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.

Abstract-Linewidth dependence of coherent terahertz emission from Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks in the hot-spot regime

http://prb.aps.org/abstract/PRB/v86/i6/e060505
Mengyue Li^1,2, Jie Yuan^2,3,*, Nickolay Kinev⁴, Jun Li^2,5, Boris Gross⁶, Stefan Guénon⁶, Akira Ishii², Kazuto Hirata², Takeshi Hatano², Dieter Koelle⁶, Reinhold Kleiner⁶, Valery P. Koshelets⁴, Huabing Wang^1,2,†, and Peiheng Wu^1 
1Research Institute of Superconductor Electronics, Nanjing University, Nanjing 210093, China
²National Institute for Materials Science, Tsukuba 3050047, Japan
³Department of Applied Physics, Wuhan University of Science and Technology, Wuhan 430081, China
⁴Kotel'nikov Institute of Radio Engineering and Electronics, Moscow 125009, Russia
⁵Hokkaido University, Hokkaido 0600810, Japan
⁶Physikalisches Institut and Center for Collective Quantum Phenomena in LISA⁺, Universität Tübingen, D-72076 Tübingen, Germany

 Received 3 April 2012; revised 20 July 2012; published 8 August 2012

We report on measurements of the linewidth Δf of terahertz radiation emitted from intrinsic Josephson junction stacks, using a Nb/AlN/NbN integrated receiver for detection. Previous resolution-limited measurements indicated that Δf may be below 1 GHz—much smaller than expected from a purely cavity-induced synchronization. While at low bias we found Δf to be not smaller than ∼500 MHz, at high bias, where a hot spot coexists with regions which are still superconducting, Δfturned out to be as narrow as 23 MHz. We attribute this to the hot spot acting as a synchronizing element. Δf decreases with increasing bath temperature, a behavior reminiscent of motional narrowing in NMR or electron spin resonance (ESR), but hard to explain in standard electrodynamic models of Josephson junctions.

©2012 American Physical Society

URL:

http://link.aps.org/doi/10.1103/PhysRevB.86.060505

DOI:

10.1103/PhysRevB.86.060505

PACS:

74.50.+r, 74.72.-h, 85.25.Cp

^*phy.wust@gmail.com

^†hbwang1000@gmail.com