Control of quantum paths in harmonic generation through orthogonal fields specific frequency ratios

Abstract

By solving a two-dimensional, time-dependent Schrödinger equation, we investigate high-order harmonic generation for the H 2 + molecular ion in orthogonally polarized two-color laser pulses. We find that harmonic generation depends on the frequency ratio n = ω y ω x . When the wavelength is 800 nm and n = 1.2, the harmonic plateau becomes smoother, and the quantum orbital interference decreases. We change the fundamental wavelength and find that the harmonic spectrum exhibits a supercontinuum structure, and the quantum orbital is controllable. When the wavelength is 1600 nm and 2000 nm, and n = 1.2, we gain a deeper understanding of the physical process of harmonics. We have provided the time-frequency distribution and the probability density of an electron wave packet picture. Next, we analyzed the impact of the carrier-envelope phase on harmonics, and we combined Lissajous figures to continue our analysis. The research results find that when the carrier-envelope phase is 0, 0.5π, π, and 1.5π, the harmonic intensity becomes higher, and all exhibit a supercontinuum structure. We chose certain orders of harmonics, and isolated attosecond pulses can be synthesized.