[1] N. I. Zheludev, Y. S. Kivshar. From metamaterials to metadevices. Nat. Mater., 11, 917-924(2012).

[2] J. B. Pendry, A. J. Holden, D. Robbins, W. Stewart. Magnetism from conductors and enhanced nonlinear phenomena. IEEE Trans. Microwave Theory Tech., 47, 2075-2084(1999).

[3] I. V. Shadrivov, A. B. Kozyrev, D. W. van der Weide, Y. S. Kivshar. Tunable transmission and harmonic generation in nonlinear metamaterials. Appl. Phys. Lett., 93, 161903(2008).

[4] M. Lapine, I. V. Shadrivov, D. A. Powell, Y. S. Kivshar. Magnetoelastic metamaterials. Nat. Mater., 11, 30-33(2012).

[5] A. P. Slobozhanyuk, M. Lapine, D. A. Powell, I. V. Shadrivov, Y. S. Kivshar, R. C. McPhedran, P. A. Belov. Flexible helices for nonlinear metamaterials. Adv. Mater., 25, 3409-3412(2013).

[6] M. W. Klein, C. Enkrich, M. Wegener, S. Linden. Second-harmonic generation from magnetic metamaterials. Science, 313, 502-504(2006).

[7] K. O’Brien, H. Suchowski, J. Rho, A. Salandrino, B. Kante, X. Yin, X. Zhang. Predicting nonlinear properties of metamaterials from the linear response. Nat. Mater., 14, 379-383(2015).

[8] J. Zhou, D. R. Chowdhury, R. Zhao, A. K. Azad, H.-T. Chen, C. M. Soukoulis, A. J. Taylor, J. F. O’Hara. Terahertz chiral metamaterials with giant and dynamically tunable optical activity. Phys. Rev. B, 86, 035448(2012).

[9] M. Lapine, I. V. Shadrivov, Y. S. Kivshar. Colloquium: nonlinear metamaterials. Rev. Mod. Phys., 86, 1093-1123(2014).

[10] A. Minovich, J. Farnell, D. N. Neshev, I. McKerracher, F. Karouta, J. Tian, D. A. Powell, I. V. Shadrivov, H. H. Tan, C. Jagadish. Liquid crystal based nonlinear fishnet metamaterials. Appl. Phys. Lett., 100, 121113(2012).

[11] G. Keiser, K. Fan, X. Zhang, R. Averitt. Towards dynamic, tunable, and nonlinear metamaterials via near field interactions: a review. J. Infrared Millim. Terahertz Waves, 34, 709-723(2013).

[12] M. Seo, H. Park, S. Koo, D. Park, J. Kang, O. Suwal, S. Choi, P. Planken, G. Park, N. Park. Terahertz field enhancement by a metallic nano slit operating beyond the skin-depth limit. Nat. Photonics, 3, 152-156(2009).

[13] C. A. Werley, K. Fan, A. C. Strikwerda, S. M. Teo, X. Zhang, R. D. Averitt, K. A. Nelson. Time-resolved imaging of near-fields in THz antennas and direct quantitative measurement of field enhancements. Opt. Express, 20, 8551-8567(2012).

[14] M. Liu, H. Y. Hwang, H. Tao, A. C. Strikwerda, K. Fan, G. R. Keiser, A. J. Sternbach, K. G. West, S. Kittiwatanakul, J. Lu. Terahertz-field-induced insulator-to-metal transition in vanadium dioxide metamaterial. Nature, 487, 345-348(2012).

[15] K. Iwaszczuk, M. Zalkovskij, A. C. Strikwerda, P. U. Jepsen. Nitrogen plasma formation through terahertz-induced ultrafast electron field emission. Optica, 2, 116-123(2015).

[16] J. Zhang, X. Zhao, K. Fan, X. Wang, G.-F. Zhang, K. Geng, X. Zhang, R. D. Averitt. Terahertz radiation-induced sub-cycle field electron emission across a split-gap dipole antenna. Appl. Phys. Lett., 107, 231101(2015).

[17] A. C. Strikwerda, M. Zalkovskij, K. Iwaszczuk, D. L. Lorenzen, P. U. Jepsen. Permanently reconfigured metamaterials due to terahertz induced mass transfer of gold. Opt. Express, 23, 11586-11599(2015).

[18] C. Lange, T. Maag, M. Hohenleutner, S. Baierl, O. Schubert, E. Edwards, D. Bougeard, G. Woltersdorf, R. Huber. Extremely nonperturbative nonlinearities in GaAs driven by atomically strong terahertz fields in gold metamaterials. Phys. Rev. Lett., 113, 227401(2014).

[19] K. Fan, H. Y. Hwang, M. Liu, A. C. Strikwerda, A. Sternbach, J. Zhang, X. Zhao, X. Zhang, K. A. Nelson, R. D. Averitt. Nonlinear terahertz metamaterials via field-enhanced carrier dynamics in GaAs. Phys. Rev. Lett., 110, 217404(2013).

[20] A. T. Tarekegne, K. Iwaszczuk, M. Zalkovskij, A. C. Strikwerda, P. U. Jepsen. Impact ionization in high resistivity silicon induced by an intense terahertz field enhanced by an antenna array. New J. Phys., 17, 043002(2015).

[21] W. Kuehn, P. Gaal, K. Reimann, M. Woerner, T. Elsaesser, R. Hey. Terahertz-induced interband tunneling of electrons in GaAs. Phys. Rev. B, 82, 075204(2010).

[22] F. Su, F. Blanchard, G. Sharma, L. Razzari, A. Ayesheshim, T. Cocker, L. Titova, T. Ozaki, J.-C. Kieffer, R. Morandotti. Terahertz pulse induced intervalley scattering in photoexcited GaAs. Opt. Express, 17, 9620-9629(2009).

[23] H. Hirori, K. Shinokita, M. Shirai, S. Tani, Y. Kadoya, K. Tanaka. Extraordinary carrier multiplication gated by a picosecond electric field pulse. Nat. Commun., 2, 594(2011).

[24] H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, A. J. Taylor. Antireflection coating using metamaterials and identification of its mechanism. Phys. Rev. Lett., 105, 073901(2010).

[25] H.-T. Chen. Interference theory of metamaterial perfect absorbers. Opt. Express, 20, 7165-7172(2012).

[26] L. Huang, D. R. Chowdhury, S. Ramani, M. T. Reiten, S.-N. Luo, A. K. Azad, A. J. Taylor, H.-T. Chen. Impact of resonator geometry and its coupling with ground plane on ultrathin metamaterial perfect absorbers. Appl. Phys. Lett., 101, 101102(2012).

[27] H. R. Seren, J. Zhang, G. R. Keiser, S. J. Maddox, X. Zhao, K. Fan, S. R. Bank, X. Zhang, R. D. Averitt. Nonlinear terahertz devices utilizing semiconducting plasmonic metamaterials(2015).

[28] K.-H. Lin, C. A. Werley, K. A. Nelson. Nonlinear terahertz devices utilizing semiconducting plasmonic metamaterials. Appl. Phys. Lett., 95, 103304(2009).

[29] H.-T. Chen, W. J. Padilla, J. M. O. Zide, A. C. Gossard, A. J. Taylor, R. D. Averitt. Active terahertz metamaterial devices. Nature, 444, 597-600(2006).

[30] H. R. Seren, G. R. Keiser, L. Cao, J. Zhang, A. C. Strikwerda, K. Fan, G. D. Metcalfe, M. Wraback, X. Zhang, R. D. Averitt. Optically modulated multiband terahertz perfect absorber. Adv. Opt. Mater., 2, 1221-1226(2014).

[31]

[32] L. V. Keldysh. Ionization in the field of a strong electromagnetic wave. Sov. Phys. JETP, 20, 1307-1314(1965).

[33] C. L. Anderson, C. R. Crowell. Threshold energies for electron-hole pair production by impact ionization in semiconductors. Phys. Rev. B, 5, 2267-2272(1972).

[34] H. Bergner, V. Brückner, M. Lenzner, R. Strobel. Investigation of the field-dependent carrier mobility in GaAs by picosecond photoconductivity measurements. Phys. Stat. Sol. B, 150, 885-889(1988).

[35] X. Zhao, K. Fan, J. Zhang, H. R. Seren, G. D. Metcalfe, M. Wraback, R. D. Averitt, X. Zhang. Optically tunable metamaterial perfect absorber on highly flexible substrate. Sens. Actuators A, 231, 74-80(2015).