Switching from electromagnetically induced absorption grating to electromagnetically induced phase grating in a closed-loop atomic system.

Abstract

The electromagnetically induced grating is investigated in a four-level double V-type quantum system. It is shown that the electromagnetically induced transparency established by the cross-Kerr nonlinear effect can be canceled by the four-wave mixing in a closed-loop atomic system and that the diffraction of the probe beam depends on the relative phase of the applied fields and can be controlled by this parameter. We find that an additional nonlinear contribution is established in the medium response by applying a microwave field to the system and that the electromagnetically induced absorption grating turns to the electromagnetically induced phase grating. This contribution leads to 100% diffraction efficiency in the first-order direction, so we can say that the proposed grating could be considered as a special candidate for the optical networking and communication.