The third-order optical nonlinearity of Bi 3.25La 0.75Ti 3O 12 ferroelectric thin film on quartz

Abstract

Bi 3.25La 0.75Ti 3O 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.