Fig. 2: Fabricated sample and the mini-BIC laser performance.

a Scanning electron microscopy (SEM) images of the mini-BIC laser with a = 495 nm and N_a = 13, the inset illustrates a magnified view of the cavity region. The photonic heterostructure of the mini-BIC lasers can be clearly seen in the optical microscopy image (the lower panel). b The emission spectrum of a mini-BIC laser with a = 495 nm and N_a = 13 under the pumping power of 257.7 μW. The mode M₁₁, M₁₂/M₂₁, M₂₂ and M₁₃/M₃₁ can be observed at 1303, 1316, 1326 and 1333 nm, respectively. c Spectral evolution of lasing mode M₁₁ under various pumping power. d The collected emission intensity and the linewidth of the lasing M₁₁ peak at 1303 nm as a function of pumping power, indicating a lasing threshold of 52 μW (227 W cm⁻²). The inset is a Lorentzian curve fitting of the spectra just below the threshold, which indicates a linewidth of ~0.56 nm and therefore a cavity Q factor of 2327. e The lasing wavelengths of each mode under various input pumping powers (diamonds) and their linear fit (dashed lines). The error bars in (c) and (d) correspond to standard errors deduced by fitting