Effect of Tb3+/Yb3+ in the nonlinear refractive spectrum of CaLiBO glasses

This paper reports a study on linear and nonlinear optical properties in a series of lithium-calcium tetraborate (CaLiBO) glasses in the presence of two rare earth ions, Tb3+ and Yb3+. The nonlinear index of refraction (n(2)) was determined in a wide wavelength range (470-1500 nm) through femtosecond Z-scan technique. Such results were modeled by KO approach, in which the optical nonlinearity was related to the oxygens present in the glasses. Also, the molar electronic polarizability evidenced that there is a strong influence of the polarizability of the rare earth ions in the nonlinear optical properties. Thus, we can infer that the cooperation of oxygens and the polarizability of rare earth ions are responsible for the nonlinearity present in the investigated vitreous system.