讨论了调谐耦合场作用下的Λ型三能级系统中的无反转光放大(AWI)现象, 调谐耦合场同时激励两个基态精细结构能级与激发态能级之间的跃迁, 使系统同时呈现电磁诱导透明(EIT)和自发诱导相干凹陷两种特性, 而且当调节这个耦合场的频率失谐量在某一特定范围时, 系统会在EIT信号上叠加出现AWI现象。研究结果表明: 该系统中EIT和自发诱导相干凹陷之间存在能量转移现象, 当EIT上出现AWI现象时, 虽然激发态能级与基态能级之间没有出现粒子数反转, 但是两个基态精细结构能级之间出现了粒子数反转。

Amplification without inversion(AWI) is discussed in a lambda three level system where a coupling field interacts with two separate optical transitions between two ground state hyperfine levels and an excited state level. Both electromagnetically induced transparency(EIT) and spontaneous radiation induced coherent dip are obtained, and AWI is observed in the EIT window by tuning the excitation frequency of the coupling field to satisfy certain conditions. The results show that, there is energy transfer between EIT and spontaneous radiation induced coherent dip, and when AWI is observed, there is no population inversion between the ground state hyperfine levels and the excited state level, but population inversion between the two ground state hyperfine levels.