T. -M. Yan | Searcharxiv

arXiv2018

Recoil-ion momentum spectroscopy of photoionization of cold rubidium atoms in a strong laser field

We study photoionization of cold rubidium atoms in a strong infrared laser field using a magneto-optical trap (MOT) recoil ion momentum spectrometer. Three types of cold rubidium target are provided, operating in two-dimension (2D) MOT, 2D molasses, and 3D MOT with densities in the orders of $10^7$ atoms/cm$^3$, $10^8$ atoms/cm$^3$, and $10^9$ atoms/cm$^3$, respectively. The density profile and the temperature of 3D MOT are characterized using the absorption imaging and photoionization. The momentum distributions of Rb$^+$ created by absorption of two- or three-photon illuminate a dipole-like double-peak structure, in good agreement with the results in the strong field approximation. The yielding momentum resolution of $0.12 \pm 0.03$ a.u. is achieved in comparison with theoretical calculations, exhibiting the great prospects for the study of electron correlations in alkali metal atoms through interaction with strong laser pulses.

quant-ph↗

arXiv2018

Terahertz generation in dual-color laser: continuum electron in strong-field single-atom ionization

The terahertz (THz) generation in a dual-color field was investigated experimentally by precisely controlling the relative time delay $τ$ and polarization $θ$ of dual-color lasers, where the accompanying third-harmonic generation (THG) is employed to determine $τ$ up to the sub-wavelength accuracy. An anticorrelation of the yields between THz and THG with $τ$ was displayed. Compared with the theoretical simulations, the experimental results reveal that the continuum-continuum transitions of the released electron after single-atom ionization are the dominating mechanism for THz generation, which is opposite to the high-harmonic generation (HHG) based on the recollision mechanism, or the radiation induced by perturbative bound-bound transitions.

physics.optics↗