Polarization correlations in backscattering from media with different optical densities.

Random electromagnetic fields have a number of distinctive statistical properties that may depend on their origin. We show that, when two mutually coherent fields overlap, their individual characteristics are not completely lost. If assumptions can be made regarding the coherence properties of one of the fields, then the correlation length of the second one can be retrieved using the higher-order polarization properties of the combined field. We demonstrate experimentally that colloidal particles of different sizes can be identified based on polarization correlations measured even in situations of strong multiple scattering.

Correlations of polarization in random electro-magnetic fields.

Random electromagnetic fields have a number of distinctive statistical properties that may depend on their origin. We show here that when two mutually coherent fields are overlapped, the individual characteristics are not completely lost. In particular, we demonstrate that if assumptions can be made regarding the coherence properties of one of the fields, both the relative average strength and the field correlation length of the second one can be retrieved using higher-order polarization properties of the combined field.

Complex degree of mutual polarization in randomly scattered fields.

Random electromagnetic fields resulting from light-matter interaction have strong intensity fluctuations and are characterized by various statistical parameters. The local polarization of these fields can also vary randomly leading to different degrees of global depolarization. Here we demonstrate that the spatial variability of the vectorial properties contains information about the origins of randomly scattered fields. In particular, we show that the complex degree of mutual polarization provides the high-order polarization correlations necessary to identify the sources of different random fields. Scattered fields with similar global properties but different origins can be efficiently discriminated from one single realization of the light-matter interaction.

Fluctuations of scattered waves: going beyond the ensemble average.

The interaction between coherent waves and random media is a complicated, deterministic process that is usually examined upon ensemble averaging. The result of one realization of the interaction process depends on the specific disorder present in an experimentally controllable interaction volume. We show that this randomness can be quantified and structural information not apparent in the ensemble average can be obtained. We use the information entropy as a viable measure of randomness and we demonstrate that its rate of change provides means for discriminating between media with identical mean characteristics.

Ballistic dynamics of Airy beams.

We demonstrate both theoretically and experimentally that optical Airy beams propagating in free space can perform ballistic dynamics akin to those of projectiles moving under the action of gravity. The parabolic trajectories of these beams as well as the motion of their center of gravity were observed in good agreement with theory. The possibility of circumventing an obstacle placed in the path of the Airy beam is discussed.

Observation of accelerating Airy beams.

We report the first observation of Airy optical beams. This intriguing class of wave packets, initially predicted by Berry and Balazs in 1979, has been realized in both one- and two-dimensional configurations. As demonstrated in our experiments, these Airy beams can exhibit unusual features such as the ability to remain diffraction-free over long distances while they tend to freely accelerate during propagation.