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 $8\text{to}16\mathrm{W}∕{\mathrm{cm}}^2$ . Modal linewidths of $0.09\mathrm{nm}$ were reported, which was near the resolution of the measurement equipment. Quality factors for the microdisks were $>4600$ . The observed lasing threshold was $12.1\mathrm{W}∕{\mathrm{cm}}^2$ . At higher excitation powers, heating effects and degradation were observed in the optical response of the microdisks.