| Autor: |
Fan K; Department of Mechanical Engineering, Boston University, 110 Cummington Street, Boston, Massachusetts 02215, USA., Hwang HY, Liu M, Strikwerda AC, Sternbach A, Zhang J, Zhao X, Zhang X, Nelson KA, Averitt RD |
| Jazyk: |
angličtina |
| Zdroj: |
Physical review letters [Phys Rev Lett] 2013 May 24; Vol. 110 (21), pp. 217404. Date of Electronic Publication: 2013 May 21. |
| DOI: |
10.1103/PhysRevLett.110.217404 |
| Abstrakt: |
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. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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