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

• Published in: Chinese physics B 2012-02, Vol.21 (2), p.322-332
• Main Author: 刘中波 梁颖 贾克宁 樊锡君
• Format: Article
• Language: English
• Subjects: Coherence; Doppler; Doppler effect; Entrances; Gain; Inversions; Lasing; Pumps; Strength; λ-型; 传播; 四能级系统; 多普勒展宽; 强度值; 无粒子数反转激光; 激光增益; 连贯性
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/21/2/024206

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.