中文摘要：

为了获得位相敏感的无粒子数反转探测增益,研究了一个三能级闭合环路子系统控制的四能级原子系统.在三光子共振情况下,获得了大的稳态无反转探测增益.由于量子干涉效应,探测增益对三能级闭合环路子系统的相对位相是敏感的.三能级闭合环路子系统中的场强也是影响探测场增益特性的重要参数.

英文摘要：

We study a four-level atomic system controlled by a three-level closed loop subsystem in order to obtain the phase-sensitive probe gain without population inversion.In the case of three-photon resonance,a large steady-state inversionless probe gain can be obtained.Due to the quantum interference effect,the inversionless gain is sensitive to the relative phase of the three-level closed loop subsystem.Further,the field intensity of the three-level closed loop subsystem is also an important parameter that can affect gain characteristic of the probe field.