  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.
