SrTiO₃, a near-field terahertz sensor

Nonlinear optics at spatially resolved terahertz (THz) frequencies under diffraction remains an almost unexplored field. We report here the performance of a bulk SrTiO3 (STO) crystal as a near-field sensor using a combination of a high-field terahertz source and a two-dimensional imaging capability. Thanks to the Kerr effect detection of THz waves, the STO sensor outperforms current Pockels effect-based near-field THz sensors. Furthermore, its ability to remain polarized for several picoseconds could pave the way for a new strategy to build an ultrafast space-time THz memory.