The third-order optical nonlinearity of Bi3.25La0.75Ti3O12 ferroelectric thin film on quartz

Abstract Bi 3.25 La 0.75 Ti 3 O 12 (BLT) thin film was prepared on quartz substrates using chemical solution deposition. The sign and magnitude of both real and imaginary parts of third-order nonlinear susceptibility χ (3) of the BLT thin film have been determined by the Z-scan technique performed at 800 nm with a femtosecond laser. The nonlinear refractive index coefficient γ and the nonlinear absorption coefficient β of the BLT thin film are − 1.915 × 10 − 12 cm 2  / W and − 6.764 × 10 − 8 m/W, respectively, the real part and imaginary part of the third-order nonlinear susceptibility χ (3) of the BLT thin film are − 5.81 × 10 − 18 m 2  / V 2 and − 1.31 × 10 − 18 m 2  / V 2 , respectively. Both the real and the imaginary parts of the third-order nonlinear susceptibility χ (3) contribute to the nonlinearity of the film. These experimental results show that BLT thin film is a promising material for applications in nonlinear optical devices.