We present an extreme skin-depth (e-skid) waveguide scheme, whose evanescent field is suppressed significantly. We demonstrate it on a monolithic silicon chip, reducing the waveguide crosstalk and bending loss for a high-density photonic chip integration.

Ultra-compact, densely integrated optical components manufactured on a CMOS-foundry platform are highly desirable for optical information processing and electronic-photonic co-integration. However, the large spatial extent of evanescent waves arising from nanoscale confinement, ubiquitous in silicon photonic devices, causes significant cross-talk and scattering loss. Here, we demonstrate that anisotropic all-dielectric metamaterials open a new degree of freedom in total internal reflection to shorten the decay length of evanescent waves. We experimentally show the reduction of cross-talk by greater than 30 times and the bending loss by greater than 3 times in densely integrated, ultra-compact photonic circuit blocks. Our prototype all-dielectric metamaterial-waveguide achieves a low propagation loss of approximately 3.7±1.0 dB/cm, comparable to those of silicon strip waveguides. Our approach marks a departure from interference-based confinement as in photonic crystals or slot waveguides, which utilize nanoscale field enhancement. Its ability to suppress evanescent waves without substantially increasing the propagation loss shall pave the way for all-dielectric metamaterial-based dense integration.

The miniaturization of optical devices with low power consumption on CMOS platforms can pave the way for densely integrated photonic circuits. A major roadblock in this process is the large skin depth of evanescent light waves generated in nanoscale light confinement. In this paper, we demonstrate the roll of multilayer anisotropic alldielectric metamaterials in the control of evanescent waves. This fundamentally new approach uses optical waveguides with an average index higher in the cladding compared to that of the core. It marks a completely different approach of light confinement compared to photonic crystal and slot waveguides. These devices are a scalable process and can be implemented on a CMOS platform which will lead to a large impact on future devices designs in photonic integrated circuits.

Metamaterials are nano-engineered media with designed properties beyond those available in nature with applications in all aspects of materials science. In particular, metamaterials have shown promise for next generation optical materials with electromagnetic responses that cannot be obtained from conventional media. We review the fundamental properties of metamaterials with hyperbolic dispersion and present the various applications where such media offer potential for transformative impact. These artificial materials support unique bulk electromagnetic states which can tailor light-matter interaction at the nanoscale. We present a unified view of practical approaches to achieve hyperbolic dispersion using thin film and nanowire structures. We also review current research in the field of hyperbolic metamaterials such as sub-wavelength imaging and broadband photonic density of states engineering. The review introduces the concepts central to the theory of hyperbolic media as well as nanofabrication and characterization details essential to experimentalists. Finally, we outline the challenges in the area and offer a set of directions for future work.