Carrier-envelope phase-stable spatiotemporal light bullets.

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.

Nature of spatiotemporal light bullets in bulk Kerr media.

We present a detailed experimental investigation which uncovers the nature of light bullets generated from self-focusing in a bulk dielectric medium with Kerr nonlinearity in the anomalous group velocity dispersion regime. By high dynamic range measurements of three-dimensional intensity profiles, we demonstrate that the light bullets consist of a sharply localized high-intensity core, which carries the self-compressed pulse and contains approximately 25% of the total energy, and a ring-shaped spatiotemporal periphery. Subdiffractive propagation along with dispersive broadening of the light bullets in free space after they exit the nonlinear medium indicate a strong space-time coupling within the bullet. This finding is confirmed by measurements of a spatiotemporal energy density flux that exhibits the same features as a stationary, polychromatic Bessel beam, thus highlighting the nature of the light bullets.

Self-reconstructing spatiotemporal light bullets.

We show that spatiotemporal light bullets generated by self-focusing and filamentation of 100 fs, 1.8 µm pulses in a dielectric medium with anomalous group velocity dispersion (sapphire) are extremely robust to external perturbations. We present the experimental results supported by the numerical simulations that demonstrate complete spatiotemporal self-reconstruction of the light bullet after hitting an obstacle, which blocks its intense core carrying the self-compressed pulse, in nonlinear as well as in linear (free-space) propagation regimes.