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  • 11
    Electronic Resource
    Electronic Resource
    Monolithic arrays of absorber-coupled voltage-biased superconducting bolometers (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 4040-4042 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a design for bolometric detectors of infrared and mm-wave radiation produced in large-format filled arrays by standard planar lithography. A square grid of metallized silicon nitride absorbs the radiation. The bolometer suspension, sensor, and wiring occupy a small fraction of the area. We have produced a 1024 element array of fully released and suspended 1.5 mm×1.5 mm bolometer micromeshes with a filling factor of 88%. We describe a voltage-biased superconducting bolometer built as a prototype for one array element. We have measured noise equivalent power =2.3×10−17 W/Hz, τ=24 ms, and G=2.7×10−11 W/K at 304 mK. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1326844
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  • 12
    Electronic Resource
    Electronic Resource
    A fully lithographed voltage-biased superconducting spiderweb bolometer (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 868-870 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the fabrication and characterization of superconducting transition-edge bolometers for astrophysical applications at far-infrared and mm wavelengths. The sensor is voltage biased and the current is measured with a superconducting quantum interference ammeter. Strong negative electrothermal feedback keeps the sensor temperature nearly constant, reduces the response time significantly, and improves linearity. It also makes the responsivity relatively insensitive to changes in optical background loading and refrigerator temperature. The bolometers are made using standard microlithographic techniques suitable for fabrication of large scale arrays. Detailed measurements of optical response are presented for a range of bias conditions and are compared with theory. Measured noise spectra are shown and a model for the noise is presented. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123393
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  • 13
    Electronic Resource
    Electronic Resource
    Single superconducting quantum interference device multiplexer for arrays of low-temperature sensors (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 371-373 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present the design and experimental evaluation of a superconducting quantum interference device (SQUID) multiplexer for an array of low-temperature sensors. Each sensor is inductively coupled to a superconducting summing loop which, in turn, is inductively coupled to the readout SQUID. The flux-locked loop of the SQUID is used to null the current in the summing loop and thus cancel crosstalk. The sensors are biased with an alternating current, each with a separate frequency, and the individual sensor signals are separated by lock-in detection at the SQUID output. We have fabricated a prototype 8 channel multiplexer and discuss the application to a larger array. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1338963
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  • 14
    Electronic Resource
    Electronic Resource
    Measurements of thermal transport in low stress silicon nitride films (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2250-2252 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the thermal conductance, G, of (approximate)1 μm thick low stress silicon nitride membranes over the temperature range, 0.06〈T〈6 K, as a function of surface condition. For T〉4 K, G is independent of surface condition indicating that the thermal transport is determined by bulk scattering. For T〈4 K, scattering from membrane surfaces becomes significant. Membranes which have submicron sized Ag particles glued to the surface or are micromachined into narrow strips have a G that is reduced by a factor as large as 5 compared with that of clean, solid membranes with the same ratio of cross section to length. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121269
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  • 15
    Electronic Resource
    Electronic Resource
    Residual losses in epitaxial thin films of YBa2Cu3O7 from microwave to submillimeter wave frequencies (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2326-2328 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the residual loss in five epitaxial a-b plane films of the high-Tc superconductor YBa2Cu3O7. Microwave measurements near 10 GHz were made by resonance techniques at 4 K. Submillimeter measurements from ∼1.5 to 21 THz were made at 2 K by a direct absorption technique. We use a model of weakly coupled superconducting grains and a homogeneous two-fluid model to fit the data for each film below the well-known absorption edge at 13.5 THz. When the penetration depth determined from muon spin rotation measurements is used to constrain each model, the weakly coupled grain model is able to fit the measured absorptivities for all films, but the two-fluid model is less successful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106058
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  • 16
    Electronic Resource
    Electronic Resource
    New designs for antenna-coupled superconducting bolometers (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2329-2331 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We propose a novel antenna-coupled low Tc superconducting bolometer which makes use of the thermal boundary resistance and the trapping of quasiparticles at metal-superconducting interfaces. A thin strip of superconductor, whose temperature is regulated at the midpoint of its resistive transition, serves both as a resistive load to thermalize the infrared current from the antenna and as a thermometer to measure the resulting temperature rise. Calculations give a noise equivalent power (NEP)≈7×10−16 T5/2 WHz−1/2 and a time constant τ≈10−8 T−2 s for a 2×2 μm2 thermometer area at temperature T (K). Designs for efficient on-chip rf matching and filter networks with well-defined bandpasses are presented. These detectors can be used to make frequency-multiplexed array receivers for astronomical observations at near millimeter wavelengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106059
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  • 17
    Electronic Resource
    Electronic Resource
    Thermal boundary resistance for YBa2Cu3O7−δ films (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 2034-2036 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have made direct measurements of the thermal boundary resistance, Rbd, between high quality epitaxial films of YBa2Cu3O7−δ and a variety of substrates with and without buffer layers. The boundary resistance was deduced from measurements of the electrical resistance changes in three parallel strips of YBa2Cu3O7−δ when one was electrically heated. Our measurements indicate that Rbd is weakly dependent on temperature and, for all the measured samples, has a value of 0.8–1.4×10−3 K cm2/W between 90 and 200 K, which is a factor of ≈80 larger than the prediction of the acoustic mismatch model at 100 K. The thermal response time of ≈1 ns which results from the heat capacity of the film and Rbd is observed in many experiments with pulsed laser sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106123
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  • 18
    Electronic Resource
    Electronic Resource
    Quantum-limited heterodyne detection of millimeter waves using superconducting tantalum tunnel junctions (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2487-2489 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have made accurate measurements of the noise and gain of heterodyne mixers employing small-area (1 μm2) Ta/Ta2O5/Pb0.9Bi0.1 superconductor-insulator-superconductor tunnel junctions. These junctions have very low subgap leakage current and an extremely sharp current rise at the sum gap. We have measured an added mixer noise of 0.61±0.31 quanta at 95.0 GHz, which is within 25% of the quantum limit of 0.5 quanta for a single-sideband mixer. Values of the imbedding admittances are deduced from the shapes of I-V curves pumped at the upper and lower sideband frequencies. Using these admittances, the mixer performance calculated from the quantum theory is in good agreement with the experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104111
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  • 19
    Electronic Resource
    Electronic Resource
    Wide-band low noise MM-wave SIS mixers with a single tuning element (1986)
    Springer
    International journal of infrared and millimeter waves 7 (1986), S. 1835-1852 
    Details
    ISSN: 1572-9559
    Keywords: SIS mixer ; mm-wave ; scaled modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Several SIS quasiparticle mixers have been designed and tested for the frequency range from 80 to 115 GHz. The sliding backshort is the only adjustable RF tuning element. The RF filter reactance is used as a fixed RF matching element. A mixer which uses a single 2×2 μm2 Pb-alloy junction in a quarter-height waveguide mount has a coupled conversion gain of GM(DSB)=2.6±0.5 dB with an associated noise temperature of TM(DSB)=16.4±1.8 K at the best DSB operation point. The receiver noise temperature TR(DSB) is 27.5±0.8 K for the mixer test apparatus. This mixer provides a SSB receiver noise temperature below 50 K over the frequency range from 91 to 96 GHz, the minimum being TR(SSB)=44±4 K. Another mixer with an array of five 5×5 μm2 junctions in series in a full-height wave-guide mount has much lower noise temperature TM(DSB)=6.6±1.6 K, but less gain GM(DSB)=−5.1±0.5 dB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01011991
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  • 20
    Electronic Resource
    Electronic Resource
    Scaled model measurements of embedding impedances for SIS waveguide mixers (1985)
    Springer
    International journal of infrared and millimeter waves 6 (1985), S. 1169-1189 
    Details
    ISSN: 1572-9559
    Keywords: SIS-mixer ; mm-wave ; embedding impedance ; scaled model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Several scaled models have been used to determine the contributions of various waveguide mount parameters to the embedding impedance of a mm-wave SIS mixer. Measured effects of waveguide height, substrate orientation and width, junction location, lead inductance and RF-filter impedance are presented and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01013208
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