  We propose a novel antenna structure which funnels single photons from a
single emitter with unprecedented efficiency into a low-divergence fundamental
Gaussian mode. Our device relies on the concept of creating an omnidirectional
photonic bandgap to inhibit unwanted large-angle emission and to enhance
small-angle defect-guided-mode emission. The new photon collection strategy is
intuitively illustrated, rigorously verified and optimized by implementing an
efficient body-of-revolution finite-difference time-domain method for in-plane
dipole emitters. We investigate a few antenna designs to cover various boundary
conditions posed by fabrication processes or material restrictions and
theoretically demonstrate that collection efficiencies into the fundamental
Gaussian mode exceeding 95% are achievable. Our antennas are broadband,
insensitive to fabrication imperfections and compatible with a variety of
solid-state emitters such as organic molecules, quantum dots and defect centers
in diamond. Unidirectional and low-divergence Gaussian-mode emission from a
single emitter may enable the realization of a variety of photonic quantum
computer architectures as well as highly efficient light-matter interfaces.
