YBCO-Film Based FIR Detectors in Not Dissipative Regime: Local THz Response by Heavy-Ion Nanostructure Implantation

Broadband electromagnetic characterization of hot plasmas and electron beams requires real-time, direct detection of high flux of electromagnetic radiation. We report about a project aimed at creating robust THz detectors based on YBa₂Cu₃O_7-x (YBCO) films, working around liquid nitrogen temperature and in a regime of low dissipation. The sensor layout mainly consists in two contiguous meanders that are integrated on the same substrate. One of them is nanostructured by local high-energy heavy-ion irradiation; the other one (as-grown YBCO) is used for thermo-electric signal reference. By measuring the voltage response to THz excitation of YBCO film, at a given bias current and temperature, on selected substrates (Yttria Stabilized Zirconia (YSZ) and MgO), it turns out that only the nanostructured part is brought in the dissipative state when exposed to THz radiation. We present estimated noise equivalent power and relaxation times for YBCO grown on YSZ and on MgO substrates. On the latter, we experimentally checked out the device response to time-varying Far-Infrared (FIR) signals up to 800 Hz. The proposed device turns out to fit the necessary requirements for measurement of electron cyclotron emission of hot plasmas or of electron beams in the FIR spectrum.