Metamaterial-Enhanced Nonlinear Terahertz SpectroscopyH. Y. Hwang, M. Liu, K. Fan, J. Zhang, A. C. Strikwerda, A. Sternbach, N. C. Brandt, B. G. Perkins, X. Zhang, R. D. Averitt and K. A. NelsonEPJ Web of Conferences, 41 (2013) 09005DOI: https://doi.org/10.1051/epjconf/20134109005