@article{MaierGoldForcheletal.2014, author = {Maier, Sebastian and Gold, Peter and Forchel, Alfred and Gregersen, Niels and Mork, Jesper and H{\"o}fling, Sven and Schneider, Christian and Kamp, Martin}, title = {Bright single photon source based on self-aligned quantum dot-cavity systems}, series = {Optics Express}, volume = {22}, journal = {Optics Express}, number = {7}, issn = {1094-4087}, doi = {10.1364/OE.22.008136}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119801}, pages = {8136-42}, year = {2014}, abstract = {We report on a quasi-planar quantum-dot-based single-photon source that shows an unprecedented high extraction efficiency of 42\% without complex photonic resonator geometries or post-growth nanofabrication. This very high efficiency originates from the coupling of the photons emitted by a quantum dot to a Gaussian shaped nanohill defect that naturally arises during epitaxial growth in a self-aligned manner. We investigate the morphology of these defects and characterize the photonic operation mechanism. Our results show that these naturally arising coupled quantum dot-defects provide a new avenue for efficient (up to 42\% demonstrated) and pure (g(2)(0) value of 0.023) single-photon emission.}, language = {en} } @article{TempelVeitAssmannetal.2012, author = {Tempel, Jean-Sebastian and Veit, Tempel and Assmann, Marc and Kreilkamp, Lars Erik and H{\"o}fling, Sven and Kamp, Martin and Forchel, Alfred and Bayer, Manfred}, title = {Temperature dependence of pulsed polariton lasing in a GaAs microcavity}, series = {New Journal of Physics}, volume = {14}, journal = {New Journal of Physics}, number = {083014}, doi = {10.1088/1367-2630/14/8/083014}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134022}, year = {2012}, abstract = {The second-order correlation function g\(^2\)(\(\tau\) = 0), input-output curves and pulse duration of the emission from a microcavity exciton-polariton system subsequent to picosecond-pulsed excitation are measured for different temperatures. At low temperatures a two-threshold behaviour emerges, which has been attributed to the onset of polariton lasing and conventional lasing at the first and the second threshold, respectively. We observe that polariton lasing is stable up to temperatures comparable with the exciton binding energy. At higher temperatures a single threshold displays the direct transition from thermal emission to photon lasing.}, language = {en} } @article{RauHeindelUnsleberetal.2014, author = {Rau, Markus and Heindel, Tobias and Unsleber, Sebastian and Braun, Tristan and Fischer, Julian and Frick, Stefan and Nauerth, Sebastian and Schneider, Christian and Vest, Gwenaelle and Reitzenstein, Stephan and Kamp, Martin and Forchel, Alfred and H{\"o}fling, Sven and Weinfurter, Harald}, title = {Free space quantum key distribution over 500 meters using electrically driven quantum dot single-photon sources-a proof of principle experiment}, series = {New Journal of Physics}, volume = {16}, journal = {New Journal of Physics}, number = {043003}, doi = {10.1088/1367-2630/16/4/043003}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-116760}, year = {2014}, abstract = {Highly efficient single-photon sources (SPS) can increase the secure key rate of quantum key distribution (QKD) systems compared to conventional attenuated laser systems. Here we report on a free space QKD test using an electrically driven quantum dot single-photon source (QD SPS) that does not require a separate laser setup for optical pumping and thus allows for a simple and compact SPS QKD system. We describe its implementation in our 500 m free space QKD system in downtown Munich. Emulating a BB84 protocol operating at a repetition rate of 125 MHz, we could achieve sifted key rates of 5-17 kHz with error ratios of 6-9\% and g((2))(0)-values of 0.39-0.76.}, language = {en} } @article{LeeSongHanetal.2015, author = {Lee, Eun-Hye and Song, Jin-Dong and Han, Il-Ki and Chang, Soo-Kyung and Langer, Fabian and H{\"o}fling, Sven and Forchel, Alfred and Kamp, Martin and Kim, Jong-Su}, title = {Structural and optical properties of position-retrievable low-density GaAs droplet epitaxial quantum dots for application to single photon sources with plasmonic optical coupling}, series = {Nanoscale Research Letters}, volume = {10}, journal = {Nanoscale Research Letters}, number = {114}, doi = {10.1186/s11671-015-0826-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143692}, year = {2015}, abstract = {The position of a single GaAs quantum dot (QD), which is optically active, grown by low-density droplet epitaxy (DE) (approximately 4 QDs/μm\(^{2}\)), was directly observed on the surface of a 45-nm-thick Al\(_{0.3}\)Ga\(_{0.7}\)As capping layer. The thin thickness of AlGaAs capping layer is useful for single photon sources with plasmonic optical coupling. A micro-photoluminescence for GaAs DE QDs has shown exciton/biexciton behavior in the range of 1.654 to 1.657 eV. The direct observation of positions of low-density GaAs DE QDs would be advantageous for mass fabrication of devices that use a single QD, such as single photon sources.}, language = {en} }