Here we report the robust propagation, refraction and reflection of optical spatial solitons at the interface between two regions of a nematic liquid crystal. The ability to independently tune the optical properties of each region enables us to steer the beams by refraction and total internal reflection by as much as −18 and +22 degrees, respectively. Moreover, the extended (nonlocal) and anisotropic response of our system supports polarization healing of the solitons across the interface as well as non-specular filament reflection. Finally, exploiting the inherent and alloptically tunable birefringence, we demonstrate unprecedented nonlinear Goos-Hänchen lateral shifts in excess of 0.5 mm.

We investigate the interaction between two beams differing in wavelength and the properties of dual-frequency spatial solitons in nonlocal birefringent reorientational media. We report the first experimental observations of anisotropic nonlocal vector solitons in unbiased nematic liquid crystals. Model and simulations, based on the paraxiality along the Poynting vectors, include joint walk-off and breathing.

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In liquid crystal cells with photoconductive poly͑N-vinlyl carbazole) polymer layers, an external dc field can be completely screened by surface charge layers that develop at the liquid crystalpolymer interface. Under spatially modulated illumination, surface charge layers can be discharged in bright areas and lead to reorientation and spatially modulated Freedericksz transition. As a result, an asymmetric energy exchange in the photorefractive two-beam coupling process can take place. We propose a model to explain the origin of reorientation and phase shift in the two-beam coupling process, based on the profile and tilt of the refractive index grating. We also show that cells with just one photoconducting layer are more efficient than a typical design with two layers.

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