Abstract

Intrapulse Difference Frequency Generation (iDFG) is an interesting technique for generating femtosecond pulses in the Mid-Infrared (MIR) range with unique properties such as robust Carrier-Envelope Phase (CEP) stability. However, its efficiency is low compared to other techniques. In this paper, we describe an iDFG system operating within the 4–10 \(\upmu\) m range that features an original architecture to enhance efficiency. First, we introduce an interesting technique on the generation process. This approach involves polarization and spectral phase shaping techniques on the driving pulse to maximize the number of photons enrolled in the process. Second, we demonstrate that the polarization shaping allows further enhancement of efficiency by recycling the iDFG signal to pump a subsequent optical parametric amplification (OPA) stage. These two concepts and the associated parameters optimization are described into details, and supported by experimental results. Combined with a high-power Yb-fiber-based pump laser, these techniques allow to achieve record efficiencies, and generate \(\upmu\) J-level, few-cycle, tunable, CEP-stable pulses in the MIR at repetition rates above 100 kHz.

中文翻译：

---

通过脉冲整形和回收最大限度地提高脉冲内差频生成的效率

摘要

脉冲内差频生成 (iDFG) 是一种有趣的技术，用于生成中红外 (MIR) 范围内的飞秒脉冲，具有强大的载波包络相位 (CEP) 稳定性等独特特性。然而，与其他技术相比，其效率较低。在本文中，我们描述了一个在 4-10 \(\upmu\) m 范围内运行的 iDFG 系统，该系统采用原始架构来提高效率。首先，我们介绍一种关于生成过程的有趣技术。这种方法涉及驱动脉冲上的偏振和光谱相位整形技术，以最大限度地增加参与该过程的光子数量。其次，我们证明偏振整形可以通过循环利用 iDFG 信号来泵浦后续的光参量放大 (OPA) 阶段，从而进一步提高效率。这两个概念和相关参数优化得到了详细描述，并得到了实验结果的支持。与高功率 Yb 光纤泵浦激光器相结合，这些技术可以实现创纪录的效率，并以重复率在 MIR 中生成\(\upmu\) J 级、少周期、可调谐、CEP 稳定的脉冲高于 100 kHz。