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

Abstract

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.

An all-optical tunable polymer WGM laser pumped by a laser diode

“… 29 Li et al proposed an all-optical tunable whispering gallery mode (WGM) laser from a liquid-filled hollow glass microsphere. 32 A secondary laser at 793 nm was used to irradiate the liquid-filled hollow glass microsphere to excite the NaNdF 4 in the liquid core, resulting in a maximum tuning range of 4.95 nm and a sensitivity of 2.95 nm W −1 mm −2 . Zhang et al have reported a tunable WGM laser based on the polymer thermo-optic effect.…”

“…The WGM microcavity resonators with a small mode volume and high quality (Q) factor are ideal cavities for polymer lasers that are pumped by LD or by light emitting diodes. Currently, various methods for achieving the wavelength tuning of WGM lasers have been reported, [27][28][29][30][31][32] such as strain, injecting liquid, and temperature. Chen et al have developed an optically pumped mechanically tunable WGM laser from polymer microber, demonstrating that bending is a powerful way for tuning the wavelength of WGM laser.…”