All-optical tunable whispering gallery mode lasing in a PMMA-coated microcavity embedded with a high-efficiency nanoheater

•By analyzing the effect of Nd3+ doping concentration on the photothermal conversion efficiency of Nd:NaGdF4 nanoparticles under continuous wave laser irradiation, the highest value in NaNdF4 as a nanoscale heat source in the microstructure can reach 82.5%, which is greater than the currently reported nanoheaters.•The nanoheater is doped into the silica core by infrared laser ablation of microfibers, and the 793 nm trigger laser is injected axially through the fiber stem to trigger the photothermal effect, so that the PMMA-coated microcavity maintains a high intrinsic Q factor during all-optical tuning process, and possesses improved integration.•The nanoheater-doped microlaser achieves a wavelength tuning range of over 3.1 nm within the applied power intensity range of 1 to 1.62 W/mm2, which is more than 2.5 times larger than that of the undoped microlaser, confirming that nanoheater doping is an effective way to improve all-optical wavelength tunability.