Applications of metasurfaces in terahertz radiation generation and manipulation

Terahertz (THz) waves, positioned between microwave and optical frequencies in the electromagnetic spectrum, offer unique advantages for fundamental scientific research and emerging technological applications due to their distinct frequency range. THz waves are non-ionizing, can penetrate non-metallic and non-polar materials, and exhibit "fingerprint" spectral features of biomacromolecules, making them highly promising for applications in life sciences, communication technology, and physical sciences. To unlock the potential of THz waves, the development of novel, efficient THz sources and advanced techniques for complex light-field manipulation has become a critical area of research. This article focuses on innovative broadband coherent THz source technologies, active and passive control techniques for THz radiation, and the integration of these approaches to create metasurface-based THz sources. Special attention is given to spintronic THz sources and their combined applications with metasurfaces.