Spectral characteristics of low threshold microdisks

Arrays of thin semiconductor disks and rings were grown on glass substrates with perimeters having low roughness and minimized surface recombination and diameters ranging from 3 to 14 μm. Examination of the disks revealed the existence of whispering gallery modes, the exact locations of which were sensitive to the precise disk diameter, and the separation of which increased with increasing diameter. Well above threshold, mode competition ensured that the longer wavelength mode dominates. An observed mismatch between the photoluminescence peak and the lasing mode decreased with decreasing disk diameters. Moreover, the disks had low threshold and high Q.