Three-photon absorption induced whispering gallery mode lasing in ZnO twin-rods microstructure

► Twin-structured ZnO microrods were fabricated by hydrothermal reaction and employed as whispering gallery cavities. ► The stimulated UV emission was observed under the excitation of a femtosecond laser pulses at wave length 800 nm. ► The spectra and the output-input relationship demonstrated that the whispering gallery mode lasing was induced by an efficient 3-photon absorption process. ► The different size of the two branches are response to the variation of lasing modes, threshold and Q factor.