The nonlinearity of the refractive index of optical media in the terahertz spectral rangeA.N. Tcypkin, S.E. Putilin, M.S. Kulya, A.A. Drozdov, M. Siddiqui, S. Choudhary, J. Zhao, V.G. Bespalov, R.W. Boyd, X.C. Zhang and S.A. KozlovEPJ Web Conf., 149 (2017) 05005DOI: https://doi.org/10.1051/epjconf/201714905005