Coherent Emission of Intrinsic Josephson Junctions at Zero-Field Steps

We investigated numerically IV-characteristics of the wide Josephson junction. Parameters of the junction were close to parameters of intrinsic junctions in high-temperature superconductors. We found zero-field steps in the IV-characteristic. These steps correspond to frequencies of even modes of geometrical resonances in the junction. Maxima of coherent emission appear around zero-field steps. The dependence of the difference between resonant frequencies on the reciprocal length of the junction is in agreement with the theory. We also discuss processes which lead to the excitation of the standing waves in the junction.