2ND-HARMONIC GENERATION AND ORIGIN OF POLAR CONFIGURATION IN KTAO3-LI

Results are presented for the second-harmonic generation of light in K(1-x)Li(x)TaO3 for x = 1.6%, 2.6%, 3.4%, and 6%. From the second-harmonic efficiency and from birefringence results, it is concluded that below the freezing temperature T(f), KTaO3:Li polar displacements are correlated over distances xi-d, which increase continuously with dopant concentration x from 6 nm at x = 1.6% to 23 nm at x = 6%. Below T(f), xi-d is nearly independent of T. Quadrupolar distortions are correlated over much larger distances, comparable to the wavelength of light.