Surface plasmon-quantum dot coupling from arrays of nanoholes

The coupling of semiconductor quantum dots (QDs) to the surface plasmon (SP) modes of nanohole arrays in a metal film was demonstrated for the first time, showing enhancement in the spontaneous emission by 2 orders of magnitude. The SP-enhanced transmission resonances of the nanohole arrays were tuned around the photoluminescence (PL) peak of polystyrene-b-poly(acrylic acid) (PS-b-PAA)-stabilized cadmium sulfide (CdS) quantum dots (QDs) in contact with the arrays. As a result the overall PL from the SP-QD system was enhanced by 2 orders of magnitude, even after excluding the enhanced transmission of the nanohole array without the QDs. The maximum enhancement occurred when the resonance from the nanohole array matched the QD PL spectrum. Time-resolved PL measurements were used to estimate the relative contribution of different physical mechanisms to the enhanced spontaneous emission. The increased spontaneous emission in the SP-QD system is promising for prospective plasmonic light-emitting devices incorporating QDs.