Investigation of Phonon Polaritons in an hBN GaN Heterostructure

There have been many great advances in the generation and manipulation of optics in the visible and near infrared (IR) range over the past decade. This is largely due to plasmonic enhancement, which has led to new technology in biosensing and molecule detection, solid-state lighting, and solar energy harvesting. The field of plasmonics uses quanta of plasma oscillations, plasmons, formed from the interaction between electromagnetic radiation and free electrons to enhance optical near field magnitudes. However, there is still a large region of the electromagnetic spectrum, covering the mid-infrared (MIR) and terahertz (THz) regions, ranging from 3 μm to 1 mm, that has not benefitted from this research. Polaritonics have recently gained attention from the scientific community to access this region and enhance current technologies. Polaritons are an IR alternative to plasmons; these quasiparticles are formed from light coupling to an elementary material excitation, such as phonons, plasmons, magnons, or excitons. In this project, we look at the past, present, and future of terahertz technology and the role phonon polaritons play in their advancement. A hexagonal boron-nitride/gallium nitride superlattice is examined through simulated reflection experiments to identify phonon polariton modes