Strain and temperature sensitivity of chiral long period fiber gratings

Mode couplings of the core modes to cladding modes with both lower and higher angular orders in chiral long period gratings (CLPGs) are analyzed. The sensing sensitivity of the resonant wavelength in response to strain and temperature are demonstrated, respectively. Both single- and double-helix CLPGs formed by silica and polymer fiber are considered. This provides useful guidance for practical designs of CLPGs to enhance the optical sensing sensitivity of the strain and temperature, or to decrease the environmental influence on spectral characteristics of CLPGs.