Makoto KUMATORIYA^*, Miki NAKABAYASHI¹, Masaaki SAKAKURA², Yasuhiko SHIMOTSUMA², Kiyotaka MIURA¹, Takashi FUJII, and Kazuyuki HIRAO¹

Technology and Business Development Unit, Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto 615-8555, Japan
¹Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8520, Japan
²Innovate Collaboration Center, Kyoto University, Kyoto 615-8520, Japan

(Received June 1, 2010; Revised October 15, 2010; Accepted October 21, 2010)

Optical waveguides were fabricated by modifying the optical properties inside a LiTaO₃ crystal by irradiation with femtosecond laser pulses, and the performance and optical properties of the waveguide were investigated. On the basis of near-field pattern of the light guided through the waveguides, the optimum writing conditions such as the pulse energy and the pulse duration were determined. The waveguide written inside a LiTaO₃ crystal had a strong polarization dependence of guided light. Observation by a polarized microscope suggested that the stress distribution around the photoexcited region should be responsible for the polarization dependence of guided light. In addition, the second harmonic generation from a laser beam passing through the waveguide was observed, which suggests that the ferroelectric properties of LiTaO₃ were preserved after the photoexcitation.

Key words: femtosecond pulse laser, LiTaO₃, refractive index, near-field pattern, optical waveguide, photoexcitation

^*E-mail address: kumatry@murata.co.jp