Dipole spectrum structure of non-resonant non-pertubative driven two-level atoms

TL;DR

This paper analyzes the complex dipole spectrum of a two-level atom driven by a non-resonant intense field, revealing structured families of harmonic and nonlinear fluorescence spectra, with implications for ultrashort pulse generation.

Contribution

It provides a comprehensive description of the spectral structure beyond the rotating wave approximation, including quantitative laws for spectral features and phase locking phenomena.

Findings

Spectral structure described by harmonic and nonlinear fluorescence families

Quantitative laws for harmonic ratios, phases, and Stark shift

Phase locking at the harmonic plateau edges enables ultrashort pulse generation

Abstract

We analize the dipole spectrum of a two-level atom excited by a non-resonant intense monochromatic field, under the electric dipole approximation and beyond the rotating wave approximation. We show that the apparently complex spectral structure can be completely described by two families: harmonic frequencies of the driving field and field-induced nonlinear fluorescence. Our formulation of the problem provides quantitative laws for the most relevant spectral features: harmonic ratios and phases, non-perturbative Stark shift, and frequency limits of the harmonic plateau. In particular, we demonstrate the locking of the harmonic phases at the wings of the plateau opening the possibility of ultra-short pulse generation through harmonic filtering.