Coherent optical processes on Cs D2 line magnetically induced transitions

Abstract

The increased spectral resolution allowed by the use of extremely thin vapor cells has led to the observation of interesting behavior of alkali transitions when placed in a magnetic field. Particularly, the probabilities of transitions obeying an apparent Fe−Fg≡ΔF=±2 selection rule, referred to as magnetically-induced (MI) transitions, largely increase in the intermediate interaction regime while being null at zero and higher magnetic fields. With an 800 nm-thick Cs vapor cell placed in a field up to 1.5 kG, we show here that the generation of electromagnetically induced transparency (EIT), realized in Λ-systems involving ΔF=−2 MI transitions, is only possible when both the coupling and probe beams are σ−-circular polarized, demonstrating that EIT is affected by magnetic circular dichroism. A similar rule of thumb can be extrapolated for ΔF=+2 MI transitions and σ+ polarization. Because of the high frequency shift slope (typ. 4 MHz/G), the generation of EIT resonances involving MI transitions is interesting, especially in the context of growing attention towards micro-machined alkali vapor cell sensors.