Understanding the dynamics of ferroelectric polarization switching under external stimuli is crucial for optimizing device performance, particularly in terms of operating speed and bandwidth. Here, we employ time-resolved second-harmonic generation (SHG) spectroscopy to probe ultrafast optically driven polarization modulation in bulk NbOCl2. Upon above-bandgap photoexcitation, a significant suppression of the SHG intensity occurs within subpicosecond time scales. The maximum modulation depth of the ferroelectric polarization reaches nearly 50% and scales linearly with pump fluences up to 10 mJ/cm2, reflecting the high stability of both electronic and lattice subsystems in NbOCl2. Supported by time-resolved reflectivity measurements, our findings reveal that polarization dynamics are primarily governed by photocarrier screening coupled with transient electron heating. These results highlight the promise of NbOCl2 for applications in high-speed optically controlled ferroelectric devices.
Zhang et al. (Wed,) studied this question.