Femtosecond third-order optical nonlinearity of BiFeO3

We report both linear and nonlinear optical properties of a ferroelectric thin film of polycrystalline BiFeO(3) deposited on a quartz substrate. The linear refraction index and absorption coefficient of the film are determined as a function of light wavelength by optical transmittance measurements. By performing Z-scan experiments with femtosecond laser pulses at a wavelength of 780 nm, the third-order nonlinear refraction index and two-photon absorption (2PA) coefficient are measured to be 1.5 x 10(-4) cm(2)/GW and 16 cm/GW, respectively. The results indicate that the thin film of polycrystalline BiFeO(3) is a promising candidate for applications in nonlinear photonic devices.