2019 Volume 88 Issue 11 Pages 725-729
Since the discovery of continuous, coherent THz radiation from a mesa structure of intrinsic Josephson junction fabricated on a single crystal of Bi2Sr2CaCu2O8+δ in 2007, intensive studies, not only of the basic physics but also of applications, have been performed. So far, the best performance has been achieved within the frequency range from 0.3 to 11 THz, with the maximum output power of 30 µW, and with a spectral width of the coherent and continuous emission of THz radiation that is generally less than 0.5 GHz. Furthermore, a synchronized operation of an array of three such emitters was reported to yield the greatly enhanced power of 610 µW. We describe a brief overview of the development of superconducting THz emitters.