Abstract-Structural control of metamaterial oscillator strength and electric field enhancement at terahertz frequencies

G. R. Keiser^1,a), H. R. Seren², A. C. Strikwerda^1,3, X. Zhang² and R. D. Averitt^1,4
 HIDE AFFILIATIONS
1 Department of Physics, Boston University, Boston, Massachusetts 02215, USA
2 Department of Mechanical Engineering, Boston University, Boston, Massachusetts 02215, USA
3 Department of Photonics Engineering, Technical University of Denmark, DTU Fotonik, Kgs. Lyngby DK-2800, Denmark
4 Department of Physics, UC San Diego, La Jolla, California 92093, USA
a) grkeiser@physics.bu.edu
Appl. Phys. Lett. 105, 081112 (2014); http://dx.doi.org/10.1063/1.4894466

http://scitation.aip.org/content/aip/journal/apl/105/8/10.1063/1.4894466

The design of artificial nonlinear materials requires control over internal resonant charge densities and local electric field distributions. We present a MM design with a structurally controllable oscillator strength and local electric field enhancement at terahertz frequencies. The MM consists of a split ring resonator (SRR) array stacked above an array of closed conducting rings. An in-plane, lateral shift of a half unit cell between the SRR and closed ring arrays results in an increase of the MM oscillator strength by a factor of 4 and a 40% change in the amplitude of the resonant electric field enhancement in the SRR capacitive gap. We useterahertz time-domain spectroscopy and numerical simulations to confirm our results. We show that the observed electromagnetic response in this MM is the result of image chargesand currents induced in the closed rings by the SRR.