Near-Zero Index Materials for Low-Loss Integrated Photonics

The need of miniaturization and faster electronic devices resulted in the rise of photonics, with the big promise of light circuits with low heating. Then, new challenges have arisen, therefore exploring new exotic materials is the key to overcome them. In this thesis we describe a particular class of materials, named near-zero index materials. Their peculiar electromagnetic properties, such as enlargement of the wavelength, show great potential for enhancing transmission of a signal inside photonic waveguides. Besides, their constant phase property finds great applications in the field of quantum photonics, where information generated by quantum emitters can be preserved instead of degraded by the environment, causing decoherence. However their
realization still remains a challenge, as it requires very specific geometries to fulfil some requirements related to the effective medium theory. The first part of this PhD project is composed of a theoretical foundation where
we present novel possibilities and challenges of integrating such a materials with quantum emitters. In the next part we investigate potential plasmonic materials that could exhibit such low-index behaviour and show their experimental characterization and possible applications. The last part of the project includes design and experimental verification of a dielectric low-index material in a photonic crystal environment. We also explore the combination of near-zero index modes with bound states in the continuum (BIC) as a way to suppress radiative losses on-chip. Finally, we discuss the prospects of such combination and their great potential for photonic circuitry.