Spatiotemporal sectioning of two-photon fluorescence ellipsoid with a CsPbBr3 nanosheet

Two-photon fluorescence (TPF) ellipsoid formed by a focused femtosecond laser into luminescent media serves as a fundamental pixel for TPF spatiotemporal imaging. Visualizing spatiotemporal evolution of the TPF ellipsoid itself in a selected luminescent medium is important for correctly reconstructing and interpreting spatiotemporal information of imaged targets. Here, we report a new spatiotemporal sectioning technique with a luminescent CsPbBr3 nanosheet and visualize the spatiotemporal evolution of TPF ellipsoid along the axial direction. Time-resolved axial lengths of TPF ellipsoids turn out to broaden nonlinearly with a turning point at about 600 ps. By comparison experiments, observed phenomena are attributed to photocarrier trapping and TPF photon recycling processes within CsPbBr3 nanosheets. The spatiotemporal sectioning technique is expected to be widely applicable, which will ignite a plethora of investigations and applications utilizing TPF ellipsoid.

Automated summary

A new spatiotemporal sectioning technique utilizing luminescent nanosheets has been reported, allowing for visualization of the axial evolution of TPF ellipsoid and explaining the nonlinear expansion of its axial length. The observed phenomena are attributed to photocarrier trapping and TPF photon recycling processes within the luminescent nanosheets. This technique is expected to be widely applicable and will lead to numerous investigations and applications utilizing TPF ellipsoid.