Z-scan measurement for the nonlinear absorption of Bi_(2.55)La_(0.45)TiNbO_9 thin films

摘要

Bi_(2.55)La_(0.45)TiNbO_9 (BLTN-0.45) thin films with layered aurivillius structure were fabricated on fused silica substrates by pulsed laser deposition technique. Their structure, fundamental optical constants, and nonlinear absorption characteristics have been studied. The film exhibits a high transmittance (>60%) in visible-infrared region. The optical band gap energy was found to be 3.44 eV. The optical constant and thickness of the films were characterized using spectroscopic ellipsometric (SE) method. The nonlinear optical absorption properties of the films were investigated by the single-beam Z-scan method at a wavelength of 800 nm laser with a duration of 80 fs. We obtained the nonlinear absorption coefficient β = 4.64×l0~(-8) m/W. The results show that the BLTN-0.45 thin film is a promising material for applications in absorbing-type optical device.