Van der Waals phonon polariton microstructures for configurable infrared electromagnetic field localizations

TL;DR

This paper demonstrates how patterning van der Waals crystals into microstructures enables control over phonon polariton interference, allowing for customizable infrared electromagnetic field localization at the nanoscale.

Contribution

It introduces a method to engineer infrared light flow by patterning vdW crystals to support anisotropic phonon polaritons, enabling tunable field localizations.

Findings

Enhanced phonon polariton interference in microstructured crystals.

Control of electromagnetic field localization through microstructure orientation.

Tunable infrared light flow by adjusting microstructure size, shape, and excitation frequency.

Abstract

Polar van der Waals (vdW) crystals that support phonon polaritons have recently attracted much attention because they can confine infrared and terahertz (THz) light to deeply subwavelength dimensions, allowing for the guiding and manipulation of light at the nanoscale. The practical applications of these crystals in devices rely strongly on deterministic engineering of their spatially localized electromagnetic field distributions, which has remained challenging. This study demonstrates that polariton interference can be enhanced and tailored by patterning the vdW crystal {\alpha}-MoO3 into microstructures that support highly in-plane anisotropic phonon polaritons. The orientation of the polaritonic in-plane isofrequency curve relative to the microstructure edges is a critical parameter governing the polariton interference, rendering the configuration of infrared electromagnetic field localizations by enabling the tuning of the microstructure size and shape and the excitation frequency. Thus, our study presents an effective rationale for engineering infrared light flow in planar photonic devices.