Impact of Oxide Aperture on the Static and Dynamic Performance of 850-nm VCSELs

We fabricate 850-nm vertical-cavity surface-emitting lasers (VCSELs) with oxide-aperture diameters of 5, 7, 9 and $11~\mu $ m and study the effect of oxide-aperture size on the threshold current, output power, differential quantum efficiency and wall-plug efficiency of the devices. We characterize the small-signal modulation bandwidth ( ${f} _{3dB}$ ) of the devices and explore the impact of oxide-aperture size and bias current on the modulation bandwidth. We analyze the relationship between electrical power and the ${f} _{3dB}$ of the VCSELs with different aperture diameters. The fabricated 850-nm VCSEL with the oxide-aperture diameter of $7~\mu $ m at room temperature shows a maximum ${f} _{3dB}$ of nearly 20 GHz and an output power of 9.09 mW. When the oxide-aperture increases to $11~\mu $ m, the ${f} _{3dB}$ remains above 17 GHz and the optical output power exceeds 14 mW.