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- Title
Single-shot real-time femtosecond imaging of temporal focusing.
- Authors
Liang, Jinyang; Zhu, Liren; Wang, Lihong V.
- Abstract
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 non-repeatable 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. Improvements in a photography technique allows seeing instantaneous light patterns in real time. While standard optical instruments focus on a spatial point, temporal microscopes confine photons along a narrow plane that can penetrate samples and excite multiple components simultaneously. Lihong Wang from the California Institute of Technology in Pasadena, U.S.A. and colleagues have now developed the world’s fastest camera that can capture the temporal focus dynamics by taking trillions of images per second in a single exposure. The team’s setup records a sample’s dynamic intensity patterns, then splits them into two optical pathways retaining spatial and temporal information. Aided by compressed imaging and a fast streak camera, this division helps minimize the number of measurements and enables image reconstruction algorithms to achieve frame rates two orders of magnitude better than current receive-only ultrafast cameras.
- Publication
Light: Science & Applications, 2018, Vol 7, Issue 1, p1
- ISSN
2047-7538
- Publication type
Article
- DOI
10.1038/s41377-018-0044-7