Using an experimental work on 'stopped light' as an example, we show how a classical phenomenon of linear optics, the interference of polarized light, can imitate the effect of electromagnetically induced transparency.
We report a simplified all-optical scheme that achieves dynamical switching between electromagnetically induced transparency (EIT) and absorption (EIA) in a [Formula: see text]-type atomic system using only two lasers. The switch is controlled via the polarization ([Formula: see text]) and propagation direction of the optical fields. By applying a weak magnetic field, we spectroscopically resolve the degenerate transition into Zeeman-split subsystems and identify an effective N-type pathway as the physical origin of the switching. Theoretical analysis based on dressed-state perturbation theory reveals that the EIT–EIA transition results from constructive quantum interference between secondary dressed states. The scheme also generates tunable dual transparency windows, enabling potential applications in multi-channel signal routing and polarization-controlled slow-light devices.
Summary form only given. Electromagnetically induced transparency (EIT) refers to a phenomenon, whereby the optically resonant transition is rendered nearly transparent by applying a strong coupling laser field. The mechanism of EIT is usually explained in terms of quantum coherence or quantum interference. This EIT has attracted increasing interest because absorption associated with nonlinear optical processes can be removed. In the typical three-level /spl lambda/-system, which includes the ground state and the metastable state, when the atomic population is prepared in the superposition of the states by the coupling fields, the optical response of the media to the probe field is significantly modified. Since this is a coherent control of an electric field by another field via the atomic coherence, several schemes to control light coherently have been suggested. We propose an optical coherent control scheme of the polarization of optical pulses using the EIT quantum coherence, and numerically study its applicability to fast optical switching.