Ultrafast reflectivity modulation in AlxGa1-xAs/InyAlxGa1-x-yAs multiple quantum well photonic crystal waveguides

We report an ultrafast optical tuning of the reflectivity of AlxGa1-xAs/InyAlxGa1-x-yAs multiple quantum well photonic crystal waveguides using a reflection geometry, pump-probe technique. Nonlinear shifts of the photonic resonances between 800 and 900 nm are demonstrated with a measured response time of similar to 300-400 fs. The nonlinear shift is attributed to virtual carriers, with the response time determined by the pump pulse duration. This demonstrates ultrafast photonic switching in a high-contrast photonic structure based on III-V quantum wells.