A femtosecond mid-infrared optical vortex laser can be used for high harmonic generation to extend cutoff energy to the kilo-electron-volt range with orbital angular momentum, as well as other secondary radiations. For these, we demonstrate a high-energy femtosecond 4 μm optical vortex laser based on optical parametric chirped pulse amplification (OPCPA) for the first time. The optical vortex seed is generated from a femtosecond 4 μm laser by a silicon spiral phase plate with the topological charge l of 1 before the stretcher. Through using a two-stage collinear OPCPA amplifier, the chirped vortex pulse is amplified to 12.4 mJ with 200 nm full width at half-maximum bandwidth. After compression, the vortex laser pulse with 9.53 mJ, 119 fs can be obtained. Furthermore, the vortex characteristics of the laser beam are investigated and evaluated. This demonstration can scale to generate a higher-peak-power vortex mid-IR laser and pave a new way for high field physics.

中文翻译：

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基于光学参量啁啾脉冲放大的飞秒中红外光学涡旋激光器

飞秒中红外光学涡旋激光器可用于产生高次谐波，以将截止能量扩展到具有轨道角动量以及其他二次辐射的千电子伏范围。为此，我们首次展示了基于光学参量啁啾脉冲放大 (OPCPA) 的高能飞秒 4 μm 光学涡旋激光器。光学涡旋种子是由4 μm 飞秒激光器通过展宽器前拓扑电荷l 为1 的硅螺旋相位板产生的。通过使用两级共线 OPCPA 放大器，啁啾涡旋脉冲被放大到 12.4 mJ，半高带宽全宽为 200 nm。压缩后可获得9.53 mJ、119 fs的涡旋激光脉冲。此外，研究和评估了激光束的涡流特性。