“…18) This extremely high value of 50 cm −1 represents more than two-thirds of the total internal loss in VCSELs with a lateral anti-guiding structure, leading to superior performance such as lower threshold current, higher efficiency, and higher light output power (LOP) compared to anti-guiding VCSELs. 18,23) Several research groups have developed various lateral index guide structures in GaNbased VCSELs by employing Si-diffusion confinement, 15) a photoelectrochemically etched air-gap aperture, 14,29) a SiO 2 -buried lateral index guide, 18,20,23,26,27) a Nb 2 O 5 convex structure, 19) a monolithic curved mirror, 21,25) and tunnel junction intracavity contact. 11,22,28,[30][31][32] Among them, a high LOP of 22 mW, an external differential quantum efficiency (η d ) of 40%, and a wall plug efficiency (WPE) of around 10% have been demonstrated by incorporating the SiO 2 -buried lateral index guide.…”