Two-state lasing at room temperature in InAs/InP quantum dots

Abstract

The two-state lasing conditions at room temperature in InAs/InP quantum dot (QD) lasers under a continuous wave electrical bias current are studied. It is found that excited state (ES) lasing is promoted by moderately decreasing spacer thickness and increasing dot-size dispersion in a QD stack, and the physical origins are due to the increased bottleneck effect and inhomogeneous broadening. Moreover, it is proved theoretically that ground state (GS) lasing with high inhomogeneous broadening may result in high phase and intensity noise at a high bias current. Therefore, an appropriate spacer thickness together with appropriate inhomogeneous broadening is critical to the GS and/or ES lasing, which helps an optimal design of laser geometry.