3. Conclusion

Since the renaissance of terahertz electromagnetic wave science in the 1980s-1990s, this field has been the subject of a huge number of studies. Knowledge and technology have progressed enormously. Today, research in this field is carried out in many countries on all five continents, by several hundred laboratories and companies. Fundamental research using terahertz waves as an investigative tool has produced remarkable results. However, applications and transfer to industry have not yet reached the level hoped for 10 or 20 years ago. Some devices and techniques, such as temporal spectroscopy in the terahertz range (THz-TDS), are now mature. Other components still need to be improved, in terms of performance, reliability, compactness and, above all, cost. This is the case, for example, with terahertz radiation sources. For active components such as sources and detectors, it seems that microelectronic...