Nonlinear response and optical limiting in SrBi2Ta2O9 thin films

SrBi2Ta2O9 (SBT) thin films on quartz substrates were prepared by use of th e pulsed-laser deposition technique. The nonlinear refractive indices, n(2) , Of the SBT films were measured by use of z-scan techniques with picosecon d pulses. Large negative nonlinear refractive indices of 3.84 and 3.58 cm(2 )/GW were obtained for the wavelengths 532 nm and 1.064 mum, respectively. The two-photon absorption coefficient was determined to be 7.3 cm/GW for 53 2 nm. The limiting behavior of SBT thin film on a quartz substrate was inve stigated in an f/5 defocusing geometry by use of 38-ps-duration, 532-nm, 1. 064-mum. laser excitation. (C) 2001 Optical Society of America.