Investigation of the effects of nonlinear optical gain and thermal carrier excitation on characteristics of self-assembled quantum-dot lasers

Abstract

Comparing simulation results with experimental findings, it is found that considering nonlinear optical gain is quite essential to accurately obtain dynamic and static characteristics of self-assembled quantum-dot lasers (SAQDLs). In fact, the nonlinear optical gain prevents extreme decline or growth of photon population as the time increases and of output power as the injected current enhances. It also results in multi-mode lasing and increasing the number of lasing modes with elevation of the injected current. In addition, the best performance of SAQDLs, at a certain injected current, depends on homogeneous and inhomogeneous broadening. Thermal carrier excitation results in degradation of light-current characteristics. It also leads to a red shift in dominant lasing modes at low injected currents, the dominant lasing modes move toward higher energies as the current enhances until the most dominant mode becomes the central one.