Slotted nanoresonator geometry: A route for Purcell enhancement and nearfield intensity amplification in all-dielectric nanophotonics

Plasmonic nanoresonators exhibiting localized surface plasmon resonance (LSPR) have been extensively investigated for enhancing light-matter interaction and have revolutionized biochemical sensing. However, the high optical absorption in plasmonic materials presents several problems, including the rapid quenching of quantum emitters. Additionally, the incompatibility of common plasmonic materials with the CMOS manufacturing process their incorporation in integrated photonic systems. Although Mie resonant all-dielectric nanostructures could potentially replace plasmonic nanoresonators, higher radiation losses in high refractive-index dielectric nanoparticles prevent high local-field amplification and result in far lower Purcell enhancement. This paper proposes slotted all-dielectric nanodisks and, through systematic numerical study, predicts that high local field enhancement and significantly higher Purcell enhancement can be achieved in such geometries. The following single and arrayed configurations: single asymmetric, chain symmetric, single symmetric with different emitter positions are investigated. In the near IR region, intensity enhancement and the Purcell factor of 1150 and 1800 respectively are predicted for a single slotted nanodisk compared to 30 times near field intensity enhancement and a Purcell enhancement of 20 for a nanodisk. The Purcell factor of a single slotted nanodisk can be further improved to around 2800 by controlling the degree of asymmetry by shifting the slot position. In three symmetric slotted nanodisks, a record high enhancement factor of the Purcell factor of up to 3200 and intensity enhancement exceeding three orders of magnitude was observed. Our findings could lead to novel CMOS-compatible nanoantenna designs for fluorescence signal amplification in biochemical applications and electrical excitation of quantum emitters. � 2021 Elsevier B.V., All rights reserved.