The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Qiang Zhang - One of the best experts on this subject based on the ideXlab platform.

  • ultralow noise up conversion detector and Spectrometer for the telecom band
    Optics Express, 2013
    Co-Authors: Guoliang Shentu, Qiang Zhang, Martin M Fejer, Jason S Pelc, Xiaodong Wang, Qichao Sun, Mingyang Zheng, Jianwei Pan
    Abstract:

    We demonstrate up-conversion single-photon detection for the 1550-nm telecommunications band using a PPLN waveguide, long-wavelength pump, and narrowband filtering using a volume Bragg grating. We achieve total-system detection efficiency of around 30% with noise at the dark-count level of a Silicon APD. Based on the new detector, a single-pixel up-conversion Infrared Spectrometer with a noise equivalent power of −142 dBm Hz-1/2 was demonstrated, which was as good as a liquid nitrogen cooled CCD camera.

  • waveguide based single pixel up conversion Infrared Spectrometer
    Optics Express, 2008
    Co-Authors: Qiang Zhang, Carsten Langrock, Martin M Fejer, Yoshihisa Yamamoto
    Abstract:

    A periodically poled lithium niobate (PPLN) waveguide-based single-pixel up-conversion Infrared Spectrometer was demonstrated. Sum-frequency generation between a 1.5-microm-band scanning pump laser and a 1.3-microm-band signal generated visible radiation which was detected by a silicon single-photon detector. The up-conversion Spectrometer's sensitivity was two-orders-of-magnitude higher than that of a commercial optical spectrum analyzer.

  • waveguide based single pixel up conversion Infrared Spectrometer
    arXiv: Instrumentation and Detectors, 2008
    Co-Authors: Qiang Zhang, Carsten Langrock, Martin M Fejer, Yoshihisa Yamamoto
    Abstract:

    A periodically poled lithium niobate (PPLN) waveguide-based single-pixel up-conversion Infrared Spectrometer was demonstrated. Sum-frequency generation between a 1.5 micrometer band scanning pump laser and a 1.3 micrometer band signal generated visible radiation which was detected by a silicon single-photon detector. The noise equivalent power of the upconversion Spectrometer was two-orders-of-magnitude lower than that of a commercial optical spectrum analyzer.

Yoshihisa Yamamoto - One of the best experts on this subject based on the ideXlab platform.

  • waveguide based single pixel up conversion Infrared Spectrometer
    Optics Express, 2008
    Co-Authors: Qiang Zhang, Carsten Langrock, Martin M Fejer, Yoshihisa Yamamoto
    Abstract:

    A periodically poled lithium niobate (PPLN) waveguide-based single-pixel up-conversion Infrared Spectrometer was demonstrated. Sum-frequency generation between a 1.5-microm-band scanning pump laser and a 1.3-microm-band signal generated visible radiation which was detected by a silicon single-photon detector. The up-conversion Spectrometer's sensitivity was two-orders-of-magnitude higher than that of a commercial optical spectrum analyzer.

  • waveguide based single pixel up conversion Infrared Spectrometer
    arXiv: Instrumentation and Detectors, 2008
    Co-Authors: Qiang Zhang, Carsten Langrock, Martin M Fejer, Yoshihisa Yamamoto
    Abstract:

    A periodically poled lithium niobate (PPLN) waveguide-based single-pixel up-conversion Infrared Spectrometer was demonstrated. Sum-frequency generation between a 1.5 micrometer band scanning pump laser and a 1.3 micrometer band signal generated visible radiation which was detected by a silicon single-photon detector. The noise equivalent power of the upconversion Spectrometer was two-orders-of-magnitude lower than that of a commercial optical spectrum analyzer.

C A Nixon - One of the best experts on this subject based on the ideXlab platform.

  • cassini composite Infrared Spectrometer cirs observations of titan 2004 2017
    Astrophysical Journal Supplement Series, 2019
    Co-Authors: C A Nixon, R K Achterberg, G L Bjoraker, Todd M Ansty, Nicholas A Lombardo, A M Annex, Malena Rice, P N Romani
    Abstract:

    From 2004 to 2017, the Cassini spacecraft orbited Saturn, completing 127 close flybys of its largest moon, Titan. Cassini's Composite Infrared Spectrometer (CIRS), one of 12 instruments carried on board, profiled Titan in the thermal Infrared (7-1000 microns) throughout the entire 13-year mission. CIRS observed on both targeted encounters (flybys) and more distant opportunities, collecting 8.4 million spectra from 837 individual Titan observations over 3633 hours. Observations of multiple types were made throughout the mission, building up a vast mosaic picture of Titan's atmospheric state across spatial and temporal domains. This paper provides a guide to these observations, describing each type and chronicling its occurrences and global-seasonal coverage. The purpose is to provide a resource for future users of the CIRS data set, as well as those seeking to put existing CIRS publications into the overall context of the mission, and to facilitate future inter-comparison of CIRS results with those of other Cassini instruments, and ground-based observations.

  • composite Infrared Spectrometer cirs on cassini
    Applied Optics, 2017
    Co-Authors: Donald E Jennings, F M Flasar, V G Kunde, C A Nixon, M Segura, P N Romani, Nicolas Gorius, S A Albright, J C Brasunas, R C Carlson
    Abstract:

    The Cassini spacecraft orbiting Saturn carries the composite Infrared Spectrometer (CIRS) designed to study thermal emission from Saturn and its rings and moons. CIRS, a Fourier transform Spectrometer, is an indispensable part of the payload providing unique measurements and important synergies with the other instruments. It takes full advantage of Cassini’s 13-year-long mission and surpasses the capabilities of previous Spectrometers on Voyager 1 and 2. The instrument, consisting of two interferometers sharing a telescope and a scan mechanism, covers over a factor of 100 in wavelength in the mid and far Infrared. It is used to study temperature, composition, structure, and dynamics of the atmospheres of Jupiter, Saturn, and Titan, the rings of Saturn, and surfaces of the icy moons. CIRS has returned a large volume of scientific results, the culmination of over 30 years of instrument development, operation, data calibration, and analysis. As Cassini and CIRS reach the end of their mission in 2017, we expect that archived spectra will be used by scientists for many years to come.

  • titan s middle atmospheric temperatures and dynamics observed by the cassini composite Infrared Spectrometer
    Icarus, 2008
    Co-Authors: R K Achterberg, B J Conrath, Peter J Gierasch, Michael F Flasar, C A Nixon
    Abstract:

    The Composite Infrared Radiometer–Spectrometer (CIRS) instrument, on the NASA Cassini Saturn orbiter, has been acquiring thermal emission spectra from the atmosphere of Titan since orbit insertion in 2004. Observation sequences for measuring stratospheric temperatures have been obtained using both a nadir mapping mode and a limb viewing mode. The limb observations give better vertical resolution, and give information from higher altitudes, while the nadir observations provide more complete longitude coverage. Because the scale height of Titan’s atmosphere is large enough so that emission from a grazing ray is influenced by horizontal temperature variations in the atmosphere, we have developed a twodimensional temperature retrieval algorithm for reducing the limb spectra, which solves simultaneously for meridional and vertical temperature variations. The analyzed nadir mapping data have sampled nearly all longitudes at latitudes from about 90 ◦ St o 60 ◦ N, providing temperatures between pressure levels of about 5 to 0.2 mbar. The limb data covers latitudes between about 75 ◦ S and 85 ◦ N, and yields temperatures between about 1 and 0.005 mbar, at a small number of longitudes. The retrieved temperatures are consistent with early results from nadir observations [Flasar, F.M., and 44 colleagues, 2005. Science 308, 975–978] between 0.5 and 5 mbar where both results are valid, with the warmest temperatures at the equator, and much stronger meridional temperature gradients in the northern (winter) hemisphere than in the southern. At higher altitudes not probed by nadir viewing, the limb data reveal that the stratopause is nearly 20 K warmer in the northern polar regions than at the equator and southern hemisphere, and that the altitude of the stratopause shifts from ≈0.1 mbar (300 km) near the equator to 0.01 mbar (400 km) poleward of about 40 ◦ N. When the gradient wind equation is used to construct a zonal mean wind, the reversal in sign of the temperature leads to capping of the winter westerly flow. The core of the resulting jet is about 190 m s −1 in magnitude, spans between 30 ◦ N and 60 ◦ N, and peaks near 0.1 mbar. Estimates of the radiative heating associated with the radiative disequilibrium lead to a meridional overturning timescale of about three Earth years.

  • jupiter s atmospheric composition from the cassini thermal Infrared spectroscopy experiment
    Science, 2004
    Co-Authors: Virgil G. Kunde, B J Conrath, F M Flasar, C A Nixon, G L Bjoraker, D E Jennings, B Bezard, Darrell F Strobel, Paul N Romani, R K Achterberg
    Abstract:

    The Composite Infrared Spectrometer observed Jupiter in the thermal Infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral Infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral Infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral Infrared hot spot.

  • the nitrogen isotopic ratio in jupiter s atmosphere from observations by the composite Infrared Spectrometer on the cassini spacecraft
    The Astrophysical Journal, 2004
    Co-Authors: M M Abbas, A Leclair, T Owen, B J Conrath, F M Flasar, V G Kunde, C A Nixon, R K Achterberg, G L Bjoraker, D J Jennings
    Abstract:

    The Composite Infrared Spectrometer (CIRS) on the Cassini spacecraft made Infrared observations of Jupiter's atmosphere during the flyby of 2000 December to 2001 January. The unique database in the 600-1400 cm-1 region with 0.53 and 2.8 cm-1 spectral resolutions obtained from the observations permits retrieval of global maps of the thermal structure and composition of Jupiter's atmosphere, including the distributions of 14NH3 and 15NH3. Analysis of Jupiter's ammonia distributions from three isolated 15NH3 spectral lines in eight latitudes is presented for evaluation of the nitrogen isotopic ratio. The nitrogen isotopic ratio 14N/15N (or 15N/14N) in Jupiter's atmosphere in this analysis is calculated to be 448 ± 62 [or (2.23 ± 0.31) × 10-3]. This value of the ratio determined from CIRS data is found to be in very close agreement with the value previously obtained from the measurements by the Galileo Probe Mass Spectrometer. Some possible mechanisms to account for the variation of Jupiter's observed isotopic ratio relative to those of various astrophysical environments are discussed.

Martin M Fejer - One of the best experts on this subject based on the ideXlab platform.

  • ultralow noise up conversion detector and Spectrometer for the telecom band
    Optics Express, 2013
    Co-Authors: Guoliang Shentu, Qiang Zhang, Martin M Fejer, Jason S Pelc, Xiaodong Wang, Qichao Sun, Mingyang Zheng, Jianwei Pan
    Abstract:

    We demonstrate up-conversion single-photon detection for the 1550-nm telecommunications band using a PPLN waveguide, long-wavelength pump, and narrowband filtering using a volume Bragg grating. We achieve total-system detection efficiency of around 30% with noise at the dark-count level of a Silicon APD. Based on the new detector, a single-pixel up-conversion Infrared Spectrometer with a noise equivalent power of −142 dBm Hz-1/2 was demonstrated, which was as good as a liquid nitrogen cooled CCD camera.

  • waveguide based single pixel up conversion Infrared Spectrometer
    Optics Express, 2008
    Co-Authors: Qiang Zhang, Carsten Langrock, Martin M Fejer, Yoshihisa Yamamoto
    Abstract:

    A periodically poled lithium niobate (PPLN) waveguide-based single-pixel up-conversion Infrared Spectrometer was demonstrated. Sum-frequency generation between a 1.5-microm-band scanning pump laser and a 1.3-microm-band signal generated visible radiation which was detected by a silicon single-photon detector. The up-conversion Spectrometer's sensitivity was two-orders-of-magnitude higher than that of a commercial optical spectrum analyzer.

  • waveguide based single pixel up conversion Infrared Spectrometer
    arXiv: Instrumentation and Detectors, 2008
    Co-Authors: Qiang Zhang, Carsten Langrock, Martin M Fejer, Yoshihisa Yamamoto
    Abstract:

    A periodically poled lithium niobate (PPLN) waveguide-based single-pixel up-conversion Infrared Spectrometer was demonstrated. Sum-frequency generation between a 1.5 micrometer band scanning pump laser and a 1.3 micrometer band signal generated visible radiation which was detected by a silicon single-photon detector. The noise equivalent power of the upconversion Spectrometer was two-orders-of-magnitude lower than that of a commercial optical spectrum analyzer.

R W Carlson - One of the best experts on this subject based on the ideXlab platform.

  • silicates on iapetus from cassini s composite Infrared Spectrometer
    arXiv: Earth and Planetary Astrophysics, 2015
    Co-Authors: J R Spencer, Roger N. Clark, Cindy L Young, J J Wray, Donald E Jennings, Kevin P Hand, Michael J Poston, R W Carlson
    Abstract:

    We present the first spectral features obtained from Cassini's Composite Infrared Spectrometer (CIRS) for any icy moon. The spectral region covered by CIRS focal planes (FP) 3 and 4 is rich in emissivity features, but previous studies at these wavelengths have been limited by low signal to noise ratios (S/Rs) for individual spectra. Our approach is to average CIRS FP3 spectra to increase the S/R and use emissivity spectra to constrain the composition of the dark material on Iapetus. We find an emissivity feature at ~855 cm-1 and a possible doublet at 660 and 690 cm-1 that do not correspond to any known instrument artifacts. We attribute the 855 cm-1 feature to fine-grained silicates, similar to those found in dust on Mars and in meteorites, which are nearly featureless at shorter wavelengths. Silicates on the dark terrains of Saturn's icy moons have been suspected for decades, but there have been no definitive detections until now. Serpentines reported in the literature at ambient temperature and pressure have features near 855 and 660 cm-1. However, peaks can shift depending on temperature and pressure, so measurements at Iapetus-like conditions are necessary for more positive feature identifications. As a first investigation, we measured muscovite at 125K in a vacuum and found that this spectrum does match the emissivity feature near 855 cm-1 and the location of the doublet. Further measurements are needed to robustly identify a specific silicate, which would provide clues regarding the origin and implications of the dark material.

  • silicates on iapetus from cassini s composite Infrared Spectrometer
    The Astrophysical Journal, 2015
    Co-Authors: J R Spencer, Roger N. Clark, Cindy L Young, J J Wray, Donald E Jennings, Kevin P Hand, Michael J Poston, R W Carlson
    Abstract:

    We present the first spectral features obtained from Cassini’s Composite Infrared Spectrometer (CIRS) for any icy moon. The spectral region covered by CIRS focal planes (FP) 3 and 4 is rich in emissivity features, but previous studies at these wavelengths have been limited by low signal-to-noise ratios (S/Ns) for individual spectra. Our approach is to average CIRS FP3 spectra to increase the S/N and use emissivity spectra to constrain the composition of the dark material on Iapetus. We find an emissivity feature at ∼855 cm{sup −1} and a possible doublet at 660 and 690 cm{sup −1} that do not correspond to any known instrument artifacts. We attribute the 855 cm{sup −1} feature to fine-grained silicates, similar to those found in dust on Mars and in meteorites, which are nearly featureless at shorter wavelengths. Silicates on the dark terrains of Saturn’s icy moons have been suspected for decades, but there have been no definitive detections until now. Serpentines reported in the literature at ambient temperature and pressure have features near 855 and 660 cm{sup −1}. However, peaks can shift depending on temperature and pressure, so measurements at Iapetus-like conditions are necessary for more positive feature identifications. As a first investigation, wemore » measured muscovite at 125 K in a vacuum and found that this spectrum does match the emissivity feature near 855 cm{sup −1} and the location of the doublet. Further measurements are needed to robustly identify a specific silicate, which would provide clues regarding the origin and implications of the dark material.« less

  • exploring the saturn system in the thermal Infrared the composite Infrared Spectrometer
    Space Science Reviews, 2004
    Co-Authors: F M Flasar, M M Abbas, V G Kunde, G L Bjoraker, B Bezard, J C Brasunas, R K Achterberg, Antonella Barucci, S B Calcutt, R W Carlson
    Abstract:

    The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm− 1 (1 mm to 7μ m), with a spectral resolution that can be set from 0.5 to 15.5 cm− 1. The far Infrared portion of the spectrum (10–600 cm− 1) is measured with a polarizing interferometer having thermopile detectors with a common 4-mrad field of view (FOV). The middle Infrared portion is measured with a traditional Michelson interferometer having two focal planes (600–1100 cm− 1, 1100–1400 cm− 1). Each focal plane is composed of a 1× 10 array of HgCdTe detectors, each detector having a 0.3-mrad FOV. CIRS observations will provide three-dimensional maps of temperature, gas composition, and aerosols/condensates of the atmospheres of Titan and Saturn with good vertical and horizontal resolution, from deep in their tropospheres to high in their mesospheres. CIRS’s ability to observe atmospheres in the limb-viewing mode (in addition to nadir) offers the opportunity to provide accurate and highly resolved vertical profiles of these atmospheric variables. The ability to observe with high-spectral resolution should facilitate the identification of new constituents. CIRS will also map the thermal and compositional properties of the surfaces of Saturn’s icy satellites. It will similarly map Saturn’s rings, characterizing their dynamical and spatial structure and constraining theories of their formation and evolution. The combination of broad spectral range, programmable spectral resolution, the small detector fields of view, and an orbiting spacecraft platform will allow CIRS to observe the Saturnian system in the thermal Infrared at a level of detail not previously achieved.