Figure 1

(a) Experimental interferometry setup, showing imaging lenses and the microscope objective. The inset shows the filament width $d$ and probe crossing angle $\theta$. (b) Spatial sequence of bow-tie phase images showing filament collapse, for a 2.85 mJ, 72 fs pulse focused at $f_{\#}=345$. The frames show a sequence of 1-cm-spaced axial positions of the interferometer object plane, (i) $z=-39\mathrm{cm}$ through (vi) $z=-34\mathrm{cm}$.Reuse & Permissions

Figure 2

On-axis electron density and filament FWHM vs axial distance for (a) lens focal length $f=95\mathrm{cm}$, $f_{\#}=240$, laser peak power $P=17\mathrm{GW}$, ${\tau }_{\mathrm{short}}=40\mathrm{fs}$ (red circles), and ${\tau }_{\mathrm{long}}=120\mathrm{fs}$ (black squares) and (b) $f=306\mathrm{cm}$, $f_{\#}=505$, $P=19\mathrm{GW}$, ${\tau }_{\mathrm{short}}=44\mathrm{fs}$ (red circles), and ${\tau }_{\mathrm{long}}=132\mathrm{fs}$ (black squares). Each point is a 200-shot average. The inset in (b) shows a sample electron density profile from $z=-75\mathrm{cm}$. Peak values shown have $\sim 20\%$ uncertainty near the collapse point and $\sim 10\%$ over the rest of the filament.Reuse & Permissions

Figure 3

On-axis filament spectra corresponding to the conditions of Fig. 2, with (i) $f_{\#}=240$ and (ii) $f_{\#}=505$. Also shown are the input spectra. The insets in (ii) show the filament spots on a far field screen for ${\tau }_{\mathrm{short}}$ and ${\tau }_{\mathrm{long}}$.Reuse & Permissions

Figure 4

Simulation results for the conditions of Fig. 2 (solid lines). Additional runs have been performed at 20% higher power (dashed lines). Red, short pulse; black, long pulse.Reuse & Permissions