Colloidal quantum-dot vertical-cavity surface-emitting laser based on gain-integrated distributed Bragg reflector

Abstract

The longitudinal optical confinement factor (Γz) in vertical-cavity surface-emitting lasers (VCSELs) is typically negatively correlated with the lasing threshold (Pth), but is commonly small due to the limited distribution of the active layer in a cavity. To enhance Γz and reduce Pth, we introduce a novel design for colloidal quantum-dot (CQD) VCSELs based on the gain medium integrated distributed Bragg reflector (GI-DBR). The CQDs integrated into these VCSELs not only act as the high-index medium of the DBR that supports a high reflectivity but also as the active medium for amplifying the emission. The overlap between the electric field antinodes and the gain region is significantly improved, leading to a Γz up to 83%, which is 108% higher than that of the control sample with a traditional dielectric DBR-based structure. Consequently, the Pth is expected to be 59% lower according to the simulation result. Moreover, this GI-DBR-based structure reveals excellent general applicability to enable low-threshold lasing from VCSELs composed of diverse materials.