Final PhD Seminar
Manipulation of light-emitting properties of 2D materials by photonic nanostructures
Monolayers of transition-metal dichalcogenides (TMDs) exhibit unique optoelectronic properties, such as direct bandgap, robust valley polarization and strong electric tunability. In particular, they are promising to be used as light sources because they show both strong photoluminescence and second-harmonic emission. On the other hand, the sub-nanometer thickness (light-matter interaction length) of such active materials limits their overall emission conversion efficiency and prevents practical applications. Resonant nanostructures, such as plasmonic nanoantennas and subwavelength Si gratings could effectively control and boost light-matter interaction at the nanoscale. Here we demonstrate how to manipulate the photoluminescence of monolayer MoSe2 by coupling it with resonant plasmonic nanoantenna. We also show enhanced and directional emission from monolayer WSe2 by coupling to a multi-resonant dielectric subwavelength Si grating-waveguide structure. Plasmonic schemes that could effectively separate emission from different valleys in a monolayer TMDCs spatially are also proposed and demonstrated numerically. Furthermore, we show how to integrate such materials with waveguide structures to boost the second-harmonic generation from the monolayer MoSe2 through pumping the material by guided modes.