Generation of high-temporal-quality sub-two-cycle pulses by self-cleaning of spatiotemporal solitons in air-plasma channels

The temporal sidelobes of few-cycle pulses seriously restrict their applications in ultrafast science. We propose a unique mechanism that enables the generation of sub-two-cycle pulses with a high temporal quality. A robust spatiotemporal soliton could be formed from pulse self-compression by modulating the dispersion of the air-plasma channel via the adjusted plasma density. The self-cleaning of the spatiotemporal soliton leads to the elimination of sidelobes in the temporal profile of the sub-two-cycle pulse. The required density of the preformed plasma for an arbitrary central wavelength from the near-infrared to midinfrared regime is predicted theoretically and confirmed by (3D+1) simulations.