We present experimental and numerical investigations of high-energy mid-infrared filamentation with multi-octave-spanning supercontinuum generation (SCG), pumped by a 2.4 μm, 250 fs Cr:ZnSe chirped-pulse laser amplifier. The SCG is demonstrated in both anomalous and normal dispersion regimes with YAG and polycrystalline ZnSe, respectively. The formation of stable and robust single filaments along with the visible-to-mid-infrared SCG is obtained with a pump energy of up to 100 μJ in a 6-mm-long YAG medium. To the best of the authors’ knowledge, this is the highest-energy multi-octave-spanning SCG from a laser filament in a solid. On the other hand, the SCG and even-harmonic generation based on random quasi-phase matching (RQPM) are simultaneously observed from the single filaments in a 6-mm-long polycrystalline ZnSe medium with a pump energy of up to 15 μJ. The numerical simulations based on unidirectional pulse propagation equation and RQPM show excellent agreement with the measured multi-octave-spanning SCG and even-harmonic generation. They also reveal the temporal structure of mid-infrared filaments, such as soliton-like self-compression in YAG and pulse broadening in ZnSe.

中文翻译：

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通过 2.4 μm 飞秒 Cr:ZnSe 激光器泵浦的 YAG 和 ZnSe 中的高能激光灯丝产生多倍频程超连续谱

我们提出了由 2.4 μm、250 fs Cr:ZnSe 啁啾脉冲激光放大器泵浦的具有多倍频程跨超连续谱 (SCG) 的高能中红外丝状结构的实验和数值研究。SCG 分别在 YAG 和多晶 ZnSe 的异常和正常色散状态下得到证明。在 6 mm 长的 YAG 介质中，通过高达 100 μJ 的泵浦能量可以形成稳定且坚固的单丝以及可见光到中红外 SCG。据作者所知，这是来自固体中激光灯丝的最高能量多倍频程 SCG。另一方面，在泵浦能量高达 15 μJ 的 6 mm 长多晶 ZnSe 介质中，从单丝同时观察到基于随机准相位匹配 (RQPM) 的 SCG 和偶次谐波产生。基于单向脉冲传播方程和 RQPM 的数值模拟与测量的多倍频程 SCG 和偶次谐波产生非常吻合。他们还揭示了中红外灯丝的时间结构，例如 YAG 中的类孤子自压缩和 ZnSe 中的脉冲展宽。