Lasing characteristics of 12-fold symmetric quasi-periodic photonic crystal slab nanolasers

We fabricated a 12-fold symmetric quasiperiodic photonic crystal (QPC) into a GaInAsP slab, and obtained a lasing action in a single-defect nanocavity and a defect-free area at room temperature. Four defect modes observed by a lithographic tuning were clearly explained by finite-difference time-domain calculation. The lowest threshold was obtained for the quadrupole mode, which has a small modal volume of 0.58 times the cubic wavelength in the cavity, by the fine-tuning of adjacent airholes to the defect. The lasing in the defect-free area was also suggested to be due to the localization of two-dimensional Bragg modes at the photonic gap edge. Because of its high structural flexibility, the QPC nanocavity has the potential of becoming a good alternative to the PC nanocavity.