Highly nonlinear silica spiral photonic crystal fiber for supercontinuuam generation extending from 320 nm to 2620 nm

Abstract

We present a design of a highly nonlinear silica spiral photonic crystal fiber with nonlinear coefficient of 648.48 W−1 km−1 and group velocity dispersion of 20.75 ps2/km at 532 nm pump wavelength for widely extended supercontinuum generation. In the proposed design the first hole in a spiral arm is bigger in size and the subsequent holes are smaller. We use full vector finite element method to evaluate the modal properties of the fiber. The proposed fiber design provides better mode confinement and dispersion control than the conventional triangular and hexagonal core photonic crystal fibers. Our numerical simulations using split step Fourier method show 2300 nm wide blue extended supercontinuum generation ranging from 320 nm to 2620 nm wavelength using a 100 fs, 60 kW pump at 532 nm wavelength using the proposed fiber design. The generated supercontinuum would be useful in optical coherence tomography, fluorescence imaging, and absorption spectroscopy.