为了解决在平均场近似速率方程中自洽地由激光器腔内平均场来确定输出场的问题，以半导体激光器为例，采用集总形式的端面反射率，通过求解行波速率方程组，得出了半导体激光器腔内平均光子数密度与输出光子数密度的解析关系式.结果表明，半导体激光器输出场与腔内平均场之比是一个与泵浦电流有关的量，把它当成常数是有偏见的.

Semiconductor laser as an example,using the form of end-reflection coefficient and traveling wave rate equations,an analytical expression relating the average photon density inside the cavity and the output photon density of the semiconductor laser is derived to establish the relation between the average photon density inside the cavity and the output density of the laser in a self-consistent fashion of the rate equations based on mean-field approximation (MFREs) .The result is that ratio of the output field and the average field inside the cavity is related to the pumping current.The ratio cannot be considered as a constant.