The steady-state light-vs-pumping characteristic for lasers is modeled by a rate-equation and Fabry-Perot approach. It is found that the two models predict a similar dependence of the output power on pumping rate in the limit of vanishingly small gain and loss. It is also discovered that the Fabry-Perot result contains multiplicative factors which arise from an explicit consideration of the resonator. These factors are missing in the rate-equation analysis but can be included by redefining the equivalent cavity loss and scaling the spontaneous emission factor and gain in an appropriate fashion. The results of this investigation indicate that, for diode lasers, the Fabry-Perot approach to modeling the steady-state behavior should be preferred.
Daniel T. Cassidy, "Comparison of rate-equation and Fabry-Perot approaches to modeling a diode laser," Appl. Opt. 22, 3321-3326 (1983)