| This work focuses on analyzing and improving the performance of smaller vertical cavity lasers which employ transparent, insulating apertures (commonly made by lateral etching or oxidation) for optical and current confinement.; Improved performance of smaller vertical cavity lasers is important for applications which require arrays of vertical cavity lasers operating at low power such as free-space optical interconnections between computer boards or even computer chips or highly parallel laser printing schemes. And if properly scaled, smaller lasers have better characteristics at lower output powers.; We analyze two major barriers to shrinking the aperture size: optical scattering losses and current spreading. These analyses helped explain the observed drop in efficiency and rise of threshold current density in earlier. oxide apertured, small lasers, and directed changes in the aperture design such as tapering the oxide front for a more lens-like shape. In addition, these analyses were reduced to simple formulas involving normalized parameters which can be applied to a variety of designs.; We also demonstrate experimentally the impact of improvements in aperture design which enabled small, single-mode, VCSELs <2μm diameter to reach record efficiencies and enabled 2–3μm diameter devices to reach power conversion efficiencies of 20% at output powers as low as 150μW. And we discuss how these results can be unproved with carbon doping and better tailoring of the doping profile to minimize resistance with the least absorptive loss. |
