MICROWAVE-INDUCED STEPS IN JOSEPHSON-JUNCTIONS, DC-SQUIDS AND PARALLEL ARRAYS

We have studied the characteristics of Shapiro steps in DC-SQUIDs and parallel Josephson junction arrays by means of numerical circuit simul ation within the RCSJ model. Particular interest was dedicated to the occurence of fractional (subharmonic) steps, looking for possible rela tions to recent observations of this effect in high-T-C junctions. Bes ides this, some new, peculiar effects in the dependence of step height vs. RF amplitude have been found, that correspond to characteristics measured on high-T-C junctions and SQUIDs. The results cast be useful for characterizing experimental Josephson junctions and circuits by st udying dependencies of Shapiro steps.