Fiber bragg grating hydrogen sensing system based on amorphous palladium-based alloy and sensor

[0005] However, fiber gratings have the problem of cross-sensitivity between strain and temperature. In order to achieve high-precision measurement, it is usually necessary to perform temperature compensation on the fiber grating sensing system.

Patent CN105841840A proposes an optical fiber sensor capable of simultaneously measuring hydrogen gas concentration and temperature. Its essence is to realize simultaneous measurement of hydrogen gas concentration and temperature by monitoring the interference spectrum generated by the coreless fiber and the reflect...

Referring to accompanying drawing 1, corrode the fiber cladding (2) engraved with fiber Bragg grating (1) with hydrofluoric acid, make its thickness reduce, thereby improve sensor sensitivity. With the corroded cladding as the substrate, a certain thickness of polyimide film and Ni film are coated successively as the adhesion layer (3), the purpose is to increase the adhesion between the sensing layer and the optical fiber cladding to prevent hydrogen Sensitive material falls off. The amorphous palladium-based alloy film coated on the outside of the adhesion layer constitutes the outermost sensing layer (4) of the hydrogen-sensitive probe. The Pd-Cu-Si amorphous alloy film is selected as the hydrogen-sensitive material, and its preparation method is as follows: coating The method uses the vacuum magnetron sputtering method, the target material is a Pd target with a purity of 99.99% and a CuSi alloy target with a purity of 99.9%, and the atomic ratio of the CuSi alloy target is Cu:Si=5:17; the Pd target is connected to a DC power supply CuSi target Connect the radio frequency power supply; control the thickness of the film by changing the current of the DC power supply and the power of the radio frequency power supply, and finally anneal the film. It should be pointed out that the ratio of the cross-sectional area of ​​the film to the optical fiber will directly affect the sensitivity and time response of the sensor. The sensitivity increases with the increase of the ratio, but the response time decreases with the increase of the film thickness. In order to obtain a fast-response fiber-optic hydrogen sensor, the thickness of the film layer in this example is selected as 30 nm. In order to increase the sensitivity and ensure the mechanical strength, the diameter o...