Polariton condensation in a strain-compensated planar microcavity with InGaAs quantum wells

Cilibrizzi, Pasquale; Askitopoulos, Alexis; Silva, Matteo; Bastiman, F.; Clarke, Edmund M.; Zajac, Joanna M.; Langbein, Wolfgang Werner; Lagoudakis, Pavlos G.

doi:10.1063/1.4901814

Cited by 43 publications

(36 citation statements)

References 26 publications

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“…Let us note here that, in InGaAs-based cavities, spontaneous condensation is very difficult to observe also because of the coupling between the different quantum wells due to their very shallow depth [38]. Getting quantum wells with a larger indium content is therefore a necessity to obtain condensation [39], which comes at the expense of the quality of the quantum wells, and therefore of their linewidth.…”

Section: Samples and Experimentsmentioning

confidence: 99%

Polariton interactions in semiconductor microcavities

Deveaud

2016

Comptes Rendus. Physique

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In this review, we will try to summarize the results that we have obtained on the measurement of polariton interactions. We will describe here the samples, the experimental systems and some of the important results. We will also give a few highlights on the theoretical description of these results. One of the main topics of this review will be the observation of the Feshbach resonance for polaritons, and its interpretation through the coupling of two lower polaritons into a biexciton.

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Section: Samples and Experimentsmentioning

confidence: 99%

Polariton interactions in semiconductor microcavities

Deveaud

2016

Comptes Rendus. Physique

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“…The condensation threshold is also manifested by a decrease of the linewidth of the measured emission, which drops down by a factor of 5 at threshold, and by a blueshift of the emission peak of about 3 meV [20]. The energy shift of the propagating condensate created nonresonantly is composed of the kinetic energy of polaritons, repulsive interactions within the condensate, and a term coming from the interaction of polaritons with the pump-spot-induced reservoir of noncondensed quasiparticles [15,21]. Hence, the condensate energy is shifted above the minimum of the bare cavity mode, while the strong coupling is preserved.…”

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Ghost Branch Photoluminescence From a Polariton Fluid Under Nonresonant Excitation

et al. 2015

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An expanding polariton condensate is investigated under pulsed nonresonant excitation with a small laser pump spot. Far above the condensation threshold we observe a pronounced increase in the dispersion curvature, with a subsequent linearization of the spectrum and strong luminescence from a ghost branch orthogonally polarized with respect to the linearly polarized condensate emission. Polarization of both branches is understood in terms of spin-dependent polariton-polariton scattering. The presence of the ghost branch has been confirmed in time-resolved measurements. The effects of disorder and dissipation in the photoluminescence of polariton condensates and their excitations are discussed. DOI: 10.1103/PhysRevLett.115.186401 PACS numbers: 71.36.+c, 67.10.-j, 71.35.Lk, 78.67.De Exciton polaritons are composite bosons consisting of strongly coupled microcavity photons and quantumwell excitons. They are able to form a novel class of condensates (for recent reviews see, e.g., [1,2]). Despite their nonequilibrium and dissipative nature, they behave as condensates of weakly interacting bosons. Collective phenomena like condensation [3], off-diagonal long-range order [4,5], topological excitations [6], or superfluid features in the propagation of polariton flows [7] have been demonstrated in such systems. A spectacular consequence of the parametric scattering in polariton gases is the appearance of nonparabolic scattering bands, including normal branches (NBs) and ghost branches (GBs), where the latter are populated by the virtual off-branch excitonpolaritons [7,8]. Excitations of polariton condensates are expected to be characterized by linearized dispersions of the Bogoliubov-like spectra [9]. The fluid excitations at low momenta are expected to behave as collective sound waves rather than as single particles. Recently, the linear dispersion NB and the GB of a resonantly pumped polariton condensate [10] have been observed in a four-wave mixing experiment.The experiment providing direct access to the dispersion of excitations of spontaneously formed condensates in polariton systems is photoluminescence (PL) under nonresonant excitation. The nonresonant pumping can be realized with either a detuned laser or the current injection [11,12]. In the nonresonant pumping scheme, incoherent excitons are generated and then relax, subsequently feeding the reservoir and governing the dynamics of the system [13]. The relaxation of the created hot excitons involves multiple-scattering processes, which destroy the coherence and phase of the excitation; this ensures that these properties are not inherited by the condensate, in contrast to the resonant excitation case. At the same time, the incoherent reservoir causes additional decoherence [14], forming a repulsive potential [15] which shapes the condensate spatially and spectrally. Moreover, it significantly affects the excitation spectrum of the condensate [16]. Bogoliubov dispersions have been reported in this excitation scheme; however, no fingerprints of the GB have been...

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“…27 This work was supported by EPSRC Programme Grant No. EP/J007544/1, ERC Advanced Investigator Grant Excipol 320570, and the Leverhulme Trust.…”

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Design and characterization of high optical quality InGaAs/GaAs/AlGaAs-based polariton microcavities

Tinkler

Walker

Clarke

et al. 2015

Applied Physics Letters

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The presence of dislocations arising from strain relaxation strongly affects polaritons through their photonic component and ultimately limits experiments involving polariton propagation. In this work, we investigate the range of growth parameters to achieve high optical quality GaAs/AlxGa1−xAs-based microcavities containing strained InxGa1−xAs quantum wells and using differential interference contrast (Nomarski) microscopy deduce a design rule for homogeneous versus disordered structures. We illustrate the effect of disorder by contrasting observations of polariton condensates in relaxed and unrelaxed microcavities. In our optimized device, we generate a polariton condensate and deduce a lifetime for the interacting polariton fluid of 39 ± 2 ps.

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Polariton condensation in a strain-compensated planar microcavity with InGaAs quantum wells

Cited by 43 publications

References 26 publications

Polariton interactions in semiconductor microcavities

Polariton interactions in semiconductor microcavities

Ghost Branch Photoluminescence From a Polariton Fluid Under Nonresonant Excitation

Design and characterization of high optical quality InGaAs/GaAs/AlGaAs-based polariton microcavities

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