We proposed spectrally temporally cascaded optical parametric amplification (STOPA) using pump energy recycling to simultaneously increase spectral bandwidth and conversion efficiency in optical parametric amplification (OPA). Using BiB₃O₆ and KTiOAsO₄ nonlinear crystals, near-single-cycle mid-infrared (MIR) pulses with maximum energy conversion efficiencies exceeding 25% were obtained in simulations. We successfully demonstrated sub-two-cycle, CEP-stable pulse generation at 1.8 µm using a four-step STOPA system in the experiment. This method provides a solution to solve the limitations of the gain bandwidth of nonlinear crystals and the low conversion efficiency in broadband OPA systems, which is helpful for intense attosecond pulse generation and strong laser field physics studies.

中文翻译：

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通过光谱时间级联光学参量放大和泵浦能量回收来产生高效的单周期中红外飞秒激光脉冲

我们提出了使用泵浦能量回收的光谱时间级联光学参量放大（STOPA），以同时增加光学参量放大（OPA）的光谱带宽和转换效率。使用BiB ₃ O ₆和KTiOAsO ₄非线性晶体，在模拟中获得了最大能量转换效率超过25%的近单周期中红外（MIR）脉冲。我们在实验中使用四步 STOPA 系统成功演示了 1.8 µm 的亚两周期、CEP 稳定脉冲生成。该方法为解决非线性晶体增益带宽的限制和宽带OPA系统转换效率低的问题提供了解决方案，有助于强阿秒脉冲产生和强激光场物理研究。