Linear and nonlinear optical properties of BiFeO3

Using spectroscopic ellipsometry, the room temperature refractive index and absorption versus wavelength of the ferroelectric antiferromagnet bismuth ferrite, BiFe O3, are reported. The material has a direct band gap at 442 nm wavelength (2.81 eV). Using optical second harmonic generation, the nonlinear optical coefficients were determined to be d15 d22 =0.20±0.01, d31 d22 =0.35±0.02, d33 d22 =-11.4±0.20, and ∫ d22 ∫ =298.4±6.1 pmV at a fundamental wavelength of 800 nm. © 2008 American Institute of Physics.