Fig. 3: Experimental characterization of the topological Dirac-vortex microcavity lasers.

a Measured μ-PL spectra of the Dirac-vortex lasers with structural parameters R₀ = 2a₀ and δ_max = 35 nm as a function of the pump power. b Measured μ-PL intensity (purple dots) and linewidth (orange squares) as a function of the pump intensity I_pump. The error bars represent the standard deviation in the linewidth fitting. The lasing threshold is I_th = 0.4 kW cm⁻². c μ-PL spectrum measured at pump intensity I_pump = 0.395 kW cm⁻². The Lorentzian fit (purple solid line) indicates a linewidth of δλ = 1.461 nm. d Measured lasing wavelength λ (purple dots) as a function of the pump intensity I_pump, where a linear fit (orange line) suggests a linear coefficient of dλ/dI_pump = 0.22 nm cm² kW⁻¹. e Measured normalized lasing spectra from the Dirac-vortex lasers with varying s₀ and fixed R₀ = a₀ and δ_max = 35 nm. The lasing wavelength can be tuned in a range wider than 70 nm