Light localization induced enhancement of third order nonlinearities in a GaAs photonic crystal waveguide

Nonlinear propagation experiments in GaAs photonic crystal waveguides (PCW) were performed, which exhibit a large enhancement of third order nonlinearities, due to light propagation in a slow mode regime, such as two-photon absorption (TPA), optical Kerr effect and refractive index changes due to TPA generated free-carriers. A theoretical model has been established that shows very good quantitative agreement with experimental data and demonstrates the important role that group velocity plays. These observations give a strong insight into the use of PCWs for optical switching devices.