Full-color WGM lasing in nested microcavities

A full-color whispering-gallery mode (WGM) laser has been fabricated by partitioning different light-emitting polymers in a nested microcavity. Red-green-blue WGM lasing with a high quality factor above 104 and a narrow linewidth of 0.025 nm emits from nested capillaries when excited with a nanosecond laser. The full-color WGM lasing shows a low excitation threshold for the nested microcavities, which can avoid fluorescence resonant energy transfer. We also achieve wavelength tunable lasing upon altering the different polymers in the nested microcavities. The work demonstrates a simple method to fabricate a full-color WGM laser and its potential applications in compact lighting devices and white laser sources.