Electromagnetically induced transparency in Y-type atomic system

Abstract

Probe field propagation through a four-level Y-type system is studied analytically under steady state condition by using density matrix formulation. The probe field scans the intermediate state from the ground state whereas two other coherent radiation fields, namely the control field and the coupling field, are set to couple two different excited states from the intermediate energy level. Under Doppler free condition, simulated probe absorption shows single or twin EIT windows depending on whether the control and the coupling field are onresonant or detuned. Under Doppler broadened condition, the residual Doppler averaging due to wavelength mismatch between the probe field and the control field as well as that between the probe field and the coupling field plays significant role in the formation of transparency window.