Spectrally-tunable quantum-light sources are key elements for the realization of long-distance quantum communication. A deterministically fabricated single-photon source with a photon-extraction efficiency of {\eta}=(20 +- 2) % and a tuning range of {\Delta}E=2.5 meV is presented here. The device consists of a single pre-selected quantum dot monolithically integrated into a microlens which is bonded onto a piezoelectric actuator via thermocompression goldbonding. The thin gold layer simultaneously acts as a backside mirror for the quantum dot emission, which is efficiently extracted from the device by an optimized lens structure patterned via 3D in-situ electron-beam lithography. The single-photon nature of the emission is proven by photon-autocorrelation measurements with g(2) ({\tau}=0)=0.04 +- 0.02. The combination of deterministic fabrication, spectral-tunability and high broadband photon-extraction efficiency makes the microlens single-photon source an interesting building block towards the realization of quantum repeaters networks.
@article{arxiv.1805.10623,
title = {A deterministically fabricated spectrally-tunable quantum dot based single-photon source},
author = {S. Fischbach and M. v. Helversen and M. Schmidt and A. Kaganskiy and R. Schmidt and A. Schliwa and T. Heindel and S. Rodt and S. Reitzenstein},
journal= {arXiv preprint arXiv:1805.10623},
year = {2018}
}