Dynamic control of dipole decay rate via graphene plexcitons

TL;DR

The paper addresses dynamic, on-demand control of quantum emitter radiative properties using graphene-based plexcitons. It integrates a quantum dot with a graphene spherical shell to form strongly coupled plexcitons whose spectral position is gate-tunable through the graphene chemical potential $\mu$ via voltage bias; the analysis relies on 3D Maxwell simulations using the MNPBEM toolbox and graphene's surface conductivity $\sigma(\omega)$. The results show sharp plexcitonic resonances with linewidths tighter than bare graphene plasmons and enable continuous modulation of the total decay rate $\Gamma_{tot}$ of a nearby dipole, including pronounced enhancement or suppression in the near- to far-infrared, even off-resonance. This programmable platform supports reconfigurable quantum photonic devices such as tunable single-photon sources and ultrafast optical switches, advancing graphene-based integrated photonics for quantum technologies.

Abstract

Active control of the radiative properties of quantum emitters through engineered light-matter interactions is a key challenge in nanophotonics and quantum optics. In this work, we demonstrate dynamic modulation of dipole's decay rate by exploiting the tunable plexcitonic modes (graphene plasmons and QD-excitons) in the strong coupling regime. By integrating a quantum dot inside a graphene spherical shell and tuning the local optical response of hybrid modes via voltage-bias, we achieve continuous and reversible control over the decay rate, leading to significant enhancement or suppression of dipole emission from near- to far-infrared regime. Furthermore, the plexcitonic peaks shows much sharper linewidths in contrast to bare graphene plasmons even in the off-resonant coupling which indicates higher sensitivity of the systems at tuned wavelengths. We demonstrate the phenomenon with the numerical solution of 3D Maxwell's equations using MNPBEM tool. Our approach demonstrate a versatile platform for programmable emission control and offer a promising pathway for developing reconfigurable quantum photonic devices, such as tunable single-photon sources and ultrafast optical switches.

Figures (5)

• Figure 1: (a) Interaction of graphene plexcitons supported by graphene plasmons of GSS and excitons of QD with a florescent molecule. (b) Illustration of ultrafast photonic sensor operating in infrared regime.
• Figure 2: (a,b) Extinction/absorption spectrum of (a) GSS and (b) GSS/QD for different chemical potential of graphene as a function of excitation wavelength.
• Figure 3: Total decay rate of a dipole emitter coupled with (a) GSS and (b) GSS/QD structures as a function of wavelength. The chemical potential of graphene is taken as 1 eV. The transition wavelength ($\lambda_{eg}$) of QD is 1460 nm.
• Figure 4: Total decay rate of a dipole emitter as a function of $\mu$ for different (a) LP and (b) UP plexcitonic spectral position . The transition wavelength $\lambda_{eg}$ of QD is taken as 1460 nm.
• Figure 5: Decay rate modulation as a function of chemical shift $(\Delta\mu)$ at different spectral positions of UP.