Carrier-envelope phase-stable spatiotemporal light bullets

Abstract

We present an extensive experimental investigation of the self-focusing and filamentation of intense 90 fs, 1.8 μm, carrier-envelope phase-stable laser pulses in fused silica in the anomalous group velocity dispersion region. Spectral measurements in a wedge-shaped sample uncover dynamics of spectral broadening, which captures the evolution of third-harmonic, resonant radiation, and supercontinuum spectra as a function of the propagation distance with unprecedented detail. The relevant events of spectral broadening are linked to the formation and propagation dynamics of spatiotemporal light bullets as measured by a three-dimensional imaging technique. We also show that at a higher input power, the light bullet splits into two bullets, which retain characteristic O-shaped spatiotemporal intensity distributions and propagate with different group velocities. Finally, we demonstrate that the light bullets have a stable carrier-envelope phase that is preserved even after the bullet splitting event, as verified by f-2f interferometric measurements.