Electro-optical effect in poled side chain polymers

The linear electro-optical effect has been studied in test samples of two different nonlinear optical polymers--with Tg of 140°C and 175°C, respectively--during and after poling. The electro-optical coefficients were measured between crossed polarizers (r33-r13) and using the test samples as Fabry-Perot interferometers (r13). The field strength dependence of the coefficients has been measured during poling of the polymer with Tg=140°C, and compared with theory. Also, the ratio r33/r13 has been investigated. A quasi-instantaneous loss of the field-induced electro-optical activity is observed when the poling field is switched off at ambient temperature after poling in the vicinity of Tg. The influence of an annealing step on the relaxation behavior is discussed. Results of relaxation experiments in the two polymers performed at several constant temperatures are presented.