Abstract

For integrated optics applications, LiTaO₃ offers an attractive alternative to the more commonly used LiNbO₃.¹ This stems from its higher optical damage threshold level, and smaller birefringence. However no extensive use has been made of this material because of its relatively high optical loss and its low Curie temperature (T_c ~ 510 – 690°C depending on composition). The latter causes domain inversion and makes repoling of crystals a necessity for producing electrooptical devices when waveguides are formed by diffusion at a temperature higher than T_c. Attempts to fabricate waveguides below the Curie temperature have been reported. These include ion exchange,^2,3 and electrodiffusion.⁴ However in the ion exchange method, an index increase is observed only for the extraordinary mode, while in the field assisted diffusion the limitation is prompted by strong absorption peaks and surface damage.

© 1988 Optical Society of America