Nanoheater-tuned whispering gallery mode lasing in liquid-filled hollow microcavities

An all-optical tunable whispering gallery mode (WGM) lasing from the liquid-filled hollow glass microsphere (LFHGM) is proposed and experimentally verified. The LFHGM-based microlaser is prepared by injecting N a N d F 4 / d y e co-doped liquid into the HGM, and WGM resonance is obtained under excitation of a 532 nm pulse laser. Since the high-efficiency absorption of the 793 nm continuous-wave laser by N a N d F 4 nanocrystals (NCs) can result in photothermal effect-induced effective refractive index change of the microcavity, a secondary 793 nm laser is irradiated into the LFHGM to excite the N a N d F 4 dispersed in the liquid core, thereby realizing a shift of resonant frequencies. The influence of the doping concentration of N a N d F 4 NCs on the tuning range and the sensitivity over the power intensity range of 0 − 1. 68 W / m m 2 are investigated experimentally, obtaining maximum values of 4.95 and 2 . 95 n m / ( W m m − 2 ) . The ability to generate stable lasing in a LFHGM cavity highlights the practical application of the microscale lasers in future all-optical networks.