利用PeggBarnett 相位理论，研究了耗散腔中多个Λ型原子与相干态光场在拉曼相互作用下光场的相位特性，讨论了原子数、光场平均光子数和腔场耗散系数对光场相位特性的影响。研究表明，当腔不存在耗散时，光场与原子相互作用使相位分布以周期为π/λ振荡；在t=nπ/λ时刻，光场和原子退纠缠，相位分布概率曲线在极坐标图中呈单叶型结构；在演化周期内，光场与原子的相互作用使相位分布概率曲线分裂为多叶型结构。当腔存在耗散时，相位分布概率的叶型结构逐渐演化为以坐标原点为中心的圆，即光场相位最终演化为随机分布；腔的耗散系数越大，光场相位趋于随机分布越快。另外，原子数的变化，并不影响相位分布的叶形结构，只是引起相位涨落周期性振荡的加剧。

By means of PeggBarnett phase formalism, the phase properties of the field interacting with more Λtype threelevel atoms via Raman coupling in a phase damped cavity are investigated. The influences of decay coefficient of the cavity, the intensity of the field and the number of atoms on the phase distribution as well as its fluctuation are discussed. The results show that if there is absence of the phase damping, the phase distribution oscillates with the period π/λ. It presents a structure of single leaf at t=nπ/λ, but it splits into multileaf structure during the evolution period due to the interaction between the field and the atoms. If there is presence of the phase damping, the obvious leaf structure of the phase distribution becomes obscure and contracts into a circle, which indicates the random distribution of the phase. The larger the decay coefficient is, the more rapidly the phase becomes random distribution. Otherwise，the change of the number of atoms does not affect the leaf structure of the phase distribution, but intensifies the oscillation of the phase fluctuation.