Abstract

High δn_e Proton Exchanged (PE) waveguides in LiNbO₃¹ are extremely interesting when dealing with phenomena where power confinement is a key factor. However it was noted that in many cases it was not possible to keep the losses under several dB/cm. In this paper we will show how a correlation between the crystalline and the optical properties of these waveguides allows us to explain the propagation losses either by scattering induced by the presence of dislocations in the exchanged layer, or by stress induced rotation of the principal axes of the exchanged layer with respect to the substrate axes, or a combination of the two. The importance of these loss mechanisms is strongly related to the fabrication parameters, especially the temperature of the exchange melt, and we will show that increasing this temperature dramatically improves the crystalline quality of the layer and the properties of the waveguide.

© 1993 Optical Society of America