Developing coherent light sources from plasmonic lattices combined with van der Waals heterostructures

Moilanen, A. J. and Novotny, L.
Photonics Laboratory, The Department of Information Technology and Electrical Engineering, ETH Zurich, Switzerland

Plasmonic lattices, periodic arrays of metal nanoparticles, give rise to collective resonant modes known as surface lattice resonances (SLRs). The SLRs form by the hybridization of the localized surface plasmon resonances (LSPRs) and the diffraction orders (DOs) of light in the periodic array. Combining plasmonic lattices with a suitable gain material, such as organic fluorescent molecules, has enabled the observation of lasing and Bose-Einstein condensation (BEC). Characteristic features of plasmonic lattice lasers and condensates are ultrafast dynamics and large extent of spatial coherence realized at ambient conditions.

Semiconducting transition metal dichalcogenide (TMDC) monolayers have a direct bandgap, which makes their excitons suitable for light-emitting applications. Interlayer excitons in van der Waals (vdW) heterostructures, such as bi-layer MoSe2/WSe2 studied in this project, have a long radiative lifetime and an energy level structure suitable for population inversion. Lasing by optical excitation of TMDCs has been demonstrated in various types of cavities, for instance, planar microcavities and photonic crystal cavities.

This project focuses on developing coherent light sources from vdW heterostructures combined with plasmonic lattices. Starting from optical characterization of the devices and demonstrating coherent light emission by optical excitation, the grand goal of the project is to achieve an electrically driven laser on chip.