Terahertz Detectors Based On HTS YBCO Bi-crystal Junction

Terahertz(THz)wave is the last wave band to be fully researched and developed in electromagnetic spectrum.In recent years,the development of the terahertz wave sources and detection technology promot the development and application of THz wave.High temperature superconducting(HTS)Josephson junction has highly nonlinear and good characteristics such as high frequency response.THZ detector based on these characteristics has high sensitivity,low noise factor,wide working frequency band and so on.This paper has been successfully prepared HTS Josephson bi-crystal junction of stable performance and harmonic mixing experiment,measured and analyzed the noise coefficient influence on the performance of mixer,improved Josephson junction plane antenna and the basic measurement analysis.The specific contents as follows:1)The preparation methods and technology of THz detector for HTS YBCO junction have been studied.The bi-crystal junctions with stable performance and bridge of different size width were successfully prepared.A HTS THz detection system based on the GM refrigerator has been developed.Carried on tests to YBCO junction with bridge of 1 ?m*6?m size,we found it achieved good respond to 623 GHz signal.The harmonic number achieved more than 220 times.The results show that our HTS Josephson junction have high sensitivity in the high frequency band.2)The basic performance of the THz mixer is analyzed.The paper analysised the basic performance of the THz mixing detector.The HTS Josephson detector noise coefficient was measured and calculated.The results show the minimum noise coefficient of system is about 11 dB with 220 GHZ signal radiation.Due to the lack of performance of the pulse tube refrigerator,a simple design improvement was made based on the original design.3)In order to strengthen the coupling of Josephson junction to terahertz signal,the structures of butterfly antenna and impedance matching structure were designed.Terahertz detectors with 4 ?m micro bridge width were developed.We measured the affect of the signal power to Shapiro bench height under the different frequency,obtained the resonance frequency of the antenna and verified.The results show that this kind of antenna structure can effectively improve the available power of the detector.