Signatures of polaritonic normal modes in the photoluminescence from periodic multiple quantum well structures following continuum excitation

Summary form only given. Several studies have demonstrated the strong influence of radiative exciton coupling on the resonant optical response of periodic quantum well (PQW) structures in the vicinity of the heavy-hole (hh)-exciton Bragg resonance for d=/spl lambda//2, where d is the distance between adjacent quantum wells (QWs) and /spl lambda/ is the hh-exciton resonance wavelength inside the structure. In this work, we present photoluminescence (PL) experiments on high quality InGaAs/GaAs PQW structures with up to N=100 QWs, where the exciton emission is strongly influenced by the coherent interwell coupling, showing up in multiple line-splitting and a crossing of the normal modes around Bragg resonance. For N/spl ges/30 and certain d´s we find a quadratic increase of the amplitude and an increasing directionality of the vertical (perpendicular to QWs) emission. The weakest emission occurs in Bragg resonance, where under resonant excitation a strong superradiant reemission takes place.