Dispersion properties of hollow-core photonic bandgap fibers based on a square lattice cladding

摘要

In this paper the dispersion properties and confinement loss of hollow-core photonic bandgap fibers (PBGFs) based on a square lattice (SL) with rounded square air-holes was investigated for the first time, by using a full-vector finite element method (FEM). The waveguide group velocity dispersion (GVD) curves with different core diameter D, air hole size d, rounded diameter d_(c) and hole pitch LAMBDA are presented. The influence of the number of cladding rings on dispersion and confinement loss were also calculated. It was found that as LAMBDA or d increases, the width of PBG becomes wider, and that D and the number of cladding rings have a smaller influence on waveguide GVD. The ratio between bandgap width and central wavelength in our simulation is about 38.1percent, which is larger than that of hollow-core PBGFs with triangular lattice (TL) (approx25percent). By simulation, the desired zero dispersion wavelength or desired dispersion slope could be obtained by properly choosing the value of d_(c) or LAMBDA. Compared to TL PBGF, at least nine cladding rings is needed to achieve the confinement loss less than 0.1 dB/m for future application.