Observation of whispering gallery modes in nonpolar m-plane GaN microdisks

We have fabricated nonpolar GaN/InGaN microdisks using band-gap selective photoelectrochemical etching. These microdisks have a smoother optical cavity than our previous c-plane microdisks, and they support whispering gallery modes with quality factors as high as 2000 after a focused ion beam treatment to the quantum wells. Because of the lack of a Stokes shift in the quantum wells of these m-plane disks, absorption losses play a much more significant role than in our earlier c-plane microdisks, and the light which couples into the modes is emission from the InGaN post rather than the quantum wells within the cavity.