Abstract-Compact high- T c superconducting terahertz emitter operating up to 86 Kelvin

Hancong Sun, Raphael Wieland, Zuyu Xu, Zaidong Qi, Yangyang Lv, Ya Huang, Huili Zhang, Xianjing Zhou, Jun Li, Yonglei Wang, Fabian Rudau, Johannes S. Hampp, Dieter Koelle, Shigeyuki Ishida, Hiroshi Eisaki, Yoshiyuki Yoshida, Biaobing Jin, Valery P. Koshelets, Reinhold Kleiner, Huabing Wang, Peiheng Wu,

https://journals.aps.org/prapplied/accepted/c4071A2fE601520eb1472e406dee8430aae0a3f93

We report on a Stirling-cooled compact Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$ intrinsic Josephson-junction stack with very high critical current density and improved cooling, operating at bath temperatures $T_b$ up to 86\,K. The square stand-alone stack is embedded between two sapphire substrates. For bath temperatures between 27.8\,K and 86\,K emission was observed at frequencies from 0.356\,THz to 2.09\,THz. The emission power exceeded 1\,$\mu$W at bath temperatures between 60\,K and 80\,K for emission frequencies between 0.5\,THz and 0.88\,THz. A record high value of 0.577\,THz was obtained for the emission frequency at $T_b$ = 80\,K, which is important for potential applications using liquid nitrogen as coolant. We also compare our experimental results to numerical simulations based on 3D coupled sine-Gordon equations combined with heat diffusion equations.