Coupling to external structures: Boundary conditions for the Bi2212-based superconducting THz emitter

Abstract

It is known that a mesa fabricated from intrinsic Josephson junctions of Bi2Sr2CaCu2O8+δ emits intense terahertz radiation at a certain frequency in accordance with the ac-Josephson relation and the general resonance conditions determined by the geometrical shape and dimensions. When more than two mesas are placed on the crystal surface, synchronization phenomenon of two mesas and the cavity resonance due to the coupling to the external structures outside the biased mesa are observed. These phenomena are interpreted by the current propagation effect through the superconducting substrate over the range of a few hundreds of μm even with the phase coherency. This opens up the possibilities of improving the individual device by external antenna and cavity, and of constructing the large-scale planer array of mesas for the purpose of power enhancement. © Published under licence by IOP Publishing Ltd.