Second-harmonic generation in highly textured LiNbO3 films prepared by pulsed laser deposition

LiNbO3 films have been deposited on (001) sapphire substrates by pulsed las er deposition, in an oxygen environment. Films grown at substrate temperatu res of 650 degrees C are crystalline, strongly textured, and show a degree of twining that is lower the higher the oxygen pressure is in the range of 0.5-1 Torr. Values of the nonlinear optical coefficients d(33) and d(31) of the films, measured via second-harmonic generation, are close to those for the bulk LiNbO3 single crystal. The dependence of both the degree of twini ng and the nonlinear optical response on the film thickness suggests that t he films become closer to single domain for larger thickness. (C) 2000 Amer ican Institute of Physics. [S0021-8979(00)01519-X].