Free-standing, optically pumped, GaN∕InGaN microdisk lasers fabricated by photoelectrochemical etching

GaN-based, mushroom-shaped microdisk lasers were fabricated using band-gap selective photoelectrochemical etching. The optically pumped microdisks had well-defined, distinct modes at excitation powers ranging from about 8to16W∕cm2. Modal linewidths of 0.09nm were reported, which was near the resolution of the measurement equipment. Quality factors for the microdisks were >4600. The observed lasing threshold was 12.1W∕cm2. At higher excitation powers, heating effects and degradation were observed in the optical response of the microdisks.