Rate-equation analysis of output efficiency and modulation rate of photonic-crystal light-emitting diodes

The performance characteristics of photonic-crystal light-emitting diodes ( LEDs) are analyzed, taking into account the effects of both nonradiative re combination and photon reabsorption processes using multimode rate equation s, It is shown that, in the presence of strong photon reabsorption, the opt imum output efficiency and modulation rates are achieved when the width of the photon density-of-state distribution function is comparable to the widt h of the spontaneous emission lineshape of the active material. On the othe r hand, when photon reabsorption is weak, it becomes beneficial to construc t high-Q cavities, Based on this analysis, the characteristics of different photonic-crystal LED configurations are discussed.