On-chip all-dielectric fabrication-tolerant zero-index metamaterials

TL;DR

This paper presents a robust all-dielectric zero-index metamaterial fabricated on a silicon-on-insulator platform that maintains photonic Dirac-cone dispersion despite fabrication imperfections, enabling practical optical applications.

Contribution

The work introduces a fabrication-tolerant all-dielectric ZIM supporting PDC dispersion over a wide parameter range, overcoming sensitivity issues of prior designs.

Findings

Supports PDC dispersion over wide parameter space

Fabricated on SOI platform at telecom wavelengths

Demonstrates robustness against fabrication imperfections

Abstract

Zero-index metamaterials (ZIMs) offer unprecedented ways to manipulate the flow of light, and are of interest for wide range of applications including optical cloaking, super-coupling, and unconventional phase-matching properties in nonlinear optics. Impedance-matched ZIMs can be obtained through a photonic Dirac-cone (PDC) dispersion induced by an accidental degeneracy of two linear bands - typically an electric monopole mode and a transverse magnetic dipole mode - at the center of the Brillouin zone. Consequently, PDC can only be achieved for a particular combination of geometric parameters of the metamaterial, and hence is sensitive to fabrication imperfections. These fabrication imperfections may limit the usefulness in practical applications. In this work we overcome this obstacle and demonstrate robust all-dielectric (AD) ZIM that supports PDC dispersion over wide parameter space. Our structure, consisting of an array of Si pillars on silica substrate, is fabricated in silicon-oninsulator (SOI) platform and operates at telecom wavelengths.