Polarization-Dependent Third-Order Optical Nonlinearity of Crystal

摘要

We investigated the third-order optical nonlinearity of a new nonlinear optical crystal ${rm BaAlBO}_{3}{rm F}_{2}$ (BABF) using Z-scan technique with a picosecond 532-nm laser. Polarization-dependent nonlinear refractive index $gamma$ of the BABF crystal was measured with an a-cut sample and a sample cut along the type I phase-matching angle for third-harmonic-generation of lasers at 1064 nm (THG-cut). Anisotropy was observed with positive $gamma$ values in the range of $10^{-16}~{rm cm}^{2}/{rm W}$, indicating self-focusing Kerr effects. The measurements agreed well with the theoretical prediction. The corresponding third-order nonlinear optical susceptibility $chi_{eff}^{(3)}$ was estimated to be ${sim} 10^{-14}~{rm esu}$.