Experimental Investigation of a Broadband High-Temperature Superconducting Terahertz Mixer Operating at Temperatures Between 40 and 77 K

Abstract

This paper presents a systematic investigation of a broadband thin-film antenna-coupled high-temperature superconducting (HTS) terahertz (THz) harmonic mixer at relatively high operating temperature from 40 to 77 K. The mixer device chip was fabricated using the CSIRO established step-edge YBa2Cu3O7-x (YBCO) Josephson junction technology, packaged in a well-designed module and cooled in a temperature adjustable cryocooler. Detailed experimental characterizations were carried out for the broadband HTS mixer at both the 200 GHz and 600 GHz bands in harmonic mixing mode. The DC current-voltage characteristics (IVCs), bias current condition, local oscillator (LO) power requirement, frequency response as well as conversion efficiency under different bath temperatures were thoroughly investigated for demonstrating the frequency down-conversion performance.

Design, modelling and simulation of a monolithic high-T c superconducting terahertz mixer

“…Furthermore, it is found from figure 11 that the mixer has a relatively wide bias current range (more than 200 μA at PLO = -35 dBm) which further increases as the LO power rises. The achieved mixer conversion gain is around dB higher than the best reported results [8,10] improvement from our previous mixer results [10] assuming the same Josephson junction characteristics. Such a large improvement is mainly due to the removal of resistive connection losses between components, better signal coupling designs, and efficient signal isolation circuit for the RF, LO, and IF ports.…”

“…Due to the removal of resistive connection losses between components and better signal coupling design, significant performance improvement is expected from such a design. We shall show in this paper by modelling and simulation that significantly better mixer performance is indeed obtained based on the same Josephson junction parameters as that of the previously measured mixer [9,10]. To the best of our knowledge, this is the first attempt of designing a full on-chip HTS THz mixer receiver.…”

“…found that as shown in figure 3, the antenna has a high coupling efficiency achieving -3.1 dB at the resonant frequency of 600 GHz, and a 1.5-dB operating bandwidth of 570 to 627 GHz. The good results are attributed to an effective design for minimizing impedance mismatch loss, where the optimized antenna input resistance of 20 Ω at 600 GHz is relatively low, closer to the junction normal resistance (assumed 5 Ω here), than the antennas in earlier work [8][9][10][11]. Figure 3 also shows the axial ratio characteristics in the negative Z direction.…”

“…shows the simulated DC IVCs of the presented HTS THz mixer (assume T = 40 K, where the junction characteristics were extensively measured in previous work[9,10]). Clearly, the unpumped HTS Josephson junction exhibits a typical resistively-shunted-junction (RSJ) behaviour (see black curves).…”

Nonmonotonous temperature dependence of Shapiro steps in YBCO grain boundary junctions

“…Such abilities raise not only fundamental interest in HTSC JJs but also an active search for ways to practically use such JJs. In recent years, the limiting characteristics of detectors and mixers based on HTSC JJs [6][7][8][9][10][11] have been actively studied. Josephson junctions have also been used for various spectroscopic applications [12].…”