Investigation on third-order nonlinear optical properties of undoped LiNbO3 by modified Z-scan technique

A new method for measuring third-order nonlinear optical properties of photo refractive materials based on modified Z-scan technique in which employing focus-tunable lens was proposed. By this method, the nonlinear refractive index and the nonlinear absorption coefficient of an undoped LiNbO3\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{LiNb}}{{\text{O}}_{\text{3}}}$$\end{document} crystal were investigated γ=-1.48×10-12m2/W\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma = - 1.48 \times {10^{ - 12}}\;{{\text{m}}^{\text{2}}}{\text{/W}}$$\end{document} and β=0.33mm/W\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta = 0.33\;{\text{mm/W}}$$\end{document}, respectively. The investigation suggests that the calculated results keep agreement with the traditional Z-scan technique in the order of magnitude.