Ferroelectric thin films with liquid crystal for gradient index applications

Improvement of liquid crystal tunable lenses with weakly conductive layers using multifrequency driving

A common technique to realize the gradient electric field profile that is required in liquid crystal tunable lenses is the use of a weakly conductive layer. Thanks to this layer, an applied voltage with a certain frequency allows us to obtain a refractive index profile that is required for the lens operation. Due to the limited degrees of freedom, however, it is not possible to avoid aberrations in a weakly conductive layer-based tunable lens for a continuously tunable focal length. In this work, we discuss the use of additional higher frequency components in the voltage signal to reduce the lens aberrations drastically.

Multi-electrode tunable liquid crystal lenses with one lithography step

Electrically tunable lenses offer the possibility to control the focal distance by applying an electric field. Different liquid crystal tunable lenses have been demonstrated. In order to minimize lens aberrations, multi-electrode designs allow us to fine-tune the applied voltages for every possible focal distance. In this Letter, we provide a novel multi-electrode design in which only one lithography step is necessary, thereby offering a greatly simplified fabrication procedure compared to earlier proposed designs. The key factor is the use of a high-permittivity layer, in combination with floating electrodes.

Static and dynamic electro-optical properties of liquid crystals mediated by ferroelectric polymer films

Liquid crystals (LC) can reveal the fractal dimension of multi-domain ferroelectric films (FF) while these films can control the switching time of FF–LC hybrids.

Fast switching cholesteric liquid crystal optical beam deflector with polarization independence

Optical beam deflectors based on the combination of cholesteric liquid crystals and polymer micro gratings are reported. Dual frequency cholesteric liquid crystal (DFCh-LC) is adopted to accelerate the switching from the homeotropic state back to the planar state. Polarization independent beam steering components are realized whose transmission versus the polarizing angle only varies 4.4% and 2.6% for the planar state and the homeotropic state, respectively. A response time of 451 ms is achieved for DFCh-LC-grating beam deflectors, which is fast compared to other nematic LC beam steerers with similar LC thickness.