Accurate second-order susceptibility measurements of visible and infrared nonlinear crystals

Abstract

Using the wedge technique we have directly compared the second-order nonlinear susceptibilities of infrared and visible nonlinear crystals. The measured nonlinear coefficient ratios at 2.12 \ensuremath{\mu}m relative to ${d}_{31}(\mathrm{LiI}{\mathrm{O}}_{3})$ are: for $\mathrm{LiNb}{\mathrm{O}}_{3}({d}_{33})$, 4.53 \ifmmode\pm\else\textpm\fi{} 4.3; $\mathrm{GaP} ({d}_{36})$, 12.1 \ifmmode\pm\else\textpm\fi{} 1.7; $\mathrm{GaAs} ({d}_{36})$, 26.9 \ifmmode\pm\else\textpm\fi{} 2.1; $\mathrm{AgGa}{\mathrm{Se}}_{2} ({d}_{36})$, 10.5 \ifmmode\pm\else\textpm\fi{} 1.2; $\mathrm{CdSe} ({d}_{33})$, 10.2 \ifmmode\pm\else\textpm\fi{} 1.2. The measured ratios at 1.318 \ensuremath{\mu}m relative to ${d}_{31}(\mathrm{LiI}{\mathrm{O}}_{3})$ are: for $\mathrm{LiI}{\mathrm{O}}_{3} ({d}_{33})$, 0.990 \ifmmode\pm\else\textpm\fi{} 0.05; $\mathrm{LiNb}{\mathrm{O}}_{3} ({d}_{31})$, 0.870 \ifmmode\pm\else\textpm\fi{} 0.07; $\mathrm{LiNb}{\mathrm{O}}_{3} ({d}_{33})$, 4.66 \ifmmode\pm\else\textpm\fi{} 0.56; $\mathrm{K}{\mathrm{H}}_{2}{\mathrm{PO}}_{4} ({d}_{36})$, 0.088 \ifmmode\pm\else\textpm\fi{} 0.01; $\mathrm{GaP} ({d}_{36})$, 12.0 \ifmmode\pm\else\textpm\fi{} 1.2. We have used the parametric fluorescence method to accurately measure the absolute second-order susceptibility of $\mathrm{LiI}{\mathrm{O}}_{3} ({d}_{31})$ and $\mathrm{LiNb}{\mathrm{O}}_{3} ({d}_{31})$ at 4880 and 5145 \AA{}. Our recommended values for ${d}_{31}(\mathrm{LiIO}{\mathrm{O}}_{3})=(7.31\ifmmode\pm\else\textpm\fi{}0.62)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$ and ${d}_{31}(\mathrm{LiNb}{\mathrm{O}}_{3})=(5.82\ifmmode\pm\else\textpm\fi{}0.70)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$ m/V agree very well with previous independent absolute measurements. By scaling the nonlinear susceptibilities through the relatively dispersionless Miller's $\ensuremath{\Delta}$ and using the wedge ratio results, we have, for the first time, established a uniform scale of nonlinear susceptibility values relative to ${d}_{31}(\mathrm{LiI}{\mathrm{O}}_{3})$ that extends from 0.488 to 10.6 \ensuremath{\mu}m in the infrared.