Mechanism of asymmetric longitudinal mode competition in InGaAsP/InP lasers

Abstract
The mechanism of asymmetric longitudinal mode competition in InGaAsP/InP lasers is discussed. It is shown that the asymmetric mode competition is not due to the spatial hole burning. When we assume that the energy relaxation time of electrons in the conduction band is ∼0.3 ps, we find that the asymmetric longitudinal mode competition is well explained by the model of Bogatov et al. for the external cavity laser. The asymmetric mode competition can be understood on the basis of the pulsation of the electron population at the beat frequency between two longitudinal modes of ∼1012 Hz. The long energy relaxation time may have relevance to the observed low characteristic temperature of the quaternary lasers.