Narrow Results

Optical nonlinearity and feedback through Bragg periodicity are the basic ingredients for light localization into gap solitons. We review the basic concepts and model equations for gap solitons in Kerr and quadratic nonlinear media encompassing a one-dimensional Bragg resonance. With specific regard to frequency doubling media, we generalize the concept of a photonic crystal to band-gaps of a nonlinear origin, and finally address the slow character of quadratic gap-solitons with reference to their excitation.

An alternative experimental technique for the determination of weak localization of light in partially ordered nanostructured materials is proposed. The technique is based on the criterion for weak localization of light that the transport mean free path length of multiply scattered photons is reduced down to shorter than the wavelength of the light. This mean free path is calculated from the experimental dwell time of the photons in the scattering structure and by applying the photon random walk model using the diffusion approximation. The dwell time is experimentally determined by multifrequency phasefluorimetry. This technique is capable of providing corroborative intensity demodulation data that can be linked to the wavelength dependent transmission (optical bandgap) of colloidal crystals.