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1
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InAs on InP Quantum Dashes as Single Photon Emitters at the Second Telecommunication Window: Optical, Kinetic, and Excitonic Properties

100%
Mrowiński P., Dusanowski Ł., Somers A., Höfling S., Reithmaier J., Misiewicz J., Sęk G.
Acta Physica Polonica A
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2017
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vol. 132
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issue 2
382-386
EN
In this work, InAs/InGaAlAs/InP quantum dashes have been investigated in terms of their optical, kinetic, and excitonic properties with respect to their application within the 1300± 40 nm spectral range, i.e. the O-band of the telecommunication technologies. We focused on the basic excitonic complexes such as neutral exciton, biexciton, and charged exciton, which have been identified by means of photoluminescence measurements. Emission and carriers' dynamics have been analyzed using rate equation model and fitting the experimental data obtained for both continuous-wave and pulsed excitation regimes. There has been found a significant impact of the charge carrier imbalance in the system and electron capturing rate on the dynamics of the optical and electronic transitions, which results in a high occupation of the negatively charged trion state. Autocorrelation measurements show clear antibunching of trion emission for non-resonant excitation which indicates a potential of such kind of emitters as single photon sources for short-range quantum communication schemes.
2
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Lateral Spin Diffusion Probed by Two-Color Hanle-MOKE Technique

100%
Quast J., Astakhov G., Ossau W., Molenkamp L., Heinrich J., Höfling S., Forchel A.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1311-1316
EN
We report on all optical spatially resolved spin diffusion experiments in an unstrained, unbiased n-GaAs layer. Optical pump and probe intensities are varied over a wide range to study the impact of optical disturbance on spin transport. Both quantities have a considerable influence on the measured spin diffusion length and spin lifetime. Furthermore, an effective spin diffusion coefficient was obtained as a function of temperature.
3
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Room Temperature Carrier Kinetics in the W-type GaInAsSb/InAs/AlSb Quantum Well Structure Emitting in Mid-Infrared Spectral Range

84%
Syperek M., Ryczko K., Dallner M., Dyksik M., Motyka M., Kamp M., Höfling S., Misiewicz J., Sęk G.
Acta Physica Polonica A
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2016
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vol. 130
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issue 5
1224-1228
EN
Room temperature carrier kinetics has been investigated in the type-II W-design AlSb/InAs/Ga_{0.80}In_{0.20}As_{0.15}Sb_{0.85}/InAs/AlSb quantum well emitting in the mid-infrared spectral range (at 2.54 μ m). A time-resolved reflectance technique, employing the non-degenerated pump-probe scheme, has been used as a main experimental tool. Based on that, a primary carrier relaxation time of 2.3±0.2 ps has been found, and attributed to the initial carrier cooling process within the quantum well states, while going towards the ground state via the carrier-optical phonon scattering mechanism. The decay of a quasi-equilibrium carrier population at the quantum well ground states is primarily governed by two relaxation channels: (i) radiative recombination within distribution of spatially separated electrons and holes that occurs in the nanosecond time scale, and (ii) the hole tunnelling out of its confining potential, characterized by a 240±10 ps time constant.
4
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Temperature Dependence of Photoluminescence from Epitaxial InGaAs/GaAs Quantum Dots with High Lateral Aspect Ratio

84%
Musiał A., Sęk G., Maryński A., Podemski P., Misiewicz J., Löffler A., Höfling S., Reitzenstein S., Reithmaier J., Forchel A.
Acta Physica Polonica A
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2011
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vol. 120
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issue 5
883-887
EN
Hereby, we present a study of a thermal quenching of emission from self-assembled epitaxial highly asymmetric quantum dots in InGaAs/GaAs material system for both ensemble and single dot regime. Pronounced interplay between the intensity of wetting layer and quantum dots originated emission was observed as the temperature was increased, evidencing a thermally activated energy transfer between the two parts of the system and an important role of the wetting layer in determining the optical properties of these anisotropic nanostructures. The carrier activation energies have been derived and possible carrier loss mechanisms have been analyzed. Single dot study revealed activation energies slightly varying from dot to dot due to size and shape distribution. The problem of the shape uniformity of individual quantum dot has also been addressed and possibility of additional carrier localization within the investigated structures has been found to be insignificant based on the recorded spectroscopic data.
5
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Effect of Confinement Anisotropy on Excitonic Properties in InAs/InP Quantum Dashes

84%
Mrowiński P., Musiał A., Sęk G., Misiewicz J., Höfling S., Somers A., Hein S., Forchel A.
Acta Physica Polonica A
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2013
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vol. 124
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issue 5
801-804
EN
The influence of confinement potential anisotropy on emission properties of strongly elongated single InAs/InGaAlAs/InP quantum dashes has been investigated by polarization-resolved microphotoluminescence spectroscopy at around 1.5 μm. There have been determined the exciton fine structure splitting, degree of linear polarization of surface emission and biexciton binding energy. The investigated dashes exhibited usually: the exciton anisotropy splitting larger than 100 μeV, the corresponding biexciton binding energy of about 3 meV, and the degree of linear polarization values in the range from 24% to 55%. Here, we presented a correlation of these parameters for several quantum dashes, which can be attributed either to a change in lateral aspect ratio within the ensemble, or the carrier localization on random fluctuations of the dash confinement potential.
6
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GaAs-Based Quantum Well Exciton-Polaritons beyond 1 μm

84%
Pieczarka M., Podemski P., Musiał A., Ryczko K., Sęk G., Misiewicz J., Langer F., Höfling S., Kamp M., Forchel A.
Acta Physica Polonica A
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2013
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vol. 124
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issue 5
817-820
EN
Realization of the Bose-Einstein condensate can provide a way for creation of an inversion-free coherent light emitter with ultra-low threshold power. The currently considered solutions provide polaritonic emitters in a spectral range far below 1 μm limiting their application potential. Hereby, we present optical studies of InGaAs/GaAs based quantum well in a cavity structure exhibiting polaritonic eigenmodes from 5 to 160 K at a record wavelength exceeding 1 μm. The obtained Rabi splitting of 7 meV was almost constant with temperature, and the resulting coupling constant is close to the calculated QW exciton binding energy. This indicates the very strong coupling conditions explaining the observation of polaritons at temperatures where the exciton dissociation is already expected, and allows predicting that room temperature polaritons could still be formed in this kind of a system.
7
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Effect of Dielectric Medium Anisotropy on the Polarization Degree of Emission from a Single Quantum Dash

68%
Mrowiński P., Tarnowski K., Olszewski J., Somers A., Kamp M., Höfling S., Reithmaier J., Urbańczyk W., Misiewicz J., Machnikowski P., Sęk G.
Acta Physica Polonica A
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2016
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vol. 129
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issue 1a
A-48-A-52
EN
Excitonic emission from single InAs/InGaAlAs/InP quantum dashes has been investigated in the context of degree of linear polarization by post-growth modification of its surrounding dielectric medium. We present optical spectroscopy measurements on a symmetric squared pedestal structures (mesas), and asymmetric rectangular ones oriented parallel or perpendicular to the main in-plane axis of the dashes [1-10]. Polarization resolved microphotoluminescence shows a significant quantitative modification of the degree of linear polarization value from -20% up to 70%. These results have been confronted with calculations of the coupling between the exciton transition dipole moment and electromagnetic field distributed in the vicinity of a quantum dash inside a processed mesa.
8
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Semiconductor Cavity Quantum Electrodynamics with Single Quantum Dots

68%
Reitzenstein S., Schneider C., Münch S., Kistner C., Strauss M., Huggenberger A., Franeck P., Weinmann P., Kamp M., Höfling S., Worschech L., Forchel A.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
445-450
EN
This paper summarizes recent progress achieved in the field of semiconductor cavity quantum electrodynamics with single quantum dots with the focus being on micropillar cavities. Light-matter interaction both in the strong and weak coupling regime is presented. Resonance tuning of the quantum dot by temperature, electric fields and magnetic fields is demonstrated while the strong coupling regime can be reached. Additionally, deterministic device integration of single positioned quantum dots is reported by a combination of site controlled quantum dot growth via directed nucleation and subsequent device alignment to overcome the degree of randomness of the quantum dot position in so far most common quantum dot-cavity systems.
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