I propose a new mechanism of intense high-frequency electromagnetic wave generation by spatially uniform stacked Josephson junctions at zero magnetic field. The ac-Josephson effect converts the dc-bias voltage into ac-supercurrent, however, in the absence of spatial variation of Josephson phase difference, does not provide dc-to-ac power conversion, needed for emission of electromagnetic waves. Here I demonstrate that at geometrical resonance conditions, the spatial homogeneity of phase can be spontaneously broken by appearance of breathers (bound fluxon-antifluxon pairs), facilitating effective dc-to-ac power conversion. The proposed mechanism explains all major features of recently observed THz radiation from large area Bi2Sr2CaCu2O8+x mesa structures.
@article{arxiv.1010.6176,
title = {THz emission from intrinsic Josephson junctions at zero magnetic field via breather auto-oscillations},
author = {V. M. Krasnov},
journal= {arXiv preprint arXiv:1010.6176},
year = {2011}
}