Liquid crystal modulator(LCM) is now widely applied, especially in optical telecommunication networks. However, according to the electro-optic characteristic of liquid crystal, we will obtain nonlinear phase response when LCM is driven by the voltage varying with time linearly(v=kt+v0). And in practical application this nonlinear phase response will affect the modulation precision, communication modulation efficiency and so on. This paper presents a logarithm driving signal model to linearize the nonlinear phase response of LCM between 0 and π. When driven by a periodic signal whose voltage varies from 2.0 to 10.7V in the way of logarithm in every periods, the LCM's phase response hops in the point of intersection of two voltage periods. Therefore, we advance another periodic logarithm driving signal, whose voltage ascends from 2.0 to 10.7V in first half periods and descends from 10.7 to 2.0V in the other half periods. Furthermore, We find that the degree of phase response linearization of LCM decreases with the frequency of driving signal increasing. This paper proposes mapping the nonlinear phase response to linear one to overcome this problem. The experimental results indicate that obtaining the linear phase response of liquid crystal between 0 and π with different-frequency driving signals is feasible.

Date Published: 18 November 2008
PDF: 7 pages
Proc. SPIE 7135, Optoelectronic Materials and Devices III, 71351G (18 November 2008); doi: 10.1117/12.802607

Published in SPIE Proceedings Vol. 7135:
Optoelectronic Materials and Devices III
Yi Luo; Jens Buus; Fumio Koyama; Yu-Hwa Lo, Editor(s)