title: Widely Tunable Infrared Antennas Using Free Carrier Refraction.
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.
authors.affiliation: Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States.
authors.forename: Tomer
authors.initials: T
authors.lastname: Lewi
authors.affiliation: Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States.
authors.forename: Prasad P
authors.initials: PP
authors.lastname: Iyer
authors.affiliation: Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States.
authors.forename: Nikita A
authors.initials: NA
authors.lastname: Butakov
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Mikhailovsky
authors.affiliation: Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Schuller
keywords: Mie resonators; Optical antennas; free carrier refraction; semiconductor nanoparticles; silicon photonics; tunable metamaterials