Non-plasmonic nanoantennas for surface enhanced spectroscopies with ultra-low heat conversion

Abstract

Nanoplasmonics has recently revolutionized our ability to control light on the nanoscale. Using metallic nanostructures with tailored shapes, it is possible to efficiently focus light into nanoscale field ?hot spots?. High field enhancement factors have been achieved in such optical nanoantennas, enabling transformative science in the areas of single molecule interaction, highly enhanced nonlinearities, and nanoscale waveguiding. Unfortunately, these large enhancements come with the price of high optical losses due to absorption in the metal, severely limiting real-world applications. For example, localized heating strongly limits the total power that can be delivered to a nanoscale field hot spot before the nanostructure melts and reshapes, affecting their nanoscale lighting and photonic modulation capabilities. The interaction and properties of nanoemmitters and molecules close to the nanoantennas can also be modified due to the local heat. Via the realization of a novel nanophotonic platform based on dielectric nanostructures to form efficient nanoantennas with ultra-low light-into-heat conversion, we demonstrate here an approach that overcomes these limitations. We show, that dimer-like silicon-based single nanoantennas produce both high surface enhanced fluorescence (SEF) and surface enhanced Raman scattering (SERS), while at the same time producing a negligible temperature increase in their hot spots and surrounding environments.