A study of distributed dielectric bragg reflectors for vertically emitting lasers of the near-IR range

Abstract

Studies aimed at optimization of the design of a dielectric distributed Bragg reflector (DBR) produced by the reactive magnetron sputtering method for applications in near-IR vertical-cavity surface-emitting lasers with intracavity contacts (ICC-VCSELs) are carried out. It is shown that the reflectivity of the dielectric DBRs based on SiO₂/TiO₂ decreases due to the polycrystalline structure of the TiO₂ layers, which causes diffusive scattering of light. In contrast, amorphous Ta₂O₅ layers is characterized by a low surface roughness and low fluctuation in the refractive index. Single-mode ICC-VCSELs in the 980-nm spectral range with dielectric DBR based on SiO₂/Ta₂O₅ with a threshold current less than 0.27 mA, electric resistance of less than 200 Ω, and differential efficiency of more than 0.8 W/A are demonstrated.