Fiber Micro-cavity And Its Applications In Hydrogen Sensing

In the paper,fiber micro-cavity and its applications in Hydrogen sensing have been proposed.Starting from the theoretical analysis of the cascade structures of optical fiber microcavities,the sensing characteristics of structures combined with different sensitive membranes are explored,and Hydrogen sensor with different structures has been realized.The details are shown as following:1.The characteristics of cascaded fiber optic microcavity have been studied.The envelope of the reflection spectrum is periodic and is related with?FSR.The amplification factor of cascaded FPI sensitivity is determined by?FSR.When cascaded optical fiber microcavity FPI is applied to measurement,the direction of wavelength shift with parameters varies is determined by the relationship between cascaded double cavities.2.An optical cascaded Fabry-Perot interferometer hydrogen sensor based on the vernier effect has been proposed.The proposed sensor,is composed of a segment of large mode area fiber?LMAF?and a segment of hollow-core fiber?HCF?,which total length is⁵94?m.The proposed sensor is coated with the Pt-loaded WO₃/SiO₂powder which will result in the increase of local temperature of the sensor head when exposed to hydrogen atmosphere.The hydrogen sensitivity is-1.04 nm/%within the hydrogen concentration range of 0%-2.4%.The response time is⁸0 s.3.A C-type micro-cavity structure based on PDMS has been proposed.Experiments show that the temperature sensitivity of the proposed sensor is-1.29 nm/?.Based on these experiments,an optical hydrogen sensor based on PDMS-formed double-C type cavities with embedded Pt-loaded WO₃/SiO₂ has been proposed.Inner C-type cavity forms a micro-cavity FPI while outer C-type cavity with embedded Pt-loaded WO₃/SiO₂ powder serves as a sensitive area.The hydrogen sensitivity is-15.14nm/%within the hydrogen concentration range of 0%¹%.The response time is short,²3s.