Ultralow threshold current 780-nm vertical-cavity surface-emitting lasers with oxide current aperture

Summary form only given. We demonstrate the new type of 780 nm VCSELs having Al/sub 0.11/Ga/sub 0.89/As quantum wells (QWs) as the active medium. The oxide aperture is located just above the active region for efficient current confinement. These VCSELs have a highly doped cap layer, so the characterization of lasers is possible using just a probe tip and does not require a p-electrode. This simple two-step process is a convenient way of characterizing VCSEL wafers. The CW L-I curve of the 3.4-/spl mu/m square aperture VCSEL measured at room temperature is shown. It shows extremely low threshold current of 200 /spl mu/A, slope efficiency of 33%, and single mode peak power of 1.1 mW. The 7.6 /spl mu/m square VCSEL has threshold current of 1 mA, peak power of 2.7 mW, and slope efficiency of 37%. The devices smaller than about 4 /spl mu/m operate on single mode over all the range.