@article{BeierleinEgorovHarderetal.2021,
  author    = {Beierlein, J. and Egorov, O. A. and Harder, T. H. and Gagel, P. and Emmerling, M. and Schneider, C. and H{\"o}fling, S. and Peschel, U. and Klembt, S.},
  title     = {Bloch Oscillations of Hybrid Light-Matter Particles in a Waveguide Array},
  series = {Advanced Optical Materials},
  volume    = {9},
  journal   = {Advanced Optical Materials},
  number    = {13},
  doi       = {10.1002/adom.202100126},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239814},
  year      = {2021},
  abstract  = {Bloch oscillations are a phenomenon well known from quantum mechanics where electrons in a lattice experience an oscillatory motion in the presence of an electric field gradient. Here, the authors report on Bloch oscillations of hybrid light-matter particles, called exciton-polaritons (polaritons), being confined in an array of coupled microcavity waveguides. To this end, the waveguide widths and their mutual couplings are carefully designed such that a constant energy gradient is induced perpendicular to the direction of motion of the propagating polaritons. This technique allows us to directly observe and study Bloch oscillations in real- and momentum-space. Furthermore, the experimental findings are supported by numerical simulations based on a modified Gross-Pitaevskii approach. This work provides an important transfer of basic concepts of quantum mechanics to integrated solid state devices, using quantum fluids of light.},
  language  = {en}
}
@article{BraunSchneiderMaieretal.2014,
  author    = {Braun, T. and Schneider, C. and Maier, S. and Igusa, R. and Iwamoto, S. and Forchel, A. and H{\"o}fling, S. and Arakawa, Y. and Kamp, M.},
  title     = {Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots},
  series = {AIP Advances},
  volume    = {4},
  journal   = {AIP Advances},
  number    = {9},
  issn      = {2158-3226},
  doi       = {10.1063/1.4896284},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-115448},
  year      = {2014},
  abstract  = {In this letter we study the influence of temperature and excitation power on the emission linewidth from site-controlled InGaAs/GaAs quantum dots grown on nanoholes defined by electron beam lithography and wet chemical etching. We identify thermal electron activation as well as direct exciton loss as the dominant intensity quenching channels. Additionally, we carefully analyze the effects of optical and acoustic phonons as well as close-by defects on the emission linewidth by means of temperature and power dependent micro-photoluminescence on single quantum dots with large pitches. (C) 2014 Author(s).},
  language  = {en}
}
@article{BrixnerAeschlimannFischeretal.2013,
  author    = {Brixner, T. and Aeschlimann, M. and Fischer, A. and Geisler, P. and Goetz, S. and Hecht, B. and Huang, J. S. and Keitzl, T. and Kramer, C. and Melchior, P. and Pfeiffer, W. and Razinskas, G. and Rewitz, C. and Schneider, C. and Str{\"u}ber, C. and Tuchscherer, P. and Voronine, D. V.},
  title     = {Coherent spectroscopies on ultrashort time and length scales},
  series = {EPJ Web of Conferences},
  volume    = {41},
  journal   = {EPJ Web of Conferences},
  doi       = {10.1051/epjconf/20134109017},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-129073},
  pages     = {09017},
  year      = {2013},
  abstract  = {Three spectroscopic techniques are presented that provide simultaneous spatial and temporal resolution: modified confocal microscopy with heterodyne detection, space-time-resolved spectroscopy using coherent control concepts, and coherent two-dimensional nano-spectroscopy. Latest experimental results are discussed.},
  language  = {en}
}
@article{CzerniukBrueggemannTepperetal.2014,
  author    = {Czerniuk, T. and Br{\"u}ggemann, C. and Tepper, J. and Brodbeck, S. and Schneider, C. and Kamp, M. and H{\"o}fling, S. and Glavin, B. A. and Yakovlev, D. R. and Akimov, A. V. and Bayer, M.},
  title     = {Lasing from active optomechanical resonators},
  series = {Nature Communications},
  volume    = {5},
  journal   = {Nature Communications},
  doi       = {10.1038/ncomms5038},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121559},
  pages     = {4038},
  year      = {2014},
  abstract  = {Planar microcavities with distributed Bragg reflectors (DBRs) host, besides confined optical modes, also mechanical resonances due to stop bands in the phonon dispersion relation of the DBRs. These resonances have frequencies in the 10- to 100-GHz range, depending on the resonator's optical wavelength, with quality factors exceeding 1,000. The interaction of photons and phonons in such optomechanical systems can be drastically enhanced, opening a new route towards the manipulation of light. Here we implemented active semiconducting layers into the microcavity to obtain a vertical-cavity surface-emitting laser (VCSEL). Thereby, three resonant excitations--photons, phonons and electrons--can interact strongly with each other providing modulation of the VCSEL laser emission: a picosecond strain pulse injected into the VCSEL excites long-living mechanical resonances therein. As a result, modulation of the lasing intensity at frequencies up to 40 GHz is observed. From these findings, prospective applications of active optomechanical resonators integrated into nanophotonic circuits may emerge.},
  language  = {en}
}
@article{EstrechoGaoBrodbecketal.2016,
  author    = {Estrecho, E. and Gao, T. and Brodbeck, S. and Kamp, M. and Schneider, C. and H{\"o}fling, S. and Truscott, A. G. and Ostrovskaya, E. A.},
  title     = {Visualising Berry phase and diabolical points in a quantum exciton-polariton billiard},
  series = {Scientific Reports},
  volume    = {6},
  journal   = {Scientific Reports},
  number    = {37653},
  doi       = {10.1038/srep37653},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167496},
  year      = {2016},
  abstract  = {Diabolical points (spectral degeneracies) can naturally occur in spectra of two-dimensional quantum systems and classical wave resonators due to simple symmetries. Geometric Berry phase is associated with these spectral degeneracies. Here, we demonstrate a diabolical point and the corresponding Berry phase in the spectrum of hybrid light-matter quasiparticles—exciton-polaritons in semiconductor microcavities. It is well known that sufficiently strong optical pumping can drive exciton-polaritons to quantum degeneracy, whereby they form a macroscopically populated quantum coherent state similar to a Bose-Einstein condensate. By pumping a microcavity with a spatially structured light beam, we create a two-dimensional quantum billiard for the exciton-polariton condensate and demonstrate a diabolical point in the spectrum of the billiard eigenstates. The fully reconfigurable geometry of the potential walls controlled by the optical pump enables a striking experimental visualization of the Berry phase associated with the diabolical point. The Berry phase is observed and measured by direct imaging of the macroscopic exciton-polariton probability densities.},
  language  = {en}
}
@article{HopfmannAlbertSchneideretal.2013,
  author    = {Hopfmann, C. and Albert, F. and Schneider, C. and H{\"o}fling, S. and Kamp, M. and Forchel, A. and Kanter, I. and Reizenstein, S.},
  title     = {Nonlinear emission characteristics of quantum dot-micropillar lasers in the presence of polarized optical feedback},
  series = {New Journal of Physics},
  volume    = {15},
  journal   = {New Journal of Physics},
  number    = {025030},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/15/2/025030},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123127},
  year      = {2013},
  abstract  = {We report on electrically pumped quantum dot-microlasers in the presence of polarized self-feedback. The high-\(\beta\) microlasers show two orthogonal, linearly polarized emission modes which are coupled via the common gain medium. This coupling is explained in terms of gain competition between the two lasing modes and leads to distinct differences in their input-output characteristics. By applying polarized self-feedback via an external mirror, we are able to control the laser characteristics of the emission modes in terms of the output power, the coherence time and the photon statistics. We find that linearly polarized self-feedback stabilizes the lasing of a given mode, while cross-polarized feedback between the two modes reduces strongly the intensity of the other emission mode showing particular high-intensity fluctuations and even super-thermal values of the photon autocorrelation function \(g^{(2)} (\tau)\) at zero delay. Measurements of \(g^{(2)} (\tau)\) under external feedback also allow us to detect revival peaks associated with the round trip time of the external cavity. Analyzing the damping and shape of the \(g^{(2)} (\tau)\) revival peaks by a phenomenological model provides us insight into the underlying physics such as the effective exciton lifetime and gain characteristics of the quantum dots in the active region of these microlasers.},
  language  = {en}
}
@article{KasprzakSivalertpornAlbertetal.2013,
  author    = {Kasprzak, J. and Sivalertporn, K. and Albert, F. and Schneider, C. and H{\"o}fling, S. and Kamp, M. and Forchel, A. and Muljarov, E. A. and Langbein, W.},
  title     = {Coherence dynamics and quantum-to-classical crossover in an exciton-cavity system in the quantum strong coupling regime},
  series = {New Journal of Physics},
  volume    = {15},
  journal   = {New Journal of Physics},
  number    = {045013},
  issn      = {1367-2630},
  doi       = {10.1088/1367-2630/15/4/045013},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123005},
  year      = {2013},
  abstract  = {Interaction between light and matter generates optical nonlinearities, which are particularly pronounced in the quantum strong coupling regime. When a single bosonic mode couples to a single fermionic mode, a Jaynes-Cummings (JC) ladder is formed, which we realize here using cavity photons and quantum dot excitons. We measure and model the coherent anharmonic response of this strongly coupled exciton-cavity system at resonance. Injecting two photons into the cavity, we demonstrate a \(\sqrt 2\) larger polariton splitting with respect to the vacuum Rabi splitting. This is achieved using coherent nonlinear spectroscopy, specifically four-wave mixing, where the coherence between the ground state and the first (second) rung of the JC ladder can be interrogated for positive (negative) delays. With increasing excitation intensity and thus rising average number of injected photons, we observe spectral signatures of the quantum-to-classical crossover of the strong coupling regime.},
  language  = {en}
}
@article{LaihoPresslSchlageretal.2016,
  author    = {Laiho, K. and Pressl, B. and Schlager, A. and Suchomel, H. and Kamp, M. and H{\"o}fling, S. and Schneider, C. and Weihs, G.},
  title     = {Uncovering dispersion properties in semiconductor waveguides to study photon-pair generation},
  series = {Nanotechnology},
  volume    = {27},
  journal   = {Nanotechnology},
  number    = {43},
  doi       = {10.1088/0957-4484/27/43/434003},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-187025},
  pages     = {434003},
  year      = {2016},
  abstract  = {We investigate the dispersion properties of ridge Bragg-reflection waveguides to deduce their phasematching characteristics. These are crucial for exploiting them as sources of parametric down-conversion (PDC). In order to estimate the phasematching bandwidth we first determine the group refractive indices of the interacting modes via Fabry-Perot experiments in two distant wavelength regions. Second, by measuring the spectra of the emitted PDC photons, we gain access to their group index dispersion. Our results offer a simple approach for determining the PDC process parameters in the spectral domain, and provide important feedback for designing such sources, especially in the broadband case.},
  language  = {en}
}
@article{SuchomelBrodbeckLiewetal.2017,
  author    = {Suchomel, H. and Brodbeck, S. and Liew, T. C. H. and Amthor, M. and Klaas, M. and Klembt, S. and Kamp, M. and H{\"o}fling, S. and Schneider, C.},
  title     = {Prototype of a bistable polariton field-effect transistor switch},
  series = {Scientific Reports},
  volume    = {7},
  journal   = {Scientific Reports},
  number    = {5114},
  doi       = {10.1038/s41598-017-05277-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158323},
  year      = {2017},
  abstract  = {Microcavity exciton polaritons are promising candidates to build a new generation of highly nonlinear and integrated optoelectronic devices. Such devices range from novel coherent light emitters to reconfigurable potential landscapes for electro-optical polariton-lattice based quantum simulators as well as building blocks of optical logic architectures. Especially for the latter, the strongly interacting nature of the light-matter hybrid particles has been used to facilitate fast and efficient switching of light by light, something which is very hard to achieve with weakly interacting photons. We demonstrate here that polariton transistor switches can be fully integrated in electro-optical schemes by implementing a one-dimensional polariton channel which is operated by an electrical gate rather than by a control laser beam. The operation of the device, which is the polariton equivalent to a field-effect transistor, relies on combining electro-optical potential landscape engineering with local exciton ionization to control the scattering dynamics underneath the gate. We furthermore demonstrate that our device has a region of negative differential resistance and features a completely new way to create bistable behavior.},
  language  = {en}
}