Abstract

In addition to being a superior material for SHG of Nd:YAG and Nd:YLF, KTiOPO₄ (KTP) has been shown to have electrooptic and dielectric properties that make it attractive for various optical waveguide devices (1). It's electrooptic waveguide modulator figure-of-merit (n³r/ε_eff) is nearly double that of any other candidate integrated optic substrate material. A waveguide fabrication process has been previously described which is based on ion exchange of Rb, Cs, and Tl for K using various molten nitrate salts (2). This process has given refractive index increases of up to 0.23 and the channel guides fabricated show essentially no lateral diffusion. Since this is a diffusion process waveguide refractive index and depth uniformity depend critically on the uniformity of the KTP substrate ionic properties. Early work showed that fairly large variations can exist in ionic properties of typical KTP substrates which in some cases led to relatively uniform guides in certain regions of the substrate to no guiding at all in other regions. Such large variations obviously make fabrication of useable devices difficult.

© 1988 Optical Society of America