Plasmon emission by interlayer excitons in twisted bilayers: Effect of large plasmonic wavevector components

Abstract

While the emission of localized plasmons is often treated in the real-space picture, working in wavevector space makes it possible to resolve the contributions of various plasmonic Fourier components. By calculating the rate of plasmon emission by interlayer excitons in twisted ${\mathrm{MoSe}}_{2}/{\mathrm{WSe}}_{2}$ van der Waals heterostructures as a function of plasmon localization, twist angle, and temperature, we show that a much wider range of exciton states can radiate into subwavelength plasmon modes than into free space. Most of the emission in this case takes place via plasmonic Fourier components that exceed the maximum photon wavevector in free space. We demonstrate that this provides an avenue for continued Purcell scaling of the emission rate with mode size. Furthermore, the scaling is well in excess of the Purcell trend for sufficiently large twist angles and strong plasmonic localization.