Single-shot real-time femtosecond imaging of temporal focusing

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.

Single-shot compressed ultrafast photography: a review

“…Nevertheless, the unsheared view still improves the image reconstruction quality in some situations, and it is adopted in a few approaches. 34,35 It is worth mentioning that both schemes can effectively improve CUP's performance by increasing the sampling rate. Moreover, as demonstrated in Ref.…”

“…Based on a prototype of CUP, Liang et al recently established a trillion-frame-per-second compressed ultrafast photography (T-CUP) system and realized real-time, ultrafast, passive imaging of temporal focusing with 100-fs frame intervals in a single camera exposure. 34 A diagram of the T-CUP system is shown in Fig. 5.…”

BMC Biomedical Engineering: a home for all biomedical engineering research

“…Photoacoustic tomography (PAT) is now able to image large spatial scales, from organelles to small animals, at very high speeds [11]. In fact, single-shot real-time imaging can operate at 10 trillion frames per second and is finding applications in breast cancer diagnosis [12,13].…”

Improving the image reconstruction quality of compressed ultrafast photography via an augmented Lagrangian algorithm

“…It is a great challenge to further increase the imaging speed under the current technical conditions. Recently, a compressed ultrafast photography (CUP) technique employed a new imaging strategy to break this technical limitation [2][3][4][5][6], which recorded the whole dynamic scene and then recovered it by a computational imaging method. Now, the imaging speed of CUP can be up to 10 13 fps; it can increase by six orders compared to that of a CCD or CMOS.…”