Ultrafast nonlinear response of AlGaAs/InAlGaAs MQW photonic crystal waveguides

We report ultrafast optical tuning of the reflection properties of MQW AlGaAs/lnAlGaAs 1D photonic crystal waveguides using a reflection geometry, pump-probe technique. Very fast pump-induced shifts of photonic resonances between 800-900 nm by up to 18 nm nanometers are demonstrated. This is followed by a fast decay which varies from 5 to 30 ps depending on the sample dimensions. Together with the maximum reflectivity change of Delta R/R > 30%, this demonstrates excellent potential for application of photonic crystals as ultrafast nonlinear switches with decay times depending on the structure period.