开放V型四能级系统无粒子数反转激光的研究

Study on an Open V-Type Four-Level Inversionless Lasing System

利用电偶极和旋转波近似下的密度矩阵方程组,探过了无粒子数反转激光产生的物理机制;利用数值计算结果分析了驱动场的Rabi频率、非线性项对系统无反转激光增益和粒子数差的影响。提出了开放的V型四能级系统无粒子数反转激光理论模型。通过计算,当驱动场和探测场共振时,色散为0,在驱动场Rabi频率变化的整个区间内都可得到无反转的激光增益,非线性项的存在使增益出现饱和现象。

With the density matrix equations of motion under the electric dipole and the rotating wave approximations, the mechanism of LWI gain was analyzed. By numerical results, the effects of the Rabi frequencies of the driving fields and nonlinear term on the gain without inversion and the population difference of the system were studied. Theoretical model of an open V-type four-level atomic system was presented. Through calculation, when both the probing and driving fields are resonant, the dispersion equals to zero. A LWI gain was got during the region of Rabi frequencies of the driving fields. The gain was saturated because of nonlinear term.