Fig. 1. Schematic of cross spiral micro-structured FBG. (a) Processing diagram; (b) SEM picture of spiral microstructure after processing

Fig. 2. SEM picture and EDS pattern of Pt-WO₃. (a) SEM picture; (b) result of EDS

Fig. 3. Response curves and fitting sensitivity curves of spiral microstructure and standard FBG probe. (a) Response curve of S-1 at different hydrogen concentrations; (b) linear fitting curve of wavelength drift of S-1; (c) response curve of FBG-1 at different hydrogen concentrations; (d) linear fitting curve of wavelength drift of FBG-1

Fig. 4. Comparison of wavelength shifts. (a) Wavelength shifts of microstructred FBG probe and standard FBG probe; (b) experimental and simulation results of standard FBG probe