Ultrasensitive and Broadband Optical Toroidal Modes in all‐Dielectric Nanostructures (Laser Photonics Rev. 16(3)/2022)

Toroidal Metamaterials In article number 2100404, Hui-Hsin Hsiao, and Ai-Yin Liu demonstrate optical toroidal dipole and anapole metamaterials through the designs of periodic amorphous silicon nano-pillars embedded in a spin-on glass layer. Upon normal incidence of plane wave, the transverse toroidal moment, stemming from a complete head-to-tail configuration of the magnetic dipole moments within each individual nanopillar, are excited in optical regime. The toroidal response can be enhanced and spectrally tuned by elongating cylindrical axis perpendicular to the light polarization and exhibit ultrahigh refractive index sensitivity compared to other multipoles.