Tunable coherent hyperspectral patterns of Rabi sidebands from excitation gridirons in argon gas
Phys. Rev. A 114, 013526 – Published 30 July, 2026
DOI: https://doi.org/10.1103/kct8-lsby
Abstract
Coherent, spectrally modulated sideband radiation results from interaction of a moderately intense picosecond laser pulse with nearly resonant emitters. We theoretically analyze a situation where these emitters are excited argon atoms arranged in a rhombic gridiron formation. This latter is generated in a relatively dense gas by femtosecond laser filamentation at a small-angle crossing of two identical pump laser beams, when an interference-borne intensity comb swipes along the crossing area. The geometry and content of the excitation gridiron are controlled by the beam radius, the crossing angle, and the phase delay between the two pump pulses. The picosecond probe pulse engages multiple transitions in the distributed excited argon atoms and produces coherent sideband radiation of considerable complexity, from which various coherent frequency arrays can be extracted. In one extraction scheme, the sideband radiation is collected and spectrally analyzed on a remote output screen, which is parallel to the gridiron plane. The resulting signal depends on the wavelength and two spatial coordinates; this three-variable distribution makes for a four-dimensional coherent hyperspectral interference pattern, whose three-dimensional sections (two-variable distributions) can be rendered by observation slits on the screen. We traced the modifications of such a section as controlled by the parameters of the pump pulses and the probe pulse. In particular, the positions of the bright spots in the patterns have been quantitatively associated with the crossing angle of the pump beams and the radius of the probe beam.
