Communication-Electro-Optic Coefficient Measurement by Using Linearity between Refractive Index Change and Externally Applied Electric Field

We propose a method to measure electro-optic(EO) coefficient of either a bulk crystal or a thin-film or a planar/slab waveguide by using the linearity between refractive index change induced by EO effect and externally applied electric field. A LiNbO₃ single-crystal is exemplified. By using prism coupling technique the EO-effect-induced refractive index change at crystal surface was measured vs electric field. By using their linearity the EO coefficient is determined. A comparison with previously reported values shows that the measured data can be considered as identical to the reported within the error, confirming feasibility of the method. The accuracy is ∼7%.