Phase Dependence Of The Fluorescence Spectrum Under Trichromatic Excitation

In this paper, the phase-dependent resonance fluorescence spectrum of a two-level system in a trichromatic field is calculated by the quantum regression theorem, Fourier transform and matrix inversion method. It is revealed that the spectrum strongly depends on the sum of relative phases of the sideband components compared to the central component, not simply on the respective phases. When the sum phase of the sideband components to the central component is changed from 0 to π or from π to 0, the spectral structure will alter greatly. The appearance or disappearance of the central peak and the selective elimination of the sidebands are achieved simply by varying the sum phase. Once the sum phase is fixed, the spectrum keeps its features unchanged regardless of the respective relative phase.