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Author Zhang, Zijing; Zhang, Jianlong; Wu, Long; Zhang, Yong; Zhao, Yuan; Su, Jianzhong doi  openurl
  Title (up) Photon-counting chirped amplitude modulation lidar using a smart premixing method Type Journal Article
  Year 2013 Publication Opt. Lett. Abbreviated Journal Opt. Lett.  
  Volume 38 Issue 21 Pages 4389-4392  
  Keywords photon-counting detector, lidar, Geiger mode APD, Geiger mode lidar  
  Abstract We proposed a new premixing method for photon-counting chirped amplitude modulation lidar (PCCAML). Earlier studies used the counting results of the returned signal detected by a Geiger mode avalanche photodiode detector (Gm-APD) to mix with the reference signal, called the postmixing method. We use an alternative method known as the premixing method, in which the reference signal is used to directly modulate the sampling gate width of the Gm-APD, and the mixing of the returned signal and the reference signal is completed before the Gm-APD. This premixing method is more flexible and may perform better than the postmixing method in terms of signal-to-noise ratio by cutting down a separated mixer commonly used in the postmixing lidar system. Furthermore, this premixing method lowers the demand for the sampling frequency of the Gm-APD. It allows the use of a much wider modulation bandwidth to improve the range accuracy and resolution. To the best of our knowledge, this is the first report to use the premixing method in the PCCAML system, which will benefit future lidar applications.  
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  Notes Approved no  
  Call Number Serial 1006  
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Author Fedorov, G.; Kardakova, A.; Gayduchenko, I.; Charayev, I.; Voronov, B.M.; Finkel, M.; Klapwijk, T.M.; Morozov, S.; Presniakov, M.; Bobrinetskiy, I.; Ibragimov, R.; Goltsman, G. url  doi
openurl 
  Title (up) Photothermoelectric response in asymmetric carbon nanotube devices exposed to sub-terahertz radiation Type Journal Article
  Year 2013 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.  
  Volume 103 Issue 18 Pages 181121 (1 to 5)  
  Keywords carbon nanotubes, CNT, THz radiation, SiO2 substrate  
  Abstract We report on the voltage response of carbon nanotube devices to sub-terahertz (THz) radiation. The devices contain carbon nanotubes (CNTs), which are over their length partially suspended and partially Van der Waals bonded to a SiO2 substrate, causing a difference in thermal contact. We observe a DC voltage upon exposure to 140 GHz radiation. Based on the observed gate voltage and power dependence, at different temperatures, we argue that the observed signal is both thermal and photovoltaic. The room temperature responsivity in the microwave to THz range exceeds that of CNT based devices reported before. Authors thank Professor P. Barbara for providing the catalyst for CNT growth and Dr. N. Chumakov and V. Rylkov for stimulating discussions. The work was supported by the RFBR (Grant No. 12-02-01291-a) and by the Ministry of Education and Science of the Russian Federation (Contract No. 14.B25.31.0007). G.F. acknowledges support of the RFBR grant 12-02-01005-a.  
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  ISSN 0003-6951 ISBN Medium  
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  Notes Approved no  
  Call Number Serial 1171  
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Author Korneev, A.; Korneeva, Y.; Manova, N.; Larionov, P.; Divochiy, A.; Semenov, A.; Chulkova, G.; Vachtomin, Y.; Smirnov, K.; Goltsman, G. url  doi
openurl 
  Title (up) Recent nanowire superconducting single-photon detector optimization for practical applications Type Journal Article
  Year 2013 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.  
  Volume 23 Issue 3 Pages 2201204 (1 to 4)  
  Keywords SSPD, SNSPD  
  Abstract In this paper, we present our approaches to the development of fiber-coupled superconducting single photon detectors with enhanced photon absorption. For such devices we have measured detection efficiency in wavelength range from 500 to 2000 nm. The best fiber coupled devices exhibit detection efficiency of 44.5% at 1310 nm wavelength and 35.5% at 1550 nm at 10 dark counts per second.  
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  Call Number RPLAB @ akorneev @ KorneevIEEE2013 Serial 996  
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Author Cavalié, T.; Feuchtgruber, H.; Lellouch, E.; de Val-Borro, M.; Jarchow, C.; Moreno, R.; Hartogh, P.; Orton, G.; Greathouse, T. K.; Billebaud, F.; Dobrijevic, M.; Lara, L. M.; González, A.; Sagawa, H. doi  openurl
  Title (up) Spatial distribution of water in the stratosphere of Jupiter from Herschel HIFI and PACS observations Type Journal Article
  Year 2013 Publication Astron. Astrophys. Abbreviated Journal  
  Volume 553 Issue Pages A21 (1 to 16)  
  Keywords HEB mixer applications, HIFI, Herschel  
  Abstract Context. In the past 15 years, several studies suggested that water in the stratosphere of Jupiter originated from the Shoemaker-Levy 9 (SL9) comet impacts in July 1994, but a direct proof was missing. Only a very sensitive instrument observing with high spectral/spatial resolution can help to solve this problem. This is the case of the Herschel Space Observatory, which is the first telescope capable of mapping water in Jupiter's stratosphere.

Aims. We observed the spatial distribution of the water emission in Jupiter's stratosphere with the Heterodyne Instrument for the Far Infrared (HIFI) and the Photodetector Array Camera and Spectrometer (PACS) onboard Herschel to constrain its origin. In parallel, we monitored Jupiter's stratospheric temperature with the NASA Infrared Telescope Facility (IRTF) to separate temperature from water variability.

Methods. We obtained a 25-point map of the 1669.9 GHz water line with HIFI in July 2010 and several maps with PACS in October 2009 and December 2010. The 2010 PACS map is a 400-point raster of the water 66.4 μm emission. Additionally, we mapped the methane ν4 band emission to constrain the stratospheric temperature in Jupiter in the same periods with the IRTF.

Results. Water is found to be restricted to pressures lower than 2 mbar. Its column density decreases by a factor of 2–3 between southern and northern latitudes, consistently between the HIFI and the PACS 66.4 μm maps. We infer that an emission maximum seen around 15 °S is caused by a warm stratospheric belt detected in the IRTF data.

Conclusions. Latitudinal temperature variability cannot explain the global north-south asymmetry in the water maps. From the latitudinal and vertical distributions of water in Jupiter's stratosphere, we rule out interplanetary dust particles as its main source. Furthermore, we demonstrate that Jupiter's stratospheric water was delivered by the SL9 comet and that more than 95% of the observed water comes from the comet according to our models.
 
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  Notes Approved no  
  Call Number Serial 1085  
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Author Zhang, W.; Miao, W.; Zhong, J. Q.; Shi, S. C.; Hayton, D. J.; Vercruyssen, N.; Gao, J. R.; Goltsman, G. N. openurl 
  Title (up) Temperature dependence of superconducting hot electron bolometers Type Conference Article
  Year 2013 Publication Not published results: 24th international symposium on space terahertz technology Abbreviated Journal  
  Volume Issue Pages  
  Keywords HEB  
  Abstract  
  Address Groningen,The Netherlands  
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  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1067  
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