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

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 {μ}m relative to d₃₁(LiIO₃) are: for LiNbO₃(d₃₃), 4.53 ±{} 4.3; GaP (d₃₆), 12.1 ±{} 1.7; GaAs (d₃₆), 26.9 ±{} 2.1; AgGaSe₂ (d₃₆), 10.5 ±{} 1.2; CdSe (d₃₃), 10.2 ±{} 1.2. The measured ratios at 1.318 {μ}m relative to d₃₁(LiIO₃) are: for LiIO₃ (d₃₃), 0.990 ±{} 0.05; LiNbO₃ (d₃₁), 0.870 ±{} 0.07; LiNbO₃ (d₃₃), 4.66 ±{} 0.56; KH₂PO₄ (d₃₆), 0.088 ±{} 0.01; GaP (d₃₆), 12.0 ±{} 1.2. We have used the parametric fluorescence method to accurately measure the absolute second-order susceptibility of LiIO₃ (d₃₁) and LiNbO₃ (d₃₁) at 4880 and 5145 {}. Our recommended values for d₃₁(LiIOO₃)=(7.31±0.62)×10^-12 and d₃₁(LiNbO₃)=(5.82±0.70)×10^-12 m/V agree very well with previous independent absolute measurements. By scaling the nonlinear susceptibilities through the relatively dispersionless Miller's Δ and using the wedge ratio results, we have, for the first time, established a uniform scale of nonlinear susceptibility values relative to d₃₁(LiIO₃) that extends from 0.488 to 10.6 {μ}m in the infrared.