Photonic nano materials: anisotropic transport and optical Bloch oscillations

Nowadays, propagation of light in complex dielectric nano-materials is a rich and fascinating area of research, both for its fundamental implications and for its practical technological impact. In this thesis we investigate the e ects of interference in quasi-ordered photonic systems. Light in random dielectric media is described through a random walk from scatterer to scatterer. Interference e ects do survive the multiple scattering and give rise to fascinating phenomena. In the strong scattering regime light could even become localized and propagation is no longer possible. In ordered media, the periodicity leads to cooperative scattering and interference. In this case the transport becomes strongly frequency-dependent; it can be inhibited (destructive interference) or substantially improved (constructive interference). Whereas the knowledge on the propagation of light waves in completely ordered and disordered structures is now rapidly increasing, little is known about the behavior of optical waves in the huge intermediate regime between complete order and disorder. Quasi-ordered systems show breaking of rotational or translational symmetry and exhibit novel and unusual forms of light transport. Anisotropic scattering random media and nematic liquid crystals, or specially tailored photonic crystals and Fibonacci quasi-crystals are examples of quasi-ordered systems that we will investigate in this thesis. What would happen if a preferential scattering direction or a preferential polarizability axis were to be introduced in an isotropic random scattering system? How would light propagation be in a periodic dielectric media if a linear optical potential was superimposed to the crystalline structure? In this thesis we will try to address these questions, based on theoretical arguments, numerical simulations and experimental evidences.