Polarization-Dressed Correlation and Anti-Correlation Between Phase-Conjugate Four-Wave Mixing and Fourth-Order Fluorescence

We report the two- and three-mode correlation of phase-conjugate four-wave mixing and fourth-order fluorescence in Pr
³⁺
:Y
₂
SiO
₅
crystal. The degree of correlation is controlled by changing the position of detecting time and polarization state of pumping field. The switching between correlation and anti-correlation was observed at different positions of detecting time because of the competition between four-wave mixing and fourth-order fluorescence signals. The obvious variation of correlation degree was also observed at different polarization states, which is interpreted by the different Clebsch-Gordan coefficients and the EIT subsystem induced by polarization dressing effect.