Widely tunable infrared antennas using free carrier refraction.

TitleWidely tunable infrared antennas using free carrier refraction.
Publication TypeJournal Article
Year of Publication2015
AuthorsLewi T, Iyer PP, Butakov NA, Mikhailovsky AA, Schuller JA
JournalNano Letters
Volume15
Issue12
Start Page8188
Pagination8188–8193
Date Published12/2015
ISSN1530-6992
Keywords21975, AFOSR, CNSI/MRL, CSC, DOD-Grad, FBNS02, MRL, Schuller, UCOP
Abstract

We demonstrate tuning of infrared Mie resonances by varying the carrier concentration in doped semiconductor antennas. We fabricate spherical silicon and germanium particles of varying sizes and doping concentrations. Single-particle infrared spectra reveal electric and magnetic dipole, quadrupole, and hexapole resonances. We subsequently demonstrate doping-dependent frequency shifts that follow simple Drude models, culminating in the emergence of plasmonic resonances at high doping levels and long wavelengths. These findings demonstrate the potential for actively tuning infrared Mie resonances by optically or electrically modulating charge carrier densities, thus providing an excellent platform for tunable metamaterials.

URLhttp://dx.doi.org/10.1021/acs.nanolett.5b03679
DOI10.1021/acs.nanolett.5b03679
Grant: 
MRI R2 (CNS-0960316), CSC, MRL (DMR-1121053)