Influence of Doppler broadening and spontaneously generated coherence on propagation effect in a quasi lambda-type four-level system  

作　　者：Liu Zhong-Bo Liang Ying Jia Ke-Ning Fan Xi-Jun 刘中波;梁颖;贾克宁;樊锡君(College of Physics and Electronics,Shandong Normal University,Jinan 250014,China)

机构地区：[1]College of Physics and Electronics,Shandong Normal University,Jinan 250014,China

出　　处：《Chinese Physics B》2012年第2期322-332,共11页中国物理B（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No.10875072)

摘　　要：In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the Doppler broadening is present, generally speaking, the values of gain and intensity of lasing without inversion （i.e. the probe field） in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case; considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength. The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength; when spontaneously generated coherence is present, much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained. Choosing suitable values of the probe detuning, Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.In this paper we study influences of Doppler broadening, spontaneously generated coherence, and other system parameters on propagation effect in a quasi lambda-type four-level atomic system. It is shown that when the Doppler broadening is present, generally speaking, the values of gain and intensity of lasing without inversion （i.e. the probe field） in the co-propagating probe and driving fields case are much larger than those in the counter-propagating case; considerably larger gain and intensity of lasing without inversion than those without the Doppler broadening can be obtained by choosing appropriate values of the Doppler broadening width and spontaneously generated coherence strength. The gain and intensity of lasing without inversion increase with the increase of spontaneously generated coherence strength; when spontaneously generated coherence is present, much larger gain and intensity of lasing without inversion than those in the case without spontaneously generated coherence can be obtained. Choosing suitable values of the probe detuning, Rabi frequencies of the driving and pump fields at the entrance of the medium also can remarkably enhance the gain and intensity of lasing without inversion.

关 键 词：four-level system propagation effect spontaneously generated coherence Doppler broadening lasing without inversion 

分 类 号：O431.2[机械工程—光学工程]