四能级原子系统中非线性电磁感应吸收的理论研究

在n型四能级原子系统中,研究了电磁感应吸收的非线性理论.结果表明:探测光的拉比频率和衰减分配系数A影响非线性吸收,进而影响介质吸收.当探测光光强较弱时,介质吸收和线性吸收一致,均表现为电磁感应吸收特征;当探测光光强增大时,介质吸收和线性吸收不再一致,介质吸收曲线将会呈现出烧孔现象;当探测光光强增大到控制光(或信号光)光强时,介质吸收表现出很大的增益现象.同时,非线性吸收受到衰减分配系数A的影响,即使在探测场很弱的条件下,随着A值的减小,介质吸收由电磁感应吸收现象表 关键词： 电磁感应吸收 非线性吸收 增益现象 n型四能级原子系统

Theoretical study of nonlinear electromagnetically induced absorption in four-level atomic system

In the n-type four-level atomic system, we have studied the nonlinear theory of electromagnetically induced absorption. The results show that the probe light Rabi frequency and the attenuation distribution coefficient A affect the nonlinear absorption and then the absorption of a medium. When the probe light intensity is weak, the absorption of the medium and the linear absorption are the same, showing the characteristics of electromagnetic induction absorption. When the probe light intensity is increased, the absorption of the medium and the linear absorption are no longer the same, and now the medium absorption curve will show hole burning phenomenon, and then it will show the gain phenomenon. At the same time, the nonlinear absorption is affected by the value of A. Even if the probe light is weak, the medium absorption will change the electromagnetic induction absorption into the gain phenomenon with the A value decreasing.