Superconducting Emitter Powered at 1.5 Terahertz by an External Resonator

Abstract

A different type of terahertz emitter is made by coupling a source mesa fabricated from the intrinsic Josephson junctions present in single-crystalline high-${T}_{c}$ superconducting ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{Ca}\mathrm{Cu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ ($\mathrm{Bi}2212$) to a much larger and impedance-matched external resonator with resonance frequencies up to 1.5 THz. The lateral dimensions of the source mesa are only $20\ifmmode\times\else\texttimes\fi{}20\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}{\mathrm{m}}^{2}$, about 0.5%--3% of those of conventional $\mathrm{Bi}2212$ mesas, but its thickness of $2\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ is comparable to them. The observed emission frequencies that lie near to 1.5 THz match very well the resonance frequencies of the external resonator. This result ensures that the functions of resonator and antenna are separated from that of the THz current source in the $\mathrm{Bi}2212$ mesa structure. These facts allow for much greater flexibility in the emitter design to achieve higher power and higher frequency THz wave sources.