Growth of nonlinear optical thin films of KTa1-xNbxO3 on GaAs by pulsed laser deposition for integrated optics

We report successful deposition of epitaxial nonlinear KTa0.52Nb0.48O3 (KTN ) films on (100) GaAs substrates. A buffer layer scheme consisting of epita xial MgO and SrTiO3 buffer layers and a Si3Ni4 encapsulation of the substra te was developed to alleviate chemical and structural incompatibilities bet ween the GaAs substrate and KTN film at the growth temperature (similar to 750 degrees C). The structure, composition, and preliminary optical propert ies of the KTN films were evaluated by four-circle x-ray diffraction, Ruthe rford backscattering spectrometry, and prism coupled optical waveguide mode measurements, respectively. We observed sharp and distinguishable transver se electric and transverse magnetic propagating modes in the KTN films, and measured the refractive index (n(0)) of the film at 488 nm to be 2.275 whi ch is close to the bulk value of 2.35, all of which indicates a high struct ural and optical film quality. (C) 1998 American Institute of Physics. [S00 03-6951(98)00452-5].