Nonlinear route from guiding to discrete diffraction in photonic liquid crystal fibers

We have investigated the nonlinear light propagation in photonic crystal fibers filled with nematic liquid crystals. Light with a frequency within the photonic bandgap is propagating in the central glass core being the structure defect. Outside the bandgap analyzed fiber corresponds to the matrix of liquid crystalline waveguides. The changes of refractive index due to the temperature or/and nonlinear effects can lead to the bandgap shifting. As a consequence the incident beam with a frequency initially within the bandgap is then turned outside the bandgap resulting in the changing of the propagation for the discrete diffraction effect.