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

The longitudinal optical confinement factor (${\mathrm{\ensuremath{\Gamma}}}_{z}$) in vertical-cavity surface-emitting lasers (VCSELs) is typically negatively correlated with the lasing threshold (${P}_{\mathrm{th}}$), but is commonly small due to the limited distribution of the active layer in a cavity. To enhance ${\mathrm{\ensuremath{\Gamma}}}_{z}$ and reduce ${P}_{\mathrm{th}}$, 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 ${\mathrm{\ensuremath{\Gamma}}}_{z}$ up to 83%, which is 108% higher than that of the control sample with a traditional dielectric DBR-based structure. Consequently, the ${P}_{\mathrm{th}}$ 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.