The photonic trumpet: An efficient, broadband interface between a solid-state quantum emitter and a Gaussian beam

We introduce the photonic trumpet, a dielectric structure which ensures a nearly perfect coupling between an embedded quantum light source and a Gaussian free-space beam. A photonic trumpet exploits both the broadband spontaneous emission control provided by a single-mode photonic wire and the adiabatic expansion of this mode within a conical taper. Numerical simulations highlight the outstanding performance and robustness of this concept. As a first application in the field of quantum optics, we report the realisation of an ultra-bright single-photon source. The device, a GaAs photonic trumpet containing few InAs quantum dots, demonstrates a first-lens external efficiency of $0.75 \pm 0.1$.