Formation of electromagnetically induced transparency and two-photon absorption in close and open multi-level ladder systems

Electromagnetically induced transparency and Autler-Towns effect in multi-level cascade type system in 133Cs

“…In an earlier work on four-level inverted-Y type system it was shown that the contributions of the positive and negative velocity groups of atoms having same magnitude of velocity towards probe absorption are like mirror reflections [21] but for the present work this no more holds. If this is compared with a previous work which reported observation of EIT spectra for Rb atoms at room temperature [20], visible difference in the EIT windows for Cs and Rb vapors can be noticed. The EIT windows caused by different cascade transitions excited by the pump and the probe field, involving different hyperfine levels of Rb atoms, appear distinctively in the background of an inhomogeneously broadened absorption profile (figure 3 of [20]), whereas for Cs atoms the EIT windows overlap on each other in such a fashion that an overall dip in the inhomogeneously broadened absorption profile can be obtained (figure 8(A)).…”

“…If this is compared with a previous work which reported observation of EIT spectra for Rb atoms at room temperature [20], visible difference in the EIT windows for Cs and Rb vapors can be noticed. The EIT windows caused by different cascade transitions excited by the pump and the probe field, involving different hyperfine levels of Rb atoms, appear distinctively in the background of an inhomogeneously broadened absorption profile (figure 3 of [20]), whereas for Cs atoms the EIT windows overlap on each other in such a fashion that an overall dip in the inhomogeneously broadened absorption profile can be obtained (figure 8(A)). The reason for this difference in the EIT line shapes of Rb and Cs vapors is the longer lifetime of the 5D 5/2 hyperfine levels of Rb as compared to that of 6D 5/2 hyperfine levels of Cs.…”

“…The detuning of the control field from the different transitions and the values of hyperfine strength factors (S ij as given in table 1 and table 2) also play their roles in the process. However, the three-level Ξ type system discussed in [20] is not sufficient to describe the occurrence of these weak absorption peaks in the wing of the probe absorption profile just mentioned in figures 3(A)-(D).…”

“…The probe absorption profile in the Doppler broadened medium thus can be quite dissimilar for different atomic specimens. In this work we have not included any magnetic field dependent energy level splitting and hence control and probe laser fields of orthogonal polarization may be taken for any experimental realization [20] based on this theoretical model. The splitting of energy levels into magnetic sublevels can be very complicated for this twelve-level atomic system.…”

“…This expression can be used to study the probe absorption and probe dispersion under Doppler free condition as well as under thermal averaging at comparable control and probe field intensities since no restriction on the intensities of the two fields have been imposed in solving for the probe coherence term. An experimental observation of multi-EIT window and two-photon absorption has been reported by Mondal and his co-workers while working with rubidium vapor cell at room temperature [20]. They have used a multi-level cascade type level scheme to simulate the probe absorption profile and compared the experimental findings with numerical results.…”