Fast Pump-Probe Microscopy Imaging with Asynchronous Optical Sampling.

Asynchronous optical sampling (ASOPS) allows rapid collection of transient absorption/reflection data over wide time scales with a high dynamic range in both time and signal magnitude. In this paper, a method for recording transient images using ASOPS is presented based on time-gated integration of the transient signal. This technique allows diffraction-limited pump-probe microscopy images to be rapidly collected at precise, user-specified time delays, with approximately 15 picoseconds time resolution. Results are presented for the excited-state dynamics in multilayered WSe2 flakes, charge-carrier diffusion in a silicon wafer, and images of Au nanoparticle arrays that demonstrate the spatial/temporal resolution and sensitivity of the technique. Potential applications and the ultimate time resolution that can be achieved are also discussed.