Quantum dot-based broadband optical antenna for efficient extraction of single photons in the telecom O-band
Jingzhong Yang, Cornelius Nawrath, Robert Keil, Raphael Joos, Xi Zhang, Bianca Höfer, Yan Chen, Michael Zopf, Michael Jetter, Simone Luca Portalupi, Fei Ding, Peter Michler, Oliver G. Schmidt · Optics Express · 2020
Long-distance fiber-based quantum communication relies on efficient non-classical light sources operating at telecommunication wavelengths. Semiconductor quantum dots are promising candidates for on-demand generation of single photons and entangled photon pairs for such applications. However, their brightness is strongly limited due to total internal reflection at the semiconductor/vacuum interface. Here we overcome this limitation using a dielectric antenna structure. The non-classical light source consists of a gallium phosphide solid immersion lens in combination with a quantum dot nanomembrane emitting single photons in the telecom O-band. With this device, the photon extraction is strongly increased in a broad spectral range. A brightness of 17 % (numerical aperture of 0.6) is obtained experimentally, with a single photon purity of g ( 2 ) ( 0 ) = 0.049 ± 0.02 at saturation power. This brings the practical implementation of quantum communication networks one step closer.