Gradual degradation in 850-nm vertical-cavity surface-emitting lasers

The aging process is studied in proton-implanted 850-nm vertical-cavity surface-emitting lasers (VCSEL's). We find evidence for a novel failure mode, which does not involve the growth of defects or reduction in radiative efficiency. In the proposed failure mode, point defects migrate and passivate the dopant atoms in the VCSEL mirrors, increasing mirror resistance in the device center. Thus, current is forced toward the lower resistance parallel path along the device edges, where it does not contribute to lasing. We refer to this as the "current-shunting failure mechanism". Evidence has been found to support this process for both 850- and 680-nm proton-implanted VCSEL's.