High contrast electromagnetically induced transparency in a nitrogen filled Rb vapour cell

Abstract

We observe the electromagnetically induced transparency (EIT) spectra inside a nitrogen filled Rb vapour cell (Rb-N2) in a five-level Λ-type system of D2 transition of Rb atom. The high contrast EIT resonance in buffer gas filled Rb cell is obtained under our experimental conditions. The effect of velocity changing coherence preserving collisions to obtain the contrast resonance in buffer gas cell has been discussed. We measured the dependence of EIT width and height on pump intensity and find that the EIT width (FWHM) and peak height have a linear dependence on pump intensity. Our experimental results show that the presence of N2 buffer gas reduces the power broadening of the observed resonances.