Effects of inert background gases and photoillumination on three-color electromagnetically induced transparency of rubidium vapor

Three-color Rydberg electromagnetically induced transparency (EIT) of room-temperature $\mathrm{Rb}$ vapor in the presence of inert gases ($\mathrm{Ar}$, $\mathrm{Ne}$, and ${\mathrm{N}}_{2}$) at 50 and 500 mTorr is investigated. The observed EIT lines shift and develop blue-detuned satellite lines, dependent on inert-gas species and pressure. The separations of the satellite from the main EIT lines are approximately pressure-independent, while their strength increases with inert-gas pressure. The satellite lines are attributed to hyperfine collisions of the intermediate $5{D}_{3/2}$ state. Further, analyzing the Stark effect of Rydberg levels, it is found that the inert gases suppress static electric fields in the vapor cells, which we induce by photoillumination of the cell walls with an auxiliary 453-nm laser. In the work, we utilize Rydberg levels with principal quantum numbers $n=25$ and $50$ and angular momenta $\ensuremath{\ell}=3$ up to 6, excited by the EIT lasers and optional radio-frequency dressing fields. The work is of interest in the spectroscopic study of mixed-species warm vapors, in sensing applications of Rydberg atoms in vapor cells, and in noninvasive electric-field diagnostics of low-pressure discharge plasma.