Date of Award

5-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Computer Engineering and Sciences

First Advisor

Brian A. Lail

Second Advisor

Josko Zec

Third Advisor

Che Xinxuan

Fourth Advisor

Philip Bernhard

Abstract

For any photonic-on-chip applications long propagation waveguides are critical. The use of plasmon polaritons for near-infrared and optical networks has been extensively studied for the purpose of achieving long propagation lengths, however, due to plasmonic polariton effects being negligible in mid- to long-wave infrared (IR) applications, phonon polaritons are required. In recent years, extensive research has been carried out on hexagonal boron nitride (h-BN), and it has been found that h-BN has naturally occurring sub-range phonon volume-constrained hyperbolic phonon polaritons (HPhPs). The numerical results in this thesis show both the long-range and short-range phonon volume polaritons modes in h-BN. A hybrid long-range phononic waveguide consisting of two identical dielectric cylinder wires symmetrically placed on each side of the h-BN slab is coupled to the long-range HPhP mode. Based on the analysis of coupled-mode theory and computational finite element analysis, the modal characteristics of hybrid long-range phonon-polariton waveguides are studied. Subwavelength confinement can be achieved due to the strong coupling between the high index cylindrical-waveguide mode and the HPhPs in the h-BN thin film. The modal area ranges from 10̄⁻²λ2/0 to 10⁻¹λ2/0, while exhibiting propagation distances 7λ₀-370λ₀.

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