Beam combining using Orientational Stimulated Scattering in Liquid Crystals

Possibility of beam combining and clean-up using Orientational Stimulated Scattering in a Nematic Liquid Crystal is considered. We numerically study the dynamics of the process and find that back-conversion process tends to limit the effective interaction strength. Instability of the steady state of cross-phase modulation is demonstrated, when both waves have the same frequency. We show that high conversion efficiency can be achieved, and that the shape and wave-front of the amplified output signal are robust with respect to amplitude and phase distortions of the input pump.Comment: 24 pages, 6 figures, will be published in JOSA

Apparatus and Method for Measuring the Power Density of a Laser Beam with a Liquid Crystal

Meters detect power parameter information about laser beams using liquid crystals to propagate the beam therethrough with photodiode detectors. The power parameters include intensity in watts per square meter, beam waist size, and the location of the focal spot based in light induced orientational phenomena in the liquid crystal. The detectors can can count the number of interference fringe rings produced by a laser beam passing through the liquid crystal(LC). Alternatively, the time between the occurrence of each interference fringe ring can be measured to determine the power parameters. A preferred embodiment has a standard liquid crystal oriented at approximately 45 degrees to the axis of an incoming laser beam to be measured. The beam passing through the LC can be centered through a pinhole on a planar plate causing the interference fringe rings to appear on the surface of the plate. An alternative embodiment measures intensity based on determining the voltage necessary to produc

Realization of photoresponsive diffractive beam splitters

We report on the realization of a light beam splitting effect based on a light sensitive diffractive structure. The periodic structure is realized in soft composite materials doped with an high performance light sensitive Liquid Crystal. The capability of the structure as tunable beam splitter, is monitored by combining its zero and first diffracted orders in a MC-Zehnder geometry interferometer. The fringe visibility of the interference pattern can be finely controlled by means of an external pump source. Low driving power and short response time are the main features of this light controlled beam splitter. Copyright © Taylor & Francis Group, LLC

Optical beam steering and switching by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency PTR Bragg gratings.

Non-mechanical optical beam steering and switching is produced by optically controlled liquid crystal spatial light modulator with angular magnification by high efficiency volume Bragg gratings recorded in a photosensitive PTR glass. Small angle beam deflection in a photoactive liquid crystal cell is produced by exposing it to a controlling beam from an external source of radiation with predetermined distribution of power density which causes predetermined spatial gradients of a refractive index in a liquid crystal cell and, therefore, refraction of a controlled beam which is made to propagate in the region with spatial gradient of the refractive index. Large angle beam deflection is produced by a volume Bragg grating with angular selectivity adjusted in such way that small angle scanning produced by optically controlled liquid crystal spatial light modulator results in change of diffraction efficiency from zero to 100% for switching the beam for two Bragg angles

Optically controlled holographic beam splitter

We present the results of realization and study of a light beam splitting effect based on a full-optically controlled holographic diffraction grating. The high quality, light responsive, periodic structure, which is exploited as tunable beam splitter, is monitored by combining its zero and first diffracted orders in a Mach-Zehnder geometry interferometer. The interference pattern exhibits a dependence of the fringe visibility on the external optical pump power utilized to drive the splitting effect. The visibility, characterized by means of a standard pump-probe optical setup, reveals a strong dependence on the polarization of the probe radiation and on its incident angle as well. The effect is reversible and repeatable, and shows a continuously adjustable fringe visibility in the range 0.94-0.2, with response times in the millisecond range. © 2010 American Institute of Physics