Y型四能级系统中Doppler展宽对真空诱导相干性相关的探测场吸收的影响

利用数值计算结果,讨论了在Y型四能级原子系统中Doppler展宽对与真空诱导相干性(VIC) 相关的探测场吸收性质的影响.研究结果表明: 当无Doppler展宽时,只有不存在VIC时才可能产生电磁感应透明(EIT)现象; VIC将导致探测场吸收的明显改变和增益产生;在VIC存在和不存在两种情况中,吸收曲线都具有关于探测场失谐对称的双峰结构. 当有Doppler展宽时,在VIC存在和不存在两种情况中都能产生EIT现象; VIC仍将导致探测场吸收的明显改变和增益产生;不管是否存在VIC,探测场吸收都具有以下特征:吸收曲线不再具有关于探测场失谐的对称性且随Doppler展宽宽度(D)值的增大而逐渐从双峰结构变为单峰结构,探测场吸收不随D值的增大而单调增大或减小,在探测场和驱动场的传播方向相反时可获得比传播方向相同时更小的探测场吸收.

Effect of Doppler broadening on the vacuum induced coherence-dependent probe field absorption in Y-type four-level system

Using the numerical result, the influence of the Doppler broadening on the vacuum induced coherence (VIC) related probe field absorption is discussed. It is shown that if there exists no Doppler broadening, only when VIC is absent can the electromagnetically induced transparency (EIT) phenomenon occur; VIC leads the probe field absorption to vary obviously and the gain to appear; in both cases with and without VIC, the absorption curve has a double-peak structure which is symmetrical about the probe detuning. If there exists the Doppler broadening, in both cases with and without VIC, EIT phenomenon can always occur; VIC still leads the probe field absorption to vary obviously and the gain to appear; no matter whether the VIC is present. The probe field absorption has the following characteristics: the absorption curve no longer has symmetry about the probe field detuning and changes gradually from the double-peak structure to the single-peak structure with Doppler broadening width (D) increasing; the probe field absorption does not monotonically increase or decrease with D increasing; the probe field absorption, when the probe and driving fields propagate along the opposite directions, is smaller than that when the probe and driving fields propagate along the same directions.