Enhancement of Fluorescence Resonance Energy Transfer by Coherent Coupling In-Between Surface Plasmon and Volume Plasmon Polariton

Förster resonance energy transfer (FRET) has been widely utilized in various domains, spanning biosensors to light-emitting devices and organic photovoltaics. Enhancement of the efficiency of FRET has attracted a great deal of attention. In this study, we have proposed and demonstrated a first attempt of the integration of surface plasmon (SP) and volume surface polariton (VPP) induced by metal nanoparticles (NPs) with hyperbolic metamaterials (HMMs) in a device that possesses surface-plasmon-coupled-volume-plasmon-polariton (SPCVPP) effect for the enhancement of FRET. Notably, an enhanced FRET efficiency as high as 83.5 ± 0.1% has been attained for the donor–acceptor CdSe/ZnS quantum dot (QD) pairs implemented in the SPCVPP sample. Additionally, to further explore the SPCVPP effect, we adapted the working principle to the study of laser action and found that stimulated emission of the QD pairs is enhanced significantly based on the SPCVPP effect, driven by the enhancement of FRET. The lasing threshold is reduced by 63% via the SPCVPP effect for the mixed blue- and red-emitting QDs, compared to the same QD pairs with Au NPs. Interestingly, it is found that the SPCVPP device reveals a very large enhancement of the efficiency of FRET as well as laser action emission intensity compared to the individual HMM and Au NP effect, exceeding the simple algebraic sum of their individual enhancement. The underlying origin of the large enhancement can be well understood based on the coherent coupling of SP and VPP, which results in the enhanced FRET efficiency and amplifies the transition rate of the stimulated emission. Theoretical calculations according to Fermi’s golden rule for the coherent coupling of the Hamiltonian transition matrix element with respect to SP and VPP closely agree with experimental observations, confirming the validity of our approach. The SPCVPP effect sheds light on the underlying mechanisms driving the FRET enhancement and laser action, offering deep scientific insights into the development of advanced photonic devices with improved efficiency and performance.