能级构型对InAs/GaAs量子点电磁感应透明介质中光孤子存储的影响

Effect of energy level configuration on storage of optical solitons in InAs/GaAs quantum dot electromagnetically induced transparency medium

基于现有的实验,利用不同频率的光脉冲耦合到InAs/GaAs量子点的不同能级之间可形成梯形、Λ形和V形等3类量子点电磁诱导透明介质.继而研究这三类能级构型InAs/GaAs量子点电磁诱导透明介质中的光孤子形成和存储性质,结果表明,梯形和Λ形InAs/GaAs量子点体系不但可形成光孤子还可以实现光孤子的存储与读取,且其所存储光孤子的保真度比光存储的保真度高;但V形InAs/GaAs量子点体系却不能形成光孤子,这是由于体系的非线性效应非常弱.有趣的是在相同的实验参数下,Λ形InAs/GaAs量子点体系所存储的光孤子幅度比梯形所存储的光孤子幅度大.这为半导体量子点器件对所存储光孤子进行调幅操作提供了理论依据.

Based on the current growth technology of quantum dot in the experiment,considering that the probe fields and control fields at different frequencies are coupled between different energy levels of the InAs/GaAs quantum dot,the ladder-type,Λ-type and V-type energy level configurations can be formed.The linear and nonlinear properties of these energy level configurations of InAs/GaAs quantum dots are studied by using semiclassical theory combined with multiple scale method.It is shown that in the linear case,electromagnetic induction transparency windows can be formed among ladder-type,Λ-type and V-type energy level configurations.And the width of the transparent window increases with the strength of the control pulse increasing.For the nonlinear case,under the current experimental condition,optical solitons can be formed and stored in ladder-type configuration andΛ-type energy level configuration.However,optical solitons cannot be formed in the V-type energy level configurations,which is because the nonlinear effect of the system is very weak.Furthermore,it is demonstrated that the fidelity of the storage and retrieval of the optical solitons is higher than that of linear optical pulse and strongly nonlinear optical pulse.Interestingly,it is also found that the amplitude of stored optical solitons inΛ-type energy level configuration is higher than that in ladder-type energy level configuration.This study provides a theoretical basis for semiconductor quantum dot devices to modulate the amplitude of the stored optical solitons.