Programme

P.23 -- Poster, VCTP-46

Date: Tuesday, 5 October 2021

Time: 08:30 - 10:00

Multiple rescatterings in harmonic spectra in multicycle midinfrared lasers

Cam-Tu Le (1,2), Ngoc-Loan Phan (3)

(1) Atomic Molecular and Optical Physics Research Group, Advanced Institute of Materials Science, Ton Duc Thang University (2) Faculty of Applied Sciences, Ton Duc Thang University (3) Department of Physics, Ho Chi Minh City University of Education

High-order harmonic generation is one of nonlinear phenomena occurring when atoms/molecules are subjected to intense ultrashort laser [1]. The underlying physics is well described by the three-step model [2] in which an electron is ionized from the atoms/molecules, then accelerated in the laser electric field, and when the electric field reverses its direction, the electron can recombine to the parent ones and emit energetic photon called high-order harmonics. The electron can revisit its parent ion many times before recombining. This can lead to the generation of the pulse train of atto- or even zepto-second timescale [3] that is interesting from theoretical aspect as well as application. This work is to study the multiple rescattering events in the harmonic spectra from hydrogen atom exposed to multicycle midinfrared lasers by solving the time-dependent Schroedinger equation. To uncover the contribution of multiple returns with different laser profiles, we perform the time-frequency analysis based on a synchrosqueezed transform and classical electron trajectories. The results show that the multiple rescatterings strongly depend on the change of the temporal laser profile, such as changing from chirp-free to chirped with different chirped parameters. References [1] A. McPherson et al., J. Opt. Soc. Am. B 4, 595 (1987). [2] M. Lenwenstein et al., Phys. Rev. A 49, 2117 (1994). [3] C. Hernández-García et al., Phys. Rev. Lett. 111, 033002 (2013)

Presenter: Le Thi Cam Tu