Theory of main resonances in directly modulated diode lasers

Domains of existence of the main resonances in directly modulated semiconductor lasers are obtained by application of quasi-conservation theory. The predictions are compared with numerical results coming from a direct integration of the model equations and with experimental observations reported by other groups. In both cases we find a qualitative good agreement. We consider a model that contains explicitly the gain saturation and spontaneous emission terms. We find that the spontaneous emission strongly modifies the qualitative behavior of the instabilities boundaries, while the gain saturation leads to a simple quantitative shift of boundaries. We also find that modulation of the pump or loss produce equivalent results if the respective modulation amplitudes are conveniently rescaled.