Application of PN-Heterojunctions in Photorefractive Liquid Crystal Light Valves

Date of Award


Degree Name

Ph.D. in Electro-Optics


Department of Electro-Optics


Advisor: Dean Evans


This dissertation describes the first application, of Copper Oxide (Cu(II)O or CuO) and Zinc Oxide (ZnO) pn-junction thin films in photorefractive liquid crystal light valve applications. A novel thin film preparation technique was developed based on ball milling, spin coating, and thermal treatment that is able to produce optically transparent (>80% transmission in the visible) multilayer thin films of ZnO (~75 nm) and CuO (~6 nm). The electro-optic response of liquid crystal light valves prepared with CuO/ZnO pn-junction thin films was demonstrated using optical Freedericksz measurements and two-wave mixing. Results from the optical Freedericksz showed a forward and reverse bias response when the illumination intensity was varied, which was attributed to the photodiode behavior of the pn-junction. The results from the two-wave mixing experiment showed a photorefractive asymmetric energy exchange between two laser beam inputs of equal power. A new model was proposed to explain the origins of this asymmetric coupling response based on the anisotropy of the liquid crystal medium, the two input beam's polarization states, and k-vectors.


Optics, Nanotechnology, Electrical Engineering, Photorefractive, Photovoltaic, Liquid Crystal, Light Valve, ZnO, CuO, Zinc Oxide, Copper Oxide

Rights Statement

Copyright © 2019, author