Optical Nanoantennas as Magnetic Nanoprobes for Enhancing Light-Matter Interaction

A class of optical nanoantennas utilized as photoinduced magnetic nanoprobes is studied for enhancing magnetic near-field in a magnetic-dominant region with vanishing electric field. We examine the illumination of such magnetic nanoprobes that guarantees selective excitation of magnetic resonances, such as azimuthally electric polarized beams (APBs) which possess a strong longitudinal magnetic field on the beam axis where the electric field is ideally null. Magnetic nanoprobes whose magnetic resonances are selectively excited show a large magnetic near-field enhancement and large magnetic-to-electric-field contrast ratio. Such nanoprobes are the basis for the development of future magnetic-base spectroscopy and macroscopy systems.