Fri, 23/09/2016 – 12:15pm to 1:55pm
S16 Level 6 – Theory conference room
Impressive properties arise from the atomically-thin nature of transition metal dichalcogenide 2D materials. However, being atomically thin limits their optical absorption or emission. Hence, enhancing their photoluminescence (PL) and second harmonic generation (SHG) by plasmonic nanostructures is critical for integrating these materials in optoelectronic and photonic devices. Typical PL enhancement from transition metal dichalcogenides is hundred-fold, with recent enhancement of thousand-fold achieved by simultaneously enhancing absorption, emission and directionality of the system. By suspending WSe2 flakes onto sub-20 nm wide trenches in gold substrate, we report a giant PL enhancement of ~20,000-fold (Nature Communications, 7, 11283, 2016). It is attributed to an enhanced absorption of the pump laser due to the lateral gap plasmons confined in the trenches and the enhanced Purcell factor by the plasmonic nanostructure. In addition, significant enhancement of SHG in WSe2 due to the plasmon-enhanced light-matter interaction has also been observed. The work demonstrates the feasibility of giant PL and SHG enhancement in WSe2 with judiciously designed plasmonic nanostructures and paves a way towards the implementation of plasmon-enhanced transition metal dichalcogenide photodetectors, sensors and emitters.