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We report on the observation of the strong-coupling regime between quantum well excitons and a high incidence “Brewster cavity mode” previously identified as the generalized Brewster angle condition in multilayer structures [H. F. Mahlein, J. Opt. Soc. Am. 64, 647 (1974)]. This propagating mode is inside the light cone and therefore can be accessed from the top side of the sample without the need for prism or grating coupling methods. The observed anticrossing is clear evidence of the strong light-matter coupling regime. All the results are accurately reproduced by transfer matrix simulations. These results demonstrate the high potential of such structures for the study of propagating polaritons at high k, which could be harnessed for the realization of polaritonic circuit devices.

The stability of spin of macroscopic quantum states to intrinsic noise is studied for non-resonantly pumped optically-trapped polariton condensates. We demonstrate flipping between the two spinpolarised states with >10⁴ slow-down of the flip rate by tuning the optical pump power. Individual spin flips faster than 50 picosecond are time resolved using single-shot streak camera imaging. We reproduce our results within a mean-field model accounting for cross-spin scattering between excitons and polaritons, yielding a ratio of cross- to co-spin scattering of ~0.6, in contrast with previous literature suggestions.

The stability of spin of macroscopic quantum states to intrinsic noise is studied for non-resonantly pumped optically-trapped polariton condensates. We demonstrate flipping between the two spinpolarised states with >10⁴ slow-down of the flip rate by tuning the optical pump power. Individual spin flips faster than 50 picosecond are time resolved using single-shot streak camera imaging. We reproduce our results within a mean-field model accounting for cross-spin scattering between excitons and polaritons, yielding a ratio of cross- to co-spin scattering of ~0.6, in contrast with previous literature suggestions., ERC LINASS 320503. Leverhulme Trust Grant No. VP1-2013-011. Bilateral Greece-Russia “Polisimulator” project co-financed by Greece and the EU Regional Development Fund. Stavros Niarchos Foundation, “ARCHERS” project. Horizon 2020 programme (No. FETPROACT-2016 732894-HOT). CONACYT (Mexico) grant No. 251808. Institute for Basic Science in Korea (IBS-R024-D1)

Recent work on polariton-polariton scattering in semiconductor microcavities under continuous wave excitation conditions is reviewed. For weak non-resonant laser excitation, a marked bottleneck in the polariton distribution is observed, but which is suppressed by polariton-polariton scattering as the laser intensity is increased. However, the high excitation conditions necessary to observe stimulated emission lead to loss of strong coupling and conventional lasing in the weak coupling regime, By contrast for resonant excitation, polaritons are created directly in the polariton trap formed by the microcavity dispersion curve. Stimulated scattering of the bosonic quasi-particles occurs to the emitting state at the centre of the Brillouin zone, and to a companion state at high wavevector. The stimulation phenomena lead to condensation of the bosonic quasi-particles to two specific regions of k-space, and to the formation of a new state with macroscopic coherence. The prospects to achieve a polariton laser under conditions of non-resonant excitation are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.

We report spin and intensity coupling of an exciton-polariton condensate to the mechanical vibrations of a circular membrane microcavity. We optically drive the microcavity resonator at the lowest mechanical resonance frequency while creating an optically-trapped spin-polarized polariton condensate in different locations on the microcavity, and observe spin and intensity oscillations of the condensate at the vibration frequency of the resonator. Spin oscillations are induced by vibrational strain driving, whilst the modulation of the optical trap due to the displacement of the membrane causes intensity oscillations in the condensate emission. Our results demonstrate spin-phonon coupling in a macroscopically coherent condensate.