Ultrafast switching in Si-embedded opals

We present the first femtosecond pump–probe study of the transient reflectivity of an opal filled by silicon around the stop-band. We observe an ultrafast View the MathML source photoinduced response of the reflectivity of the opal that is synchronous with the pump pulse. In addition, an ultrafast step followed by a multi-exponential picosecond decay is measured that is related to the creation and relaxation of free carriers.