Numerical analysis of femtosecond pulse propagation and supercontinuum generation in tapered fiber

Dispersion property is an important fact to generate white light. Different structures could change the dispersion properties of fibers. This paper demonstrates how the white light was generated when the ultrashort pulse propagated in a tapered fiber. We simulated how the supercontinuum was generated in a variety of tapered fibers which have different parameters. The supercontinuum range could be reached from 680nm to1750nm. It is shown that the width and the shape of the supercontinuum depend on both the fiber parameters such as the diameter or the length of tapered waist regime and pulse peak power. The paper also discussed the influence of the different dispersion and nonlinear effects in detailed, including GVD (Grouped Velocity Dispersion), SPM (Self Phase Modulation), TOD (Third Order Dispersion), SS (Self Steeping), and SRS (Stimulated Raman Scattering). Through the numerical simulation, it presents when the ultrashort pulse propagates in tapered fibers with anonymous dispersion, the Stimulated Raman Scattering effect plays an important role in the long wave range of the supercontinuum. The influence of the higher order dispersion, especially third order dispersion, on the anti-Stokes part in the supercontinuum process was also discussed. A smoother and broader supercontinuum could be obtained after choosing the suitable parameters of the tapered optical fibers, especially the diameter or the length of tapered waist regime.