We designed, fabricated and tested short one dimensional arrays of masked ion-irradiated YBa2Cu3O7 Josephson junctions (JJ) embedded into log-periodic spiral antennas. Our arrays consist of 4 or 8 junctions separated either by 960~nm or 80~nm long areas of undamaged YBCO. Samples with distanced junctions and with closely spaced junctions showed qualitatively different behaviors. Well separated arrays demonstrated giant Shapiro steps in the hundreds-GHz band at 66K and were tested as Josephson mixers with improved impedance matching. All closely spaced arrays behaved as one junction with a lower superconducting transition temperature, hence forming a single weak link on distances up to 880~nm. Such design opens a new way to increase the IcRN product of ion-irradiated junctions and we speculate that the phenomena and physics behind it might be similar to the so-called "giant" Josephson coupling observed in cuprates.
@article{arxiv.1701.02320,
title = {Ion-irradiated YBa$_2$Cu$_3$O$_7$ Josephson arrays},
author = {A. Sharafiev and M. Malnou and C. Feuillet-Palma and C. Ulysse and P. Febvre and J. Lesueur and N. Bergeal},
journal= {arXiv preprint arXiv:1701.02320},
year = {2017}
}