High-frequency electromagnetic interactions in multijunction Josephson structures

Studies performed in the last decade at Moscow State University and the Ins titute of Radio Engineering and Electronics of the Russian Academy of Scien ces and concerned with theoretical and experimental investigations of high- frequency interactions that result in synchronism in multijunction Josephso n structures are reviewed. Efficient methods for numerical analysis of the dynamics of multijunction Josephson structures in the presence of thermal f luctuations are developed. The domains of synchronism of Josephson oscillat ions in one- and two-dimensional arrays of Josephson junctions with lumped and distributed circuits of electrodynamic coupling are studied. It is show n that the width of a synchronous-generation line in structures with lumped parameters decreases with increasing number of Josephson junctions only as long as this number is smaller than the effective radius of interaction be tween the junctions. It is found that, in structures with distributed param eters, the width of the Josephson generation line may decrease inversely pr oportional to the number of Josephson junctions and the number of distribut ed coupling elements. Technology for producing the high-temperature bicryst al Josephson junctions feasible for manufacturing the multijunction structu res based on these junctions and designed for operation in the millimeter a nd submillimeter regions of the spectrum was developed. The results of stud ying bicrystal Josephson junctions and arrays of junctions with distributed coupling circuits designed to operate at dc and in the millimeter waveleng th region of the spectrum are reported.