四能级原子系统中非线性原子吸收的理论研究

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

利用精确求解的方法,以N型四能级原子系统为例研究了原子吸收的非线性理论.借助于数学计算,探讨了外场失谐、探测光强及激发态能级向低能级衰减的分配系数对原子吸收的影响.结果表明:信号光的失谐使原子吸收谱发生纵向变化,增强透明效应;控制光的失谐使原子吸收谱吸收发生横向变化,透明窗口右移.当探测光强远小于或接近于信号光和控制光时,原子吸收均表现为电磁感应透明特征,只是在共振处透明程度发生改变.当衰减向两通道的分配系数改变时,原子吸收也改变.

In the degenerate N-type four-level atomic system,we have studied the nonlinear theory of atomic absorption using exact solution method.We have explored the effects of the detuning of the outfield,the probe light intensity and the attenuation distribution coefficient of the excited level to the low level.The results show that the detuning of the signal light makes atomic absorption spectrometry modified in longitudinal orientation and transparency effect enhanced.The detuning of the control light makes atomic absorption spectrometry modified in crosswise orientation and transparent window shifted light.When the probe light intensity is far less than or close to that of the signal light and control light,atomic absorption both presents electromagnetically induced transparent characteristic only changing transparency in resonance place.When the probe light intensity is increased,the transparency of atomic absorption in resonance place is enhanced.