Design of photonic crystal fiber with elliptical air-holes to achieve simultaneous high birefringence and nonlinearity

A new type of V-shaped photonic crystal fiber with elliptical air-holes is proposed to realize simultaneous high birefringence and nonlinearity at a wavelength of 1.55 μm. The full vector finite element method was adopted to investigate its characteristics, including birefringence, nonlinearity, and dispersion. The PCF exhibited a very high birefringence of 2.89×10^-2 and very high nonlinear coefficient of 102.69 W^-1·km^-1. In particular, there were two zero-dispersion wavelengths (ZDWs) in the visible (X:640-720 nm and Y:730-760 nm) and near-infrared regions (X:1050-1606 nm and Y:850-1500 nm). The combination of high birefringence and nonlinearity allowed the PCF to maintain the polarization state and generate a broadband super continuum, with potential applications in nonlinear optics.