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Some of terahertz detectors such as high temperature superconducting (HTS) YBa2Cu2Ox (YBCO) Josephson junction mixer are suffering from impedance mismatching problem with antenna where the junction impedance barely reaches several ohms. This paper presents two impedance matching methods based on impedance-wideband bow-tie antennas. First, a quarter of wavelength impedance matching network is proposed...
This paper presents a terahertz (THz) spectrometer based on high temperature superconducting Josephson junction. The YBa2Cu3O7 (YBCO) bi-crystal Josephson junctions (JJS) with log-periodic antennas are used as detectors. In the low temperature, with the signal measurement, data acquisition and human-computer interactive system, the automatic measurement system of THz spectrometer is finally accomplished...
To evaluate terahertz emission from intrinsic Josephson junctions, we used a YBa2Cu3O7−δ (YBCO) grain boundary Josephson junction as a terahertz detector. Shapiro steps have been clearly seen on the current-voltage curves of the YBCO junction irradiated with the emission from either a VDI-Tx-S140 transmitter (tens of μW at 620 GHz) or a Bi2Sr2CaCu2O8−x stack (25 μW at 500 GHz). While the harmonic...
In recent years coherent terahertz (THz) radiation from stacks containing nearly 1000 Bi2Sr2CaCu2O8 (BSCCO) intrinsic Josephson junctions (IJJs) has attracted a lot of research interest. However, in most cases, reported have been frequencies well below 1 THz, or typically around 500 GHz, which obviously can be a bottleneck for many applications. In our experiments, by optimizing sample structures...
Using a double-sided fabrication method, we fabricated Bi2Sr2CaCu2O8 (BSCCO) intrinsic Josephson junctions (IJJs) with a gold-BSCCO-gold structure. Coherent emission is observed at large dc input power, where a hot spot and “cold” part of the stack, coexist. The power, directly detected with a bolometer, is as high as 25 µW, implying the integrated power should be already in the order of sub-mW. We...
To evaluate terahertz emission from intrinsic Josephson junctions, we use a YBa2Cu3O7 grain boundary Josephson junction as a detector. Shapiro steps on the current-voltage characteristics of the detector were clearly observed and their positions moved with the bias voltage of the emitter accordingly. Analyzing the current-voltage characteristics of the detector, we found that the emission was tuned...
Using the Y-factor measurement method, we estimated the noise figure (NF) of the high temperature superconducting bi-crystal Josephson junction mixer. The experiment was based on small pulse tube refrigerator, working at 60 K. We tested and analysed the dependence of bias voltage and local oscillation signal power with the noise figure.
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