Third-order optical nonlinear absorption in Bi1.95La1.05TiNbO9 thin films

Single phase Bi1.95La1.55TiNbO9 (LBTN-1.05) thin films with a layered aurivillius structure have been fabricated on fused silica substrates by pulsed laser deposition at 700 degrees C. The X-ray diffraction pattern revealed that the films are single-phase aurivillius. The band gap, linear refractive index and linear absorption coefficient were obtained by optical transmittance measurements. The film exhibits a high transmittance (>70%) in visible-infrared region and the dispersion relation of the refractive index vs. wavelength follows the single electronic oscillator model. The nonlinear optical absorption property of the film was determined by the single beam Z-scan method using 800 nm with a duration of 100 fs. A large positive nonlinear absorption coefficient beta=5.95 x 10(-8) m/W was determined experimentally. The results showed that the LBTN-1.05 is a promising material for applications in absorbing-type optical devices. (C) 2010 Elsevier B.V. All rights reserved.