Detection of terahertz pulses using optical second-harmonic generation

In this summary, we describe the first demonstration of an electric field induced optical second harmonic (EFISH) sampling technique that allows for the detection of freely propagating THz radiation. In contrast to electro-optic sampling, which typically relies on the use of non-centrosymmetric ionic crystals, the present second-harmonic (SH) sampling technique is also applicable to centrosymmetric media. This is particularly important, since it creates the possibility for using materials with better suited low-frequency characteristics.