Understanding asymmetry in electromagnetically induced transparency for 87Rb in strong transverse magnetic field

We present the results of our experimental investigation performed for D-2 line of Rb-87. In this work, we have studied the phenomenon of electromagnetically induced transparency of Rb-87 in presence of a transverse magnetic field and it is interesting to find the EIT spectrum shows signature of the closely lying hyperfine excited states in particular F = 1. We choose two different configurations for our study namely, Lambda (1) and Lambda (2) realised by locking probe beam at two different transition i.e. |F = 1 > -> |F ' = 2 > and |F = 2 > -> |F ' = 2 > respectively. We observe asymmetric features in both configurations at high magnetic field and for Lambda (1) configuration we find complete conversion from transmission to absorption. We explain the observations by quantitative assessment of the impurities in the dark states which arises because of the influence of the neighbouring states. We substantiate our experimental findings with density based numerical calculations.