Topological lasing from embedded III-V 1D photonic crystal lattices in the telecom O-band

We demonstrate an embedded one-dimensional (1D) topological photonic structure based on a III-V photonic crystal (PhC) lattice on silicon. Localized emission is detected from the topological state which forms at the interface between two lattices with different topological invariants, whereby this single mode is centered in the photonic bandgap. The 1D beam structure significantly reduces the area compared to a 2D structure, which together with our embedded fabrication platform is an important metric for future dense integration. The emission from this topological mode shows evidence of lasing in the telecom O-band with the threshold of around ~14 μW at room temperature. Compared to a similar trivial PhC structure, the topological design is inherently single mode. We evaluate the robustness of the topological resonant mode by introducing a defect right at the interface, which does not affect the existence of the topological state.