Fast Electro-optic Response Research Articles

Fluid biaxial banana phases: Symmetry at work

Fluid biaxial smectics made from compounds without asymmetric carbons but nevertheless with a spontaneous polarization are now known as banana smectics because of their molecular shape. Here we show that symmetry changes under parity (r ← - r) are an efficient way to summarize and differentiate their electro-optic properties. Typical of fluid biaxial smectics, there are also a large number of stacking options endowing them with opto-electric properties spanning a broad range of economically viable applications. “Value-added features” of some banana smectics include a faster electro-optic response than found in liquid crystals with a helix structure, their steric property allowing rotations about an axis in a layer plane without compromising smectic layer stability and ambidextrous chirality.

Novel Thermally Stable Polymer Materials for Second-Order Nonlinear Optics

A novel method of preparing thermally stable thin films with intrinsic second-order nonlinear optical activity is described. Design and synthesis yielded new ferroelectric bifunctional liquid crystalline acrylate monomer mixtures with a fast electro-optical response in the chiral smectic C (SmC*) phase. The ferroelectric liquid crystalline monomer mixtures were poled and subsequently cross-linked by in-situ photopolymerization in the surface-stabilized ferroelectric liquid crystal state. After cross-linking the polarization is no longer reversible, hence the material is pyroelectric and not ferroelectric. The cross-linked pyroelectric materials displayed a thermally stable nonlinear optical response.

The pi-Cell: A Fast Liquid-Crystal Optical-Switching Device

Abstract A new approach is given for obtaining fast electro-optical response and good angular-viewing characteristics in a liquid-crystal variable-retardation device. The improved characteristics make the new device well suited for use in field-sequential color systems.

Physical properties of new liquid-crystal mixtures and electrooptical performance in twisted nematic displays

Complete sets of measurements are reported of the elastic, dielectric, optical, and viscous properties of new liquid-crystal mixtures for twisted nematic displays. Their optical and capacitive threshold voltages were shown to be identical and were used to determine the twist elastic constants k 22 . The splay (k 11 ) and bend (k 33 ) elastic constants were measured using a novel phase sensitive capacitance bridge, The new mixtures consist of nematic and isotropic components belonging to different chemical classes. Large mesomorphic temperature ranges (T c > 100° C), fast electrooptical response, 1.5-V operation, and 3-V 1:3 multiplexability could be achieved with different eutectic mixtures. Good agreement was found between material properties of physically and chemically different mixtures and their static and dynamic electrooptical performance in twisted nematic displays.