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Nano-height cylindrical waveguide in GaN-based vertical-cavity surface-emitting lasers

We have proposed a novel nano-height cylindrical waveguide in blue GaN-based vertical-cavity surface-emitting lasers (VCSELs). The proposed 5 nm step height cylindrical waveguide using simple processes provides lateral optical confinement and excellent performance in terms of light output power (LOP) and wall plug efficiency (WPE). A fabricated multi-mode VCSEL with 7 μm emission diameter achieved a LOP of 23.7 mW, maximum external differential quantum efficiency of 43.6%, and WPE of 10% under continuous wave operation at 20 °C. Additionally, a single-mode VCSEL with 3.3 μm emission diameter exhibited LOP of more than 5 mW and WPE of 9.9%.