Semi-Empirical Model for the Thermally tunable LPFG

We propose a semi-empirical model for the analysis of a temperature-tuned long-period fiber gratings (LPFG) filter. Applying the multi-port lattice model to LPFGs, meanwhile utilizing the empirically determined temperature-dependence of core-to-clad mode-coupling coefficients, we achieve a precise, practical means of the transmission spectrum analysis featuring an excellent fit with the experiment.