THz Mixing with High-TC Hot Electron Bolometers: A Performance Modeling Assessment for Y-Ba-Cu-O Devices

Abstract

Hot electron bolometers (HEB) made from high-TC superconducting YBa2Cu3O7–x (YBCO) oxide nano-constrictions are promising THz mixers, due to their expected wide bandwidth, large mixing gain, and low intrinsic noise. The challenge for YBCO resides, however, in the chemical reactivity of the material and the related aging effects. In this paper, we model and simulate the frequency dependent performance of YBCO HEBs operating as THz mixers. We recall first the main hypotheses of our hot spot model taking into account both the RF frequency effects in the YBCO superconducting transition and the nano-constriction impedance at THz frequencies. The predicted performance up to 4 THz is given in terms of double sideband noise temperature TDSB and conversion gain G. At 2.5 THz for instance, TDSB  1000 K and G 6 dB could be achieved at 12.5 W local oscillator power. We then consider a standoff target detection scheme and examine the feasibility with YBCO devices. For instance, detection at 3 m through cotton cloth in passive imaging mode could be readily achieved in moderate humidity conditions with 10 K resolution.

Roadmap of Terahertz Imaging 2021

“…Although cryo-cooling has advanced enormously and closed-cycle cooling units avoid the costs for the delivery of cryogenic liquids, it seems that THz (security) scanners which require sub-10 K cooling are not accepted commercially. It is an interesting question whether detectors based on high-T C superconductors [425,426] could lead to a change.…”

Fast and Uncooled Semiconducting Ca-Doped Y-Ba-Cu-O Thin Film-Based Thermal Sensors for Infrared

“…YBa 2 Cu 3 O 6+ x is well known as a high-critical-temperature superconductor for an oxygen content x higher than 0.7. This superconducting phase has been largely explored for developing cooled highly sensitive hot electron nanobolometers for terahertz waves [ 18 , 19 ]. But YBCO also exhibits a semiconducting phase when oxygen depleted (with x < 0.5), which has been explored for the development of pyroelectric detectors exhibiting high performances [ 20 , 21 , 22 ].…”