title: Micro-concave waveguide antenna for high photon extraction from nitrogen vacancy centers in nanodiamond.
abstract: The negatively charged nitrogen-vacancy colour center (NV(-) center) in nanodiamond is an excellent single photon source due to its stable photon generation in ambient conditions, optically addressable nuclear spin state, high quantum yield and its availability in nanometer sized crystals. In order to make practical devices using nanodiamond, highly efficient and directional emission of single photons in well-defined modes, either collimated into free space or waveguides are essential. This is a Herculean task as the photoluminescence of the NV centers is associated with two orthogonal dipoles arranged in a plane perpendicular to the NV defect symmetry axis. Here, we report on a micro-concave waveguide antenna design, which can effectively direct single photons from any emitter into either free space or into waveguides in a narrow cone angle with more than 80% collection efficiency irrespective of the dipole orientation. The device also enhances the spontaneous emission rate which further increases the number of photons available for collection. The waveguide antenna has potential applications in quantum cryptography, quantum computation, spectroscopy and metrology.
authors.affiliation: Department of Electrical and Electronic Engineering, The University of Melbourne, Melbourne, Victoria 3010 Australia.
authors.forename: Ranjith
authors.initials: R
authors.lastname: Rajasekharan
authors.affiliation: Nano-Optics, Institute of Physics, Humboldt-Universität zu Berlin, Newtonstraße 15, D-12489 Berlin, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Kewes
authors.affiliation: School of Physics, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Amir
authors.initials: A
authors.lastname: Djalalian-Assl
authors.affiliation: School of Physics, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Kumaravelu
authors.initials: K
authors.lastname: Ganesan
authors.affiliation: School of Physics, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Snjezana
authors.initials: S
authors.lastname: Tomljenovic-Hanic
authors.affiliation: School of Physics, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: McCallum
authors.affiliation: School of Physics, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Ann
authors.initials: A
authors.lastname: Roberts
authors.affiliation: Nano-Optics, Institute of Physics, Humboldt-Universität zu Berlin, Newtonstraße 15, D-12489 Berlin, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Benson
authors.affiliation: School of Physics, The University of Melbourne, Victoria 3010, Australia.
authors.forename: Steven
authors.initials: S
authors.lastname: Prawer