# Enhanced nonlocal effects in metamaterials with moderate-index inclusions

## TL;DR

This paper explores multilayered metamaterials with moderate-index inclusions, revealing significant nonlocal effects and novel dispersion phenomena that could advance optical material engineering.

## Contribution

It demonstrates non-resonant enhancement of spatial dispersion effects in moderate-index inclusions, enabling new dispersion regimes and topological phase transitions.

## Key findings

- Enhanced nonlocal effects comparable to local response
- Identification of a novel configuration with disconnected isofrequency contours
- Potential for practical optical applications without high-index inclusions

## Abstract

We investigate a class of multilayered metamaterials characterized by moderate-index inclusions and low average permittivity. Via first-principle calculations, we show that in such scenario first- and second-order spatial dispersion effects may exhibit a dramatic and non-resonant enhancement, and may become comparable to the local response. Their interplay gives access to a wealth of dispersion regimes encompassing additional extraordinary waves and topological phase transitions. In particular, we identify a novel configuration featuring bound and disconnected isofrequency contours. Since they do not rely on high-index inclusions, our proposed metamaterials may constitute an attractive and technologically viable platform for engineering nonlocal effects in the optical range.