Ultrafast Spectroscopy Based on Temporal Focusing and Its Applications

The whole family of the parametric spectro-temporal analyzer (PASTA) system has enriched the capability of our tool box in ultrafast spectrum measurements. The advent of the dispersive stretching technology started the era of the temporal spectrum analyzer, and it is easy to implement with stable results, while only capable of short pulses at low-repetition-rate. To enlarge the temporal observation window, a time-lens is first incorporated in the single-lens PATSA system. It can characterize stationary sources as well as some nonperiodic waveforms. To further enhance the observation flexibility, a pair of time-lens structure is introduced to perform the telescope/wide-angle PASTA. Leveraging the merit of instantaneous response, as well as the flexible lens structure; here, we present a 100-MHz frame rate PASTA system, with 17 times zoom in/out ratio for different observation ranges. Each configuration has its optimum application range. As a proof of concept and also for the first time, we demonstrate some of its bio-imaging applications, including the time-stretch microscopy and the tomography systems.