  On a slice of Bi_2Sr_2CaCu_2O_{8+x} 200~300 nm thick, stacks of intrinsic
Josephson junctions are patterned, connected to each other, and integrated with
a bow-tie antenna and some chokes. Over an area of 150 microns by 170 microns,
so far we are able to fabricate up to 256 stacks with over 11,000 junctions.
Such 3-dimensional arrays of intrinsic Josephson junctions respond sensitively
to irradiation at 760 GHz from a far-infrared laser, showing clear
zero-crossing Shapiro steps up to 0.75 V. In addition, possible applications in
quantum voltage standard etc are also discussed here. The high density of
integration of Josephson junctions is also promising for many other
applications.
