Noise and conversion performance of a high-Tc superconducting Josephson junction mixer at 0.6 THz

Abstract

This letter presents both theoretical and experimental investigations on the noise and conversion performance of a high-Tc superconducting (HTS) step-edge Josephson-junction mixer at the frequency of 0.6 THz and operating temperatures of 20 to 40 K. Based on the Y-factor and U-factor methods, a double-sideband noise temperature of around 1000 K and a conversion gain of -3.5 dB were experimentally obtained at 20 K. At the temperature of 40 K, the measured mixer noise and conversion efficiency are around 2100 K and -10 dB, respectively. The experimental data are in good agreement with the numerical analysis results using the three-port model. A detailed performance comparison with other reported HTS terahertz mixers has confirmed the superior performance of our presented mixer device.

The effects of nonlinear thermal fluctuation and series junction array on high-T c superconducting terahertz mixer performance

“…The hot blackbody was implemented by placing a piece of THz absorber in a metallic thermal-insulated container at room temperature (295 K), while the cold load was realized by pouring liquid nitrogen into the container until the absorber was immersed and liquid nitrogen boiling settled. The experimental set-up is similar to that shown in figure 2 in [15] except for two following modifications. First, two wire-grid polarizers (see figure 6) were utilized to adjust the THz LO power for achieving an optimum pumping condition.…”

“…A number of YBa 2 Cu 3 O 7-δ (YBCO) junction based HTS THz mixers or receivers have been reported in recent years [9][10][11][12][13][14][15][16][17][18][19], and considerable efforts have been made to improve their noise performance. By controlling impedance to achieve strongest resonant coupling between the junction and the radio-frequency (RF) environment, Scherbel et al developed a 345 GHz HTS Josephson mixer operating at 20 K with a noise temperature as low as 1003 K [9].…”

“…Based on our prior work in advanced device circuit designs, accurate parametric simulation and junction parameter optimization, we reported a 340 GHz HTS mixer with noise temperature of 470 and 780 K at temperatures of 20 and 40 K [19], respectively. The three-port theoretical model developed by Taur [20] has been applied to effectively predicting the noise performance of those HTS Josephson junction mixers [15]. However, as the increase of operating frequency and decrease of temperature, the white noise assumed thermal fluctuation in this model is no longer valid, since the Rayleigh-Jeans law would be broken and the influence of quantum noise must be considered [21].…”

Hot spot formation in focused-ion-beam-fabricated YBa2Cu3O7−x nanobridges with high critical current densities

“…Very recently, a high-temperature superconducting (HTS) mixer operating at 0.6 terahertz (THz) has been demonstrated for potential application in THz wireless communication and sensing [1]. The device used an HTS step-edge Josephson junction as the mixing element and a relatively low noise temperature was observed when measured using a two-stage pulse-tube cryocooler.…”

0.34- THz High-Temperature Superconducting Josephson-Junction Mixer with Superior Noise and Conversion Performance

“…Based on the CSIRO patented YBCO step-edge junction technology [1], we have achieved major research progress in developing HTS THz narrowband [2] and broadband [3] Josephson-junction mixers. These devices are capable of operating at temperatures up to 77 K (liquid nitrogen temperature) and have been demonstrated excellent mixer conversion gain and noise temperature [4]. In this work, we present our new development of a novel dual-meander-slot thin-film antenna-coupled HTS THz Josephson mixer that exhibits superior performance at the 0.34-THz band.…”