Generation of Terahertz Radiation via The Transverse Thermoelectric Effect
Terahertz (THz) radiation is a powerful tool with widespread applications ranging from imaging, sensing, and broadband communications to spectroscopy and nonlinear control of materials. Future progress in THz technology depends on the development of efficient, structurally simple THz emitters that can be implemented in advanced miniaturized devices. Researchers at the Max Planck Institute for Solid State Research and their collaborators at the Universities of Stuttgart and Dresden have demonstrated the generation of terahertz radiation via the transverse thermoelectric effect in thin films of layered conducting transition metal oxides grown on offcut substrates, such that the highly conducting layers subtend an angle with the substrate plane. Ultrafast out-of-plane temperature gradients induced by femtosecond lasers launch in-plane thermoelectric currents leading to intense THz emission. The film geometry allows efficient emission of the resulting THz field out of the film structure. The experimental scheme does not require elaborate fabrication methods and complementary microstructure elements, and is not limited to a particular material or specific operational conditions. It thus offers a simple and promising avenue for versatile THz sources and integrable emitter elements.