TY - JOUR A1 - Braun, T. A1 - Schneider, C. A1 - Maier, S. A1 - Igusa, R. A1 - Iwamoto, S. A1 - Forchel, A. A1 - Höfling, S. A1 - Arakawa, Y. A1 - Kamp, M. T1 - Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots JF - AIP Advances N2 - 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). KW - GAAS Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-115448 SN - 2158-3226 VL - 4 IS - 9 ER - TY - JOUR A1 - Suchomel, H. A1 - Brodbeck, S. A1 - Liew, T. C. H. A1 - Amthor, M. A1 - Klaas, M. A1 - Klembt, S. A1 - Kamp, M. A1 - Höfling, S. A1 - Schneider, C. T1 - Prototype of a bistable polariton field-effect transistor switch JF - Scientific Reports N2 - 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. KW - materials for optics KW - nanoscience and technology KW - optics and photonics KW - semiconductors Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158323 VL - 7 IS - 5114 ER - TY - JOUR A1 - Czerniuk, T. A1 - Brüggemann, C. A1 - Tepper, J. A1 - Brodbeck, S. A1 - Schneider, C. A1 - Kamp, M. A1 - Höfling, S. A1 - Glavin, B. A. A1 - Yakovlev, D. R. A1 - Akimov, A. V. A1 - Bayer, M. T1 - Lasing from active optomechanical resonators JF - Nature Communications N2 - 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. KW - physical sciences KW - applied physics KW - optical physics Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121559 VL - 5 ER - TY - JOUR A1 - Hopfmann, C. A1 - Albert, F. A1 - Schneider, C. A1 - Höfling, S. A1 - Kamp, M. A1 - Forchel, A. A1 - Kanter, I. A1 - Reizenstein, S. T1 - Nonlinear emission characteristics of quantum dot-micropillar lasers in the presence of polarized optical feedback JF - New Journal of Physics N2 - 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. KW - semiconductor lasers KW - coherence KW - system KW - gain Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123127 SN - 1367-2630 VL - 15 IS - 025030 ER - TY - JOUR A1 - Beierlein, J. A1 - Egorov, O. A. A1 - Harder, T. H. A1 - Gagel, P. A1 - Emmerling, M. A1 - Schneider, C. A1 - Höfling, S. A1 - Peschel, U. A1 - Klembt, S. T1 - Bloch Oscillations of Hybrid Light‐Matter Particles in a Waveguide Array JF - Advanced Optical Materials N2 - 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. KW - Bloch oscillations KW - exciton‐polaritons KW - polariton condensation KW - waveguides Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239814 VL - 9 IS - 13 ER - TY - JOUR A1 - Estrecho, E. A1 - Gao, T. A1 - Brodbeck, S. A1 - Kamp, M. A1 - Schneider, C. A1 - Höfling, S. A1 - Truscott, A. G. A1 - Ostrovskaya, E. A. T1 - Visualising Berry phase and diabolical points in a quantum exciton-polariton billiard JF - Scientific Reports N2 - 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. KW - Berry phase KW - diabolical points KW - quantum billiard KW - exciton-polariton Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167496 VL - 6 IS - 37653 ER - TY - JOUR A1 - Hargart, F A1 - Roy-Choudhury, K A1 - John, T A1 - Portalupi, S L A1 - Schneider, C A1 - Höfling, S A1 - Kamp, M A1 - Hughes, S A1 - Michler, P T1 - Probing different regimes of strong field light-matter interaction with semiconductor quantum dots and few cavity photons JF - New Journal of Physics N2 - In this work we present an extensive experimental and theoretical investigation of different regimes of strong field light–matter interaction for cavity-driven quantum dot (QD) cavity systems. The electric field enhancement inside a high-Q micropillar cavity facilitates exceptionally strong interaction with few cavity photons, enabling the simultaneous investigation for a wide range of QD-laser detuning. In case of a resonant drive, the formation of dressed states and a Mollow triplet sideband splitting of up to 45 μeV is measured for amean cavity photon number \(\leq\) 1. In the asymptotic limit of the linear ACStark effect we systematically investigate the power and detuning dependence of more than 400 QDs. Some QD-cavity systems exhibit an unexpected anomalous Stark shift, which can be explained by an extended dressed 4-levelQDmodel.Weprovide a detailed analysis of the QD-cavity systems properties enabling this novel effect. The experimental results are successfully reproduced using a polaron master equation approach for the QD-cavity system, which includes the driving laser field, exciton-cavity and exciton-phonon interactions KW - light–matter interaction KW - quantum dots KW - AC Stark effect KW - dressed states Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166278 VL - 18 ER - TY - JOUR A1 - Laiho, K. A1 - Pressl, B. A1 - Schlager, A. A1 - Suchomel, H. A1 - Kamp, M. A1 - Höfling, S. A1 - Schneider, C. A1 - Weihs, G. T1 - Uncovering dispersion properties in semiconductor waveguides to study photon-pair generation JF - Nanotechnology N2 - 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. KW - Parametric down-conversion KW - Entanglement KW - CHIP KW - PUMP KW - Bragg-reflection waveguide KW - Information KW - phasematching KW - group refractive index Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-187025 VL - 27 IS - 43 ER - TY - JOUR A1 - Kasprzak, J. A1 - Sivalertporn, K. A1 - Albert, F. A1 - Schneider, C. A1 - Höfling, S. A1 - Kamp, M. A1 - Forchel, A. A1 - Muljarov, E. A. A1 - Langbein, W. T1 - Coherence dynamics and quantum-to-classical crossover in an exciton-cavity system in the quantum strong coupling regime JF - New Journal of Physics N2 - 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. KW - Jaynes-Cummings ladder KW - spectral interferometry KW - photon KW - dot KW - spectroscopy KW - oscillations KW - microcavity KW - resonance KW - light Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123005 SN - 1367-2630 VL - 15 IS - 045013 ER - TY - JOUR A1 - Kim, N. Y. A1 - Kusudo, K. A1 - Löffler, A. A1 - Höfling, S. A1 - Forchel, A. A1 - Yamamoto, Y. T1 - Exciton-polariton condensates near the Dirac point in a triangular lattice JF - New Journal of Physics N2 - Dirac particles, massless relativistic entities, obey linear energy dispersions and hold important implications in particle physics. The recent discovery of Dirac fermions in condensed matter systems including graphene and topological insulators has generated a great deal of interest in exploring the relativistic properties associated with Dirac physics in solid-state materials. In addition, there are stimulating research activities to engineer Dirac particles, elucidating their exotic physical properties in a controllable setting. One of the successful platforms is the ultracold atom-optical lattice system, whose dynamics can be manipulated and probed in a clean environment. A microcavity exciton-polariton-lattice system offers the advantage of forming high-orbital condensation in non-equilibrium conditions, which enables one to explore novel quantum orbital order in two dimensions. In this paper, we experimentally construct the band structures near Dirac points, the vertices of the first hexagonal Brillouin zone with exciton-polariton condensates trapped in a triangular lattice. Due to the finite spectral linewidth, the direct map of band structures at Dirac points is elusive; however, we identify the linear part above Dirac points and its associated velocity value is similar to ~0.9-2 x \(10^8 cm s^{-1}\), consistent with the theoretical estimate \(1 x 10^8 cm s^{-1}\) with a \(2 \mu m\) lattice constant. We envision that the exciton-polariton condensates in lattices would be a promising solid-state platform, where the system order parameter can be accessed in both real and momentum spaces. KW - Bose-Einstein condensation KW - carbon nanotubes KW - graphene KW - electron KW - dynamics KW - fermions KW - trap KW - gas Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123103 SN - 1367-2630 VL - 15 IS - 035032 ER - TY - JOUR A1 - Yu, Leo A1 - Natarajan, Chandra M. A1 - Horikiri, Tomoyuki A1 - Langrock, Carsten A1 - Pelc, Jason S. A1 - Tanner, Michael G. A1 - Abe, Eisuke A1 - Maier, Sebastian A1 - Schneider, Christian A1 - Höfling, Sven A1 - Kamp, Martin A1 - Hadfield, Robert H. A1 - Fejer, Martin M. A1 - Yamamoto, Yoshihisa T1 - Two-photon interference at telecom wavelengths for time-bin-encoded single photons from quantum-dot spin qubits JF - Nature Communications N2 - Practical quantum communication between remote quantum memories rely on single photons at telecom wavelengths. Although spin-photon entanglement has been demonstrated in atomic and solid-state qubit systems, the produced single photons at short wavelengths and with polarization encoding are not suitable for long-distance communication, because they suffer from high propagation loss and depolarization in optical fibres. Establishing entanglement between remote quantum nodes would further require the photons generated from separate nodes to be indistinguishable. Here, we report the observation of correlations between a quantum-dot spin and a telecom single photon across a 2-km fibre channel based on time-bin encoding and background-free frequency downconversion. The downconverted photon at telecom wavelengths exhibits two-photon interference with another photon from an independent source, achieving a mean wavepacket overlap of greater than 0.89 despite their original wavelength mismatch (900 and 911 nm). The quantum-networking operations that we demonstrate will enable practical communication between solid-state spin qubits across long distances. KW - atom KW - 1550 nm KW - up-conversion KW - heralded entanglement KW - emission KW - interface KW - generation KW - communication KW - downconversion Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138677 VL - 6 ER - TY - JOUR A1 - Syperek, M. A1 - Andrzejewski, J. A1 - Rudno-Rudziński, W. A1 - Maryński, A. A1 - Sȩk, G. A1 - Misiewicz, J. A1 - Reithmaier, J. P. A1 - Somers, A. A1 - Höfling, S. T1 - The issue of 0D-like ground state isolation in GaAs- and InP-based coupled quantum dots-quantum well systems JF - Journal of Physics: Conference Series N2 - The issue of quantum mechanical coupling between a semiconductor quantum dot and a quantum well is studied in two families of GaAs- and InP- based structures at cryogenic temperatures. It is shown that by tuning the quantum well parameters one can strongly disturb the 0D-character of the coupled system ground state, initially located in a dot. The out-coupling of either an electron or a hole state from the quantum dot confining potential is viewed by a significant elongation of the photoluminescence decay time constant. Band structure calculations show that in the GaAs-based coupled system at its ground state a hole remains isolated in the dot, whereas an electron gets delocalized towards the quantum well. The opposite picture is built for the ground state of a coupled system based on InP. KW - quantum mechanical coupling KW - quantum well KW - semiconductor quantum dot Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-262876 SN - 1742-6588 SN - 1742-6596 VL - 906 IS - 1 ER - TY - JOUR A1 - Motyka, M. A1 - Dyksik, M. A1 - Ryczko, K. A1 - Weih, R. A1 - Dallner, M. A1 - Höfling, S. A1 - Kamp, M. A1 - Sęk, G. A1 - Misiewicz, J. T1 - Type-II quantum wells with tensile-strained GaAsSb layers for interband cascade lasers with tailored valence band mixing JF - Applied Physics Letters N2 - Optical properties of modified type II W-shaped quantum wells have been investigated with the aim to be utilized in interband cascade lasers. The results show that introducing a tensely strained GaAsSb layer, instead of a commonly used compressively strained GaInSb, allows employing the active transition involving valence band states with a significant admixture of the light holes. Theoretical predictions of multiband k.p theory have been experimentally verified by using photoluminescence and polarization dependent photoreflectance measurements. These results open a pathway for practical realization of mid-infrared lasing devices with uncommon polarization properties including, for instance, polarization-independent midinfrared light emitters. KW - modulation spectroscopy KW - semiconductors KW - Type-II quantum well KW - interband cascade laser KW - GaAsSb Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-189795 VL - 108 IS - 10 ER - TY - JOUR A1 - Dyksik, M. A1 - Motyka, M. A1 - Kurka, M. A1 - Ryczo, K. A1 - Dallner, M. A1 - Höfling, S. A1 - Kamp, M. A1 - Sęk, G. A1 - Misiwicz, J. T1 - Photoluminescence quenching mechanisms in type IIInAs/GaInSb QWs on InAs substrates JF - Optical and Quantum Electronics N2 - Optical properties of AlSb/InAs/GaInSb/InAs/AlSb quantum wells (QWs) grown on an InAs substrate were investigated from the point of view of room temperature emission in the mid- and long-wavelength infrared ranges. By means of two independent techniques of optical spectroscopy, photoreflectance and temperature-dependent photoluminescence, it was proven that the main process limiting the performance of such InAs substrate-based type II structures is related to the escape of carriers from the hole ground state of the QW. Two nonradiative recombination channels were identified. The main process was attributed to holes tunneling to the valence band of the GaAsSb spacing layer and the second one with trapping of holes by native defects located in the same layer. KW - Interband cascade lasers KW - Quantum wells KW - MU-M KW - Fourier-transform spectroscopy KW - Mid-infrared photoluminescence KW - Type II quantum wells KW - Localized states Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204672 VL - 48 IS - 401 ER - TY - JOUR A1 - Rudno-Rudziński, W. A1 - Syperek, M. A1 - Andrezejewski, J. A1 - Maryński, A. A1 - Misiewicz, J. A1 - Somers, A. A1 - Höfling, S. A1 - Reithmaier, J. P. A1 - Sęk, G. T1 - Carrier delocalization in InAs/InGaAlAs/InP quantum-dash-based tunnel injection system for 1.55 μm emission JF - AIP Advances N2 - We have investigated optical properties of hybrid two-dimensional-zero-dimensional (2D-0D) tunnel structures containing strongly elongated InAs/InP(001) quantum dots (called quantum dashes), emitting at 1.55 μm. These quantum dashes (QDashes) are separated by a 2.3 nm-width barrier from an InGaAs quantum well (QW), lattice matched to InP. We have tailored quantum-mechanical coupling between the states confined in QDashes and a QW by changing the QW thickness. By combining modulation spectroscopy and photoluminescence excitation, we have determined the energies of all relevant optical transitions in the system and proven the carrier transfer from the QW to the QDashes, which is the fundamental requirement for the tunnel injection scheme. A transformation between 0D and mixed-type 2D-0D character of an electron and a hole confinement in the ground state of the hybrid system have been probed by time-resolved photoluminescence that revealed considerable changes in PL decay time with the QW width changes. The experimental discoveries have been explained by band structure calculations in the framework of the eight-band k·p model showing that they are driven by delocalization of the lowest energy hole state. The hole delocalization process from the 0D QDash confinement is unfavorable for optical devices based on such tunnel injection structures. KW - physics KW - surface collisions KW - electronic coupling KW - transition radiation KW - time-resolved photoluminescence KW - photoluminescence excitation KW - modulation spectroscopy KW - quantum dots KW - quantum wells KW - delocalization Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-181787 VL - 7 IS - 1 ER - TY - JOUR A1 - Ryczko, K. A1 - Misiewicz, J. A1 - Hofling, S. A1 - Kamp, M. A1 - Sęk, G. T1 - Optimizing the active region of interband cascade lasers for passive mode-locking JF - AIP Advances N2 - The work proposes possible designs of active regions for a mode-locked interband cascade laser emitting in the mid infrared. For that purpose we investigated the electronic structure properties of respectively modified GaSb-based type II W-shaped quantum wells, including the effect of external bias in order to simultaneously fulfil the requirements for both the absorber as well as the gain sections of a device. The results show that introducing multiple InAs layers in type II InAs/GaInSb quantum wells or introducing a tensely-strained GaAsSb layer into “W-shaped” type II QWs offers significant difference in optical transitions’ oscillator strengths (characteristic lifetimes) of the two oppositely polarized parts of such a laser, being promising for utilization in mode-locked devices. KW - physics KW - electrostatics KW - transition radiation KW - oscillator strengths KW - laser spectroscopy KW - optical spectroscopy KW - atomic and molecular spectroscopy, KW - frequency combs KW - quantum wells KW - laser physics Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-181790 VL - 7 IS - 1 ER -