Light-matter interactions: Plasmon & phonon polaritons in refractory nitrides for nanophotonics

Abstract

The subject of light-matter interactions is of importance from fundamental science to technological aspects covering physics, chemistry, materials, electrical and optical engineering. Classically, light-matter interactions are the result of an oscillating electromagnetic (EM) field resonantly interacting with charged particles. Quantum mechanically, quantized light fields (or photon) couple to quantum states of matter. When light enters a medium, unlike propagation in a vacuum, its propagation is affected by the interaction with the material. An EM wave can cause excitation of material if it resonates with an electronic oscillator (or electric dipole) in the medium. Polaritons are hybrid quasiparticles formed by the strong coupling of electromagnetic waves to an electric dipole. Polaritons have the unique property of having a high wavenumber, which allows them to confine light to subwavelength scales, enabling the imaging and manipulation of nanoscale objects beyond the diffraction limit of light. They can also enhance absorption and emission processes in materials, leading to more efficient energy conversion and optoelectronic devices. Polaritons have been used to achieve room temperature condensation, a phenomenon in which a macroscopic fraction of particles occupies the same quantum state, leading to novel quantum fluid behavior. In addition, polaritons can exhibit strong nonlinear behavior, making them attractive for nonlinear optics applications such as all-optical switching and signal processing.