Enhanced Förster resonance energy transfer on layered metal-dielectric hyperbolic metamaterials: an excellent platform for low-threshold laser action.

Förster resonance energy transfer (FRET) is a well-known physical phenomenon, which has been widely used in a variety of fields, spanning from chemistry, and physics to optoelectronic devices. In this study, giant enhanced FRET for donor-acceptor CdSe/ZnS quantum dot (QD) pairs placed on top of Au/MoO multilayer hyperbolic metamaterials (HMMs) has been realized. An enhanced FRET transfer efficiency as high as 93% was achieved for the energy transfer from a blue-emitting QD to a red-emitting QD, greater than that of other QD-based FRET in previous studies. Experimental results show that the random laser action of the QD pairs is greatly increased on a hyperbolic metamaterial by the enhanced FRET effect. The lasing threshold with assistance of the FRET effect can be reduced by 33% for the mixed blue- and red-emitting as QDs compared to the pure red-emitting QDs. The underlying origins can be well understood based on the combination of several significant factors, including spectral overlap of donor emission and acceptor absorption, the formation of coherent closed loops due to multiple scatterings, an appropriate design of HMMs, and the enhanced FRET assisted by HMMs.