Polarization maintaining highly nonlinear photonic crystal fiber for supercontinuum generation at 1.55μm

A polarization maintaining highly nonlinear Germanium (Ge) doped photonic crystal fiber (HNL-GePCF) is proposed for supercontinuum (SC) generation at 1.55μm as polarization maintaining properties in a fiber enhance nonlinear interactions to generate SC using less optical power. By designing 3% higher refractive index Ge-doped core with core ellipticity ϵ=0.9ϵ=0.9 inside silica, nonlinear coefficient γγ and birefringence B   are increased as large as 83W−1km−1 and 2.82×10−42.82×10−4 respectively at 1.55μm. Using finite element method (FEM) with a circular perfectly matched boundary layer (PML), it is shown through simulations that the proposed HNL-GePCF offers an efficient SC generation at 1.55μm. By propagating sech2 picosecond optical pulses having 2.5 ps and 1.0 ps pulsewidth at a full width at half maximum (FWHM) through the proposed HNL-GePCF, output optical pulses are analyzed by the split-step Fourier method to obtain the spectral contents. The highest 10 dB bandwidth spectra at 1.55μm are observed as 100 nm and 150 nm for 2.5 ps input optical pulse and for 1.0 ps input optical pulse respectively.