Nanowire waveguides launching single photons in a Gaussian mode for ideal fiber coupling.

Bulgarini, Gabriele; Reimer, Michael E; Bouwes Bavinck, Maaike; Jöns, Klaus D; Dalacu, Dan; Poole, Philip J; Bakkers, Erik P A M; Zwiller, Val · Nano Lett · 2014

basic_science · Level V

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Abstract

Quantum communication as well as integrated photonic circuits require single photons propagating in a well-defined Gaussian mode. However, tailoring the emission mode to a Gaussian remains an unsolved challenge for solid-state quantum emitters due to their random positioning in the host material or photonic structure. Here, we overcome these limitations by embedding a semiconductor quantum dot in a tapered nanowire waveguide. Owing to the deterministic positioning of the emitter in the waveguide, we demonstrate a Gaussian emission profile in the far field. Hence, we further couple the emission into a single-mode optical fiber with a record efficiency of 93%, thereby addressing a major hurdle for practical implementation of single photon sources in emerging photonic technologies.