1-J white-light continuum from 100-TW laser pulses

We experimentally measured the supercontinuum generation using 3-J, 30-fs laser pulses and measured white-light generation at the level of 1 J. Such high energy is allowed by a strong contribution to the continuum by the photon bath, as compared to the self-guided filaments. This contribution due to the recently observed congestion of the filament number density in the beam profile at very high intensity also results in a wider broadening for positively chirped pulses rather than for negatively chirped ones, similar to broadening in hollow-core fibers.

Figure 1

Efficiency of the white-light generation by a 2.53-J, 30-fs, Fourier-limited laser pulse in 10-cm beam diameter after 42 m of propagation, and by the Teramobile laser (300 mJ, 100 fs in 5-cm beam diameter) after the filamenting region ($z$ ∼ 40 m) [19]. Both spectra are normalized to their total area: (a) linear scale; (b) logarithmic scale.

Figure 2

Spectra generated after 42-m propagation of a 2.53-J pulse of 30-fs Fourier-limited (FL) duration and the same pulse both positively and negatively chirped (50- and 100-fs pulse durations). All spectra have the same normalization factor, so that their amplitudes can be compared. (Inset) Blowup of the 760-to-790-nm spectral region, exhibiting a peak at 771.5 nm for Fourier-limited and positively chirped pulses.

Figure 3

Conversion efficiency and corresponding energy of the white-light continuum after 42-m propagation of a 2.53-J pulse, as a function of incident pulse energy (a) and power (b). The continuum is defined as the spectral range out of the 765-to-845-nm spectral range.

Figure 4

Beam profile on a screen of a 30-fs, 1.65-J pulse after 15-m propagation, that is, at the beginning of the filamenting region. The white contribution from the photon bath is clearly visible.

Figure 5

Simulated transversely integrated spectrum for pulses of 30 fs, Fourier-limited, and 100 fs, positively and negatively chirped. (a) 1$D$ $+$ 1, 30 mJ/cm${}^2$ (1 TW/cm${}^2$ for 30-fs pulses); (b) $2D+1$, 0.81 mJ (9 $P$${}_{\mathrm{cr}}$ for 30-fs pulses).