Variation of Longitudinal Plasma Wavelength under Irradiation and Double   Resonance in Coupled Josephson Junctions
  The effect of electromagnetic wave irradiation on the phase dynamics of intrinsic Josephson junctions in high temperature superconductors is investigated. We predict three novel effects by variation of the radiation amplitude and frequency: changing of the longitudinal plasma wavelength at parametric resonance; double resonance of the Josephson oscillations with radiation and longitudinal plasma wave; charging of superconducting layers in the current interval corresponding to the Shapiro step. The "bump" structure in IVC recently observed experimentally is demonstrated. We also observe ragged Shapiro steps at double resonance. 
Yu. M. Shukrinov, I. R. Rahmonov, and M. A. Gaafar
cond-mat.supr-con