Excitation of hybrid plasmonic waveguide modes by colloidal quantum dots

Quantum information technologies will greatly benefit from efficiently coupled quantum emitter–waveguide systems. Hybrid plasmonic waveguide modes are relatively low-loss confined modes, which provide an opportunity for coupling to quantum emitters with the rate of emission being significantly enhanced and channeled into the waveguide. Here, we report on the excitation of hybrid plasmonic waveguide modes supported by titanium dioxide nanowires placed on monocrystalline silver flakes with a low-index polymer gap. Quantum dots emitting at 630 nm are located in the gap, where the mode field strength is maximum. This results in a decay-rate enhancement of ∼42 and an outstanding figure-of-merit of ∼361, defined as a product of decay-rate enhancement, excitation efficiency of the waveguide mode, and propagation length normalized by the emission wavelength in a vacuum. We have studied this configuration numerically as well, and the results of numerical simulations support our experimental findings.