We describe digital beam deflectors (DBDs) based on liquid crystals. Each stage of the device comprises polarization rotator and birefringent prism deflector. We used prisms made of the uniaxial smectic A (SmA) liquid crystal and a solid yttrium orthovanadate crystal. SmA prisms have high birefringence and can be constructed in a variety of shapes. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Rotation of linear polarization is achieved by electrically switched twisted nematic or electrically controlled birefringent cell. We describe a four-stage DBD steering a normally incident laser beam within AE56 mrad range with 8 mrad steps.
We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polarization of transmitted light. The aligned layers of silver nano-fibers might be used in optics, microwave applications, and organic electronics.
We study a nematic dispersion formed in a UV-polymerized matrix with a low content of a liquid crystal component. The dispersions contains sub-micrometer liquid crystal droplets obtained in a two-step process: (a) phase separation during a fast cooling process (b) stabilization of droplets size by photo-polymerization caused by a low power UV exposure. The dispersion is homogeneous, highly transparent and shows little light scattering at wavelength 633 nm. We demonstrate that it can be used as an electrically-controlled birefringent slab with a relatively low driving voltage and a short response time. For example, application of the electric field 6 V=mm changes phase retardation by p=4 with the characteristic response time of several milliseconds.
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