Simulation and characteristics of long-period fiber Bragg grating coherence spectrum

The long-period fiber Bragg grating (LPFBG) coherence spectrum was investigated using mode selection rule and coupling equations. The coupling between the forward propagating core-bounded mode and multicladding-bounded modes was taken into consideration in modeling based upon their contribution to the spectrum. Modes involved in the coupling process were ranked into a converging series. This makes the modeling procedures described practical. The grating coherence spectrum under assumed testing conditions was modeled and simulated.