Novel quasi phase matching of high harmonic generation via advanced dual gas multi jet targets

超快/阿秒物理学是一门激动人心的动态研究学科，它以前所未有的空间和时间分辨率揭示原子和分子结构/过程。然而，一个重要的限制是可以转化为光谱的XUV和软X射线区域的激光能量有限。这主要是由于驱动激光和产生的谐波场之间的位相失配，这是由于自由电子对折射率的巨大贡献所引起的。准相位匹配在实现这一目标的过程中一直处于领先地位，但到目前为止，主要局限于在空心毛细管中进行平均功率较低的“原则证明”实验。这项建议旨在开发一种开创性的准相位匹配的新方法，该方法由我们在昆士兰大学的团队开发--毛细管自由几何结构中的双气体多喷流阵列--达到极高的标准。在这项建议中，我们打算建立在已经进行的实验观察的基础上，验证这一令人兴奋的新技术。与我们在HASYLAB(DESY，汉堡)和TEI RETYNO(克里特岛)的合作伙伴一起，当前的设计将被扩展，以产生适合在DESY播种闪光自由电子激光的高平均功率谐波源。在这项提议的第二条线索中，我们将利用这一源的独特能力来精细控制HHG发射的相位，以产生强烈的单阿秒脉冲。这项提议将构成旨在提供第一个高平均功率HHG源和强阿秒脉冲的国际合作的核心，并将在QUB、DESY和TEI克里特岛开展激光工作。

Ultrafast/attosecond physics is an exciting and dynamic research discipline, revealing atomic and molecular structures/processes with unprecedented spatial and temporal resolution. A significant limitation, however, has been the limited amount of laser energy that can be converted into XUV and soft x-ray regions of the spectrum. This is primarily due to phase mismatch between the driving laser and generated harmonic field, induced by the large free-electron contribution to the refractive index. Quasi-phasematching has been a front runner in the drive towards this objective but to date has been largely confined to low average power 'proof-of-principle' experiments in hollow core capillaries. This proposal seeks to develop a ground breaking new approach to quasi-phasematching developed by our group at QUB - dual gas multi-jet arrays in a capillary free geometry - to an exceptionally high standard.In this proposal we intend to build upon experimental observations already made which verify this exciting new technique. Together with our collaborators at the HASYLAB (DESY, Hamburg) and TEI Rethymno (Crete) the current design will be extended to generate a high average power harmonic source suitable for seeding the FLASH free electron laser at DESY. In a second strand of this proposal we will use the unique ability of this source to fine-control the phase of HHG emission for intense single attosecond pulse generation. This proposal will form the core of an international collaboration aimed at delivering the first high average power HHG source and intense attosecond pulses, and work will be performed on lasers at QUB, DESY and TEI Crete.