Near infrared few-cycle pulses for high harmonic generation

We report on the development of intense tunable few-cycle pulses with central wavelengths ranging from to . These pulses were used as a proof of principle for high harmonic generation in atomic and molecular targets. In order to generate such pulses, we produced a filament in a four-bar krypton cell. Spectral broadening by a factor of two to three of a 40 fs near-infrared input pulse was achieved. The spectrally broadened output pulses were then compressed by fused silica plates down to the few-cycle regime close to the Fourier limit. The auto-correlation of these pulses revealed durations of ~ three cycles for all investigated central wavelengths. Pulses with a central wavelength of and up to energy per pulse were employed to generate high-order harmonics in Xe, Ar, and N2. Moving to near-infrared few-cycle pulses opens the possibility of operating deeply in the non perturbative regime with a Keldysh parameter, . Hence, this source is suitable for the study of the non perturbative tunneling regime in most generating systems used for high-order harmonic generation and attoscience.