Design of optical anapole modes of all-dielectric nanoantennas for SERS applications

To obtain large electric field enhancement while mitigating material losses, an all-dielectric nanoantenna com-posed of a heptamer and nanocubes is designed and analyzed. A numerical simulation by the finite element method reveals that the nanoantenna achieves the optical electric anapole modes, thereby significantly enhancing the cou-pling between different dielectrics to further improve the near-field enhancement and spontaneous radiation. Field enhancement factors |E/E0|2 of 3,563 and 5,395 (AM1 and AM2) anda Purcell factor of 3,872 are observed in the wavelength range between 350 and 800 nm. This nanoantenna has promising potential in applications involving surface-enhanced Raman scattering and nonlinearities due to its low cost and excellent compatibility. & COPY; 2023 Optica Publishing Group