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Strongly coupled optical microcavities containing different exciton states permit the creation of hybrid-polariton modes that can be described in terms of a linear admixture of cavity-photon and the constituent excitons. Such hybrid states have been predicted to have optical properties that are different from their constituent parts, making them a test bed for the exploration of light-matter coupling. Here, we use strong coupling in an optical microcavity to mix the electronic transitions of two J-aggregated molecular dyes and use both non-resonant photoluminescence emission and photoluminescence excitation spectroscopy to show that hybrid-polariton states act as an efficient and ultrafast energy-transfer pathway between the two exciton states. We argue that this type of structure may act as a model system to study energy-transfer processes in biological light-harvesting complexes.

Article:Stevenson, R.M., Astratov, V.N., Skolnick, M.S. et al. (6 more authors) (2000) Continuous wave observation of massive polariton redistribution by stimulated scattering in semiconductor microcavities. Physical Review Letters, 85 (17 ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. A massive redistribution of the polariton occupancy to two specific wave vectors, zero and ϳ3.9 3 10 4 cm 21 , is observed under conditions of continuous wave excitation of a semiconductor microcavity. The "condensation" of the polaritons to the two specific states arises from stimulated scattering at final state occupancies of order unity. The stimulation phenomena, arising due to the bosonic character of the polariton quasiparticles, occur for conditions of resonant excitation of the lower polariton branch. High energy nonresonant excitation, as in most previous work, instead leads to conventional lasing in the vertical cavity structure.

Seeing macroscopic quantum states directly remains an elusive goal. Particles with boson symmetry can condense into such quantum fluids producing rich physical phenomena as well as proven potential for interferometric devices [1-10]. However direct imaging of such quantum states is only fleetingly possible in high-vacuum ultracold atomic condensates, and not in superconductors. Recent condensation of solid state polariton quasiparticles, built from mixing semiconductor excitons with microcavity photons, offers monolithic devices capable of supporting room temperature quantum states [11-14] that exhibit superfluid behaviour [15,16]. Here we use microcavities on a semiconductor chip supporting two-dimensional polariton condensates to directly visualise the formation of a spontaneously oscillating quantum fluid. This system is created on the fly by injecting polaritons at two or more spatially-separated pump spots. Although oscillating at tuneable THz-scale frequencies, a simple optical microscope can be used to directly image their stable archetypal quantum oscillator wavefunctions in real space. The self-repulsion of polaritons provides a solid state quasiparticle that is so nonlinear as to modify its own potential. Interference in time and space reveals the condensate wavepackets arise from non-equilibrium solitons. Control of such polariton condensate wavepackets demonstrates great potential for integrated semiconductor-based condensate devices.Comment: accepted in Nature Physic