Programme

O.35 -- Oral, VCTP-51

Date: Thursday, 6 August 2026

Time: 09:10 - 09:30

CONTROLLING HIGH-ORDER HARMONIC PEAK SHIFTS IN TWO-COLOR LASER FIELDS

Thanh-Duy D.Nguyen (1), Doan-An Trieu (2), Trong-Thanh D. Nguyen (1) Van-Hoang Le (1), and Ngoc-Loan Phan (1)* *Author to whom correspondence should be addressed: loanptn@hmue.edu.vn

(1)Computational Physics Key Laboratory K002, Department of Physics, Ho Chi Minh City University of Education, Ho Chi Minh City 72711, Vietnam (2)Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 700000, Vietnam

Precisely controlling the frequency of high-order harmonic generation (HHG) from interaction of matter with infrared (IR) pulses is crucial for driving and steering ultrafast physical and chemical processes [1]. To this end, although terahertz fields can be used to analytical control frequency of emitted harmonics, this method is challenging with expensive setup of terahertz and IR generation systems. In this work, we suggest using second-harmonic pulse of the IR, also called as $2\omega$ pulse, to control the frequencies of emitted harmonics. By using strong-field approximation, the harmonic frequencies are predicted to be shifted peroidically with varying time delay between two pulses, and amplitude of this oscillation can be controlled by varying the strength of $2\omega$ pulse. We validate our analytical predictions by numerically solving the three-dimensional time-dependent Schrödinger equation for a hydrogen atom in the two-color $\omega - 2\omega$ field using a self-developed computational code. The numerical results show a good agreement with the analytical predictions and evident for the independence of atomic parameters. These findings propose a practical tool for controlling the harmonic frequency to steer ultrafast physical and chemical processes. Keywords: Strong-field physics, Ultrafast laser-matter interaction, High-order harmonic generation References: [1] F. Krausz and M. Ivanov, Rev. Mod. Phys. 81, 163 (2009). [2] D.-A. Trieu, T.-T. D. Nguyen, T.-D. D. Nguyen, T. Tran, V.-H. Le, and N.-L. Phan, Phys. Rev. A 110, L021101 (2024). [3] M.-Q. Bao and A. F. Starace, Phys. Rev. A 53, R3723 (1996).

Presenter: Nguyễn Đinh Thanh Duy