An experimental method for pulse-width measurement in partial positions of an ultrashort-pulsed beam

摘要

We experimentally show a method for pulse-width measurement. Pulse widths at different partial positions of an ultrashort-pulsed beam are measured, results show that pulse widths in the center of the beam are less than that of in the edge because of the existence of residual chirp. We also investigate the temporal evolution at a strongest spatial modulation position of the beam during small-scale self-focusing, it finds that its pulse width decreases as power increases due to a spatiotemporal coupling effect. We find that this method not only can be used to accurately measure the pulse width at any one spatial position of the beam, but also be useful for real-time monitoring of spatial-temporal evolution.