Non-perturbative four-wave mixing in InSb with intense off-resonant multi-THz pulses B. Mayer, F. Junginger, C. Schmidt, S. Mährlein, O. Schubert, A. Pashkin, R. Huber and A. Leitenstorfer EPJ Web of Conferences, 41 (2013) 04004 Published online: 13 March 2013 DOI: 10.1051/epjconf/20134104004