# Extremely broadband topological surface states in a photonic topological metamaterials

## TL;DR

This paper reports the creation of a photonic topological metamaterial with an extremely broadband topological phase, enabling robust and wide-ranging control of light through topologically protected surface states.

## Contribution

The study introduces a novel double helix structured photonic metamaterial exhibiting broadband topological surface states from a double Weyl point, simplifying design requirements.

## Key findings

- Topological surface states observed across all frequencies below a cut-off.
- The metamaterial demonstrates extreme bandwidth and robustness.
- Potential applications include one-way waveguides and integrated photonic systems.

## Abstract

Metamaterials, artificially engineered materials consisting of subwavelength unit cell, have shown potentials in light manipulation with their extraordinary optical properties. Especially, topological metamaterials possessing topologically protected surface states enable extremely robust control of light. Here, we demonstrate extremely broadband topological phase in a photonic topological metamaterials with double helix structure. In particular topological surface states are observed for all the frequencies below a certain cut-off, originating from a double Weyl point at zero frequency. The extreme bandwidth and robustness of the photonic topological metamaterial are beneficial for practical applications such as one-way waveguide and photonic integrated systems but also advantageous in design and fabrication since the only necessary condition is to satisfy the effective hyperbolic and chiral properties, without entailing strict periodic arrangement.

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Source: https://tomesphere.com/paper/1901.01482