Research And Verification On Thermo Optic And Electro Optic Characteristics Of Chiral Liquid Crystal’s Rotatory Effect

Conventional liquid crystal optical phased array is based on electrically controlled birefringence effect of liquid crystal and the blazed grating principle, using profile electric field to control the deflection of the liquid crystal director to obtain periodic phase delay of the incident light in order to achieve beam deflection, focusing, scanning and wavefront correction for laser tracking and detection, projection displays, optical addressing purposes. Compared with other controlled devices,liquid crystal-based phase array have features like high resolution, programmable, high precision, no mechanical wear and tear and so on. The substance of the liquid crystal phase control technology is the phase delay controlled by electric. If the phase delay can be obtained by optical rotation effect. The phased array technology can be achieved by chiral liquid crystal. In this paper a method of using quarter-wave plate to convert the chiral liquid crystal optical rotation effect to phase delay which can be used in the liquid crystal phase control technology was put forward.The theoretical computing of chiral liquid rotation,electrical and heat effects on optical rotation for this approach were studied. The main process and results are as follows:1. Based on the theory of Oseen-Frank,the director of liquid crystal is calculated using differential iteration method.Using the results of director and based on Berreman4 × 4 matrix method we got the transmission light field.At last,use the Jones matrix as a tool for the analyze of transmission light field we get the numerical solution of the optical rotatory angle. By comparing the measurement results and theoretical solutions on the vertical incident and oblique incident conditions,results were got that the rotation angle varies with pitch,cell thickness,angle of incident as calculated.So we can get the conclusion: Combine differential iterative method of liquid crystal director simulation and Berreman4 × 4 matrix method can accurately calculate the angle of rotation.2.Proposed a system that make the light through the 1/4 wave plate- chiral liquid crystal- 1/4 wave plate, use the chiral liquid crystal’s optical rotation effect achieve phase delay.On this basis, use electric field to control the optical phase delayelectronically,which can be applied for LC based phase array technology.The optical effect under the different frequency AC and DC electric field is measured.By Measuring the reflection spectrum of the liquid crystal of DC condition we get the rotation vary curve versus voltage.The results show that when the negative chiral liquid crystal is in HAN type( ∥ / ⊥ orientation) cell mode, its optical rotation angle can discrete changes with DC field,using the electrically controlled optical rotation to control the phase delay is feasible.3.Experimental research on the temperature sensitive of CLC’s(chiral liquid crystal)optical rotatory was studied too. The optical rotation angle curves with temperature of chiral liquid crystal with pitch from 250 nm to 310 nm in different conditions were measured to study the thermal sensing rotatory characteristics of CLC.Results proved that even though there ’ s differences on different pitch,CLC Optical rotatory angle varies regularly and obviously with temperature in different conditions.And the thermal characteristics on phase delay converted by optical rotation was studied too. The results proved that the rotation and phase delay of CLC vary sensitively and accurately with temperature.This character can be used in temperature sensor too.