Probing Near-Field Thermal Emission of Localized Surface Phonons from Silicon Carbide Nanopillars

TL;DR

This paper experimentally investigates the near-field thermal emission spectra of silicon carbide nanopillars, demonstrating tunability through structural modifications and revealing multiple localized surface phonon modes.

Contribution

First experimental demonstration of near-field thermal emission spectra of LSPhs from SiC nanopillars, showing tunability via structural parameters and coupling effects.

Findings

Spectral peaks of LSPhs are affected by nanopillar dimensions and coupling.

Multiple modes including dipole, quadrupole, octupole, and monopole are observed.

Near-field coupling influences the spectral location of emission peaks.

Abstract

Thermal emission of localized surface phonons (LSPhs) from nanostructures of polaritonic materials is a promising mechanism for tuning the spectrum of near-field thermal radiation. Previous studies have theoretically shown that thermal emission of LSPhs results in narrow-band peaks in the near-field spectra, whose spectral locations can be modulated by changing the dimensions of the nanostructure. However, near-field thermal emission of LSPhs has not been experimentally explored yet. In this study, we measure the spectrum of near-field thermal radiation from arrays of 6H-silicon carbide (6H-SiC) nanopillars using an internal-reflection-element based spectroscopy technique. We present an experimental demonstration of thermal emission of the transverse dipole, quadrupole, and octupole, as well as longitudinal monopole from 6H-SiC nanopillars at a near-field distance from the array. We show that the spectral location of the longitudinal monopole and transverse dipole are significantly affected by the near-field coupling between neighboring nanopillars as well as the intercoupling of the nanopillars and the substrate. We also experimentally demonstrate that the spectrum of near-field thermal radiation from 6H-SiC nanopillar arrays can be tuned by varying the dimensions of the nanopillars, providing an opportunity for designing emitters with tailored near-field thermal radiation.