Optical properties and sensing applications of lithium iron phosphate thin films

► LiFePO4 was selected as sensing material for xylene detection. ► Refractive index of LiFePO4 thin films increases with annealing temperature from 120 to 450 °C. ► LiFePO4 optical waveguide sensor easily detects 50 ppm of xylene gas with response < 5 s. ► Below 100 ppm, no interference is caused by other volatile organic compounds.