Simultaneous sensing of displacement and temperature with a single FBG

Abstract:

A novel fiber Bragg grating (FBG) sensor with simultaneous sensing of displacement and temperature is presented. The FBG is affixed on the cantilever inclinedly. The midpoint of FBG exactly coincides with the zero strain layer of a rectangular beam. The vertical displacement can be measured by the broadened bandwidth of FBG as the bandwidth is insensitive to temperature, while the temperature can be measured by the center wavelength shift as the wavelength shift is insensitive to vertical displacement. With 0.1 nm spectral resolution of the analyzer, sensitivities of bandwidth-displacement and center wavelength-temperature are 0.48 nm/mm and 0.05 nm/°C, resolutions are 0.2 mm and 2.0 °C, and sensing ranges of displacement and temperature are up to 8.5 mm and 45°C respectively. Experimental results match theoretical analyses very well.