Abstract

In this article, a numerical model of the radiation pattern of filamented fiber Bragg grating (FFBG) is established and an experimental study of its radiation distribution is conducted. The radiation distribution of the FFBG is analyzed from a theoretical point of view by introducing the volume current method (VCM) into the FFBG, and the radiation distribution of the FFBG is modeled. The spatial distribution of the radiation field is also analyzed using the finite-difference time-domain (FDTD) method, and FFBG's radiation field is analyzed experimentally. Numerical calculations, simulations, and experimental results show that the FFBG can radiate light from both sides of the filament and the radiation distribution at the filament section near the core-cladding interface is stronger than in the middle of the filament. The influence of grating length on radiant intensity is also studied. The experimental results indicate that the energy radiated by the filament increases with the length of the grating.