Electromagnetically induced grating in the microwave-driven four-level atomic systems

Abstract

A new scheme to investigate an electromagnetically induced grating in an N-type configuration in the presence of a strong-standing coupling field, additional coherent fields, and microwave driven fields is presented. By considering the coherent population trapping (CPT) condition in a four-level microwave driven N-type atomic system, a novel nonlinear optical storage is obtained via linear absorption vanishing and giant Kerr nonlinearity during light propagation. It is revealed that nonlinear properties in this atomic medium are maximum in the CPT condition, and these nonlinear properties could be affected and modulated by means of a microwave driven field. In this condition high-phase modulated diffraction efficiency is attained. The diffraction pattern is sensitive to variables of the phase and amplitude of microwave field. Consequently one can control the efficiency of different orders of grating more conveniently. The first-order diffraction efficiency of the grating, about 45%, can be obtained by choosing optimum values for the phase and amplitude of the microwave field. It is shown that the phase and modulation grating could be controlled effectively by atomic field-radiation parameters such as the interaction length L of atomic samples and applied field detunings. It has been noted that a novel fast communication device could be obtained at the zero absorption point and on the superluminal light level.