循环四能级原子介质中的增益相位光栅  

Gain-phase Grating in a Closed-loop Four-level Atomic Medium

作　　者：杨丽[1] 董雅宾[1,2] 任磊 刘博 YANG Li;DONG Ya-bin;REN Lei;LIU Bo(College of Physics and Electronic Engineering,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学物理电子工程学院,山西太原030006 [2]山西大学极端光学协同创新中心,山西太原030006

出　　处：《量子光学学报》2022年第3期208-214,共7页Journal of Quantum Optics

基　　金：国家自然科学基金(61275212,11004126)。

摘　　要：本文研究了一个循环四能级原子系统中的增益相位光栅效应,基于微扰理论,用密度矩阵方法计算了稳态条件下信号场的极化率,分析了影响信号场衍射效率的相关因素。结果表明,在循环四能级原子介质中,合适的抽运场、调制场和耦合场共同作用,使得信号场产生增益。当光场失谐较小时,利用抽运场、调制场和耦合场可以调控信号场的振幅和相位,使信号场的能量放大,并将能量从零阶衍射方向转移到高阶衍射方向。当抽运场拉比频率约为1.67γ时,一阶衍射效率急剧增加,说明在调控过程中有阈值产生。该光栅在全光开关、全光调制、全光逻辑门等新型光子器件中具有重要的应用。Grating is widely used in information processing,optical communication,optical storage,and other fields.In alloptical networks,the information transmission,transformation and amplification do not need light-electricity conversion,and the optical structures are simple,and re-configurable with anti-interference capability,thus the utilization rate of network resources is improved.The purpose of this study is to realize all-optical control based on the gain-phase grating effect.In a closed-loop four-level atom system,the polarization rate of the signal field was calculated by the density matrix method under the steady-state condition based on the perturbation theory.From the numerical solution,the related factors affecting the diffraction efficiency of the signal field were analyzed,mainly including the Rabi frequencies of the pumping field,modulation field and coupling field.We focused on the amplification and diffraction capacity of the signal field and generated the diffraction curve of the signal field.The changes in diffraction intensity with Rabi frequencies,detunings of the pumping field,modulation field,and coupling field,and interaction length between light and atoms were also considered.The results show that in the closed-loop four-level atomic medium,the appropriate pumping field and coupling field work together to make the signal field generate a gain.When the detuning of the light fields are small,the amplitude and phase of the signal field can be controlled by the pumping field,modulation field and coupling field,so that the energy of the signal field can be amplified and transfer the energy from the zero-order diffraction direction to the higher-order diffraction direction.When the Rabi frequency of the pumping field is about 1.67γ,the first-order diffraction efficiency increases sharply,indicating that a threshold is generated during the modulation process.By adjusting the relevant parameters,a grating with high gain,strong diffraction capacity,and controllable threshold is obtained,which has broad

关 键 词：量子光学 循环四能级原子介质 增益相位光栅 

分 类 号：O431.2[机械工程—光学工程]