Tunable plasmonic wires at terahertz frequencies

We employed micro-electro-mechanical system (MEMS) techniques to fabricate parallel sub-wavelength thin-wire structures of metals on elastomeric matrices. From the transmission measurement by Fourier Transform Infrared Spectroscopy, we observed the depressed plasma frequencies of these thin-wire structures at terahertz (THz) ranges. Furthermore, the behavior of depressed plasma frequencies is very sensitive to the polarization of the applied field. The reasons that these engineered materials exhibit unprecedented properties not observed in nature can be interpreted by two factors: the diluted electron densities and the enhancement of electron mass. In addition, the plasma frequencies are readily tunable over a broad frequency range by extending the elastomeric matrices to change their periodicity. These novel properties of tunable and polarization-dependant plasma frequencies at THz ranges promise abundant striking applications in THz optics.