Abstract

The use of lithium tantalate for integrated optics offers an attractive alternative to lithium niobate because of its higher stability, smaller birefringence, and greatly reduced susceptibility to optical damage (one to two orders of magnitude). Because lithium tantalate has such a low Curie temperature (610°C), the fabrication of waveguides by the traditional high-temperature indiffusion of various elements presents many difficulties. The use of the low-temperature proton-exchange process alleviates many of these problems and allows the fabrication of efficient, low-loss waveguides. This talk will discuss the efforts underway in our laboratory, to understand and model the mechanisms involved in the proton-exchange process in lithium tantalate. Optical characterization of z-cut slab and channel waveguides, including m-line measurements and near-field mode sizes, will be presented. We have performed parameter-space study to determine the regions of single-mode operation in channel waveguides. The performance of fabricated directional couplers and the effects of annealing on the coupling length and the results of studies of the microscopic aspects of the proton-exchange process, obtained through the use of secondary ion mass spectrometry, will also be presented.

© 1990 Optical Society of America