Interfacial Control of ZnO Microrod for Whispering Gallery Mode Lasing

Energy loss control at interfacial areas is a significant issue to improve the optical performance of hybrid optical resonant cavities. In this work, we analyzed the simulated electric field intensity to predict the optical loss or gain in ZnO microrod cavity interfaced with both pristine and Al nanoparticles decorated GaN gratings. A single ZnO microrod was placed on GaN gratings to compose three interfacial configurations, these are, ZnO/Air, ZnO/GaN, and ZnO/Al/GaN, their lasing behaviors were investigated experimentally. Experimental results indicate that the lasing intensity, threshold power, and quality factor all depend on interfacial gain and loss. Through introducing the localized surface plasmon resonance (LSPR) of Al nanoparticles at interface areas, improved lasing performance was observed for the ZnO/Al/GaN hybrid structure. Furthermore, the LSPR coupling mechanism responsible for the observed lasing improvement was revealed by the scanning near-field optical microscopy (SNOM) and time-resolved photoluminescence (TRPL) spectroscopy.