New routes for exploiting the optical properties of artificial opals

Summary form only given. Artificial opals are nowadays acknowledged as ideal playgrounds where the optical properties of three dimensional (3D) photonic crystals can be tested. Over the past few years several works have demonstrated that a strong enhancement of the interaction between light and matter can be achieved with these systems. These type of nano-structured materials tend to grow in an FCC lattice with the (111) planes parallel to the sample surface. This characteristic fact imposes some restrictions on their dispersion relation (and hence on its optical properties) which are usually compensated for by introducing modifications in their topology by infiltrating them with high refractive index materials or introducing controlled defects. In this work we present recent results regarding the optical characterization of artificial opals containing planar defects as well as opals oriented along crystallographic directions other than the (111). The amplitude and phase of light transmitted through the samples is measured providing us with valuable information regarding the way light propagates in these structures. Our results evidence that besides the well known response in the surroundings of the stop-band, these structures can exhibit much more exciting properties such as superluminal propagation with negative group velocities.