Dynamical tuning for single mode whispering gallery mode microcavity lasing

The dynamically modulated lasing mode is extremely significant for laser applications in optical interconnections, on-chip communications and trace detection. However, tunable micro/nano laser (especially for single mode laser) is still a challenge although enormous efforts have been devoted. The coexisting modes could be selected out through light field coupling between two adjacent cavities based on Vernier effect, which could provide a compact and suitable approach for single mode lasing operation in various kinds of compound microcavity. Herein, a spherical whispering gallery cavity with small size and low threshold was rolled along a hexagonal tapered microrod to adjust the lasing mode. The coupling mechanism was explored based on static and time-resolution photoluminescence measurements in situ. The tunable lasing mode mainly derives from resonant mode of microsphere according to carrier recombination analysis. Such a spectral control establishes to realize a lasing mode selection flexibly in real-time micromanipulation.