Kuniharu TAKIZAWA, Kazuya YONEKURA, and Lianhua JIN¹

Department of Materials and Life Science, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-Kitamachi, Musashino, Tokyo 180-8633, Japan
¹Department of Mechanical Systems Engineering, Faculty of Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu 400-8510, Japan

(Received April 18, 2009; Accepted September 25, 2009)

The temperature characteristics of a Y-cut Z-propagation LiNbO₃ crystal light modulator, with manufacturing errors, in the absence and presence of an electric field have been investigated by analyses and experiments. According to our analyses, when the Z-axis of the LiNbO₃ crystal is at an angle of 0.22° with respect to the normal of the input surface of the crystal, we found the theoretical fluctuation of the normalized output-light intensity with temperature to be less than 7.75 × 10^-6/°C. This magnitude is less than 1% of the theoretical intensity fluctuation of a conventional temperature-compensation LiNbO₃ light modulator. The measured temperature characteristics of a prototype of this modulator were 2 × 10^-4/°C in the absence of an electric field (OFF state) and 2.8× 10^-4/°C in the presence of an external field (ON state). During a running test of longer than 8 hours at room temperature, the intensity fluctuation of this prototype was 0.01% in the OFF state, and 0.07% in the ON state.

Key words: LiNbO₃ crystal, light modulator, electro-optic effect, birefringence, manufacturing error