Formation of strongly shifted EIT resonances using “forbidden” transitions of Cesium

• Published in: Journal of quantitative spectroscopy & radiative transfer Vol. 303; p. 108582
• Main Authors: Sargsyan, Armen, Tonoyan, Ara, Momier, Rodolphe, Leroy, Claude, Sarkisyan, David
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-07-2023; Elsevier
• Subjects: Alkali; Atomic Physics; Electromagnetically-Induced Transparency; Magnetic field; Physics; Spectroscopy; Zeeman effect; Alkali; Spectroscopy; Zeeman effect; Electromagnetically-Induced Transparency; Magnetic field
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2023.108582

•EIT resonances are formed using “forbidden” transitions (ΔF=+2) of Cesium. They can be used for laser stabilisation on strongly shifted frequencies.•To form EIT resonances with such transitions, both probe and coupling beam need to be σ+-polarized. We verify this statement theoretically and experimentally.•Preliminary density-matrix calculations taking into account the geometry of the cell are in agreement with the experimental measurements.
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Atomic transitions satisfying Fe−Fg=ΔF=±2 (where Fe stands for excited and Fg stands for ground state) of alkali atoms have zero probability in zero magnetic field (they are so-called ”forbidden” transitions) but experience a large probabilty increase in an external magnetic field. These transitions are called magnetically induced (MI) transitions. In this paper, we use for the first time the σ+ (ΔmF=+1) MI transitions Fg=3→Fe=5 of Cesium as probe radiation to form EIT resonances in strong magnetic fields (1 - 3 kG) while the coupling radiation frequency is resonant with Fg=4→Fe=5σ+ transitions. The experiment is performed using a nanometric-thin cell filled with Cs vapor and a strong permanent magnet. The thickness of the vapor column is 852 nm, corresponding to the Cs D2 line transition wavelength. Due to the large frequency shift slope of the MI transitions (∼ 4 MHz/G), it is possible to form contrasted and strongly frequency-shifted EIT resonances. Particularly, a strong 12 GHz frequency shift is observed when applying an external magnetic field of ∼ 3 kG. Preliminary calculations performed considering Doppler-broadened three level systems in a nanocell are in reasonable agreement with the experimental measurements.