Philip Camayd-Muñoz

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

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 an electric monopole and a transverse magnetic dipole mode at the center of the Brillouin zone. Therefore, PDC is very sensitive to fabrication imperfections. In this work, we propose and demonstrate fabrication-tolerant all-dielectric ZIM in telecom regime that supports near PDC dispersion over much wider parameter space than conventional designs. The prism device integrated with Si photonics is fabricated and measured for the verification.

Monolithic CMOS-compatible zero-index metamaterials

Zero-index materials exhibit exotic optical properties that can be utilized for integrated-optics applications. However, practical implementation requires compatibility with complementary metallic-oxide-semiconductor (CMOS) technologies. We demonstrate a CMOS-compatible zero-index metamaterial consisting of a square array of air holes in a 220-nm-thick silicon-on-insulator (SOI) wafer. This design supports zero-index modes with Dirac-cone dispersion. The metamaterial is entirely composed of silicon and offers compatibility through low-aspect-ratio structures that can be simply fabricated in a standard device layer. This platform enables mass adoption and exploration of zero-index-based photonic devices at low cost and high fidelity.

Lossless integrated dirac-cone metamaterials

Zero-index metamaterials exhibit inherent losses due to poor confinement. We present a 2D photonic crystal that achieves isotropic impedance-matched zero-index propagation, but suffers no material or radiation loss due to a bound-state in the continuum.

Manipulating the flow of light using Dirac-cone zero-index metamaterials

Metamaterials with a refractive index of zero exhibit properties that are important for integrated optics. Possessing an infinite effective wavelength and zero spatial phase change, zero-index metamaterials may be especially useful for routing on-chip photonic processes and reducing the footprint of nonlinear interactions. Zero-index has only been achieved recently in an integrated platform through a Dirac-cone dispersion, enabling some of these more exciting applications in an integrated platform. This paper presents an overview of Dirac-cone zero-index metamaterials, including the fundamental physics, history and demonstration in the optical regime, as well as current challenges and future directions.

Monolithic CMOS-compatible zero-index metamaterials (Conference Presentation)

Zero-index metamaterials exhibit exotic optical properties such as uniform spatial phase and infinite wavelength. These extreme properties can be utilized for integrated-optics applications. However, practical implementation of zero-index-based photonic devices requires compatibility with complementary metallic-oxide-semiconductor (CMOS) technologies. Zero-index metamaterials have been previously demonstrated in both out-of-plane and integrated configurations by taking advantage of a photonic Dirac-cone dispersion at the center of the Brillouin zone. Such metamaterials feature a square matrix of high aspect-ratio pillars and offer matched impedance through simultaneously zero effective permittivity and permeability. However, these configurations are inherently incompatible with integrated devices due to out-of-plane excitation, metallic inclusions, or high aspect-ratio structures. This work demonstrates a CMOS-compatible zero-index metamaterial consisting of a square array of air-holes in a 220-nm-thick silicon-on-insulator wafer. To experimentally verify the refractive index, we measure the angle of refraction of light through a triangular prism consisting of the metamaterial. The index is extracted using Snells Law to verify a refractive index of zero at a wavelength of 1625 nm. Through the air-hole in silicon configuration, the proportion of silicon is increased as compared to designs based on high aspect-ratio silicon pillars. This enables a platform with low-aspect-ratio features, improved confinement of transverse electric polarized light, as well as the original benefit of matched impedance. Featuring a trivial monolithic fabrication and capacity for integration with the expansive library of existing silicon photonic devices, this metamaterial enables implementation of proposed zero-index devices and offers a powerful platform for exploring the future applications of zero-index materials.