Theoretical Study Of Two-dimensional Electromagnetically Induced Grating In Multi-level Atomic System

Quantum coherence and quantum interference can produce interesting optical phenomena in many fields,such as electromagnetically induced transparency(EIT)and electromagnetically induced grating(EIG).EIT refers the phenomenon that a transparent window appears when two laser fields are used to act on an atomic medium and the absorption of probe light in the medium is zero at the resonance frequency due to interference cancellation.On the basis of the EIT study,when the coupled field is replaced by the standing wave field,the grating with periodic changes in absorption and refraction,namely EIG,appears in the atomic medium.In this paper,two-dimensional electromagnetically induced gratings in a multi-level atom system are studied on the basis of one-dimensional electromagnetically induced grating.The main contents are as follows:1.On the basis of three-level ? type EIT,the phenomenon of EIG in three-level,four-level N type and six-level atomic system are simulated and calculated respectively,and the effects of each parameter on the diffraction phenomenon are discussed and analyzed.2.The two-dimensional electromagnetically induced grating is generated by the interaction of a weak probe light in two orthogonal coupled optical planes.The three-level two-dimensional electromagnetically induced grating is calculated and analyzed.The first order diffraction efficiency is 5.8%.Two-dimensional electromagnetically induced grating in a six-level N type atomic system also was studied the first order diffraction efficiency is 7.05%.3.On the basis of the six-level atomic model,an additional field is added to the atomic system,the absorption and refraction coefficients are obtained by using the Laplace transform method,two-dimensional electromagnetically induced gratings of two different six-level N type atomic systems are obtained,and the diffraction phenomena of the gratings are numerically simulated by analyzing the parameters and selecting appropriate parameters.The results show that the first order diffraction efficiency is 12.5% when the corresponding laser field is added between the 13 and24 energy levels.The diffraction efficiency of the first order is 18% when the field is added between 13 and 25 energy levels.The research in this paper provides a theoretical basis for the further realizing the two-dimensional electromagnetically induced grating in a more complex atomic system,and provides a reference for the corresponding experiments,and has potential application value in the field of optical information processing.