@article{KimZhangWangetal.2016, author = {Kim, Seonghoon and Zhang, Bo and Wang, Zhaorong and Fischer, Julian and Brodbeck, Sebastian and Kamp, Martin and Schneider, Christian and H{\"o}fling, Sven and Deng, Hui}, title = {Coherent Polariton Laser}, series = {Physical Review X}, volume = {6}, journal = {Physical Review X}, number = {011026}, doi = {10.1103/PhysRevX.6.011026}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166597}, year = {2016}, abstract = {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.}, language = {en} } @article{JahnkeGiesAssmannetal.2016, author = {Jahnke, Frank and Gies, Christopher and Aßmann, Marc and Bayer, Manfred and Leymann, H.A.M. and Foerster, Alexander and Wiersig, Jan and Schneider, Christian and Kamp, Martin and H{\"o}fling, Sven}, title = {Giant photon bunching, superradiant pulse emission and excitation trapping in quantum-dot nanolasers}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, number = {11540}, doi = {10.1038/ncomms11540}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166144}, year = {2016}, abstract = {Light is often characterized only by its classical properties, like intensity or coherence. When looking at its quantum properties, described by photon correlations, new information about the state of the matter generating the radiation can be revealed. In particular the difference between independent and entangled emitters, which is at the heart of quantum mechanics, can be made visible in the photon statistics of the emitted light. The well-studied phenomenon of superradiance occurs when quantum-mechanical correlations between the emitters are present. Notwithstanding, superradiance was previously demonstrated only in terms of classical light properties. Here, we provide the missing link between quantum correlations of the active material and photon correlations in the emitted radiation. We use the superradiance of quantum dots in a cavity-quantum electrodynamics laser to show a direct connection between superradiant pulse emission and distinctive changes in the photon correlation function. This directly demonstrates the importance of quantum-mechanical correlations and their transfer between carriers and photons in novel optoelectronic devices.}, language = {en} } @article{HorikiriYamaguchiKamideetal.2016, author = {Horikiri, Tomoyuki and Yamaguchi, Makoto and Kamide, Kenji and Matsuo, Yasuhiro and Byrnes, Tim and Ishida, Natsuko and L{\"o}ffler, Andreas and H{\"o}fling, Sven and Shikano, Yutaka and Ogawa, Tetsuo and Forchel, Alfred and Yamamoto, Yoshihisa}, title = {High-energy side-peak emission of exciton-polariton condensates in high density regime}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, number = {25655}, doi = {10.1038/srep25655}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167711}, year = {2016}, abstract = {In a standard semiconductor laser, electrons and holes recombine via stimulated emission to emit coherent light, in a process that is far from thermal equilibrium. Exciton-polariton condensates-sharing the same basic device structure as a semiconductor laser, consisting of quantum wells coupled to a microcavity-have been investigated primarily at densities far below the Mott density for signatures of Bose-Einstein condensation. At high densities approaching the Mott density, exciton-polariton condensates are generally thought to revert to a standard semiconductor laser, with the loss of strong coupling. Here, we report the observation of a photoluminescence sideband at high densities that cannot be accounted for by conventional semiconductor lasing. This also differs from an upper-polariton peak by the observation of the excitation power dependence in the peak-energy separation. Our interpretation as a persistent coherent electron-hole-photon coupling captures several features of this sideband, although a complete understanding of the experimental data is lacking. A full understanding of the observations should lead to a development in non-equilibrium many-body physics.}, language = {en} } @article{HolzingerSchneiderHoeflingetal.2019, author = {Holzinger, Steffen and Schneider, Christian and H{\"o}fling, Sven and Porte, Xavier and Reitzenstein, Stephan}, title = {Quantum-dot micropillar lasers subject to coherent time-delayed optical feedback from a short external cavity}, series = {Scientific Reports}, volume = {9}, journal = {Scientific Reports}, doi = {10.1038/s41598-018-36599-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-322485}, year = {2019}, abstract = {We investigate the mode-switching dynamics of an electrically driven bimodal quantum-dot micropillar laser when subject to delayed coherent optical feedback from a short external cavity. We experimentally characterize how the external cavity length, being on the same order than the microlaser's coherence length, influences the spectral and dynamical properties of the micropillar laser. Moreover, we determine the relaxation oscillation frequency of the micropillar by superimposing optical pulse injection to a dc current. It is found that the optical pulse can be used to disturb the feedback-coupled laser within one roundtrip time in such a way that it reaches the same output power as if no feedback was present. Our results do not only expand the understanding of microlasers when subject to optical feedback from short external cavities, but pave the way towards tailoring the properties of this key nanophotonic system for studies in the quantum regime of self-feedback and its implementation to integrated photonic circuits.}, language = {en} } @article{HeilSchreiberGoetzetal.2018, author = {Heil, Hannah S. and Schreiber, Benjamin and G{\"o}tz, Ralph and Emmerling, Monika and Dabauvalle, Marie-Christine and Krohne, Georg and H{\"o}fling, Sven and Kamp, Martin and Sauer, Markus and Heinze, Katrin G.}, title = {Sharpening emitter localization in front of a tuned mirror}, series = {Light: Science \& Applications}, volume = {7}, journal = {Light: Science \& Applications}, doi = {10.1038/s41377-018-0104-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-228080}, year = {2018}, abstract = {Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio1. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror2,3,4. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells.}, language = {en} } @article{HeIffLundtetal.2016, author = {He, Yu-Ming and Iff, Oliver and Lundt, Nils and Baumann, Vasilij and Davanco, Marcelo and Srinivasan, Kartik and H{\"o}fling, Sven and Schneider, Christian}, title = {Cascaded emission of single photons from the biexciton in monolayered WSe\(_{2}\)}, series = {Nature Communications}, volume = {7}, journal = {Nature Communications}, doi = {10.1038/ncomms13409}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169363}, year = {2016}, abstract = {Monolayers of transition metal dichalcogenide materials emerged as a new material class to study excitonic effects in solid state, as they benefit from enormous Coulomb correlations between electrons and holes. Especially in WSe\(_{2}\), sharp emission features have been observed at cryogenic temperatures, which act as single photon sources. Tight exciton localization has been assumed to induce an anharmonic excitation spectrum; however, the evidence of the hypothesis, namely the demonstration of a localized biexciton, is elusive. Here we unambiguously demonstrate the existence of a localized biexciton in a monolayer of WSe\(_{2}\), which triggers an emission cascade of single photons. The biexciton is identified by its time-resolved photoluminescence, superlinearity and distinct polarization in micro-photoluminescence experiments. We evidence the cascaded nature of the emission process in a cross-correlation experiment, which yields a strong bunching behaviour. Our work paves the way to a new generation of quantum optics experiments with two-dimensional semiconductors.}, language = {en} } @article{DyksikMotykaSęketal.2015, author = {Dyksik, Mateusz and Motyka, Marcin and Sęk, Grzegorz and Misiewicz, Jan and Dallner, Matthias and Weih, Robert and Kamp, Martin and H{\"o}fling, Sven}, title = {Submonolayer Uniformity of Type II InAs/GaInSb W-shaped Quantum Wells Probed by Full-Wafer Photoluminescence Mapping in the Mid-infrared Spectral Range}, series = {Nanoscale Research Letters}, volume = {10}, journal = {Nanoscale Research Letters}, number = {402}, doi = {10.1186/s11671-015-1104-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139733}, year = {2015}, abstract = {The spatial uniformity of GaSb- and InAs substrate-based structures containing type II quantum wells was probed by means of large-scale photoluminescence (PL) mapping realized utilizing a Fourier transform infrared spectrometer. The active region was designed and grown in a form of a W-shaped structure with InAs and GaInSb layers for confinement of electrons and holes, respectively. The PL spectra were recorded over the entire 2-in. wafers, and the parameters extracted from each spectrum, such as PL peak energy position, its linewidth and integrated intensity, were collected in a form of two-dimensional spatial maps. Throughout the analysis of these maps, the wafers' homogeneity and precision of the growth procedure were investigated. A very small variation of PL peak energy over the wafer indicates InAs quantum well width fluctuation of only a fraction of a monolayer and hence extraordinary thickness accuracy, a conclusion further supported by high uniformity of both the emission intensity and PL linewidth.}, language = {en} } @article{DietrichSteudeTropfetal.2016, author = {Dietrich, Christof P. and Steude, Anja and Tropf, Laura and Schubert, Marcel and Kronenberg, Nils M. and Ostermann, Kai and H{\"o}fling, Sven and Gather, Malte C.}, title = {An exciton-polariton laser based on biologically produced fluorescent protein}, series = {Science Advances}, volume = {2}, journal = {Science Advances}, number = {8}, doi = {10.1126/sciadv.1600666}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171305}, pages = {e1600666}, year = {2016}, abstract = {Under adequate conditions, cavity polaritons form a macroscopic coherent quantum state, known as polariton condensate. Compared to Wannier-Mott excitons in inorganic semiconductors, the localized Frenkel excitons in organic emitter materials show weaker interaction with each other but stronger coupling to light, which recently enabled the first realization of a polariton condensate at room temperature. However, this required ultrafast optical pumping, which limits the applications of organic polariton condensates. We demonstrate room temperature polariton condensates of cavity polaritons in simple laminated microcavities filled with biologically produced enhanced green fluorescent protein (eGFP). The unique molecular structure of eGFP prevents exciton annihilation even at high excitation densities, thus facilitating polariton condensation under conventional nanosecond pumping. Condensation is clearly evidenced by a distinct threshold, an interaction-induced blueshift of the condensate, long-range coherence, and the presence of a second threshold at higher excitation density that is associated with the onset of photon lasing.}, language = {en} } @article{AmthorWeissenseelFischeretal.2014, author = {Amthor, Matthias and Weißenseel, Sebastian and Fischer, Julian and Kamp, Martin and Schneider, Christian and H{\"o}fling, Sven}, title = {Electro-optical switching between polariton and cavity lasing in an InGaAs quantum well microcavity}, doi = {10.1364/OE.22.031146}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111130}, year = {2014}, abstract = {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.}, language = {en} }