Superconducting detectors with high-speed and high-resolution at THz band.

利用由YBa_2Cu_3O_<7-x> (YBCO)制成的高Tc超导（HTS）晶界Josephson结（GBJJs），我们成功地实现了频率高达2.5 THz、工作温度高达70K的宽带探测。此外，在2.5太赫兹范围内，零偏置电压和有限偏置电压下的高次谐波混频也得到了证明。详细研究了外加直流磁场对GBJJs太赫兹响应的影响。在直流电场作用下，高质量的宽gbjj的夏皮罗阶跃高度得到了提高。对于这种影响，采用等效双结SQUID模型进行了仿真。结果表明，所得结果与仿真结果吻合较好。因此，外置直流磁场的高质量宽gbj可能比小gbj更适用于太赫兹波段的探测系统。此外，利用高温超导gbjs可以简单地在低温下表征高温超导平面天线，这有助于改善器件与太赫兹信号之间的耦合。在此基础上，利用准光学技术，设计并实现了将整个系统体积最小化的心灵冰箱探测系统。在小型制冷机中加载HTS GBJJs时，测量了其太赫兹响应，发现形成的系统工作良好。最后，为了在短时间内简单地进行测量，我们开发了一个带有希尔伯特变换等的程序来收集和分析真实数据。结果表明，利用高温超导gbjs形成高速、高分辨率的高温探测系统是很有希望的。

Using high Tc superconducting (HTS) grain boundary Josephson junctions (GBJJs) made of YBa_2Cu_3O_<7-x> (YBCO) deposited across bicrystal boundary, we have successfully demonstrated wide band detections at frequency as high as 2.5 THz and at operating temperature up to 70K.Also, up to 2.5 THz, the high-order harmonic mixing at zero and finite bias voltage have been demonstrated. The effect of applied dc magnetic field on the THz responses of GBJJs has been investigated in detail. The enhancement of the Shapiro step height could be obtained in the high-quality wider GBJJs when a dc field was applied. For this effect, simulation by an equivalent double-junction SQUID model is justified. It was found that the obtained restults agreed with the simulation results very well. So, the high-quality wider GBJJs with an external dc magnetic field may be more useful than the small GBJJs for detecting system at THz band. Also, it was found that the HTS planar antenna, which is useful to improve the coupling between the devices and THz signals, could be simply characterized at low temperature using HTS GBJJs. Furthermore, using the quasi-optical technology, the detecting system with a mind-refrigerator, which will minimize the whole system, has been designed and made-up. The THz responses have been measured when the HTS GBJJs was load in the small-sized refrigerator and it was found the formed system worked quite well. Finally, to make the measurements simply during a short time, a program with Hilbert transform and so on has been developed to collect and analyze tlue data. The results show that it is very hopeful using HTS GBJJs to form the detecting system with high-speed and high-resolution operating at the high temperature.