Numerical simulation of supercontinuum generation in GeO_2 doped fiber

摘要

Broadband coherent anti-Stokes Raman scattering (CARS) microscopy promises non-invasive, high information content microscopic imaging for live cells and tissues. Generation of a broadband continuum with appropriate characteristics to be used for Stokes light has been a roadblock for bringing this promise to fruition. Here we present numerical and experimental work towards generation of a suitable Stokes light continuum from a femtosecond pulse laser. In the simulations, the pulse propagation along the fiber is governed by the generalized nonlinear Schrodinger equation, including linear effects from the group velocity dispersion and the nonlinear effects from self phase modulation, delayed Raman scattering process and self-steepening. The equations are integrated using a symmetrized split-step Fourier method. Optimal fiber-related simulation parameters used in the model, such as the nonlinear coefficient, dispersion coefficients and the fraction of the stimulated Raman scattering contribution etc, are systematically investigated and determined for the GeO_2 doped fiber.