TY  - JOUR
A1  - Lee, Chang-Min
A1  - Lim, Hee-Jin
A1  - Schneider, Christian
A1  - Maier, Sebastian
A1  - Höfling, Sven
A1  - Kamp, Martin
A1  - Lee, Yong-Hee
T1  - Efficient single photon source based on \(\mu\)-fibre-coupled tunable microcavity
JF  - Scientific Reports
N2  - Efficient and fast on-demand single photon sources have been sought after as critical components of quantum information science. We report an efficient and tunable single photon source based on an InAs quantum dot (QD) embedded in a photonic crystal cavity coupled with a highly curved \(\mu\)-fibre. Exploiting evanescent coupling between the \(\mu\)-fibre and the cavity, a high collection efficiency of 23% and Purcell-enhanced spontaneous emissions are observed. In our scheme, the spectral position of a resonance can be tuned by as much as 1.5 nm by adjusting the contact position of the \(\mu\)-fibre, which increases the spectral coupling probability between the QD and the cavity mode. Taking advantage of the high photon count rate and the tunability, the collection efficiencies and the decay rates are systematically investigated as a function of the QD-cavity detuning.
KW  - tapers
KW  - semiconductor quantum dots
KW  - crystal
KW  - nanowire
KW  - generation
KW  - nanoactivity
KW  - mode
KW  - emission
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145835
VL  - 5
IS  - 14309
ER  - 
TY  - JOUR
A1  - Wurdack, Matthias
A1  - Lundt, Nils
A1  - Klaas, Martin
A1  - Baumann, Vasilij
A1  - Kavokin, Alexey V.
A1  - Höfling, Sven
A1  - Schneider, Christian
T1  - Observation of hybrid Tamm-plasmon exciton-polaritons with GaAs quantum wells and a MoSe\(_{2}\) monolayer
JF  - Nature Communications
N2  - Strong light matter coupling between excitons and microcavity photons, as described in the framework of cavity quantum electrodynamics, leads to the hybridization of light and matter excitations. The regime of collective strong coupling arises, when various excitations from different host media are strongly coupled to the same optical resonance. This leads to a well-controllable admixture of various matter components in three hybrid polariton modes. Here, we study a cavity device with four embedded GaAs quantum wells hosting excitons that are spectrally matched to the A-valley exciton resonance of a MoSe\(_{2}\) monolayer. The formation of hybrid polariton modes is evidenced in momentum resolved photoluminescence and reflectivity studies. We describe the energy and k-vector distribution of exciton-polaritons along the hybrid modes by a thermodynamic model, which yields a very good agreement with the experiment.
KW  - two-dimensional materials
KW  - microresonators
KW  - nanophotonics and plasmonics
KW  - cavity device
KW  - strong coupling
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170480
VL  - 8
IS  - 259
ER  - 
TY  - JOUR
A1  - Dietrich, Christof P.
A1  - Steude, Anja
A1  - Tropf, Laura
A1  - Schubert, Marcel
A1  - Kronenberg, Nils M.
A1  - Ostermann, Kai
A1  - Höfling, Sven
A1  - Gather, Malte C.
T1  - An exciton-polariton laser based on biologically produced fluorescent protein
JF  - Science Advances
N2  - 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.
KW  - polarition condensate
KW  - enhanced green fluorescent protein
KW  - photon lasing
KW  - quantum physics
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-171305
VL  - 2
IS  - 8
ER  - 
TY  - JOUR
A1  - Pfenning, Andreas
A1  - Krüger, Sebastian
A1  - Jabeen, Fauzia
A1  - Worschech, Lukas
A1  - Hartmann, Fabian
A1  - Höfling, Sven
T1  - Single-photon counting with semiconductor resonant tunneling devices
JF  - Nanomaterials
N2  - Optical quantum information science and technologies require the capability to generate, control, and detect single or multiple quanta of light. The need to detect individual photons has motivated the development of a variety of novel and refined single-photon detectors (SPDs) with enhanced detector performance. Superconducting nanowire single-photon detectors (SNSPDs) and single-photon avalanche diodes (SPADs) are the top-performer in this field, but alternative promising and innovative devices are emerging. In this review article, we discuss the current state-of-the-art of one such alternative device capable of single-photon counting: the resonant tunneling diode (RTD) single-photon detector. Due to their peculiar photodetection mechanism and current-voltage characteristic with a region of negative differential conductance, RTD single-photon detectors provide, theoretically, several advantages over conventional SPDs, such as an inherently deadtime-free photon-number resolution at elevated temperatures, while offering low dark counts, a low timing jitter, and multiple photon detection modes. This review article brings together our previous studies and current experimental results. We focus on the current limitations of RTD-SPDs and provide detailed design and parameter variations to be potentially employed in next-generation RTD-SPD to improve the figure of merits of these alternative single-photon counting devices. The single-photon detection capability of RTDs without quantum dots is shown.
KW  - single-photon detectors
KW  - resonant tunneling diode
KW  - photon counting
KW  - III–V semiconductor devices
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-281922
SN  - 2079-4991
VL  - 12
IS  - 14
ER  - 
TY  - JOUR
A1  - van Loock, Peter
A1  - Alt, Wolfgang
A1  - Becher, Christoph
A1  - Benson, Oliver
A1  - Boche, Holger
A1  - Deppe, Christian
A1  - Eschner, Jürgen
A1  - Höfling, Sven
A1  - Meschede, Dieter
A1  - Michler, Peter
A1  - Schmidt, Frank
A1  - Weinfurter, Harald
T1  - Extending Quantum Links: Modules for Fiber‐ and Memory‐Based Quantum Repeaters
JF  - Advanced Quantum Technologies
N2  - Elementary building blocks for quantum repeaters based on fiber channels and memory stations are analyzed. Implementations are considered for three different physical platforms, for which suitable components are available: quantum dots, trapped atoms and ions, and color centers in diamond. The performances of basic quantum repeater links for these platforms are evaluated and compared, both for present‐day, state‐of‐the‐art experimental parameters as well as for parameters that can in principle be reached in the future. The ultimate goal is to experimentally explore regimes at intermediate distances—up to a few 100 km—in which the repeater‐assisted secret key transmission rates exceed the maximal rate achievable via direct transmission. Two different protocols are considered, one of which is better adapted to the higher source clock rate and lower memory coherence time of the quantum dot platform, while the other circumvents the need of writing photonic quantum states into the memories in a heralded, nondestructive fashion. The elementary building blocks and protocols can be connected in a modular form to construct a quantum repeater system that is potentially scalable to large distances.
KW  - color centers
KW  - quantum communication
KW  - quantum dots
KW  - quantum repeaters
KW  - trapped atoms/ions
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228322
VL  - 3
IS  - 11
ER  - 
TY  - JOUR
A1  - Jahnke, Frank
A1  - Gies, Christopher
A1  - Aßmann, Marc
A1  - Bayer, Manfred
A1  - Leymann, H.A.M.
A1  - Foerster, Alexander
A1  - Wiersig, Jan
A1  - Schneider, Christian
A1  - Kamp, Martin
A1  - Höfling, Sven
T1  - Giant photon bunching, superradiant pulse emission and excitation trapping in quantum-dot nanolasers
JF  - Nature Communications
N2  - 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.
KW  - photon bunching
KW  - quantum mechanics
KW  - superradiant pulse emission
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-166144
VL  - 7
IS  - 11540
ER  - 
TY  - JOUR
A1  - He, Yu-Ming
A1  - Iff, Oliver
A1  - Lundt, Nils
A1  - Baumann, Vasilij
A1  - Davanco, Marcelo
A1  - Srinivasan, Kartik
A1  - Höfling, Sven
A1  - Schneider, Christian
T1  - Cascaded emission of single photons from the biexciton in monolayered WSe\(_{2}\)
JF  - Nature Communications
N2  - 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.
KW  - lasers
KW  - LED
KW  - quantum dots
KW  - light sources
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169363
VL  - 7
ER  - 
TY  - JOUR
A1  - Rothmayr, Florian
A1  - Guarin Castro, Edgar David
A1  - Hartmann, Fabian
A1  - Knebl, Georg
A1  - Schade, Anne
A1  - Höfling, Sven
A1  - Koeth, Johannes
A1  - Pfenning, Andreas
A1  - Worschech, Lukas
A1  - Lopez-Richard, Victor
T1  - Resonant tunneling diodes: mid-infrared sensing at room temperature
JF  - Nanomaterials
N2  - Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the 2–4 μm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor's electrical response and how they allow controlling the device's sensing abilities.
KW  - resonant tunneling diode
KW  - mid-infrared sensing
KW  - photosensor
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-267152
SN  - 2079-4991
VL  - 12
IS  - 6
ER  - 
TY  - JOUR
A1  - Wyborski, Paweł
A1  - Podemski, Paweł
A1  - Wroński, Piotr Andrzej
A1  - Jabeen, Fauzia
A1  - Höfling, Sven
A1  - Sęk, Grzegorz
T1  - Electronic and optical properties of InAs QDs grown by MBE on InGaAs metamorphic buffer
JF  - Materials
N2  - We present the optical characterization of GaAs-based InAs quantum dots (QDs) grown by molecular beam epitaxy on a digitally alloyed InGaAs metamorphic buffer layer (MBL) with gradual composition ensuring a redshift of the QD emission up to the second telecom window. Based on the photoluminescence (PL) measurements and numerical calculations, we analyzed the factors influencing the energies of optical transitions in QDs, among which the QD height seems to be dominating. In addition, polarization anisotropy of the QD emission was observed, which is a fingerprint of significant valence states mixing enhanced by the QD confinement potential asymmetry, driven by the decreased strain with increasing In content in the MBL. The barrier-related transitions were probed by photoreflectance, which combined with photoluminescence data and the PL temperature dependence, allowed for the determination of the carrier activation energies and the main channels of carrier loss, identified as the carrier escape to the MBL barrier. Eventually, the zero-dimensional character of the emission was confirmed by detecting the photoluminescence from single QDs with identified features of the confined neutral exciton and biexciton complexes via the excitation power and polarization dependences.
KW  - molecular beam epitaxy
KW  - quantum dot
KW  - metamorphic buffer layer
KW  - band structure
KW  - photoluminescence
KW  - photoreflectance
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-297037
SN  - 1996-1944
VL  - 15
IS  - 3
ER  - 
TY  - JOUR
A1  - Holzinger, Steffen
A1  - Schneider, Christian
A1  - Höfling, Sven
A1  - Porte, Xavier
A1  - Reitzenstein, Stephan
T1  - Quantum-dot micropillar lasers subject to coherent time-delayed optical feedback from a short external cavity
JF  - Scientific Reports
N2  - 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.
KW  - nanophotonics and plasmonics
KW  - photonic devices
KW  - quantum dots
KW  - semiconductor lasers
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322485
VL  - 9
ER  -