A single-layer of breath figure pattern was explored via the dynamical optical images and the temperature evolution. The pattern was prepared with the solution of carbon disulfide (CS(2)) dissolved 1% weight concentration of polystyrene. The evaporation of CS(2) was considered to be the most important role to the formation of the breath figure pattern. The understanding of the breath figures pattern will promote the technique to fabricating an imprinted template with demanded hexagonal structures.
This investigation proposes a Fresnel liquid crystal (LC) lens with high diffraction efficiency and a low driving voltage. A Fresnel zone electrode was fabricated on a glass plate. A Fresnel zone-distributed electric field in the LC cell was induced by a proper driving voltage, yielding a concentric structure of LCs as a Fresnel phase lens. A remarkable diffraction efficiency of ~39%, close to the theoretical limit of 40.5%, was detected when the LC lens was probed using a polarized incident beam with a wavelength of 632.8 nm. The diffraction efficiency of the Fresnel LC lens was demonstrated to depend sensitively on the applied voltage. The most suitable driving voltage of the Fresnel LC lens was as low as 0.9 V. This study may support progress in the electrical modulation of the optical properties of various optical systems.
The authors report the observation of an enhanced optical diffraction in cholesteric liquid crystals (CLCs) due to the presence of silver nanoparticles. The silver nanoparticles are deposited on the surface of one of the indium tin oxide electrodes of the CLC cell. With the application of a proper voltage, the liquid crystals assume its cholesteric phase with the helical axis perpendicular to the applied electric field. The CLC grating was probed by a beam of polarized light in the spectral range from 450to750nm. The direction of propagation of the beam is perpendicular to the helical axis of the liquid crystals. The authors report a significant enhancement in the first-order diffraction efficiency at around 543nm. The results of the experimental observation are presented and discussed.
We investigated both theoretically and experimentally the diffraction property of cholesteric liquid crystals (CLCs) in the configuration of transmission grating. The CLCs are treated as birefringent index gratings whose diffraction property is strongly dependent on the polarization state of the incident beam. In our experimental studies, the CLC index gratings are constructed by applying an electric voltage to liquid crystal cell. The grating is probed by a monochromatic light in spectral range from 450 to 750 nm and the measured diffraction efficiency approximately agrees with the theoretical predictions. The dependence of polarization and wavelength of polarized monochromatic light may possibly lead to a light switch in optical communication system.
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