Kuniharu TAKIZAWA and Yuji YOKOTA

Department of Materials and Life Science, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-kitamachi, Musashino, Tokyo 180-8633, Japan

(Received September 2, 2005; Accepted March 20, 2006)

Accurate measurements of the composite electrooptic (EO) coefficients r_c consisting of the EO coefficients r₁₃, r₃₃, and the piezoelectric constant d₃₁ in undoped and MgO-doped LiNbO₃ (LN) were made by extracting the fundamental and third harmonic components from photo-detection signals of the parallel Nicol optics including the LN crystal driven by minimal sinusoidal voltage. The analysis of relationship between multiple-reflection rays in the EO crystal and the accuracy of measurement indicates that anti-reflection films must be coated on the end faces of the crystal for highly accurate measurements. Measured values of r_c of undoped and MgO-doped LN crystals at a wavelength of 632.8 nm were 19.8 ± 0.1 pm/V and 19.2 ± 0.1 pm/V, respectively.

Key words: electrooptic effect, electrooptic coefficient, LiNbO₃, converse piezoelectric effect, piezoelectric constant