Study of the characteristics of 1.55 μm quantum dash/dot semiconductor lasers on InP substrate

InAs quantum dash (QDH) and quantum dot (QD) lasers grown by molecular beam epitaxy on InP substrate are studied. The laser active zones with multiple stacked layers exhibit lasing wavelength at 1.55 μm. On these devices, the experimental threshold current density reaches its minimum value for a double stacked QDH/QD structure. Other basic laser properties such as gain and quantum efficiency are compared. QD lasers exhibit better threshold current densities but equivalent modal gain per layer than QDH. Finally, the analysis of the modal gain on QD lasers shows a promising potential for improvement.