Where optics meets electronics: recent progress in decreasing the terahertz gap.

The terahertz region of the electromagnetic spectrum offers considerable opportunities for exploitation. Recent advances in source and coherent-detection technology have enabled advances to be made in a wide range of applications. This article reviews the historical development of the field, summarizes the current state of system technology and outlines a number of current system applications, including medical imaging. The limitations of present-day technology are discussed and some future possible applications are considered.