Electromagnetically induced absorption of degenerate two-level system in a cesium vapor cell

Employing an intense laser field coupling to the degenerate two-level system of cesium 6²S_1/2(F = 4)-6²P_3/2(F' = 5) transition in a cesium vapor cell, electromagnetically induced absorption (EIA) has been demonstrated via probe absorption spectra, at the same time, electromagnetically induced transparency (EIT) of V-type three-level scheme has been demonstrated on the F = 4-F' = 3 and F = 4-F' = 4 transition frequency. The EIA is affected by the intensity and detuning of the coupling laser. By analyzing the effect of optical pumping between Zeeman sub-levels on the EIA and the coherent interactions between multiple degenerate two-level atoms, it is shown that the optical pumping affects the population of different Zeeman sub-levels and the number of the involved two-level atoms, the coherent time between the sub-levels is then changed and the linewidth and intensity of the EIA are affected accordingly.