Temperature dependency of cladding-etched fiber Bragg grating surrounded with liquid

Through packaging a cladding-etched fiber Bragg grating (FBG) with different liquid, we investigate the temperature dependency of etched FBG surrounded with liquid. Research results indicate that, for the etched FBG with diameter of 11.8 μm and the employed liquid with refractive index of 1.456, the Bragg wavelength and corresponding peak power are changing with the variation of ambient temperature nonlinearly. In different temperature ranges, the Bragg wavelength can shift to opposite directions with different temperature coefficient. All the characteristics are different from the temperature dependency of ordinary non-etched FBG and the etched FBG surrounded with distilled water. These characteristics of cladding-etched FBG depend on not only the refractive index and the thermo-optic coefficient of ambient liquid but also the remainder thickness of fiber-cladding. While all the factors are designed reasonably, the characteristics of ordinary FBG can be changed in accordance with the requirement, which can provide guides for the applications of etched FBG in temperature compensation, gas sensing, thermo-optic switches and other functional applications.