Enhancement of whispering-gallery-mode lasing in GaN nanoflower-type microdisk with multiple branches

We fabricate GaN-based flower-type micro-cavity lasers as an alternative to conventional microdisks and analyze their optical characteristics. The optical output intensity of the flower-type lasers is 8 times higher than that of circular microcavity lasers, which is enhanced with increasing number of petals. The emission characteristics indicate stronger emission in edge areas of the device compared to the center region due to the three-dimensional whispering gallery mode. The nano-flower devices exhibit a very low threshold current of 50 µA, which is much smaller than that of the circular counterpart. The emission modes of the flower-type lasers are in excellent agreement with a three-dimensional Rayleigh-Fabry-Pérot model. The fabrication of the petal design involves only one additional etching step, resulting in significantly higher performance. The results show that the nano-flower structure can provide enhanced performance in photonics applications relative to the conventional disk-type lasers.