Multichannel sensing platform: galleries of tunable hot spots in ring-disk dielectric dimer with rectangular cross-sections

TL;DR

This paper reports the experimental observation and theoretical analysis of multiple tunable hot spots in a dielectric ring-disk dimer with rectangular cross-sections, advancing multichannel sensing and nonlinear applications.

Contribution

It introduces galleries of hot spots generated by disk and ring modes, including Fabry-Pérot resonances, in a dielectric dimer, expanding hot spot technology beyond single hot spots.

Findings

Multiple hot spots observed experimentally and in calculations.

Hot spots can be transferred and split by frequency tuning.

Galleries of hot spots enable multichannel sensing applications.

Abstract

The creation of highly enhanced and localized electromagnetic fields in dielectric structures with low losses, that is, hot spot technology, is an important applied and fundamental problem. However, known examples are reduced to single hot spots generated by low-frequency dipole resonances. Here, a manifold of hot spots were observed experimentally and in calculations in the gap of a ring-inner disk dielectric dimer with a rectangular cross-section. In addition to dipole hot spots, galleries of equidistant hot spots were observed, generated by galleries of disk modes, as well as by galleries of ring modes, each of which begins with a transverse Fabry-P\'erot resonance. Therefore, this direction in photonics is called Fabry-P\'erot-tronics by analogy with Mie-tronics of spherical particles. The intensity contour of hot spots in the gap has a Fano contour associated with the interference of radiation from narrow longitudinal modes of the ring or disk with broadband scattering on the opposite side of the gap. Controlled transfer of hot spots along the gap and splitting of the hot spot by scanning the exciting frequency in the spectral region of the Fano contour are also implemented. Galleries of tunable bright hot spots provide a new platform for multichannel sensing, SERS and nonlinear applications.