Volume 82, Number 5, June 2008
Article Number 54003
Number of page(s) 6
Section Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics
Published online 19 May 2008
EPL, 82 (2008) 54003
DOI: 10.1209/0295-5075/82/54003

Broadening of EIT window by incoherent pumping in a three-level $\mth{\Lambda}$ system: Effect of homogeneous and inhomogeneous broadening

K. Rai Dastidar and S. Dutta

Department of Spectroscopy and Raman Centre for Atomic, Molecular and Optical Sciences, Indian Association for the Cultivation of Science - Kolkata 700032, India

received 8 February 2008; accepted in final form 8 April 2008; published June 2008
published online 19 May 2008

The interplay between dynamically induced coherence (DIC) and spontaneously generated coherence (SGC) can induce electromagnetically induced transparency (EIT) in a three-level closed $\Lambda $ system. When the contributions from these two coherences are equal in magnitude and opposite in sign at the resonances of both the coherent and probe fields, transparency of the probe light occurs at the resonance with absorption humps away from the resonance. We have demonstrated here that the broadening of the EIT window can be controlled by changing the strength of incoherent pumping. This is a new approach for achieving wide EIT window for lossless and distortionless transmission of light of large spectral width. The most attractive feature of this new method is that the FWHM (full width at half-maximum) of the EIT window is further increased when the broadening due to homogeneous/inhomogeneous decay is taken into consideration. This scheme can be applied in atoms/molecules where SGC can be invoked by dressing two closely spaced levels (e.g. hyperfine levels in atoms or rovibrational levels in molecules) by an external field. This effect has been demonstrated in a heteronuclear molecule (e.g. LiH) and examined the role of incoherent pumping for controlling the width of the EIT window in the presence and absence of homogeneous/inhomogeneous decay. The experimental realization of the widening of the EIT window in molecules has been discussed.

42.50.Gy - Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption.
42.50.Hz - Strong-field excitation of optical transitions in quantum systems; multiphoton processes; dynamic Stark shift.

© EPLA 2008