Time-resolved single-shot imaging of ultrafast polarization dynamics in barium titanate using pump-probe second-harmonic generation microscopy.

Research into ultrafast dynamic processes in solids is crucial for understanding the intrinsic properties of matter. In particular, the combination of temporal and spatial resolution provides the most valuable information on such processes. Here, we demonstrate a setup for time-resolved imaging of ferroelectric domain dynamics following excitation by infrared pulses from a free-electron laser. The contrast in full-field imaging was provided by optical second harmonic generation produced with a femtosecond laser, which allowed us to identify both 90° and 180° domains and observe the induced switching of 180° domains in barium titanate. Moreover, the dynamics of crystallographic strains resulting from the excitation could be directly visualized across sub-picosecond timescales.