Metamaterial-Enhanced Nonlinear Terahertz Spectroscopy
1 Massachusetts Institute of Technology, Department of Chemistry, Cambridge, MA 02139 USA
2 Boston University, Department of Physics, Boston, MA 02215 USA
3 Boston University, Department of Mechanical Engineering, Boston, MA 02215 USA
We demonstrate large nonlinear terahertz responses in the gaps of metamaterial split ring resonators in several materials and use nonlinear THz transmission and THz-pump/THz-probe spectroscopy to study the nonlinear responses and dynamics. We use the field enhancement in the SRR gaps to initiate high-field phenomena at lower incident fields. In vanadium dioxide, we drive the insulator-to-metal phase transition with high-field THz radiation. The film conductivity increases by over two orders of magnitude and the phase transition occurs on a several picosecond timescale. In gallium arsenide, we observe high-field transport phenomena, including mobility saturation and impact ionization. The carrier density increases by up to ten orders of magnitude at high fields. At the highest fields, we demonstrate THz-induced damage in both vanadium dioxide and gallium arsenide.
© Owned by the authors, published by EDP Sciences, 2013
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