Waveguiding epitaxial potassium lithium niobate single-crystal films deposited by metalorganic chemical vapor deposition

Epitaxial potassium lithium niobate (KLN) single-crystal films were deposited on potassium lithium tantalate (KLT) singre-crystal substrates by low-pressure metalorganic chemical vapor deposition (MOCVD). Pentaethoxyniobium [Nb(OC2H5)(5)] and K and Li-dipivaloylmethane [K(DPM), Li(DPM)] were used as volatile metalorganic precursors. The crystallinity of the films was investigated by X-ray diffraction measurements. Reciprocal space mapping indicated that good epitaxial growth had been achieved. The film surface was smooth enough to act as a waveguide. Several guided modes were observed for both TE and TM waves by the prism coupler method. Refractive indices of the films for various wavelengths were determined and the phase matching property of the waveguide is discussed. The propagation loss, estimated by the cut-back method, was found to be 0.5 dB/cm at a wavelength of 633 nm.