Y型四能级系统中Doppler展宽对VIC相关的双光子吸收的影响

Effect of Doppler broadening on VIC-dependent two-photon absorption in Y-type four-level system

利用数值计算结果讨论了Doppler展宽对Y型四能级原子系统中真空诱导相干性(VIC)相关的双光子吸收的影响.研究结果表明:1)在无Doppler展宽的情况中,不存在VIC时,吸收曲线具有双峰结构并产生电磁感应透明(EIT)现象,存在VIC时吸收曲线具有单峰结构而EIT现象不再发生;2)在有Doppler展宽的情况中,不管是否存在VIC,EIT现象都能发生;不存在VIC时,不管探测场和驱动场传播方向相同还是相反,随Doppler展宽宽度D值的增大,吸收先增大后减小,吸收曲线逐渐从双峰结构变为单峰结构;存在VIC时,若探测场和驱动场传播方向相同,随D值的增大,吸收先增大后减小,吸收曲线逐渐从单峰结构变为双峰结构;若探测场和驱动场传播方向相反,随D值的增大,吸收单调减小,但吸收曲线仍保持单峰结构.

Using the numerical result,the influence of the Doppler broadening on the two-photon absorption related to vacuum induced coherence is discussed.In the absence of Doppler broadening,when VIC is absent,the absorption curve has a double-peak structure and the electromagnetically induced transparency phenomenon can occur;when VIC is present,the absorption curve has a single-peak structure and EIT phenomenon does not appear.In the presence of Doppler broadening,regardless of VIC being present or not,EIT phenomenon always can occur;when VIC is absent,no matter whether the propagation directions of the probe and driving fields are the same or opposite,with the Doppler broadening width（D） increasing,the absorption first increases and then decreases and the absorption curve changes gradually from a double-peak structure to a single-peak structure;when VIC is present,if propagation directions of the probe and driving fields are the same,with the value of D increasing,the absorption first increases and then decreases and the absorption curve changes gradually from a single-peak structure to a double-peak structure;if propagation directions of the probe and driving fields are opposite,with the value of D increasing,the absorption decreases monotoniealiy and the absorption curve remains a single-peak structure.