We experimentally demonstrate a sub-picosecond all-optical THz switch based on three-dimensional (3D) terahertz meta-atoms. The device enables a 280 GHz switch in resonance frequency within less than 200 fs. The switch back to the original resonance takes 800 fs. Experimental results show that the speed values are strongly convoluted by the THz probing field and, thus, the real switching times are even shorter, in the few 100 fs range. This ultrafast frequency switch can be combined with the ISB transition dipoles of parabolic quantum wells to operate in the strong coupling regime at room temperature. This system would constitute a valuable tool to investigate the dynamics of polariton build-up, along with the possibility to generate nonclassical states of light via the mechanism of dynamic Casimir radiation at room temperature.
P. Goulain, A. D. Koulouklidis, J.-M. Manceau, Ch. Daskalaki, B. Paulillo, K. Maussang, S. Dhillon, J. R. Freeman, L. Li, E. H. Linfield, S. Tzortzakis, and R. Colombelli, “Femtosecond Broadband Frequency Switch of Terahertz Three-Dimensional Meta-Atoms”, ACS Photonics 2021 8 (4), 1097-1102.