Strain sensor without temperature compensation based on LPFG with strongly rotary refractive index modulation

The strain and temperature characteristics of a novel long-period fibre grating with strongly rotary refractive index change modulation (S-R-LPFG) was investigated, this believed to be for the first time. It was observed that the two split resonant peaks continually separated when the strain was applied to it, and the temperature sensitivities are all 0.07 nm/degC. Such kinds of S-R-LPFG can be used to measure strain by using the wavelength difference between the two split peaks, which do not need temperature compensation because the two peaks shift to the same direction and have the same temperature sensitivity when environmental temperature changes.