Shalaby Islam, Chakraborty Nisnat, Yanez-Pagans Sergio, Wood James, Biswas Dipayan, Sandhu Arvinder
Opt Express. 2022 Dec 19;30(26):46520-46527. doi: 10.1364/OE.478959.
Non-linear processes such as four-wave-mixing have become instrumental in attosecond EUV spectroscopy. Using EUV high harmonics in conjunction with collinear near-infrared and mid-infrared fields, we extended this approach to high-order-mixing between three colors. Specifically, we find that atomic resonances in neon exhibit a significant cross section for six-wave mixing. The MIR probe frequency tunability in our multicolor scheme is employed to access several optically dark resonances and probe the quantum beat of a coherent electronic wavepacket using background-free EUV emission as a diagnostic. This technique can be easily extended to other atomic and molecular systems, and opens the door to multi-dimensional non-linear spectroscopy.
诸如四波混频之类的非线性过程在阿秒极紫外光谱学中发挥了重要作用。通过将极紫外高次谐波与共线近红外和中红外场相结合，我们将这种方法扩展到了三色之间的高阶混频。具体而言，我们发现氖中的原子共振对于六波混频表现出显著的截面。我们的多色方案中中红外探测频率的可调性被用于获取多个光学暗共振，并利用无背景的极紫外发射作为诊断手段来探测相干电子波包的量子拍。这种技术可以很容易地扩展到其他原子和分子系统，并为多维非线性光谱学打开了大门。
