Terahertz fields and applications

Terahertz signals were until recently an almost unexplored area of research due to the difficulties in generation and detection of electromagnetic fields at these wavelengths. Neither optical nor microwave techniques are directly applicable in the terahertz range since optical wavelengths are too short and microwave wavelengths are too long compared to terahertz field wavelengths. The development of ultrafast optical techniques, the manufacturing of semi-insulating semiconductors with very short lifetimes and of band-engineered heterostructures, as well as the micromachining techniques and nanotechnology have boosted the terahertz fields as a new area of research in quantum electronics with many important applications. The paper reviews the most recent results in THz fields and is focused on the physical principles of terahertz generators and receivers, underlining the link between terahertz devices and modern technologies such as micromachining and nanotechnology.