Doppler展宽的封闭原子系统中无反转增益的相位控制

研究了在具有自发辐射诱导相干性的Doppler展宽的封闭Λ型三能级系统中探测场和驱动场之间的相对位相对探测场无反转增益的控制作用. 研究结果表明: 1) 不管探测场和驱动场是同向传播还是反向传播, 驱动场是失谐还是共振，无反转增益总是随相对位相的改变而作周期性变化，周期为2π. 2) 驱动场共振时，无反转增益极大值随Doppler展宽值的增大而单调减小，且反向传播时比同向传播时减小的速度更快；驱动场失谐时，无反转增益的极大值随Doppler展宽值的增大不再单调地减小或增大. 在以上两种情况下，均可以通过调关键词：自发辐射诱导相干相位控制Doppler展宽无反转增益

Phase control of inversionless gain in a closed atomic system with Doppler broadening

We studied the controlling role played by the relative phase between the probe and driving fields on inversionless gain of the probe field in a closed and Doppler broadened Λ-type three-level system with spontaneously generated coherence (SGC). It was found that：(1) Regardless of the driving field being in or off resonance, and regardless of the probe and driving fields being co- or counter- propagating, the gain maximum value always varies periodically with variation of the relative phase with the period 2π. (2) When the driving field is in resonance, the gain maximum value decreases monotonicly with Doppler width increasing, and moreover, the decreasing in the counter-propagation case is faster than that in the co-propagation case. When the driving field is off resonance, the gain maximum value does not monotonicly decrease or increase with Doppler width increasing. In both above cases, the largest inversionless gain can be gotten by adjusting the relative phase. (3) The contribution of SGC to the inversionless gain is much larger than that of the dynamically induced coherence.