Fast and Sensitive Terahertz Direct Detector Based on Superconducting Antenna-Coupled Hot Electron Bolometer

Abstract

We characterize superconducting antenna-coupled hot-electron bolometers for direct detection of terahertz radiation operating at a temperature of 9.0 K. The estimated value of responsivity obtained from lumped-element theory is strongly different from the measured one. A numerical calculation of the detector responsivity is developed, using the Euler method, applied to the system of heat balance equations written in recurrent form. This distributed element model takes into account the effect of nonuniform heating of the detector along its length and provides results that are in better agreement with the experiment. At a signal frequency of 2.5 THz, the measured value of the optical detector noise equivalent power is 2.0×10 -13 W·Hz -0.5 . The value of the bolometer time constant is 35 ps. The corresponding energy resolution is about 3 aJ. This detector has a sensitivity similar to that of the state-of-the-art sub-millimeter detectors operating at accessible cryogenic temperatures, but with a response time several orders of magnitude shorter.  Index Terms-Radiation detectors, hot electron bolometer, frequency response.

Hot electron energy relaxation time in vanadium nitride superconducting film structures under THz and IR radiation

“…The spiral antenna geometry was optimized for the frequency range (0.3–6) THz in which the volt-watt responsivity measurements were performed. Fabrication process of both structures included electron-beam and photo-lithography, plasma-chemical etching and was similar to fabrication of the NbN HEB 3 .…”

“…For example, the detection and study of the effect of electronic heating in superconducting NbN films, arising under the influence of radiation of different frequencies from the visible to the millimeter wave range, has led to the creation of a new class of cryogenic electronic devices 1 , 2 . One of these devices, of course, become superconducting NbN HEB (Hot-Electron Bolometer) detectors that exhibit high sensitivity (NEP ≈ 2 × 10 –13 W/√Hz) combined with record response time (τ ≈ 50 ps), as well as energy resolution δE ≈ 3 × 10 –18 J 3 – 5 . Such unique characteristics of NbN HEB detectors made possible by the use of ultra-thin (d ≈ 3–5 nm) disordered NbN films, which are characterized by a low diffusion coefficient (D ≈ 0.5 cм 2 /c), high critical temperature (T c ≈ 10 К), small width of the superconducting transition (∆T c < 0.2 К), the strong temperature dependence of the resistance in the region of the superconducting transition.…”

“…2 Superconducting Nanotechnology, LLC 5/1-14 L'va Tolstogo Str., Moscow 119021, Russia. 3 National Research University Higher School of Economics, 20 Myasnitskaya Str., Moscow 101000, Russia. * email: PentinIvan@mail.ru additional positive property when creating superconducting detectors, for example, single photon detectors in the middle infrared range 10,11 .…”

Coherent THz Repetitive Pulse Generation in a GaSe Crystal by Dual-wavelength Nd:YLF Laser

“…In the experiment, dual-wavelength laser radiation is modulated by opto-mechanical chopper with a repetition rate of 12 Hz in order to a synchronous detector for use, and then is focused by a lens with a focal length of 150 mm a nonlinear crystal GaSe of 3 and 5mm lengths. The generated THz radiation is collimated by a TPX lens with a focal length of 50 mm from a polymeric material TPX on photodetectors -Golay cell or cooled superconducting HEB-bolometer (RS 0.4-4T, "SKONTEL") with a frequency range (0.4-4) THz, response time <1 ns - Seliverstov et al (2015). Before photodetector filters are installed (plate from Si and polymer) which transmit terahertz radiation and cut off thermal and near-infrared laser radiation.…”

Characterization of the THz quantum cascade laser using fast superconducting hot electron bolometer

“…In the proposed method the THz QCL is biased by applying a smooth gradual (i.e., with a "slow-rising" front edge) voltage pulse, and the laser output power was measured using NbN superconducting hot electron bolometer (HEB) within a single voltage pulse front edge, which was possible due to sufficiently short response time (of the order of 1 ns) of the HEB. The HEB which we used was similar to that described elsewhere [5]. The primary advantage of this method over the most common THz detection techniques derives from its ability to measure THz QCL output power-current relationship within a single voltage pulse.…”