A new class of second order nonlinear optical (NLO) materials has been developed: X(2) ferro- electric liquid crystals (FLCs). Conventional FLCs readily form low- light-loss polar films in a wide range of thicknesses, and have been demonstrated as optical waveguides. The new X(2) FLCs combine the processibility of conventional FLCs with thermodynamically stable NLO susceptibility of useful magnitude. In addition, optical properties such as birefringence, dielectric permittivity, and NLO properties are highly customizable by chemical synthesis and mixing. In this Small Grant for Exploratory Research, the attractive possibility of using centimeter long, um inner diameter capillary tubes filled with X(2) FLCs for optical parametric processes will be investigated. Key questions which will be answered in this work include the following: 1) What is the intrinsic director structure in the capillary tubes--is the polarization vector field polar, and how can it be controlled? 2) What are possible phase matching schemes for FLC-cored optical waveguides? FLC alignment in capillary tubes will be examined experimentally, and the effect of FLC material parameters such as liquid crystal phase sequence, helix pitch, tilt angle, and capillary tube preparation on alignment characteristics will be determined. Using director alignment information, second harmonic generation processes will be accurately modeled by solving the wave equation with position dependent relative permittivity and nonlinear polarizability. Finally, frequency doubling of near-infrared radiation using the X(2) FLC mixture Displaytech MX-5679 in um inner diameter, centimeter long capillary tubes will be investigated experimentally.
