Kent State University

Volodymyr Borshch

Liang-Chy Chien

Oleg D Lavrentovich

Sergij V Shiyanovskii

Jeoung-Yeon Hwang

An optical modulator includes a liquid crystal cell containing liquid crystal material having liquid crystal molecules oriented along a quiescent director direction in the unbiased state, and a voltage source configured to apply an electric field to the liquid crystal material wherein the direction of the applied electric field does not cause the quiescent director direction to change. An optical source is arranged to transmit light through or reflect light off the liquid crystal cell with the light passing through the liquid crystal material at an angle effective to undergo phase retardation in response to the voltage source applying the electric field. The liquid crystal material may have negative dielectric anisotropy, and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is transverse to the quiescent director direction. Alternatively, the liquid crystal material may have positive dielectric anisotropy and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is parallel with the quiescent director direction.

Nanosecond liquid crystalline optical modulator

A surface polymer-assisted vertically aligned (SPA-VA) liquid crystal (LC) cell has a surface alignment layer of surface localized polymer nano spikes capable of controlling the pretilt angle of liquid crystal molecules and ensuring fast switching characteristics. The deposition of the polymer nanospikes as a part of the alignment layer is achieved by polymerizing a small amount of a reactive monomer in vertically aligned liquid crystal with or without an applied voltage. Due to the alignment of liquid crystal molecules by the surface alignment layers, the polymerized polymer acts as an internal surface to modify and control the field-induced reorientation of the liquid crystal molecules. The SPA-VA LC cell realizes a stable alignment and the considerable advantage of the formation of polymer spikes via UV irradiation on both substrates of the cell. Furthermore, the switch-off of a SPA-VA is fast due to the enhanced surface anchoring strength by the surface-localized polymer nano spikes.

Growing community of inventors

Kent, OH, United States of America

Volodymyr Borshch