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

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].