We investigate single-cycle terahertz (THz) field-induced nonlinear absorption in doped silicon carbide. We find that the nonlinear response is ultrafast, and we observe up to 20% reduction of transmission of single THz pulses at peak field strengths of 280 kV/cm. We model the field and temperature dependence of the nonlinear response by a finite-difference time-domain simulation that incorporates the temporally nonlocal nonlinear conductivity of the silicon carbide. Nonlinear two-dimensional THz spectroscopy reveals that the nonlinear absorption has an ultrafast subpicosecond recovery time, with contributions from both sum-frequency generation and four-wave mixing, in the form of a photon-echo signal. The ultrafast nonlinearity with its equally fast recovery time makes silicon carbide an interesting candidate material for extremely fast nonlinear THz modulators.
Tarekegne, A. T., Kaltenecker, K. J., Klarskov, P., Iwaszczuk, K., Lu, W., Ou, H., Norrman, K., & Jepsen, P. U. (2019). Subcycle Nonlinear Response of Doped 4H Silicon Carbide Revealed by Two-Dimensional Terahertz Spectroscopy. ACS Photonics, 7(1), 221-231. https://doi.org/10.1021/acsphotonics.9b01462