Continuous and reversible electrical-tuning of fluorescent decay rate via Fano resonance

We demonstrate electrically tunable control of the radiative and nonradiative decay rates of a fluorescent molecule through a Fano-resonant transparency embedded in the plasmonic local density of optical states (LDOSs). An auxiliary quantum object (QO) placed at the hotspot of a plasmonic nanoparticle suppresses the plasmonic excitation at its transition frequency ωQO, thereby creating a narrow transparency window and reducing the LDOS at ω = ωQO. When the fluorescence frequency of a nearby emitter overlaps this window, the plasmon-induced enhancement of both radiative and nonradiative decay is strongly suppressed. Because ωQO can be shifted electrically, the transparency can be moved reversibly across the fluorescence line, enabling continuous voltage control of the decay rates. Three-dimensional Maxwell simulations predict tuning of the radiative and nonradiative channels by up to two orders of magnitude. The proposed mechanism offers a compact route toward fast, reversible control of light–matter interaction in integrated photonics, with potential applications in single-photon sources, electrically programmable quantum devices, super-resolution microscopy, and surface-enhanced Raman spectroscopy.