Simultaneously achieving a large negative dispersion and a high birefringence over Er and Tm dual gain bands in a square lattice photonic crystal fiber

We proposed a novel photonic crystal fiber composed of a double-cladding square lattice that could be used in dualband, Er and Tm optical gain bands, simultaneously supporting a large negative dispersion and a high birefringence. We theoretically investigated the light guiding property through the proposed PCF by using a vectorial finite element method (FEM) with a perfectly matched layer (PML). By optimizing the structural parameters, we obtained an ultra-large negative dispersion of -20,186ps/(nm km) and a very high birefringence of 9.27 ×10^-3 at the wavelength of 1.55μm in the Er gain band and a very large negative dispersion of -8,067ps/(nm km) and a high birefringence of 1.0 ×10^-3 at the wavelength of 1.87μm in the Tm band.