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Proceedings Paper

Properties of infrared doped semiconductor Mie resonators (Presentation Recording)
Author(s): Tomer Lewi; Prasad P. Iyer; Nikita A. Butakov; Jon A. Schuller
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Paper Abstract

Dielectric optical antenna resonators have recently emerged as a viable alternative to plasmonic resonators for metamaterials and nanophotonic devices, due to their ability to support multipolar Mie resonances with low losses. In this work, we experimentally investigate the mid-infrared Mie resonances in Si and Ge subwavelength spherical particles. In particular, we leverage the electronic and optical properties of these semiconductors in the mid-infrared range to design and tune Mie resonators through free-carrier refraction. Si and Ge semiconductor spheres of varying sizes of 0.5-4 μm were fabricated using femtosecond laser ablation. Using single particle infrared spectroscopy, we first demonstrate size-dependent Si and Ge Mie resonances spanning the entire mid-infrared (2-16 μm) spectral range. Subsequently we show that the Mie resonances can be tuned by varying material properties rather than size or geometry. We experimentally demonstrate doping-dependent resonance frequency shifts that follow simple Drude models of free-carrier refraction. We show that Ge particles exhibit a stronger doping dependence than Si due to the smaller effective mass of the free carriers. Using the unique size and doping dispersion of the electric and magnetic dipole modes, we identify and demonstrate a size regime where these modes are spectrally overlapping. We also demonstrate the emergence of plasmonic resonances for high doping levels and long wavelengths. These findings demonstrate the potential for tuning infrared semiconductor Mie resonances by optically or electrically modulating charge carrier densities, thus providing an excellent platform for tunable electromagnetic metamaterials.

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9544, Metamaterials, Metadevices, and Metasystems 2015, 954414 (5 October 2015); doi: 10.1117/12.2187292
Show Author Affiliations
Tomer Lewi, Univ. of California Santa Barbara (United States)
Prasad P. Iyer, Univ. of California, Santa Barbara (United States)
Nikita A. Butakov, Univ. of California, Santa Barbara (United States)
Jon A. Schuller, Univ. of California, Santa Barbara (United States)

Published in SPIE Proceedings Vol. 9544:
Metamaterials, Metadevices, and Metasystems 2015
Nader Engheta; Mikhail A. Noginov; Nikolay I. Zheludev, Editor(s)

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