Wu, YuchangJiang, LiAsryan, Levon V.2017-06-122017-06-122015-11-140021-8979http://hdl.handle.net/10919/78016A theory of operating characteristics of quantum dot (QD) lasers is discussed in the presence of excited states in QDs. We consider three possible situations for lasing: (i) ground-state lasing only; (ii) ground-state lasing at first and then the onset of also excited-state lasing with increasing injection current; (iii) excited-state lasing only. The following characteristics are studied: occupancies of the ground-state and excited-state in QDs, free carrier density in the optical confinement layer, threshold currents for ground- and excited-state lasing, densities of photons emitted via ground- and excited-state stimulated transitions, output power, internal and external differential quantum efficiencies. Under the conditions of ground-state lasing only, the output power saturates with injection current. Under the conditions of both ground- and excited-state lasing, the output power of ground-state lasing remains pinned above the excited-state lasing threshold while the power of excited-state lasing increases. There is a kink in the light-current curve at the excited-state lasing threshold. The case of excited-state lasing only is qualitatively similar to that for single-state QDs—the role of ground-state transitions is simply reduced to increasing the threshold current.14 pagesapplication/pdfenIn CopyrightPhysics, AppliedPhysicsCARRIER RELAXATION DYNAMICSCONFINED ACTIVE-REGIONSEMICONDUCTOR-LASERSROOM-TEMPERATURESATURATIONTHRESHOLDGAINCAPTUREDENSITYArticle - Refereedhttps://doi.org/10.1063/1.493529611818Asryan, LV [0000-0002-2502-1559]