Effects of cladding radius on the optical characteristics of long-period fiber gratings

摘要

Using three-layer vector field model,the dispersion characteristics and spectral response of long-period fiber gratings(LPFGs)with different cladding radii are analyzed.Both the numerical and experimental results demonstrate that LPFG’s resonant wavelengths shift towards much longer wavelength and the transmission depth is strengthened significantly by decreasing cladding radius.When the cladding radius is less than 20μm,only a single resonant peak over a wavelength range of 600 nm(from 1200 nm to 1800 nm)is achieved,and the sensitivity of LPFG to external refractive index is enhanced significantly.