Recent experiments demonstrated high conversion efficiency in the process of Orientational Stimulated Scattering (OSS) in nematics. This fact makes OSS attractive for beam combining and clean-up. We consider a scheme for such application and study it by numerically modeling the process. As the process of energy transfer goes, the reverse transfer also begins. However, the region of the back-transfer moves inside the cell with constant velocity in +z direction and given sufficient time, leaves the cell. By modeling the OSS of diffracting one-dimensional beams we show the possibility to obtain a maximum 94% fidelity and 96% power transfer in a numerical experiment with 6 individual overlapping pump beamlets. This means that 90% of the total pump power may be converted into the diffraction-limited output. Remarkably, this output suffers very little cross-phase modulation.
We consider a nematic liquid crystal (NLC) cell with planar structure of director sinusoidally modulated in transverse direction in the cell plane. If thickness of the cell is such that it locally acts as a half-wave plate, thin screen approximation predicts complete diffraction of normally incident light into +1st and −1st diffraction orders. We numerically study the case when this periodically aligned structure is made using anchoring at surfaces. Proper direction of anchoring can be achieved by illumination of photosensitive polymer coating by interference pattern of pair of circularly polarized waves. We found that the structure is unstable when its thickness exceeds a certain critical thickness. Calculations show that for a number of commonly used NLC's this critical thickness lies between 0.66 and 0.86 of the physical period. Such thickness allows for diffraction angles up to 21°. Friedericksz transition voltage of this structure depends on its thickness. This dependence can be well described by an ellipse in the voltage-thickness coordinates. Propagation of a plane wave through the periodically aligned NLC is described using coupled-mode approach. We estimate the contrast ratio versus the influence of walk-off effects and deviation of equilibrium structure from perfectly sinusoidal. Estimations for reasonable set of NLC's parameters show that contrast ratio can be 1000:1 and higher. As a result of this analysis, the transverse size of the cell can be estimated to be less or about 0.25 mm, which suggests it for use as a pixel in projection displays.
We demonstrate a pair of 90-45-45 prisms from binoculars appropriately attached to serve as Fresnel rhomb, i.e. achromatic quarter-wave plate. One and two Dove prisms with metallic reflection instead of TIR can work as half-wave plate and polarization rotator, respectively; both achromatic.