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Author Koshelets, V. P.; Shitov, S. V.; Dmitriev, P. N., Ermakov, A. B.; Filippenko, L. V.; Koryukin, O.V.; Sobolev, A.S.; Torgashin, M.Yu.; Yagoubov, P.; Hoogeveen, R. openurl 
  Title Integrated submillimeter and terahertz receivers with superconducting local oscillator Type Abstract
  Year 2004 Publication Presanted at 8th International Workshop “From Andreev Reflection to the International Space Station” Abbreviated Journal  
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  Notes Approved no  
  Call Number Serial 513  
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Author Koshelets, V. P.; Dmitriev, P. N.; Ermakov, A. B.; Filippenko, L. V.; Khudchenko, A. V.; Koryukin, O. V.; Torgashin, M. Yu.; Hoogeveen, R.; Vreeling, W. J.; Yagoubov, P. openurl 
  Title SIR for TELIS (post-critical) review Type Miscellaneous
  Year 2004 Publication Abbreviated Journal  
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  Keywords SIR  
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  Call Number Serial 516  
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Author Korneev, A.; Kouminov, P.; Matvienko, V.; Chulkova, G.; Smirnov, K.; Voronov, B.; Gol'tsman, G. N.; Currie, M.; Lo, W.; Wilsher, K.; Zhang, J.; Słysz, W.; Pearlman, A.; Verevkin, A.; Sobolewski, Roman url  doi
openurl 
  Title Sensitivity and gigahertz counting performance of NbN superconducting single-photon detectors Type Journal Article
  Year 2004 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 84 Issue 26 Pages 5338-5340  
  Keywords SSPD, NEP, QE  
  Abstract We have measured the quantum efficiencysQEd, GHz counting rate, jitter, and noise-equivalentpowersNEPdof nanostructured NbN superconducting single-photon detectorssSSPDsdin thevisible to infrared radiation range. Our 3.5-nm-thick and 100- to 200-nm-wide meander-typedevices(total area 10310mm2), operating at 4.2 K, exhibit an experimental QE of up to 20% inthe visible range and,10% at 1.3 to 1.55mm wavelength and are potentially sensitive up tomidinfrareds,10mmdradiation. The SSPD counting rate was measured to be above 2 GHz withjitter,18 ps, independent of the wavelength. The devices’ NEP varies from,10−17W/Hz1/2for1.55mm photons to,10−20W/Hz1/2for visible radiation. Lowering the SSPD operatingtemperature to 2.3 K significantly enhanced its performance, by increasing the QE to,20% andlowering the NEP level to,3310−22W/Hz1/2, both measured at 1.26mm wavelength.  
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  ISSN 0003-6951 ISBN Medium  
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  Notes Approved no  
  Call Number Serial 532  
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Author Siddiqi, I.; Prober, D. E. url  doi
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  Title Nb–Au bilayer hot-electron bolometers for low-noise THz heterodyne detection Type Journal Article
  Year 2004 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.  
  Volume 84 Issue 8 Pages 1404  
  Keywords HEB, mixers, dynamic range, saturation, LO power, local oscillator power, Nb  
  Abstract The sensitivity of present Nb diffusion-cooled hot-electron bolometer (HEB) mixers is not quantum limited, and can be improved by reducing the superconducting transition temperature TC. Lowering TC reduces thermal fluctuations, resulting in a decrease of the mixer noise temperature TM. However, lower TC mixers have reduced dynamic range and saturate more easily due to background noise. We present 30 GHz microwave measurements on a bilayer HEB system, Nb–Au, in which TC can be tuned with Au layer thickness to obtain the maximum sensitivity for a given noise background. These measurements are intended as a guide for the optimization of THz mixers. Using a Nb–Au mixer with TC = 1.6 K, we obtain TM = 50 K with 2 nW of local oscillator (LO) power. Good mixer performance is observed over a wide range of LO power and bias voltage and such a device should not exhibit saturation in a THz receiver.  
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  Notes Approved no  
  Call Number Serial 571  
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Author van't Klooster, K.; Myasnikova, S. E.; Parshin, V. V.; Kasparek, W. openurl 
  Title Results of reflection loss measurements of sample material for radio astronomy telescope antenna for Planck Project Type Conference Article
  Year 2004 Publication Proc. 14th international crimean conference on microwave and telecommunication technology Abbreviated Journal  
  Volume Issue Pages 753-755  
  Keywords mirror, reflection index, emissivity, Fabry-Perot interferometer, space observatory, terahertz, THz  
  Abstract Advanced radio telescope antennas for space applications are realised by the use of stable composite materials, which are lighter in general than various metal realisations. Reflectivity measurements have been carried out on high technology samples for the Planck radio telescope. Highly accurate results have been obtained at the Applied Physics Institute in Nizhny Novgorod, and an independent measurement with a totally different setup at the University of Stuttgart confirmed that one of the samples showed a strange behaviour. Moreover, it confirmed the high accuracy of the testing method.  
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  Call Number Serial 579  
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Author González, Francisco Javier; Alda, Javier; Ilic, Bojan; Boreman, Glenn D. openurl 
  Title Infrared Antennas Coupled to Lithographic Fresnel Zone Plate Lenses Type Journal Article
  Year 2004 Publication Applied Optics Abbreviated Journal Appl. Opt.  
  Volume 43 Issue 33 Pages 6067-6073  
  Keywords optical antennas  
  Abstract Several designs for Fresnel zone plate lenses (FZPLs) to be used in conjunction with antenna-coupled infrared detectors have been fabricated and tested. The designs comprise square and circular FZPLs with different numbers of Fresnel zones working in transmissive or reflective modes designed to focus infrared energy on a square-spiral antenna connected to a microbolometer. A 163× maximum increase in response was obtained from a 15-zone circular FZPL in the transmissive mode. Sensor measurements of normalized detectivity D* resulted in a 2.67× increase with FZPLs compared with measurements made of square-spiral antennas without FZPLs. The experimental results are discussed and compared with values obtained from theoretical calculations.  
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  Call Number RPLAB @ gujma @ Serial 740  
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Author Kramer, B.; Chen, C-C.; Volakis, J.D. openurl 
  Title The development of a mini-UWB antenna Type Journal Article
  Year 2004 Publication Measurement and Techniques Association Symposium Abbreviated Journal AMTA  
  Volume Issue Pages 6  
  Keywords optical antennas; Ultra Wide Band; Spiral Antenna, Dielectric Loading  
  Abstract There is a great interest in the automotive and military sectors for small and broadband antennas that meet modern communication needs. These needs require ultra-wide bandwidth (>10:1) UWB antennas, such as the spiral antenna. However, the physical size at the low-frequency end typically becomes too large for practical applications. To reduce the size of the antenna, miniaturization techniques must be employed such as the use of high-contrast dielectric materials. Size reduction using high-contrast materials has been demonstrated for narrowband antennas, such as patch antennas, but not for broadband antennas to our knowledge. Therefore, the concept of miniaturizing a broadband spiral antenna using dielectric materials will be investigated experimentally and numerically.Issues that arise from dielectric loading such as impedance reduction will also be addressed. It will be shown using the results from these studies that there are practical limitations to the amount of miniaturization which can be achieved.  
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  Call Number RPLAB @ gujma @ Serial 751  
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Author Genack, Azriel Z.; Kopp, Victor I.; Churikov, Victor M.; Singer, Jonathan; Chao, Norman; Neugroschl, Daniel A. openurl 
  Title Chiral fiber Bragg gratings Type Conference Article
  Year 2004 Publication Proceedings of the SPIE Abbreviated Journal Proc. SPIE  
  Volume 5508 Issue Pages 57-64  
  Keywords optical fiber gratings, chiral fiber gratings, chiral gratings, from chiralphotonics  
  Abstract We have produced chiral fiber Bragg gratings with double-helix symmetry and measured the polarization and wavelength selective transmission properties of these structures. These gratings interact only with circularly polarized light with the same handedness as the grating twist and freely transmit light of the orthogonal polarization. The optical characteristics of chiral fibers are compared to those of planar cholesteric structures. The resonant standing wave at the band edge or at a defect state within the band gap, as well as the evanescent wave within the band gap is comprised of two counterpropagating components of equal amplitude. The electric field vector of such a circularly polarized standing wave does not rotate in time; rather it is linearly polarized in any given plane. The standing wave may be described in terms of the sense of circular polarization of the two counterpropagating components. The wavelength dependence of the angle q between the linearly polarized electromagnetic field and the extraordinary axis, which is constant throughout a long structure, is obtained in a simple calculation. The results are in good agreement with scattering matrix calculations. Resonant chiral gratings are demonstrated for microwave radiation whereas chiral gratings with pitch exceeding the wavelength are demonstrated at optical wavelengths in single-mode glass fibers. The different functionalities of these fibers are discussed.  
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  Call Number Serial 854  
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Author Krasnopolsky, Vladimir A.; Maillard, Jean Pierre; C. Owen, Tobias openurl 
  Title Detection of methane in the martian atmosphere: evidence for life? Type Journal Article
  Year 2004 Publication Icarus Abbreviated Journal Icarus  
  Volume 172 Issue 2 Pages 537-547  
  Keywords FTS, Mars atmosphere, methane absorption lines, IR spectroscopy, infrared spectroscopy, landfill gas  
  Abstract Using the Fourier Transform Spectrometer at the Canada–France–Hawaii Telescope, we observed a spectrum of Mars at the P-branch of the strongest CH4 band at 3.3 μm with resolving power of 180,000 for the apodized spectrum. Summing up the spectral intervals at the expected positions of the 15 strongest Doppler-shifted martian lines, we detected the absorption by martian methane at a 3.7 sigma level which is exactly centered in the summed spectrum. The observed CH4 mixing ratio is 10±3 ppb. Total photochemical loss of CH4 in the martian atmosphere is equal to View the MathML source, the CH4 lifetime is 340 years and methane should be uniformly mixed in the atmosphere. Heterogeneous loss of atmospheric methane is probably negligible, while the sink of CH4 during its diffusion through the regolith may be significant. There are no processes of CH4 formation in the atmosphere, so the photochemical loss must therefore be balanced by abiogenic and biogenic sources. Outgassing from Mars is weak, the latest volcanism is at least 10 million years old, and thermal emission imaging from the Mars Odyssey orbiter does not reveal any hot spots on Mars. Hydrothermal systems can hardly be warmer than the room temperature at which production of methane is very low in terrestrial waters. Therefore a significant production of hydrothermal and magmatic methane is not very likely on Mars. The calculated average production of CH4 by cometary impacts is 2% of the methane loss. Production of methane by meteorites and interplanetary dust does not exceed 4% of the methane loss. Methane cannot originate from an extinct biosphere, as in the case of “natural gas” on Earth, given the exceedingly low limits on organic matter set by the Viking landers and the dry recent history which has been extremely hostile to the macroscopic life needed to generate the gas. Therefore, methanogenesis by living subterranean organisms is a plausible explanation for this discovery. Our estimates of the biomass and its production using the measured CH4 abundance show that the martian biota may be extremely scarce and Mars may be generally sterile except for some oases.  
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  Call Number Serial 879  
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Author Klapwijk, T. M.; Barends, R.; Gao, J. R.; Hajenius, M.; Baselmans, J. J. A. openurl 
  Title Improved superconducting hot-electron bolometer devices for the THz range Type Conference Article
  Year 2004 Publication Proc. SPIE Abbreviated Journal Proc. SPIE  
  Volume 5498 Issue Pages 129-139  
  Keywords HEB mixer distributed model, numerical model  
  Abstract Improved and reproducible heterodyne mixing (noise temperatures of 950 K at 2.5 THz) has been realized with NbN based hot-electron superconducting devices with low contact resistances. A distributed temperature numerical model of the NbN bridge, based on a local electron and a phonon temperature, has been used to understand the physical conditions during the mixing process. We find that the mixing is predominantly due to the exponential rise of the local resistivity as a function of electron temperature.  
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  Notes Invited talk, Recommended by Klapwijk Approved no  
  Call Number Serial 912  
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