Restrahlen to T-rays - 100 Years of terahertz radiation

Abstract

Although a reliable source of subpicosecond terahertz (THz) pulses, or T-rays, was demonstrated in the late 1980s, it was not until 1995, when they were used for imaging, that their full potential was realized. However, much of the publicity at that time seemed to suggest that very little research had taken place in the THz (or far-infrared) region before then. With the - largely new - present-day interest in biological applications of THz radiation it is apposite to review the opening up of this spectral region over the past hundred years. This paper attempts to show many of the significant developments in sources, detectors and spectroscopic systems for the THz region and includes brief descriptions of some of the more important applications and outcomes of the research. T-rays are only one of a number of very significant arrivals on the THz scene in recent years. It does seem an ideal time to pursue the exciting biological applications of THz radiation which are to be discussed at this Workshop.