Velocities of surface acoustic waves in proton exchanged lithium niobate with different HxLi1-xNbO3 phases

Abstract

The possibilities of using surface acoustic waves for characterization of different proton-exchanged LiNbO3 layers are studied. Depending on the acidity of the proton source, as well on the temperature and duration of the exchange and annealing, the properties of formed waveguide layers vary in a large scale. Samples possessing seven different HxLi1-xNbO3 crystallographic phases have been studied. The SAW velocity has been measured acoustooptically in the range 60 to 400 MHz. The formation of HxLi1-xNbO3 layer causes the strong acoustic dispersion. No differences in the dispersion were observed in the samples with b1 , b2 , b3 phases, showing that they are identical from the acoustic point of view, whereas the appearence of b4 phase leads to stronger dispersion. The phases k which are obtained in annealed samples are characterized by much weaker dispersion.