Single-shot real-time femtosecond imaging of temporal focusing
Single-shot real-time femtosecond imaging of temporal focusing
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DOI：
10.1038/s41377-018-0044-7
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发表时间：
2018-08-08
影响因子：
19.4
通讯作者：
Wang, Lihong V.
中科院分区：
文献类型：
--
作者：
Liang, Jinyang;Zhu, Liren;Wang, Lihong V.
虽然聚焦的概念通常适用于空间域，但它同样适用于时间域。单超短激光脉冲时间聚焦的实时成像对于探索时空对偶性的物理特性和寻找多种应用具有重要意义。在时间聚焦期间，超短激光脉冲的宽度和强度的剧烈变化要求飞秒级曝光来捕捉在这种微妙现象中产生的瞬时光模式。到目前为止，现有的超快成像技术要么难以达到所需的曝光时间，要么需要重复测量。我们已经开发了每秒10万亿帧的单镜头压缩超快摄影（T-CUP），它在单次相机曝光中以100帧间隔被动捕捉动态事件。压缩感知和Radon变换之间的协同作用使T-CUP能够显著减少重建高质量三维时空数据立方体所需的投影数量。作为目前唯一可用的实时、无源成像方式，T-CUP曝光时间为飞秒，用于记录首个单超短激光脉冲在动态散射介质中不可重复时间聚焦的电影。T-CUP史无前例地能够在一次测量中清晰地揭示时间聚焦脉冲的形状、强度和宽度的复杂演变，为超短脉冲的单次表征、非线性光-物质相互作用的实验研究以及深度组织光聚焦的实时波前工程铺平了道路。
While the concept of focusing usually applies to the spatial domain, it is equally applicable to the time domain. Real-time imaging of temporal focusing of single ultrashort laser pulses is of great significance in exploring the physics of the space-time duality and finding diverse applications. The drastic changes in the width and intensity of an ultrashort laser pulse during temporal focusing impose a requirement for femtosecond-level exposure to capture the instantaneous light patterns generated in this exquisite phenomenon. Thus far, established ultrafast imaging techniques either struggle to reach the desired exposure time or require repeatable measurements. We have developed single-shot 10-trillion-frame-per-second compressed ultrafast photography (T-CUP), which passively captures dynamic events with 100-fs frame intervals in a single camera exposure. The synergy between compressed sensing and the Radon transformation empowers T-CUP to significantly reduce the number of projections needed for reconstructing a high-quality three-dimensional spatiotemporal datacube. As the only currently available real-time, passive imaging modality with a femtosecond exposure time, T-CUP was used to record the first-ever movie of nonrepeatable temporal focusing of a single ultrashort laser pulse in a dynamic scattering medium. T-CUP's unprecedented ability to clearly reveal the complex evolution in the shape, intensity, and width of a temporally focused pulse in a single measurement paves the way for single-shot characterization of ultrashort pulses, experimental investigation of nonlinear light-matter interactions, and real-time wavefront engineering for deep-tissue light focusing.