The first experimental evidence of random laser action in a partially ordered, dye doped nematic liquid crystal
with long-range dielectric tensor fluctuations is reported. Above a given pump power the fluorescence curve
collapses and discrete sharp peaks emerge above the residual spontaneous emission spectrum. The spectral
linewidth of these emission peaks is narrow banded, typically around 0.5nm. The unexpected surviving of
interference effects in recurrent multiple scattering of the emitted photons provide the required optical feedback
for lasing in nematic liquid crystalline materials. Light waves coherent backscattering in orientationally ordered
nematics manifests a weak localization, strongly supporting the diffusive laser action phenomenon in the presence
of a gain medium. Unlike distributed feedback mirror-less laser, this system can be considered as a cavity-less
microlaser where the disorder unexpectedly plays the most important role, behaving as randomly distributed
feedback laser. The far field spatial distribution of the emission intensity shows a huge number of bright tiny
spots spatially overlapped and the intensity of each pulse strongly fluctuates in time and space. Here, we report
the main characteristics of this novel systems for various confinement geometries and under different conditions.
A brief presentation of boundary-less systems such as free standing and freely suspended dye doped nematic films
and droplets is also introduced, revealing unique emission features because of the complete absence of confining borders.
The study of optical solitons and light filaments steering in liquid crystals requires utilization of particular
cells designed for top view investigation and realized with an input interface which enables both to control the
molecular director configuration and to prevent light scattering. Up to now, the director orientation imposed by
this additional interface has been only estimated by experimental observations. In this paper, we report on the
design and characterization of liquid crystal cells for investigation of optical spatial solitons as well as on a simple
model describing the configuration of the molecular director orientation under the anchoring action of multiple
interfaces. The model is based on the elastic continuum theory and only strong anchoring is considered for
boundary conditions. Controlling of the director orientation at the input interface, as well as in the bulk, allows
to obtain configurations that can produce distinct optical phenomena in a light beam propagating inside the cell.
For a particular director configuration, it is possible to produce two waves: the extraordinary and the ordinary
one. With a different director configuration, the extraordinary wave only is obtained, which propagates inside
the cell at an angle of more than 7° with respect to the impinging wave vector direction. Under this peculiar
configuration and by applying an external voltage, it is possible to have a good control of the propagation
direction of the optical spatial soliton.