A Theoretical Study of Optical Nanoantennas for Energy Harvesting and Photothermal Conversion.

Abstract:- Optical nanoantennas represent a groundbreaking advancement in nanophotonics,enabling unprecedented manipulation of light at subwavelength scales. This paper presents acomprehensive investigation of hybrid plasmonic-dielectric nanoantennas for enhanced energyharvesting and photothermal conversion applications. Through systematic design optimization, wedemonstrate a novel circular nanoantenna architecture with integrated hot spot amplificationcapabilities that achieves a remarkable 92% photothermal conversion efficiency under specific resonant conditions. The proposed design leverages multipolar interference effects to minimize back-scattering (with backward scattering cross-section reduced to less than 0.01) while simultaneously enhancing localized thermal generation. Experimental characterization via nonlinear photoemissionelectron microscopy confirms strong field localization with enhancement factors exceeding 120× atresonant wavelengths of 650 nm and 850 nm. The nanoantenna system achieves a temperature rise of45.3 K under modest illumination intensity of 0.5 mW/μm2, making it highly suitable for applicationsin solar energy harvesting, photothermal therapy, and integrated photonic systems. This workestablishes a foundation for next-generation nanoantenna designs that simultaneously optimizemultiple performance parameters through tailored electromagnetic and thermal response.