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Exciton-polariton eigenmodes in light-coupledIn0.04Ga0.96As/GaAssemiconductor multiple-quantum-well periodic structures
Journal article   Peer reviewed

Exciton-polariton eigenmodes in light-coupledIn0.04Ga0.96As/GaAssemiconductor multiple-quantum-well periodic structures

J. P Prineas, C Ell, E. S Lee, G Khitrova, H. M Gibbs and S. W Koch
Physical review. B, Condensed matter, Vol.61(20), pp.13863-13872
05/2000
DOI: 10.1103/PhysRevB.61.13863

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Abstract

Features of exciton-polariton eigenmodes in a series of light-coupled In0.04Ga0.96As/GaAs semiconductor multiple quantum wells with varying number of quantum wells N from 1 to 100, and with various periodicities (Bragg, near-Bragg, and anti-Bragg), are studied in linear measurements of reflection, transmission, and absorption. At Bragg periodicity (period d=λx/2), a photonic band-gap mode grows in amplitude and increases linearly in linewidth with increasing N. The N times increased radiative damping rate is seen to arise from the light character of the eigenmode being swept out of a photonic band-gap structure. The slope of linewidth versus N gives the radiative linewidth of the exciton. Away from Bragg periodicity two branches of energy levels can be resolved in absorption, corresponding to the N exciton-polariton normal modes in the multiple-quantum-well structure. Signatures of individual modes becoming optically active are observed in the rich structure of reflection spectra for changing quantum-well periodicity. Antireflection coating of the samples is shown to be an effective way of thus isolating the multiple-quantum-well response.

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