A nonlinear ZBLAN-based photonic crystal fiber with ultra-high birefringence and flattened dispersion in short-wavelength infrared region

Abstract

In this paper, a high nonlinear ZBLAN-based photonic crystal fiber (PCF) with ultra-high birefringence and flattened dispersion is numerically proposed in short-wavelength infrared region based on finite element method. Eight elliptical-hole arrays are arranged surrounding the fiber core to separate x-polarized and y-polarized fundamental modes. The birefringence can reach to an excellent level of 4.46 × 10−2 at wavelength 2.5 µm and interestingly shows a hopping phenomenon as the ellipticity increases from 2.2 to 3.1. In addition, the design also exhibits a single-mode propagation, short beat length (< 0.12 µm), high nonlinear coefficient 131 W−1·km−1, low confinement loss 10−9 dB/m and flattened dispersion with a maximum fluctuation 50 ps·km−1nm−1 in wavelength range from 1.5 µm to 2.5 µm. The effect of the structure parameters (air hole diameter, lattice constant and ellipticity of elliptical holes) on the optical properties is symmetrically investigated. This ZBLAN-based PCF has great potential in the nonlinear applications of fiber laser and supercontinuum generation in infrared region.