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Widely Tunable Infrared Antennas Using Free Carrier Refraction
Tomer Lewi1, Prasad P Iyer1, Nikita A Butakov1
1Department of Electrical and Computer Engineering and ‡Department of Chemistry and Biochemistry, University of California , Santa Barbara, California 93106, United States.
Nano Letters
|November 18, 2015
Summary
We show how to tune infrared Mie resonances in semiconductor antennas by changing their carrier concentration. This work offers a new platform for creating tunable metamaterials by controlling charge carrier densities.
Area of Science:
- Nanophotonics
- Metamaterials
- Semiconductor physics
Background:
- Mie resonances in semiconductor nanoparticles are crucial for nanophotonic applications.
- Controlling these resonances is key to developing tunable optical devices.
Purpose of the Study:
- To demonstrate the tuning of infrared Mie resonances in doped semiconductor antennas.
- To explore the relationship between carrier concentration and resonance frequencies.
Main Methods:
- Fabrication of spherical silicon and germanium particles with varying sizes and doping levels.
- Measurement of single-particle infrared spectra to identify various Mie resonances.
- Analysis of doping-dependent frequency shifts using the Drude model.
Main Results:
- Observed electric and magnetic dipole, quadrupole, and hexapole resonances.
- Demonstrated frequency shifts dependent on doping levels, consistent with the Drude model.
- Observed the emergence of plasmonic resonances at high doping concentrations and long wavelengths.
Conclusions:
- Carrier concentration in doped semiconductor antennas can effectively tune infrared Mie resonances.
- This provides a pathway for actively controlling optical properties of metamaterials.
- The findings establish a versatile platform for tunable infrared devices.
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