Fig. 2: Lasing in topological cavities.
From: Room-temperature lasing from nanophotonic topological cavities
a Scanning electron microscope image of the fabricated sample. The false-colour triangle marks the interior of the topological cavity. b Emission energy vs. the pump energy dependence showing a threshold transition to lasing. The sample is optically pumped at a 980 nm wavelength with 8 ns pulses at a 10 kHz repetition rate. Spatial distribution of emission for the pump intensity c below and d above the lasing threshold. e Emission spectra showing a transition to a narrow-linewidth lasing. In the lasing regime, the FWHM (full width at half maximum) does not exceed 2 nm and is resolution limited by the spectrometer
