Nondegenerate monopole-mode two-dimensional photonic band gap laser

We propose and demonstrate photonic band gap lasing action from a nondegenerate monopole-mode, high-quality factor cavity. By optical pumping at room temperature, the monopole-mode laser is realized and identified from its mode shape, spectrum, and polarization. The monopole-mode laser shows nondegeneracy and genuine two-dimensional oscillation with incident threshold pump power less than 0.3 mW. This laser mode has a small modal volume of ${\text{∼4.5(λ/2n}}_{\mathrm{slab}}{)}^3$ and shows a quality factor of larger than 1900, estimated from the spectral linewidth below threshold.