The electro-optic coefficients of urea

Abstract

The two independent electro-optic coefficients of crystalline urea, r63 and r41, are determined experimentally using a voltage modulation technique. The results are compared with theoretical values obtained by direct summation over CNDO/S generated electronic states in a perturbation theory based expression for nonlinear optical coefficients. A further comparison is made with the predicted results of an anharmonic oscillator model for nonlinear optical processes. The results obtained by all three methods, after proper internal field corrections, agree within the limitations of the theoretical calculations and the margins of experimental error.