Yan Cheng

TL;DR: Numerical simulations revealed that the experimentally observed splitting of the 3s3p⁶4p ¹P line is caused by the coupling between two short-lived highly excited states in the strong laser field.

TL;DR: A soft X-ray pulse duration of 53 is demonstrated as and single pulse streaking reaching the carbon K-absorption edge (284 eV) by utilizing intense two-cycle driving pulses near 1.8-μm center wavelength.

TL;DR: This work probes the transient changes in the absorption of an isolated attosecond extreme ultraviolet (XUV) pulse by helium atoms in the presence of a delayed, few-cycle near infrared (NIR) laser pulse, which uncovers absorption structures corresponding to laser-induced “virtual” intermediate states in the two-color two-photon (X UV+NIR+N IR) and three- photon ( XUV-NIR-Nir) absorption process.

TL;DR: The optical Stark shifts induced by a few-cycle near infrared laser field in helium bound states are probed using isolated attosecond pulses in a transient absorption scheme and a subcycle laser-induced energy level shift of the laser-dressed 1s3p state is uncovered.

TL;DR: In this paper, a new regime of below-threshold harmonic generation accompanied by the bright, coherent emission of vacuum-ultraviolet lines is reported, which is critical for extending time-resolved photo-emission spectroscopy to megahertz repetition rates and for developing high-average-power vacuumultraviolet sources.