Theoretical and experimental study of the effect of carrier relaxation on threshold and power-current characteristics of quantum well lasers

In this paper, the effect of intraband relaxation processes of non-equilibrium carriers on the threshold and power-current characteristics of quantum-well lasers is studied both theoretically and experimentally. Special attention is paid to the study of physical mechanisms, which affect the maximum laser power. It is shown that at high excitation levels, the maximum laser power gets affected, apart from lattice and carrier heating, by the phenomenon of gain saturation. Power-current characteristics of a quantum well laser are calculated with gain saturation effect being taken into account. It is shown that at high excitation levels the characteristic becomes non-linear. Calculated behavior of power-current characteristics agrees well with experimental observations.