Lithium-rich vapor transport equilibration in single-crystal lithium niobate thin film at low temperature

A lithium-rich vapor transport equilibration technique was used to increase the Li/Nb ratio in single crystal LiNbO3 thin film at low temperature (below 600 degrees C). The extraordinary refractive index n(e) of the Li-compensated thin film was measured and found to be 2.1983 at 632.8 nm using the prism coupling method, while the ne of the congruent LiNbO3 was 2.2024. The lattice parameter (c(r)) of Li-compensated LiNbO3 thin film was determined to be 13.8604 angstrom using high-resolution x-ray (HRXRD) omega-2 theta scan, which was between the values of congruent LiNbO3 (13.8650 angstrom) and stoichiometric LiNbO3 (13.8562 angstrom). The Raman spectra showed significant differences in the relative intensity and the FWHM of Raman lines between the Li-compensated thin film and congruent thin film. (C) 2015 Optical Society of America