Nonlinear optical absorption in undoped and cerium-doped BaTiO3 thin films using Z-scan technique

BaTiO3 and BaTiO3:Ce thin films with good surface morphology and tetragonal perovskite structure were fabricated on quartz substrates by pulsed-laser deposition technique at a deposition temperature of 750 degrees C. The fundamental optical constants (the band gaps, linear refractive indices and absorption coefficients) of the films were obtained through optical transmittance measurements. The nonlinear optical properties of the films were investigated using Z-scan method. The films display large nonlinear absorption effects. The two-photon absorption coefficients of the BaTiO3 and BaTiO3:Ce films were determined to be 51.7 and 59.3 cm/GW, respectively. All the results show that undoped and cerium-doped BaTiO3 ferroelectric thin films have potential applications in absorbing-type optical devices. (C) 2000 American Institute of Physics. [S0003-6951(00)03108-9].