本文在考虑驱动场相位涨落时开放的简单三能级系统的定态行为。结果表明 ,驱动场相位涨落将导致有限线宽。增益和被探测场耦合的两个能级间布居差将随线宽的增加而改变 ,并在有限线宽处发生从无粒子数反转激光到有粒子数反转激光的改变 In this paper, we consider the steady-state behavior of a simple three-level system that is open when the phase of the driving field fluctuates. The results show that the driving field fluctuations will lead to a limited line width. The difference in population between the two levels coupled with the gain and the field to be detected will change with the increase of the line width and change from the non-particle inversion laser to the particle inversion laser at the finite line width