Observation of narrow fluorescence from doubly driven four-level atoms at room temperature

Abstract

Unusually narrow spectral features are seen in fluorescence peaks from 85 Rb atoms under the action of two driving laser fields that are in a three-dimensional molasses configuration. One of the lasers, L1, is held at a fixed detuning from the "cooling" transition, while the other, L2, is scanned across the "repumping" transitions. The fluorescence peaks are split into symmetric pairs, with the separation within a pair increasing with the detuning of the L1 laser. For large detunings, additional small peaks are seen. A simple model is proposed to explain these experimental observations.

Wavelength dependence of Autler-Townes splitting in a four-level ladder molecular system

“…A longer wavelength indicates the lower photon energy, resulting in a lower photoelectron energy. This energy shift trend with laser wavelength is qualitatively identical to the observation in three/four-level atoms/molecules [3,4,9,10,18,26]. Yao and Zheng showed a similar observation in K 2 with secant pulse and square pulse, but did not give the results with the Gaussian pulse [26].…”

“…This asymmetry was also observed in double splitting in three-level atoms/molecules [4][5][6]8,9,27,28]. A similar feature was shown in the three-peak absorption/emission spectra [15,18] in four-level atoms and in five-level atoms [20]. The three peaks move toward a lower energy with increasing pump-1 wavelengths.…”

“…de Echaniz et al [16] and Dutta and Mahapatra [17] showed that the driving fields detuning affects the splitting and peak heights of the doublet/triplet in N-type atoms. Khan et al [18] demonstrated that the fluorescence peaks are split into symmetric pairs with the separation increasing with the cooling laser detuning, and for large detuning additional small peaks appear in Rb. Sandhya [19] expected the three-peak splitting with strong middle transition coupling in the absorption profile of ladder atoms.…”