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Author Tong, C.-Y. Edward; Meledin, Denis; Blundell, Raymond; Erickson, Neal; Kawamura, Jonathan; Mehdi, Imran; Gol'tsman, Gregory url  openurl
  Title A 1.5 THz hot-electron bolometer mixer operated by a planar diode-based local oscillator Type (up) Abstract
  Year 2003 Publication Proc. 14th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 14th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 286  
  Keywords waveguide NbN HEB mixers  
  Abstract We describe a 1.5 THz heterodyne receiver based on a superconductin g hot-electron bolometer mixer, which is pumped by an all-solid-state local oscillator chain. The bolometer is fabricated from a 3.5 nm-thick niobium nitride film deposited on a quartz substrate with a 200 nm-thick magnesium oxide buffer layer. The bolometer measures 0.15 fun in width and 1.5 1..tm in length. The chip consisting of the bolometer and mixer circuitry is incorporated in a fixed-tuned waveguide mixer block with a corru g ated feed horn. The local oscillator unit comprises of a cascade of four planar doublers followin g a MMIC-based W-band power amplifier. The local oscillator is coupled to the mixer using a Martin-Puplett interferometer. The local oscillator output power needed for optimal receiver performance is approximately 1 to 2 11W, and the chain is able to provide this power at a number of frequency points between 1.45 and 1.56 THz. By terminating the rf input with room temperature and 77 K loads, a Y-factor of 1.11 (DSB) has been measured at a local oscillator frequency of 1.476 THz at 3 GHz intermediate frequency.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1501  
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Author Hübers, Heinz-Wilhelm; Semenov, A.; Richter, H.; Smirnov, K.; Gol'tsman, G.; Voronov, B. url  openurl
  Title Phonon cooled far-infrared hot electron bolometer mixer Type (up) Abstract
  Year 2002 Publication NASA/ADS Abbreviated Journal NASA/ADS  
  Volume Issue Pages  
  Keywords NbN HEB mixers  
  Abstract Heterodyne receivers for applications in astronomy need quantum-limited sensitivity. At frequencies above 1.4 THz superconducting hot electron bolometers (HEB) can be used to achieve this goal. We present results of the development of a quasi-optical phonon-cooled NbN HEB mixer for GREAT, the German heterodyne receiver for SOFIA. Different mixers with logarithmic spiral and double slot feed antennas have been investigated with respect to their noise temperature, conversion loss, linearity and beam pattern at several frequencies between 0.7 THz and 5.2 THz. At 2.5 THz a double sideband noise temperature of 2200 K was achieved. The conversion loss was 16 dB. The response of the mixer was linear up to 400 K load temperature. This performance was verified by measuring an emission line of methanol at 2.5 THz. The results demonstrate that the NbN HEB is very well suited as a mixer for FIR heterodyne receivers.  
  Address Monterey, CA  
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  Area Expedition Conference Far-IR, Sub-mm & MM Detector Technology Workshop, 1-3 April 2002  
  Notes id.37 Approved no  
  Call Number Serial 1534  
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Author Okunev, O.; Smirnov, K.; Chulkova, G.; Korneev, A.; Lipatov, A.; Gol'tsman, G.; Zhang, J.; Slysz, W.; Verevkin, A.; Sobolewski, Roman url  openurl
  Title Ultrafast NBN hot-electron single-photon detectors for electronic applications Type (up) Abstract
  Year 2002 Publication Abstracts 8-th IUMRS-ICEM Abbreviated Journal Abstracts 8-th IUMRS-ICEM  
  Volume Issue Pages  
  Keywords NbN SSPD, SNSPD  
  Abstract We present a new, simple to manufacture, single-photon detector (SPD), which can work from ultraviolet to near-infrared wavelengths of optical radiation and combines high speed of operation, high quantum efficiency (QE), and very low dark counts. The devices are superconducting and operate at temperature below 5 K. The physics of operation of our SPD is based on formation of a photon-induced resistive hotspot and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-wide superconductor.  
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  Area Expedition Conference 8th IUMRS International Conference on Electronic Materials  
  Notes Approved no  
  Call Number Serial 1532  
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Author Semenov, Alexei; Hübers, Heinz-Wilhelm; Engel, Andreas; Gol'tsman, Gregory N. url  openurl
  Title Background limited superconducting quantum detector for astronomy Type (up) Abstract
  Year 2002 Publication NASA/ADS Abbreviated Journal NASA/ADS  
  Volume Issue Pages  
  Keywords SQD  
  Abstract We present the concept of the superconducting quantum detector for astronomy. Response to a single absorbed photon appears due to successive formation of a normal spot and phase-slip-centers in a narrow strip carrying sub-critical supercurrent. The detector simultaneously has a moderate energy resolution and a variable cut-off wavelength depending on both the material used and operation conditions. We simulated performance of the background-limited direct detector having the 100- micrometer cut-off wavelength. Low dark count rate will allow to realize 10-21 W Hz-1/2 noise equivalent power at 4 K background radiation. The intrinsic recovery time of the counter is rather determined by diffusion of nonequilibrium electrons, thus, thermal fluctuations do not hamper energy resolution of the detector. Provided an appropriate readout technique, the resolution should be better than 1/20 at 50- micrometer wavelength. Planar layout and relatively simple technology favor integration of the detector into an array.  
  Address Monterey, CA  
  Corporate Author Thesis  
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  Series Editor Series Title Abbreviated Series Title  
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  Area Expedition Conference Far-IR, Sub-mm & MM Detector Technology Workshop, held 1-3 April 2002  
  Notes id.62 Approved no  
  Call Number Serial 1535  
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Author Darula, Marian; Semenov, Alex D.; Hübers, Heinz-Wilhelm; Schubert, Josef url  openurl
  Title Quasioptical high-Tc superconductor Josephson mixer at terahertz frequencies Type (up) Abstract
  Year 2000 Publication Proc. 11th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 11th Int. Symp. Space Terahertz Technol.  
  Volume Issue Pages 515  
  Keywords HTS Josephson mixers  
  Abstract Mixers based on Josephson junctions from conventional superconductor materials have demonstrated excellent performance at subgap frequencies. The advantages of Josephson mixers are low optimal power of the local oscillator and large intermediate frequency bandwidth but their noise temperature increases dramatically at frequencies corresponding to the energy gap of the superconductor, which is typically below 1 THz for widely used materials. The large energy gap of oxide superconductors makes them promising candidates for development of terahertz Josephson mixers. Here we report on experimental study of the quasioptical mixer utilizing bicrystal Josephson junction from high-transition-temperature YBa 2 Cu 3 O 7-δ film. Junctions with a width of 2 µm were fabricated from 100 nm thick laser ablated films on bicrystal MgO substrates and had the and the J C R n product of about 2 mV at 4.2 K. The planar complementary logarithmic spiral antenna incorporated into co-planar waveguide was patterned from 200 nm thick gold film thermally evaporated in situ on top of the YBa 2 Cu 3 O 7-δ film. The mixer chip was clamped to the extended hemispherical silicon lens. Performance of the mixer was investigated at 4.5 K bath temperature. We used FIR laser as a local oscillator at frequencies 0.698 and 2.52 THz. System noise temperature (DSB) was determined from Y-factor measured with 300 K and 77 K loads. At 0.698 THz the lowest noise temperature 1750 K was observed when the mixer was biased with the fixed current to the region in the vicinity of either the first Shapiro step or the critical current. Between these two bias points the noise temperature increased to ≈ 20000 K. As function of the local oscillator power the noise temperature reached the minimum when the critical current was suppressed to the half of its equilibrium value. Power of the local oscillator absorbed by the mixer at optimal operation was of the order 100 nW. The present design of our antenna limits the upper operation frequency to the value of 1.8 THz. Nevertheless, we clearly observed Shapiro steps at the frequency 2.52 THz. Bearing in mind an improved design of the antenna, we estimate the 3000 K DSB noise temperature at this frequency.  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1555  
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