Electromagnetically induced phase grating via population trapping condition in a microwave-driven four-level atomic system

Abstract

An electromagnetically induced phase grating (EIG) controlled by coherent population trapping (CPT) in a four-level Y-type atomic system is studied. The CPT condition promotes significantly the dispersion of light into the first-order diffraction in constructing a phase modulation grating by transferring energy from zero-order to first-order diffraction. The diffraction efficiency of the phase grating is enhanced by up to 30% of the total probe intensity at the first-order diffraction. The present atomic scheme takes full advantage of the microwave-driven field for generating the EIG, which induces the quantum coherence and controls linear and nonlinear behaviors of the present system. Furthermore, it is noticed that the higher-order diffraction intensities are improved via a microwave-driven field and the phase and amplitude of the microwave field can improve the efficiency of the phase grating. These novel results could find potential applications in developing new photonic devices, such as all-optical switching at low light levels.