Comparison of temperature sensors using polymer materials in long period fiber grating

Abstract

Long period fiber grating (LPFG) is the most widely used in measurement of temperature, strain, pressure, bending radius, external index of refraction etc. This proposed work exhibits LPFG as temperature sensor. Basically, the shift in resonant wavelength of LPFG temperature sensor depends on thermo-optic effect. To enhance this effect thermo-optic coefficients for core and cladding are optimized. The polymers with negative thermo-optic coefficients can be used as core materials to enhance thermo-optic effect. This enhancement in thermo-optic effect shifts LPFG resonant wavelength towards negative direction. Using this concept, different sensitivities are achieved for different polymers in this research work. This design of LPFG temperature sensor uses Polycarbonate, Polymethyl methacrylate (PMMA) and Ormocomp polymers. The shift of LPFG resonant wavelength towards negative direction is the largest in Ormocomp polymer. Ormocomp as core material provides 24.6nm/°C temperature sensitivity over range from 25°C to 80°C temperature.