Fig. 3: Characteristic of the frequency-doubled lasing mode of the NW laser via the SHG process.

a Normalized spectra of the fundamental lasing mode (1016 nm) and the frequency-doubled lasing mode (508 nm). b Emission spectra of the frequency-doubled lasing mode with the increasing fundamental lasing intensity. c Dependence of the fundamental lasing mode and the frequency-doubled lasing mode intensities, showing a fitting slope 1.98 ± 0.01 on a log–log scale