Dispersion Measurement of Femtosecond Pulses through Photonic Band-Gap Edges of Cholesteric Liquid Crystals

Summary form only given. The cholesteric liquid crystal (CLC) phase exhibits a helical structure with a twist axis perpendicular to the local molecular director [1]. Because of the periodic change in refractive index, CLC exhibit 1-D photonic bandgap characteristics, through selective polarization-dependent Bragg reflection. These optical properties open some interesting prospects for dispersion management, for instance slow light or ultrafast laser modulation [2]. The experimental demonstration of femtosecond pulse compression has been recently proposed, thanks to the combination of a thick and highly birefringent CLC with a strong nonlinearity [2]. Here, we propose an advanced optical characterization of CLC samples, using ultrashort pulses and a statistical approach to experimentally quantify the temporal changes undergone when a femtosecond pulse propagates in the linear regime through the edges of the photonic bandgap.