) connected to the signal processing device (40) for displaying detection results.

10. The hydrogen detection system (1) according to claim 7, It is characterized in that The light source (20) is configured as a broadband laser source.

11. A method for measuring hydrogen concentration, It is characterized in that The method comprises: A hydrogen sensor (10) is arranged at a position to be measured, the hydrogen sensor (10) comprising an optical fiber core (101), an optical fiber cladding (102) surrounding the optical fiber core (101), and a hydrogen-sensitive coating (105) surrounding the optical fiber cladding (102), the hydrogen-sensitive coating (105) being configured to absorb hydrogen and expand, wherein the optical fiber core (101) comprises a first half (103) and a second half (104) divided by a virtual plane extending in the axial direction of the optical fiber core (101), a first Bragg grating (B1) and a second Bragg grating (B2) having different grating periods are respectively etched in the first half (103) and the second half (104), allowing light emitted by a light source (20) to pass through the hydrogen sensor (10); receiving a first optical signal reflected by the first Bragg grating (B1) and a second optical signal reflected by the second Bragg grating (B2); measuring an offset Δλ of a central wavelength of the first optical signal relative to a predetermined initial reflected light central wavelength of the first Bragg grating (B1); 1 and an offset Δλ of the central wavelength of the second optical signal relative to the central wavelength of the predetermined initial reflected light of the second Bragg grating (B2) 2 ; The offset Δλ based on the central wavelength of the first optical signal 1 and the offset Δλ of the central wavelength of the second optical signal 2 Calculating a common strain variation Δε of the first Bragg grating (B1) and the second Bragg grating (B2); and The hydrogen concentration at the position to be measured is calculated based on the strain change Δε.

12. The method according to claim 11, It is characterized in that The strain change Δε is calculated by the following formula: Among them, K ε1 is the gauge factor of the first Bragg grating (B1), K ε2 is the gauge factor of the second Bragg grating (B2), K T1 is the temperature coefficient of the first Bragg grating (B1), K T2 is the temperature coefficient of the second Bragg grating (B2).

13. The method according to claim 11, It is characterized in that The method further includes determining the offset Δλ based on the central wavelength of the first optical signal. 1 and the offset Δλ of the central wavelength of the second optical signal 2 The temperature variation ΔT of the first Bragg grating (B1) and the second Bragg grating (B2) is calculated. The temperature variation ΔT is calculated by the following formula: Among them, K ε1 is the gauge factor of the first Bragg grating (B1), K ε2 is the gauge factor of the second Bragg grating (B2), K T1 is the temperature coefficient of the first Bragg grating (B1), K T2 is the temperature coefficient of the second Bragg grating (B2).

14. The method according to claim 11, It is characterized in that The method further comprises calibrating the hydrogen concentration as a function of a common strain ε of the first Bragg grating (B1) and the second Bragg grating (B2).

15. An aircraft (2), It is characterized in that The aircraft comprises a hydrogen detection system (1) according to any one of claims 6 to 10.

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