AI 中文总结
本研究将全光非对称干涉互相关扩展至亚波长薄膜的更高非线性，实现环境水蒸气转动振动带的场分辨光谱，性能媲美电光采样，有望广泛应用并拓展灵敏度至高频率范围。
AI 中文摘要
电场的直接时域测量可实现光与物质相互作用的亚周期光谱分析，但现有技术如电光采样（electro-optic sampling）受门脉冲持续时间和相位匹配限制，带宽存在约束。近年来出现了基于高度非线性介质的非对称干涉非线性互相关的替代方法，已实现激子系综的场分辨研究等成果。然而，这些基于非线性互相关的技术几乎仅通过自参考脉冲表征进行基准测试，而非定量光谱性能测试；且全光方法的关注度低于基于直接电荷发射的方法。本研究将全光非对称干涉互相关扩展至亚波长薄膜中的更高非线性，实现了环境水蒸气两个转动振动带自由感应衰减的场分辨光谱，性能可与最先进的电光采样媲美。该测量覆盖190太赫兹带宽（80太赫兹至270太赫兹），光谱分辨率低于500吉赫兹，光谱强度动态范围达6个数量级，场强噪声基底为100千伏每米。研究预期，所提出的全光采样技术将在众多实验场景中得到快速应用，并产生超出超快光学研究界的广泛影响，因为它相比电离技术大幅简化，且能将电光采样级别的灵敏度拓展至传统工具此前无法覆盖的更高频率范围。
英文摘要
Direct time-domain measurements of electric fields enable sub-cycle spectroscopy of light-matter interactions, but established techniques such as electro-optic sampling are constrained in their bandwidth by gate-pulse duration and phase-matching limitations. Alternative approaches have emerged in recent years based on asymmetric interferometric nonlinear cross-correlations with highly nonlinear media, and have demonstrated, for example, the field-resolved study of exciton ensembles. However, these nonlinear cross-correlation-based techniques have been benchmarked almost exclusively by self-referenced pulse characterization rather than by their quantitative spectroscopic performance, and all-optical approaches have received less attention than those based on direct charge emission. Here we extend all-optical asymmetric interferometric cross-correlation to higher nonlinearities in sub-wavelength films and demonstrate field-resolved spectroscopy of the free-induction decay of two ro-vibrational bands of ambient water vapor with a performance comparable to state of the art electro-optic sampling. The measurement spans 190 THz of bandwidth (80 THz to 270 THz) with sub-500 GHz spectral resolution, a spectral intensity dynamic range of six orders of magnitude, and a field-strength noise floor of 100 kV per meter. We anticipate the rapid adoption of here presented all-optical sampling to many experimental settings and a broad impact beyond the ultrafast optics research community as it is drastically simplified in comparison to ionization based techniques and allows the translation of electro-optic-sampling-level sensitivity into higher frequency ranges not previously accessible by conventional tools.
