Tomo IWAMURA, Shota SUKA, Xin Yi LIU, and Shinsuke UMEGAKI

Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan

(Received February 12, 2008; Accepted October 28, 2008; Revised September 19, 2008)

An electro-optic (EO) coefficient can be evaluated from a modulated signal by applying an AC voltage to a plane-parallel sample in an interferometer. We proposed a method for compensating multiple-reflection of a light in the sample. The multiple-reflection causes errors in the evaluated EO coefficient. In measurement using a Mach–Zehnder interferometer, we analyzed the multiple-reflection and clarified its unfavorable effect. The effect could be avoided simply by selecting the incidence angle of the light on the sample. We confirmed this by measuring the EO coefficient of a KTiOPO₄ crystal.

Key words: electro-optic effect, electro-optic coefficient, Mach–Zehnder interferometer, multiple-reflection, potassium titanyl phosphate