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  - 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  - 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  - 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  -