Controlling fluorescence and noise correlation by phonon and double dressing in two types of Pr³⁺: YSO

We investigate the effect of single dressing and double dressing on fourth-order fluorescence (FL) and spontaneous four-wave mixing. The single dressing effect changes to a double dressing effect as we change the detuning (power) of the input beam from off-resonant (low power) to resonant point (high power). We also demonstrate the spectral and temporal nature of fourth-order FL and its Autler–Townes splitting caused by the competition of the phonon effect (at different temperatures) with a single and double dressed state in Pr³:Y₂SiO₅ crystal. To further explore the competition between the phonon and dressing effects, we investigated intensity-noise correlation of spontaneous parametric four-wave mixing at 110 K. Our results demonstrate the dependency of YSO crystal on temperature, detuning, and power, which can be controlled by the competition between a phonon with single and double dressing.