Loss and index guiding in single-mode protonimplanted holey vertical-cavity surface-emitting lasers

Abstract—Wedge-shaped holes are fabricated in the top mirror of proton-implanted vertical-cavity surface-emitting lasers (VC-SELs). A radially symmetric fill factor approach is used to calculate the resulting transverse index profile. To investigate both the index confinement provided by the etched pattern and its effect on optical loss, continuous-wave (CW) and pulsed experiments are performed. Under CW operation, we show proper wedge design leads to improved fundamental-mode output power, decreased threshold, and increased efficiency. We report a significant de-crease in threshold under pulsed operation for the etched device compared to an unetched device, indicating a significant reduc-tion in diffraction loss to the fundamental mode due to strong index guiding. Single-mode output is maintained over the entire operating range of the VCSEL due to increased loss for the higher order modes. Index Terms—Distributed Bragg reflector lasers, semiconductor lasers. I