Z-scan analyses for PbO-containing glass with large optical nonlinearity

Abstract

In order to evaluate the large third-order optical nonlinearity of materials accurately, the influence of the irradiance (I0) and sample thickness (L) on the Z-scan transmittance of PbO-containing glass as a representative material was investigated using simple and conventional Z-scan experiments and analyses. The transmittance difference between the peak and valley (ΔTp–v) in the Z-scan curve resulting from nonlinear refraction and the difference between the baseline (1.0) and valley (ΔT1−v) due to nonlinear absorption deviated from a linear relationship at increased I0 and L. It was found that an analysis based on the linear relationship at large I0 and L underestimated the third-order optical nonlinearity due to saturation. Taking into consideration the saturation of ΔTp−v and ΔT1−v with L under moderate irradiance, the intrinsic nonlinear refractive index (γ) and nonlinear absorption coefficient (β) of the present glass were calculated to be 1.58×10−17 m2 W−1 and 7.75 cm GW−1, respectively.