Two‐color pump–probe experiments on silicon inverse opals

Abstract

AbstractWe present time‐resolved pump–probe experiments in a transmission geometry using off‐resonant excitation on very high‐quality silicon inverse opals. We show that the nonlinear optical response can drastically be modified by tempering of the sample. The as‐grown samples are dominated by an absorptive response with recovery times as short as one picosecond. For the tempered samples, both the relaxation and the scattering times increase, leading to a prominent dispersive response. The data reveal a transient blue‐shift of the fundamental stop band on the order of 150 nm with transmission changes as large as a factor of five. Based on simple calculations using the Drude model we estimate corresponding refractive index changes as large as Δn = –0.5 + i0.07. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)