We have studied electromagnetically induced transparency (EIT) in the 5S1/2−5P3/2−5D5/2 ladder-type system of Rb. We observed relative changing magnitude of EIT hyperfine structures depending on not only the polarizations of the lasers but also the intensity of the coupling laser. The coupling-intensity effects are attributed to the nonlinear increase of the EIT signal to the coupling intensity. EIT signals nonlinear on the coupling intensity are analyzed by considering coherent interaction between atom and laser fields.
Multiphoton electromagnetically induced transparency (EIT) of atomic vapors involves several intermediate atomic levels. The substructure of these levels and their collisional interactions can drastically alter experimental EIT signals. Here we report on hyperfine structure and collision effects in three-photon Rydberg EIT on the cascade $5{S}_{1/2}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}5{P}_{1/2}\ensuremath{\rightarrow}5{D}_{3/2}\phantom{\rule{4pt}{0ex}}\ensuremath{\rightarrow}25{F}_{5/2}$ in a room-temperature
85Rb vapor cell. In our measurements of EIT spectra, we identify two types of EIT signatures that correspond with distinct excitation pathways and atomic velocity classes in the atomic vapor. The
5D3/2 hyperfine structure and Autler-Townes splittings lead to complex patterns in the EIT spectra, which we analyze with the aid of 10-level EIT simulations. Adding 50 mTorr of Ar gas alters the EIT spectra and induces an additional, third EIT mode. Based on our simulation results, we attribute these changes to hyperfine collisions in the Rb
5D3/2 level. Our study may become useful in quantum technologies involving Rydberg EIT and hyperfine collisions in vapor cells, including noninvasive spatiotemporally resolved electric-field sensing of electric fields in low-pressure plasmas.
Features of electromagnetically induced transparency (EIT) in potassium vapors at the D 1 line of the 39 K isotope are studied. EIT resonances with a subnatural width of 3.5 MHz have been recorded upon excitation by two independent narrow-band diode lasers in a 1-cm-long cell filled with a natural mixture of potassium isotopes and buffer gas. The splitting of EIT resonances in potassium vapors in longitudinal and transverse magnetic fields has been studied for the first time. The splitted components also have a subnatural width. The smallness of the coupling factor of the hyperfine structure in 39 K atoms leads to a transition to the Paschen—Back regime at relatively weaker magnetic fields than in the case of Cs, Rb, and Na atoms. Practical applications of the phenomena under study are noted. The theoretical model well explains the experiment.