Nonlinear Terahertz Metamaterials via Field-Enhanced Carrier Dynamics in GaAs

Kebin Fan, Harold Y. Hwang, Mengkun Liu, Andrew Strikwerda, Aaron Sternbach, Jingdi Zhang, Xiaoguang Zhao, Xin Zhang, Keith A. Nelson, Richard D. Averitt

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We demonstrate nonlinear metamaterial split ring resonators (SRRs) on GaAs at terahertz frequencies. For SRRs on doped GaAs films, incident terahertz radiation with peak fields of ~20-160 kV/cm drives intervalley scattering. This reduces the carrier mobility and enhances the SRR LC response due to a conductivity decrease in the doped thin film. Above ~160 kV/cm, electric field enhancement within the SRR gaps leads to efficient impact ionization, increasing the carrier density and the conductivity which, in turn, suppresses the SRR resonance. We demonstrate an increase of up to 10 orders of magnitude in the carrier density in the SRR gaps on semi-insulating GaAs. Furthermore, we show that the effective permittivity can be swept from negative to positive values with an increasing terahertz field strength in the impact ionization regime, enabling new possibilities for nonlinear metamaterials.
Original languageEnglish
Article number217404
JournalPhysical Review Letters
Volume110
Issue number21
Number of pages5
ISSN0031-9007
DOIs
Publication statusPublished - 2013
Externally publishedYes

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