Eur. Phys. J. D (2017) 71: 78
https://doi.org/10.1140/epjd/e2017-70637-5

Regular Article

Effect of magnetic field on the optical properties of an inhomogeneously broadened multilevel Λ-system in Rb vapor

¹ Department of Physics, Indian Institute of Technology, 247 667 Roorkee, India
² Department of Physics, Guru Nanak Dev University, 143 005 Amritsar, India

^a e-mail: wasanfph@iitr.ac.in

Received: 12 October 2016
Published online: 4 April 2017

Abstract

We present a theoretical model, using density matrix approach, to study the effect of external longitudinal and transverse magnetic fields on the optical properties of an inhomogeneously broadened multilevel Λ-system using the D2 line in ⁸⁵Rb and ⁸⁷Rb atoms. The presence of closely spaced multiple excited states causes asymmetry in the absorption and dispersion profiles. We observe a wide EIT window with a positive slope at the line center for a stationary atom. While for a moving atom, the linewidth of EIT window reduces and positive dispersion becomes steeper. When magnetic field is applied, our calculations show multiple EIT subwindows that are significantly narrower and shallow than single EIT window. The number of EIT subwindows depend on the orientation of the magnetic field. We also obtain multiple positive dispersive regions for subluminal propagation in the medium. The anomalous dispersion exists in between two subwindows showing the superluminal light propagation. Our theoretical analysis explain the experiments performed by Wei et al. [Phys. Rev. A 72, 023806 (2005)] and Iftiquar et al. [Phys. Rev. A 79, 013808 (2009)].