Noise properties of HTS Josephson mixers at 345 GHz and operating temperatures at 20 K

High-Tc superconducting Josephson mixers for terahertz heterodyne detection

“…The junction presented in this study has a characteristic frequency, which is lower than the ones usually reported in grainboundary junctions or ramp edge junctions. [10][11][12]36 However, several developments can be made to optimize the I c R n product 37,38 in our junctions. In particular, a higher irradiation fluence combined with an annealing of the sample should lead to a significant improvement.…”

Toward terahertz heterodyne detection with superconducting Josephson junctions

“…4,5 Hence, it is important to develop HTS devices and related heterodyne mixer technology for applications in the THz range. However, despite a few promising realizations mainly based on grain-boundary or ramp edge junctions, [6][7][8][9] the development was slowed down by the difficulty to build a junction technology sufficiently reliable to fabricate complex devices. In recent years, an approach based on ion irradiation has been developed to make Josephson junctions with high temperature superconductors.…”

“…The back side of the sapphire substrate is placed in contact with a silicon hyper-hemispheric lens located at the focal point of a parabolic mirror exposed to external signals through the window of the cryostat. A cryogenic HEMT amplifier [4][5][6][7][8] amplifies the output signal at the intermediate frequency (IF) before further amplification at room temperature. An isolator is placed in the chain to minimize the back-action of the amplifier on the Josephson mixer.…”

“…[6][7][8][9] However, several developments can be made to optimize the I c R n product 20,21 in our junctions. In particular, a higher fluence of irradiation combined with an annealing of the sample should lead to a qualitative improvement.…”

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

“…For sub-millimeter and THz wave applications, due to the limited transmitting power and severe atmospheric absorption attenuation, 1 the system receivers are required to be extremely sensitive and thus capable of detecting the weak arriving signals. High-Tc superconducting (HTS) Josephson-junction mixers [2][3][4][5][6][7] have been shown to be promising candidates for THz receiver frontends considering their high sensitivity, low noise, low local oscillator (LO) power requirement, and relatively cheaper cryogenic costs compared to that for cooling low-Tc superconducting (LTS) devices.…”