Quasi-phase-matched high-harmonic generation in gas-filled hollow-core photonic crystal fiber
Quasi-phase-matched high-harmonic generation in gas-filled hollow-core photonic crystal fiber
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DOI：
10.1364/optica.6.000442
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发表时间：
2019-04-20
期刊：
影响因子：
10.4
通讯作者：
Walmsley, Ian A.
中科院分区：
文献类型：
--
作者：
Wiegandt, Florian;Anderson, Patrick N.;Walmsley, Ian A.
高阶谐波发生（HHG）提供了一种有前途的相干短波长辐射桌面源。然而，当用低平均功率、kHz 重复率激光器驱动时，低产生效率限制了 HHG 源的平均光子通量。通过采用 MHz 重复率驱动激光器可以增加 HHG 通量。然而，低脉冲能量需要紧密聚焦，这限制了有效相互作用体积。在充气光子晶体光纤 (PCF) 中产生谐波可以缓解这个问题，但对于自由聚焦和 PCF 目标，HHG 转换效率在技术上具有挑战性的多巴气压下得到优化。在这里，我们在空心 PCF 中使用 mu J 级驱动脉冲执行 HHG。我们观察到，在低气压下，通过时间复用多模态准相位匹配技术，HHG 通量显着增强了 60 倍。我们还观察到高达 61.6 eV 的高次谐波光子能量，并且通过驱动激光器的受控电离引起的蓝移实现了连续光谱可调性。由光学协会根据知识共享署名 4.0 许可条款发布。
High-order harmonic generation (HHG) provides a promising tabletop source of coherent short wavelength radiation. However, the low generation efficiency limits the mean photon flux of HHG sources when driven with low average power, kHz repetition rate lasers. The HHG flux could be increased by employing MHz repetition rate driving lasers. However, the low pulse energy necessitates tight focusing, which limits the effective interaction volume. Generating harmonics in a gas-filled photonic crystal fiber (PCF) mitigates this problem, but for both free focus and PCF targets, the HHG conversion efficiency is optimized at technologically challenging multibar gas pressures. Here, we perform HHG with mu J-level driving pulses in a hollow-core PCF. We observe dramatic 60-fold enhancement of the HHG flux through a time-multiplexed multimodal quasi-phase-matching technique at low gas pressures. We also observe high harmonic photon energies up to 61.6 eV with continuous spectral tunability made possible by controlled ionization-induced blue shifting of the driving laser. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.