Optical properties of mid-infrared, Li-based nonlinear crystals (NLC) are estimated under realistic experimental conditions for high power lasers using the thermal imaging method. The study focuses on crystals with relatively large apertures for high energy and power applications that are transparent in a broad spectral range (6–16 µm). For this purpose, a high average power Yb:YAG laser amplifier system was used that pumps the crystals and the thermal response of the materials was recorded. An estimate of the linear and nonlinear absorption coefficients of different non-oxide crystals at the 1-µm pump wavelength along with their nonlinear refractive index is provided. To the best of our knowledge, linear and nonlinear absorption coefficients are presented for the first time, including the nonlinear refractive index of AGS, LGSe, LIS, and LISe. These optical material properties are of utmost importance for cutting-edge laser developments close to damage thresholds since they affect the resulting beam quality and conversion efficiencies of novel high power optical parametric amplifiers operating in the long-wavelength mid-infrared spectral range.

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在实际操作条件下以1 µm抽运的用于大功率中红外OPCPA的锂基非线性晶体的光学特性

在大功率激光器的实际实验条件下，使用热成像方法估算了中红外，基于锂的非线性晶体（NLC）的光学特性。这项研究的重点是在高能量和高功率应用中具有相对较大孔径的晶体，该晶体在较宽的光谱范围（6–16 µm）内是透明的。为此，使用了高平均功率的Yb：YAG激光放大器系统来泵浦晶体，并记录了材料的热响应。提供了在1 µm泵浦波长下不同非氧化物晶体的线性和非线性吸收系数及其非线性折射率的估计。据我们所知，首次出现了线性和非线性吸收系数，包括AGS，LGSe，LIS和LISe的非线性折射率。