Development of Ferroelectric Liquid Crystals with Enhanced Nonlinear OpticalProperties

摘要

During our Phase I research, we advanced materials synthesis and evaluationtechniques needed to develop ferroelectric liquid crystals into a useful second-order nonlinear optical material. We developed a technique for determining the second-order nonlinear susceptibility by measuring the electro-optic coefficient r22 at 633 nm, using modulation frequencies between 100 KHz-100 MHz. We evaluated two specially synthesized FLCs by measuring their r22 coefficients: previously existing MX-5679 and recently synthesized W-399, both based on a nitrobenzene hyperpolarizable moiety. Results show an increasing r22 with increasing spontaneous polarization. We also partially evaluated a new FLC material, W-371, with an ortho-situated nitroaniline hyperpolarizable moiety. Since the liquid crystalline and the linear and nonlinear materials parameters FLCs have a temperature dependence, we examined existing FLC polymers for a FLC to glass phase and discovered a polymeric/FLC system that potentially could be used to reduce temperature dependent materials properties. Our FLC synthesis efforts concentrated on synthesis of Hoffman-LaRoche compounds roche 1 and roche 2. Unfortunately, we were unable to duplicate their synthesis and instead developed an alternative core that could yield FLCs with a higher second-order nonlinear susceptibility. Ferroelectric liquid crystal, Second-order nonlinear optical material.