Generation of Terahertz Radiation via the Transverse Thermoelectric Effect

• Published in: Advanced materials (Weinheim) Vol. 35; no. 41; pp. e2305622 - n/a
• Main Authors: Yordanov, Petar, Priessnitz, Tim, Kim, Min‐Jae, Cristiani, Georg, Logvenov, Gennady, Keimer, Bernhard, Kaiser, Stefan
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.10.2023
• Subjects: Anisotropy; Broadband; Emitters; Femtosecond pulsed lasers; Femtosecond pulses; layered conducting transition metal oxides; Materials science; Nonlinear control; off‐cut thin films; Radiation; Spectral emittance; Substrates; terahertz generation; Thermoelectricity; Thin films; THz emission spectroscopy; Transition metal oxides; transverse thermoelectric effect; offcut thin films; transverse thermoelectric effect; terahertz generation; layered conducting transition metal oxides; THz emission spectroscopy
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202305622

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. Here, it is shown how the natural electronic anisotropy of layered conducting transition metal oxides enables the generation of intense terahertz radiation via the transverse thermoelectric effect. In thin films grown on off‐cut substrates, femtosecond laser pulses generate ultrafast out‐of‐plane temperature gradients, which in turn launch in‐plane thermoelectric currents, thus allowing efficient emission of the resulting THz field out of the film structure. This scheme is demonstrated in experiments on thin films of the layered metals PdCoO2 and La1.84Sr0.16CuO4, and model calculations that elucidate the influence of the material parameters on the intensity and spectral characteristics of the emitted THz field are presented. Due to its simplicity, the method opens up a promising avenue for the development of highly versatile THz sources and integrable emitter elements. Intense terahertz radiation generation via the transverse thermoelectric effect in layered conducting transition metal oxides is demonstrated . Ultrafast out‐of‐plane temperature gradients, induced by femtosecond laser pulses on thin films grown on off‐cut substrates, launch in‐plane thermoelectric currents leading to efficient THz emission. This approach offers a simple and promising avenue for versatile THz sources and integrable emitter elements.