National Institute for Materials Science, Tsukuba 3050047, Japan.
Phys Rev Lett. 2010 Jul 30;105(5):057002. doi: 10.1103/PhysRevLett.105.057002. Epub 2010 Jul 28.
We report on THz emission measurements and low temperature scanning laser imaging of Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks. Coherent emission is observed at large dc input power, where a hot spot and a standing wave, formed in the "cold" part of the stack, coexist. By changing bias current and bath temperature, the emission frequency can be varied by more than 40%; the variation matches the Josephson-frequency variation with voltage. The linewidth of radiation is much smaller than expected from a purely cavity-induced synchronization. Thus, an additional mechanism seems to play a role. Some scenarios, related to the presence of the hot spot, are discussed.
我们报告了 Bi2Sr2CaCu2O8 本征约瑟夫森结堆的太赫兹发射测量和低温扫描激光成像。在大直流输入功率下观察到相干发射，其中热点和驻波在“冷”部分的堆栈中同时存在。通过改变偏置电流和浴温，可以将发射频率变化超过 40％；变化与电压的约瑟夫森频率变化匹配。辐射的线宽比仅由腔诱导同步引起的预期小得多。因此，似乎存在另一种机制在起作用。讨论了一些与热点存在有关的情况。
