Performance and Reliability of 12.5-Gb/s Oxide-Free 850-nm Mesa VCSELs

Oxide-free mesa vertical-cavity surface-emitting lasers (VCSELs) emitting at 850 nm have been designed for short reach datacom applications at data rates up to 12.5 Gb/s. The top distributed Bragg reflector is etched away creating a mesa that provides both current and photon confinement. The devices exhibit low threshold current and a donut-shaped far-field profile that is suited for transmission on both legacy and laser-optimized multimode fibers. Open eye diagrams with high margin are observed in on-wafer testing of 8-10 mum VCSELs at 10.3125 Gb/s over 5degC-95degC. Accelerated aging tests indicate a long device lifetime, with the time for a cumulative failure of 1% estimated to be 15 million h at 40degC for 12-mum VCSELs.