Fig. 1. (a) Schematic epitaxial structure of the active region with total thickness of ∼ 362 nm. (b) A high-resolution TEM image of a single InAs QD. (c) An AFM image of uncapped InAs/GaAs QDs. (d) Collected PL spectra of the as-grown structure under various input optical powers at room temperature. Inset: temperature dependent integrated PL intensity.

Fig. 2. (a) Schematic diagram of the fabricated InAs/GaAs QD bandedge laser directly grown on an on-axis Si (001) substrate. The lattice constant and radius of air holes are a and r, respectively. (b) An SEM image of fabricated photonic crystal bandedge cavity.

Fig. 3. (a) Dispersion relation diagram of TE-like states for the photonic crystal bandedge cavity with the parameters of r/a = 0.35 and the slab thickness of 1.05a. The inset shows the irreducible Brillouin zone. The shaded blue region indicates the light cone, and the purple area represents the gain region of as-grown QDs. High symmetry points with low group velocity within the gain region are marked as X2, M1, and M2. (b) The corresponding calculated hertz (Hz) field profiles.

Fig. 4. (a) Emission spectrum of the fabricated photonic crystal bandedge laser, the pump power is 49.2 µW. Lasing modes of M1, X2, and M2 can be determined by the spectral positions. (b)–(d) The L-L curve and FWHM as a function of input power for three lasing modes M1, X2, and M2, respectively.