Single transverse mode operation in vertical-cavity surface-emitting lasers (VCSELs) is desired over multimode operation in a number of applications. This work presents a method of achieving single-mode operation by depositing an annulus-shaped semiconductor coating atop an 850 nm oxide-confined VCSEL to modify the standing wave of the optical field in the laser cavity. The devices are benchmarked for singlemode performance as well as optical output power via optical spectra and light-current-voltage (LIV) measurements respectively.
