# Light enhancement by quasi-bound states in the continuum in dielectric arrays

## TL;DR

This paper demonstrates that high-Q resonant modes in dielectric arrays, originating from bound states in the continuum, can significantly enhance near-field amplitudes in the red-to-near infrared range, with potential applications in photonics.

## Contribution

It introduces the concept of quasi-bound states in the continuum in dielectric arrays and analyzes their role in near-field enhancement, supported by theoretical and numerical results.

## Key findings

- Near-field amplitude enhancement by factor of 10-25
- High-Q resonant modes originate from bound states in the continuum
- Asymptotic Q-factor behavior explained by propagation band analysis

## Abstract

The article reports on light enhancement by structural resonances in linear periodic arrays of identical dielectric elements. As the basic elements both spheres and rods with circular cross section have been considered. In either case, it has been demonstrated that high-$Q$ structural resonant modes originated from bound states in the continuum enable near-field amplitude enhancement by factor of $10$--$25$ in the red-to-near infrared range in lossy silicon. The asymptotic behavior of the $Q$-factor with the number of elements in the array is explained theoretically by analyzing quasi-bound states propagation bands.