Aligned Layers of Silver Nano-Fibers

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

55.2: Fast Switching Dual-Frequency Liquid Crystal Optical Retarder, Driven by an Amplitude and Frequency Modulated Voltage

Abstract We Introduction Nematic cells are widely used as optical retarders in various applications where 0 ε is the electric constant, 1 γ is the rotational viscosity of the nematic liquid crystal, ∆ε=ε II -ε ⊥ is the dielectric anisotropy, ε II and ε ⊥ are the principal dielectric permittivities referred to the nematic director, threshold value of the applied voltage, K is the characteristic elastic constant. According to Eq.(1), one can decrease τ on by increasing the applied voltage. However, the relaxation time τ off depends only on the material parameters and the thickness of the cell and cannot be shortened by a higher electric field, see Eq.(2) τ off ~d 2 . The drawback is that smaller d causes smaller optical retardation (the optical path difference for ordinary and extraordinary waves) ∆L, as ∆L~d. The goal of our work was to resolve contradictory requirements of fast (sub-millisecond) switching and the broad range of switched optical retardations (∆L ≥1µm). Fast Switching Dual-Frequency Liquid Crystal Optical Retarder We use the so-called dual-frequency nematic materials in cells with a high pretilt angle (α≈45 degrees) driven by a sequence of electric pulses of different frequency and amplitude. We assembled nematic cells with an anti-parallel fashion from plates with a high pretilt angle, which was achieved by oblique deposition of SiO layers We used the optical setup with the cell placed between two crossed polarizer prisms to measure the time evolution of the optical response of the cell

Fast Switching Dual-Frequency Liquid Crystal Optical Retarder, Driven by an Amplitude and Frequency Modulated Voltage

We demonstrate theoretically and experimentally a fast-switching nematic optical retarder capable to switch a few microns of optical retardation in less than 1 ms. For example, a nematic cell of thickness 14.5 mum switches 0.3 mum of retardation within 0.15 ms and 2.5 mum within 0.5 ms for single passage of beam. The corresponding figure of merit is two orders of magnitude higher than the one known for the best nematic materials synthesized so far. The fit is achieved by employing a dual-frequency nematic liquid crystal in high-pretilt angle cells and a special addressing scheme that features amplitude and frequency modulated voltage. The scheme can be used in spatial light modulators, retarders, beam deflectors, polarization rotator, and displays. </p

Fast switching optical modulator based on dual frequency nematic cell,”

We demonstrate a fast optical modulator capable of switching large amount of optical retardation (a few microns) in less than 1 ms. The result is achieved by employing a dual frequency nematic in cells with high pre-tilt alignment and by providing a special addressing scheme that features amplitude and frequency modulated voltage. We explore the effect of surface alignment and dielectric heating on the switching time. We also report the measurements of dielectric permittivities and crossover frequency of dual frequency nematic

Aligned Layers of Silver Nano-Fibers

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