TY - JOUR A1 - El-Helou, Sabine M. A1 - Biegner, Anika-Kerstin A1 - Bode, Sebastian A1 - Ehl, Stephan R. A1 - Heeg, Maximilian A1 - Maccari, Maria E. A1 - Ritterbusch, Henrike A1 - Speckmann, Carsten A1 - Rusch, Stephan A1 - Scheible, Raphael A1 - Warnatz, Klaus A1 - Atschekzei, Faranaz A1 - Beider, Renata A1 - Ernst, Diana A1 - Gerschmann, Stev A1 - Jablonka, Alexandra A1 - Mielke, Gudrun A1 - Schmidt, Reinhold E. A1 - Schürmann, Gesine A1 - Sogkas, Georgios A1 - Baumann, Ulrich H. A1 - Klemann, Christian A1 - Viemann, Dorothee A1 - Bernuth, Horst von A1 - Krüger, Renate A1 - Hanitsch, Leif G. A1 - Scheibenbogen, Carmen M. A1 - Wittke, Kirsten A1 - Albert, Michael H. A1 - Eichinger, Anna A1 - Hauck, Fabian A1 - Klein, Christoph A1 - Rack-Hoch, Anita A1 - Sollinger, Franz M. A1 - Avila, Anne A1 - Borte, Michael A1 - Borte, Stephan A1 - Fasshauer, Maria A1 - Hauenherm, Anja A1 - Kellner, Nils A1 - Müller, Anna H. A1 - Ülzen, Anett A1 - Bader, Peter A1 - Bakhtiar, Shahrzad A1 - Lee, Jae-Yun A1 - Heß, Ursula A1 - Schubert, Ralf A1 - Wölke, Sandra A1 - Zielen, Stefan A1 - Ghosh, Sujal A1 - Laws, Hans-Juergen A1 - Neubert, Jennifer A1 - Oommen, Prasad T. A1 - Hönig, Manfred A1 - Schulz, Ansgar A1 - Steinmann, Sandra A1 - Klaus, Schwarz A1 - Dückers, Gregor A1 - Lamers, Beate A1 - Langemeyer, Vanessa A1 - Niehues, Tim A1 - Shai, Sonu A1 - Graf, Dagmar A1 - Müglich, Carmen A1 - Schmalzing, Marc T. A1 - Schwaneck, Eva C. A1 - Tony, Hans-Peter A1 - Dirks, Johannes A1 - Haase, Gabriele A1 - Liese, Johannes G. A1 - Morbach, Henner A1 - Foell, Dirk A1 - Hellige, Antje A1 - Wittkowski, Helmut A1 - Masjosthusmann, Katja A1 - Mohr, Michael A1 - Geberzahn, Linda A1 - Hedrich, Christian M. A1 - Müller, Christiane A1 - Rösen-Wolff, Angela A1 - Roesler, Joachim A1 - Zimmermann, Antje A1 - Behrends, Uta A1 - Rieber, Nikolaus A1 - Schauer, Uwe A1 - Handgretinger, Rupert A1 - Holzer, Ursula A1 - Henes, Jörg A1 - Kanz, Lothar A1 - Boesecke, Christoph A1 - Rockstroh, Jürgen K. A1 - Schwarze-Zander, Carolynne A1 - Wasmuth, Jan-Christian A1 - Dilloo, Dagmar A1 - Hülsmann, Brigitte A1 - Schönberger, Stefan A1 - Schreiber, Stefan A1 - Zeuner, Rainald A1 - Ankermann, Tobias A1 - Bismarck, Philipp von A1 - Huppertz, Hans-Iko A1 - Kaiser-Labusch, Petra A1 - Greil, Johann A1 - Jakoby, Donate A1 - Kulozik, Andreas E. A1 - Metzler, Markus A1 - Naumann-Bartsch, Nora A1 - Sobik, Bettina A1 - Graf, Norbert A1 - Heine, Sabine A1 - Kobbe, Robin A1 - Lehmberg, Kai A1 - Müller, Ingo A1 - Herrmann, Friedrich A1 - Horneff, Gerd A1 - Klein, Ariane A1 - Peitz, Joachim A1 - Schmidt, Nadine A1 - Bielack, Stefan A1 - Groß-Wieltsch, Ute A1 - Classen, Carl F. A1 - Klasen, Jessica A1 - Deutz, Peter A1 - Kamitz, Dirk A1 - Lassy, Lisa A1 - Tenbrock, Klaus A1 - Wagner, Norbert A1 - Bernbeck, Benedikt A1 - Brummel, Bastian A1 - Lara-Villacanas, Eusebia A1 - Münstermann, Esther A1 - Schneider, Dominik T. A1 - Tietsch, Nadine A1 - Westkemper, Marco A1 - Weiß, Michael A1 - Kramm, Christof A1 - Kühnle, Ingrid A1 - Kullmann, Silke A1 - Girschick, Hermann A1 - Specker, Christof A1 - Vinnemeier-Laubenthal, Elisabeth A1 - Haenicke, Henriette A1 - Schulz, Claudia A1 - Schweigerer, Lothar A1 - Müller, Thomas G. A1 - Stiefel, Martina A1 - Belohradsky, Bernd H. A1 - Soetedjo, Veronika A1 - Kindle, Gerhard A1 - Grimbacher, Bodo T1 - The German national registry of primary immunodeficiencies (2012-2017) JF - Frontiers in Immunology N2 - Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE-syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%-subcutaneous; 29%-intravenous; 1%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment. KW - registry for primary immunodeficiency KW - primary immunodeficiency (PID) KW - German PID-NET registry KW - PID prevalence KW - European Society for Immunodeficiencies (ESID) KW - IgG substitution therapy KW - CVID Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226629 VL - 10 ER - TY - JOUR A1 - Schneider, Sonja Jasmin Maria A1 - Höhne, Christian A1 - Schneider, Martin A1 - Schmitter, Marc T1 - Photoacoustic tomography versus cone-beam computed tomography versus micro-computed tomography: Accuracy of 3D reconstructions of human teeth JF - PloS One N2 - Objectives In this in-vitro study, teeth were imaged using photoacoustic tomography (PAT), cone-beam computed tomography (CBCT), and micro-computed tomography (μ-CT). The study had aim: to identify the best wavelength for PAT images to determine the accuracy of the three imaging methods, and to determine whether PAT images of teeth can achieve acceptable reconstruction quality. Methods Nineteen human mandibular single-rooted incisors were extracted from patients with trauma or periodontitis. To determine the best wavelength for acquiring photoacoustic images, all 19 teeth were scanned in vitro with PAT, using different laser wavelengths between 680 and 960 nm. The images were analyzed using image analysis software. To assess the accuracy of PAT and compare it with the accuracy of CBCT, each tooth was also scanned in vitro using CBCT and the reference standard technique of μ-CT. Subsequently, three different three-dimensional models, one for each imaging technique, were created for each tooth. Finally, the three different three-dimensional models acquired for the same tooth were matched and analyzed regarding volume and surface. Results The highest quality tooth images were achieved using the 680 nm wavelength, which showed the best contrast ratio. The full geometry of the dental root (μ-CT compared with PAT) could be visualized with relative standard deviations of 0.12 mm for the surface and −7.33 mm3 for the volume (n = 19). The full geometry of the dental root (μ-CT compared with CBCT) could be visualized with relative standard deviations of 0.06 mm for the surface and −14.56 mm3 for the volume (n = 19). The difference between the PAT–μ-CT group and CBCT–μ-CT group regarding the total average of the root surface area was not significant (p>0.06). Conclusion Images, which were acquired using PAT at 680nm showed the best contrast ration, enabling the identification of dentin, cementum and the dental pulp. No significant differences were found between the PAT–μ-CT group and CBCT–μ-CT group regarding the total average of the RSA and the total volume. Thus, three-dimensional reconstructions based on in-vitro PAT are already of acceptable reconstruction quality. KW - teeth KW - imaging techniques KW - computer software KW - incisors KW - in vivo imaging KW - caries KW - magnetic resonance imaging KW - tomography Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301437 VL - 17 IS - 12 ER - TY - JOUR A1 - Aeschlimann, Martin A1 - Bauer, Michael A1 - Bayer, Daniela A1 - Brixner, Tobias A1 - Cunovic, Stefan A1 - Fischer, Alexander A1 - Melchior, Pascal A1 - Pfeiffer, Walter A1 - Rohmer, Martin A1 - Schneider, Christian A1 - Strüber, Christian A1 - Tuchscherer, Philip A1 - Voronine, Dimitri V. T1 - Optimal open-loop near-field control of plasmonic nanostructures N2 - Optimal open-loop control, i.e. the application of an analytically derived control rule, is demonstrated for nanooptical excitations using polarization-shaped laser pulses. Optimal spatial near-field localization in gold nanoprisms and excitation switching is realized by applying a shift to the relative phase of the two polarization components. The achieved near-field switching confirms theoretical predictions, proves the applicability of predefined control rules in nanooptical light–matter interaction and reveals local mode interference to be an important control mechanism. KW - Chemie Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75256 ER - TY - JOUR A1 - Kochereshko, Vladimir P. A1 - Durnev, Mikhail V. A1 - Besombes, Lucien A1 - Mariette, Henri A1 - Sapega, Victor F. A1 - Askitopoulos, Alexis A1 - Savenko, Ivan G. A1 - Liew, Timothy C. H. A1 - Shelykh, Ivan A. A1 - Platonov, Alexey V. A1 - Tsintzos, Simeon I. A1 - Hatzopoulos, Z. A1 - Savvidis, Pavlos G. A1 - Kalevich, Vladimir K. A1 - Afanasiev, Mikhail M. A1 - Lukoshkin, Vladimir A. A1 - Schneider, Christian A1 - Amthor, Matthias A1 - Metzger, Christian A1 - Kamp, Martin A1 - Hoefling, Sven A1 - Lagoudakis, Pavlos A1 - Kavokin, Alexey T1 - Lasing in Bose-Fermi mixtures JF - Scientific Reports N2 - Light amplification by stimulated emission of radiation, well-known for revolutionising photonic science, has been realised primarily in fermionic systems including widely applied diode lasers. The prerequisite for fermionic lasing is the inversion of electronic population, which governs the lasing threshold. More recently, bosonic lasers have also been developed based on Bose-Einstein condensates of exciton-polaritons in semiconductor microcavities. These electrically neutral bosons coexist with charged electrons and holes. In the presence of magnetic fields, the charged particles are bound to their cyclotron orbits, while the neutral exciton-polaritons move freely. We demonstrate how magnetic fields affect dramatically the phase diagram of mixed Bose-Fermi systems, switching between fermionic lasing, incoherent emission and bosonic lasing regimes in planar and pillar microcavities with optical and electrical pumping. We collected and analyzed the data taken on pillar and planar microcavity structures at continuous wave and pulsed optical excitation as well as injecting electrons and holes electronically. Our results evidence the transition from a Bose gas to a Fermi liquid mediated by magnetic fields and light-matter coupling. KW - Bose-Fermi KW - magnetic fields KW - Bose gas KW - Fermi liquid KW - light-matter coupling Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-168152 VL - 6 IS - 20091 ER - TY - JOUR A1 - Kim, Seonghoon A1 - Zhang, Bo A1 - Wang, Zhaorong A1 - Fischer, Julian A1 - Brodbeck, Sebastian A1 - Kamp, Martin A1 - Schneider, Christian A1 - Höfling, Sven A1 - Deng, Hui T1 - Coherent Polariton Laser JF - Physical Review X N2 - The semiconductor polariton laser promises a new source of coherent light, which, compared to conventional semiconductor photon lasers, has input-energy threshold orders of magnitude lower. However, intensity stability, a defining feature of a coherent state, has remained poor. Intensity noise many times the shot noise of a coherent state has persisted, attributed to multiple mechanisms that are difficult to separate in conventional polariton systems. The large intensity noise, in turn, limits the phase coherence. Thus, the capability of the polariton laser as a source of coherence light is limited. Here, we demonstrate a polariton laser with shot-noise-limited intensity stability, as expected from a fully coherent state. This stability is achieved by using an optical cavity with high mode selectivity to enforce single-mode lasing, suppress condensate depletion, and establish gain saturation. Moreover, the absence of spurious intensity fluctuations enables the measurement of a transition from exponential to Gaussian decay of the phase coherence of the polariton laser. It suggests large self-interaction energies in the polariton condensate, exceeding the laser bandwidth. Such strong interactions are unique to matter-wave lasers and important for nonlinear polariton devices. The results will guide future development of polariton lasers and nonlinear polariton devices. KW - polariton laser KW - condensed matter physics KW - photonics KW - quantum physics KW - coherent light Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166597 VL - 6 IS - 011026 ER - TY - JOUR A1 - Redlich, Christoph A1 - Lingnau, Benjamin A1 - Holzinger, Steffen A1 - Schlottmann, Elisabeth A1 - Kreinberg, Sören A1 - Schneider, Christian A1 - Kamp, Martin A1 - Höfling, Sven A1 - Wolters, Janik A1 - Reitzenstein, Stephan A1 - Lüdge, Kathy T1 - Mode-switching induced super-thermal bunching in quantum-dot microlasers JF - New Journal of Physics N2 - The super-thermal photon bunching in quantum-dot (QD) micropillar lasers is investigated both experimentally and theoretically via simulations driven by dynamic considerations. Using stochastic multi-mode rate equations we obtain very good agreement between experiment and theory in terms of intensity profiles and intensity-correlation properties of the examined QD micro-laser's emission. Further investigations of the time-dependent emission show that super-thermal photon bunching occurs due to irregular mode-switching events in the bimodal lasers. Our bifurcation analysis reveals that these switchings find their origin in an underlying bistability, such that spontaneous emission noise is able to effectively perturb the two competing modes in a small parameter region. We thus ascribe the observed high photon correlation to dynamical multistabilities rather than quantum mechanical correlations. KW - microlaser KW - nonlinear dynamics KW - correlation properties KW - photon statistics KW - noise and multimode dynamics KW - quantum dot laser Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166286 VL - 18 IS - 063011 ER - TY - JOUR A1 - Nitsche, Wolfgang H. A1 - Kim, Na Young A1 - Roumpos, Georgios A1 - Schneider, Christian A1 - Höfling, Sven A1 - Forchel, Alfred A1 - Yamamoto, Yoshihisa T1 - Spatial correlation of two-dimensional bosonic multimode condensates JF - Physical Review A N2 - The Berezinskii-Kosterlitz-Thouless (BKT) theorem predicts that two-dimensional bosonic condensates exhibit quasi-long-range order which is characterized by a slow decay of the spatial coherence. However previous measurements on exciton-polariton condensates revealed that their spatial coherence can decay faster than allowed under the BKT theory, and different theoretical explanations have already been proposed. Through theoretical and experimental study of exciton-polariton condensates, we show that the fast decay of the coherence can be explained through the simultaneous presence of multiple modes in the condensate. KW - Exciton-polariton condensate KW - Long-range order KW - Microcavity KW - Vortices KW - Systems Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-188897 VL - 93 IS - 5 ER - TY - JOUR A1 - Lundt, Nils A1 - Klembt, Sebastian A1 - Cherotchenko, Evgeniia A1 - Betzold, Simon A1 - Iff, Oliver A1 - Nalitov, Anton V. A1 - Klaas, Martin A1 - Dietrich, Christof P. A1 - Kavokin, Alexey V. A1 - Höfling, Sven A1 - Schneider, Christian T1 - Room-temperature Tamm-plasmon exciton-polaritons with a WSe\(_{2}\) monolayer JF - Nature Communications N2 - Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light–matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe\(_{2}\), hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy–momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons. KW - optics and photonics KW - two-dimensional materials KW - electronic properties and materials Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169470 VL - 7 ER - TY - THES A1 - Schneider, Christian T1 - Konzepte zur skalierbaren Realisierung von effizienten, halbleiterbasierten Einzelphotonenquellen T1 - Concepts for the scalable realization of efficient semiconductor single photon sources N2 - Dem Einsatz niederdimensionaler Nanostrukturen als optisch aktives Medium wird enormes Potential vorausgesagt sowohl in den klassischen optoelektronischen Bauteilen (wie z.B. Halbleiterlasern) als auch in optischen Bauteilen der näachsten Generation (z.B. Einzelphotonenquellen oder Quellen verschränkter Photonenpaare). Dennoch konnten sich quantenpunktbasierte Halbleiterlaser, abgesehen von einigen wenigen Ausnahmen (QDLaser inc.), im industriellen Maßstab bisher nicht gegen Bauelemente mit höherdimensionalen Quantenfilmen als optisch aktivem Element durchsetzen. Deshalb scheint der Einsatz von Quantenpunkten (QPen) in nichtklassischen Lichtquellen gegenwärtig vielversprechender. Um jedoch solche Bauteile bis zur letztendlichen Marktreife zu bringen, müssen neben der starken Unterdrückung von Multiphotonenemission noch wesentliche Grundvoraussetzungen erfüllt werden: In dieser Arbeit wurden grundlegende Studien durchgeführt, welche insbesondere dem Fortschritt und den Problemen der Effizienz, des elektrischen Betriebs und der Skalierbaren Herstellung der Photonenqullen dienen sollte. Zum Einen wurden hierfür elektrisch betriebene Einzelphotonenquellen basierend auf gekoppelten QP-Mikroresonatoren realisiert und de ren Bauteileffizienz gezielt optimiert, wobei konventionelle selbstorganisierte InAs-QPe als aktives Medium eingesetzt wurden. Für die skalierbare Integration einzelner QPe in Mikroresonatoren wurde des Weiteren das gesteuerte QP-Wachstum auf vorstrukturierten Substraten optimiert und auf diese Art ortskontrollierte QPe in Bauteile integriert. Für die Realisierung hocheffizienter, elektrisch gepumpter inzelphotonenquellen wurde zunächst das Wachstum von binären InAs-QPen im Stranski-Krastanov-Modus optimiert und deren optische Eigenschaften im Detail untersucht. Durch das Einbringen einer Schicht von Siliziumatomen nahe der QP-Schicht konnten die Emitter negativ geladen werden und der helle Trionenzustand der QPe als energetischer Eigenzustand des Systems zur effizienten Extraktion einzelner Photonen ausgenutzt werden. Durch die Integration dieser geladenen QPe in elektrisch kontaktierte, auf Braggspiegel basierte Mikrotürmchen konnten Einzelphotonenquellen realisiert werden, in denen gezielt Licht-Materie- Wechselwirkungseffekte zur Steigerung der Bauteileffizienz ausgenutzt wurden. Basierend auf theoretischen Überlegungen wurde die Schichtstruktur soweit optimiert, dass letztendlich experimentell eine elektrisch gepumpte Einzelphotonenquelle mit einer Photonenemissionsrate von 47 MHz sowie einer zuvor unerreichten Bauteileffizienz von 34 % im Regime der schwachen Licht-Materie-Kopplung demonstriert werden konnte. Da Effekte der Licht-Materie-Wechselwirkung zwischen QP und Resonator neben der spektralen Resonanz ebenfalls von der relativen Position von Resonator und QP zueinander abhängen, ist eine Kombination von positionierten QPen und Bauteilausrichtung nahezu unumg¨anglich für die skalierbare, deterministische Herstellung von Systemen aus perfekt angeordnetem Emitter und Resonator. Deshalb wurden bestehende Konzepte zum geordneten Wachstum von QPen weiterentwickelt: Hierbei wurde geordnetes InAs-QP-Wachstum mit Perioden realisiert, die vergleichbare Abmessungen wie optische Resonatoren aufweisen, also Nukleationsperioden zwischen 500 nm und 4 μm. Durch ein genaues Anpassen der Wachstums- und Prozessbedingungen konnte des Weiteren die Bildung von QP-Molekülen auf den Nukleationsplätzen nahezu unterdrückt beziehungsweise gesteuert werden. Durch eine systematische Optimierung der optischen Eigenschaften der QPe konnten Emitter mit Einzelquantenpunktlinienbreiten um 100 μeV realisiert werden, was eine Grundvoraussetzung zur Studie ausgeprägter Licht-Materie-Wechselwirkungseffekte in Mikroresonatoren darstellt. Letztendlich konnten durch die Integration derartiger QPe in optisch sowie elektrisch betriebene Mikroresonatoren erstmals Bauteile realisiert werden, welche einige der prinzipiellen, an eine Einzelphotonenquelle gestellten Anforderungen erfüllen. Insbesondere konnten deutliche Signaturen der schwachen Licht-Materie-Kopplung einzelner positionierter QPe in photonische Kristallresonatoren, Mikroscheibenresonatoren sowie Mikrotürmchenresonatoren festgestellt werden. Darüberhinaus konnte an einem spektral resonanten System aus einem positionierten QP und der Grundmode eines Mikrotürmchenresonators eindeutig Einzelphotonenemission unter optischer Anregung demonstriert werden. Ebenfalls konnten Mikrotürmchenresonatoren mit integrierten positionierten QPen erstmals elektrisch betrieben werden und somit die Grundvoraussetzung für eine der skalierbaren Herstellung effizienter Einzelphotonenquellen geschaffen werden. N2 - Employing low dimensional nanostructures as active medium in classical optoelectronic devices (for instance semiconductor laser diodes) as well as optical devices of the next generation (such as single photon sources or sources of entangled photon pairs promises enormous potential. Yet, despite some exceptions (for example QDLasers inc.), quantum dot (QD)-based semiconductor lasers can hardly compete with devices exploiting higher dimensional gain material so far. Hence, using QDs as single photon emitters seems very promising. In order to achieve compatibility on the market, some urgent pre-requisites still need to be met in such devices besides the surpression of multiphoton emission: • Efficiency: Only a highly efficient single photon source can be reasonably employed in applications. • Electrical operation: In order to achieve a high integration density and for reasons of user friendlyness, the device needs to be driven electrically. • Scalability: The scalable fabrication of single photon sources is pre-requisite and one of the greatest technological challenges. • Temperature: Eventually, single photon sources will only be established in the wide field of secure data transmission if their operation at room temperature can be assured. In this work, basic studies were carried out especially devoted to the progress in the first three challenges. On the one hand, electrically driven single photon sources based on coupled QD-microcavities were realized and optimized by employing conventional self organized InAs QDs as active material. On the other hand, in order to facilitate a scalable integration of single QDs into microcavities, directed QD nucleation on pre-patterned substrate was optimized. These site-controlled QDs were at last integrated into resonator devices. In order to realize highly efficient, electrically driven single photon sources, at first the growth of binary Stranski-Krastanov InAs QDs was optimized and their emission properties were investigated in detail. By introducing Silicon atoms in the vicinity of the QD-layer, the emitters could be negatively charged. The resulting bright trion state of the QDs can subsequently be exploited as the energetic eigenstate of the system for the extraction of single photons. By integrating these charged QDs in contacted, Bragg-reflector based micropillars, single photon sources were realized exploiting light-matter coupling to enhance the device’s efficiency. Based on theoretical considerations, the grown layer sequence was optimized to an extent that eventually an electrically driven single photon source with an emission rate of 47 MHz and an unprecedented device efficiency of 34 % in the weak coupling regime could be demonstrated. Since the effects of light-matter coupling between QD and resonator rely on the QD’s position in the device, a combination of site-controlled QD-growth and device alignment is almost inevitable for a scalable, deterministic fabrication of perfectly aligned emittercavity systems. Therefore, existing concepts for ordered QD-growth were adapted and improved [KH07]: Ordered QD-growth on periods comparable to dimensions of optical resonators between 500 nm und 4 μm was realized. By carefully adjusting the growth and process conditions, formation of QD-molecules on nucleation sites could be controlled and supressed almost entirely. Carrying out a systematic optimization of the QD’s optical properties, emitters with single QD-linewidth around 100 μeV were realized. This is pre-requsite for the study of pronounced light-matter interaction in microcavities. Finally, the integration of such QDs in optically and electrically driven microresonators resulted in devices demonstrating some of the fundamental properties requested from a single photon source. Pronounced signatures of the weak light-matter coupling between a site-controlled QD in a photonic crystal cavity, a microdisk cavity and micropillar cavities were observed. Furthermore, single photon emission of a spectrally resonant system of sitecontrolled QD and micropillar cavity under pulsed optical excitation was unambigiously demonstrated. Beyond this, micropillar cavities with site-controlled QDs were electrically driven for the first time, which is pre-requisite for the scalable fabrication of efficient single photon sources. KW - Einzelphotonenemission KW - Quantenpunkt KW - Positionierung KW - Drei-Fünf-Halbleiter KW - Optischer Resonator KW - Mikrokavität KW - Single photon emission KW - quantum dot KW - site-controlled KW - semiconductor KW - microcavity Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-73506 ER - TY - JOUR A1 - Amthor, Matthias A1 - Weißenseel, Sebastian A1 - Fischer, Julian A1 - Kamp, Martin A1 - Schneider, Christian A1 - Höfling, Sven T1 - Electro-optical switching between polariton and cavity lasing in an InGaAs quantum well microcavity N2 - We report on the condensation of microcavity exciton polaritons under optical excitation in a microcavity with four embedded InGaAs quantum wells. The polariton laser is characterized by a distinct nonlinearity in the input-output-characteristics, which is accompanied by a drop of the emission linewidth indicating temporal coherence and a characteristic persisting emission blueshift with increased particle density. The temporal coherence of the device at threshold is underlined by a characteristic drop of the second order coherence function to a value close to 1. Furthermore an external electric field is used to switch between polariton regime, polariton condensate and photon lasing. KW - Quantum-well, -wire and -dot devices KW - Scattering KW - stimulated KW - Resonators KW - Microcavity devices Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-111130 ER -