Integrated photonics with near-zero index materials

Near-zero index (NZI) materials have gained attention due to their properties, which enable peculiar effects such as extraordinary transmission in extremely thin or corrugated waveguides, enhancement of electric field, wave front shaping, etc. The functionalities that NZI materials can grant bring great prospects toward implementation of such materials in photonic on-chip devices. In this chapter, we present a theoretical overview of the most intriguing yet useful characteristics of low-index materials and their prospective applications. We first classify different examples of NZI materials and their optical properties. We extend our analysis by showing efficient tunneling of radiation through different waveguide configurations aiming for better distribution of both classical and quantum information on-chip. Besides the almost complete transmission, radiation inside such materials experiences constant phase propagation, which can find great applications in the field of quantum photonics. In NZI materials, information generated by quantum emitters can be preserved instead of degraded by the environment. We also show an example of how the NZI properties can be invoked in an all-dielectric platform on the basis of photonic crystal configurations. Specified examples support the claim for rich potential of materials exhibiting very low refractive indices in various nanophotonic applications.