Nonlinear optical dynamics in femtosecond laser processing of silicon waveguides (Conference Presentation)

Abstract

In recent years, femtosecond-laser writing has recently emerged as one of the most versatile techniques for direct waveguide microfabrication of transparent optical materials. Femtosecond-laser-based fabrication of three-dimensional silicon waveguide enables compact silicon photonics and their integration as large third-order nonlinearity and the high refractive index of silicon allows for tightly confining optical waves to a sub-micron region. The writing process is however challenging because the unique features exhibited by the semiconductor crystal, such as two-photon absorption, free-carrier absorption / dispersion, anisotropic and dispersive third-order nonlinearity, which may drastically influence the writing process at high intensities required for the femtosecond-laser writing. In this work, we provide a detailed description of the underlying physics behind nonlinear optical dynamics in femtosecond laser processing of silicon waveguides, considering the generation of free carriers induced by various absorption mechanisms, plasma formation, refractive index change and their impact on the waveguide microfabrication and performance.