Temperature compensation of long-period fiber grating for refractive-index sensing with bending effect

In this letter, we show that by properly mounting a bent long-period fiber grating (LPFG) on a suitable material, the temperature dependence of the resonance wavelength of the LPFG can be largely eliminated. With this method, we reduced the temperature sensitivity of the resonance wavelength of a typical LPFG by two orders of magnitude from -0.933 nm//spl deg/C to 0.008 nm//spl deg/C. The principle of using this mounted LPFG as a temperature-insensitive chemical concentration or refractive-index sensor is demonstrated.