Nonlinear propagation of ultrafast 1.5 μm pulses in high-index-contrast silicon-on-insulator waveguides

Propagation through silicon-on-insulator (SOI) waveguide structures of 1.53 mum, 100 fs laser pulses with peak powers up to 400 W is studied experimentally and theoretically. The dominant nonlinear effects are two-photon absorption and self-phase modulation. The two-photon absorption coefficient and the nonlinear refractive index of Si obtained in this work are beta(2)=0.9 cm/GW and n(2)=0.7x10(-13) cm(2)/W, respectively. At high intensities, free carriers generated by two-photon absorption are demonstrated to have a significant influence on pulse spectra and transmitted power. The figure of merit for all-optical switching obtained in this work (T=1.8) indicates that a switch based on a SOI waveguide structure might be possible at 1.55 mum. (C) 2004 American Institute of Physics.