Millimetre and sub-mm wavelength radiation sources based on discrete Josephson junction arrays

This paper reviews the present status and future perspectives of discrete Josephson junction arrays for applications as sub-mm wavelength radiation sources. It is intended to cover the whole field, i.e. theory, fabrication and experimental results. The theoretical part reviews the fundamental aspects of Josephson junctions for oscillator applications and introduces the different possible array types. The recent results of analytical as well as numerical investigations are discussed. After the description of the fabrication of both low-Tc as well as high-Tc superconductor Josephson junctions and arrays, methods to investigate the array dynamics experimentally are mentioned. Finally, the recent experimental results are reviewed. This topic is divided into two parts, the first dealing with low-Tc arrays, the second with high-Tc arrays. The different possibilities to design arrays and to include them in practical applications are discussed and compared, with special emphasis on those experiments where radiation was generated successfully. The article is completed with a discussion of the most important experimental results. (author)