Study on temperature characteristics of the transmission spectra of three-layer model long period fiber gratings

In order to study temperature characteristics of the transmission spectra of long period fiber gratings,simulation was carried out based on the three-layer fiber model,and the change rule of transmission spectra was obtained in the case of coupling between lowest-order cladding modes and the fundamental core mode.It is shown that the depth of harmonic wave is almost independent of temperature within the low temperature range.Different harmonic wave has different temperature sensitivity,the bigger the order,the higher the temperature sensitivity,K7=0.04951 nm/℃,K3=0.04246nm/℃.But the response the same harmonic wave is linear with temperature.