Single Transverse Mode Microcavity Laser with Ultralow Threshold

Abstract

We report on experiments with surface emitting microcavity semiconductor lasers with a mesa-like three-dimensional structure. Mode selectivity is introduced by the small diameter of the top mirror, making single transverse mode oscillation possible. This leads to a reduced threshold pump power as compared with a planar sample with the same structure; on optical pumping we observed a threshold power of about 7 µW at 4 K. The observed laser threshold and spontaneous emission coefficient were compared with the theoretical prediction, giving a reasonable agreement.