Korneev, A., Divochiy, A., Marsili, F., Bitauld, D., Fiore, A., Seleznev, V., et al. (2008). Superconducting photon number resolving counter for near infrared applications. In P. Tománek, D. Senderáková, & M. Hrabovský (Eds.), Proc. SPIE (Vol. 7138, 713828 (1 to 5)). Spie.
Abstract: We present a novel concept of photon number resolving detector based on 120-nm-wide superconducting stripes made of 4-nm-thick NbN film and connected in parallel (PNR-SSPD). The detector consisting of 5 strips demonstrate a capability to resolve up to 4 photons absorbed simultaneously with the single-photon quantum efficiency of 2.5% and negligibly low dark count rate.
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Marsili, F., Bitauld, D., Divochiy, A., Gaggero, A., Leoni, R., Mattioli, F., et al. (2008). Superconducting nanowire photon number resolving detector at telecom wavelength. In CLEO/QELS (Qmj1 (1 to 2)). Optical Society of America.
Abstract: We demonstrate a photon-number-resolving (PNR) detector, based on parallel superconducting nanowires, capable of resolving up to 5 photons in the telecommunication wavelength range, with sensitivity and speed far exceeding existing approaches.
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Meledin D., Desmaris V., Ferm S.-E., Fredrixon M., Henke D., Lapkin I., et al. (2008). APEX Band T2: A 1.25 – 1.39 THz Waveguide Balanced HEB Receiver.181–185.
Abstract: A waveguide 1.25–1.39 THz Hot Electron Bolometer (HEB) balanced receiver was successfully developed, characterized and installed at the Atacama Pathfinder EXperiment (APEX) telescope. The receiver employs a quadrature balanced scheme using a waveguide 90-degree 3 dB RF hybrid, HEB mixers and a 180-degree IF hybrid. The HEB mixers are based on ultrathin NbN film deposited on crystalline quartz with a MgO buffer layer. Integrated into the multi-channel APEX facility receiver (SHeFI), the results presented here demonstrate exceptional performance; a receiver noise temperature of 1000 K measured at the telescope at the center of the receiver IF band 2-4 GHz, and at an LO frequency of 1294 GHz. Stability of the receiver is fully in line with the SIS mixer bands of the SHeFI, and gives a spectroscopic Allan time of more than 200 s with a noise bandwidth of 1 MHz.
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Feautrier, P., le Coarer, E., Espiau de Lamaestre, R., Cavalier, P., Maingault, L., Villégier, J. - C., et al. (2008). High-speed superconducting single photon detectors for innovative astronomical applications. In J. Phys.: Conf. Ser. (Vol. 97, 10).
Abstract: Superconducting Single Photon Detectors (SSPD) are now mature enough to provide extremely interesting detector performances in term of sensitivity, speed, and geometry in the visible and near infrared wavelengths. Taking advantage of recent results obtained in the Sinphonia project, the goal of our research is to demonstrate the feasibility of a new family of micro-spectrometers, called SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer), associated to an array of SSPD, the whole assembly being integrated on a monolithic sapphire substrate coupling the detectors array to a waveguide injecting the light. This unique association will create a major breakthrough in the domain of visible and infrared spectroscopy for all applications where the space and weight of the instrument is limited. SWIFTS is an innovative way to achieve very compact spectro-detectors using nano-detectors coupled to evanescent field of dielectric integrated optics. The system is sensitive to the interferogram inside the dielectric waveguide along the propagation path. Astronomical instruments will be the first application of such SSPD spectrometers. In this paper, we describes in details the fabrication process of our SSPD built at CEA/DRFMC using ultra-thin NbN epitaxial films deposited on different orientations of Sapphire substrates having state of the art superconducting characteristics. Electron beam lithography is routinely used for patterning the devices having line widths below 200 nm and down to 70 nm. An experimental set-up has been built and used to test these SSPD devices and evaluate their photon counting performances. Photon counting performances of our devices have been demonstrated with extremely low dark counts giving excellent signal to noise ratios. The extreme compactness of this concept is interesting for space spectroscopic applications. Some new astronomical applications of such concept are proposed in this paper.
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Seleznev, V. A., Tarkhov, M. A., Voronov, B. M., Milostnaya, I. I., Lyakhno, V. Y., Garbuz, A. S., et al. (2008). Deposition and characterization of few-nanometers-thick superconducting Mo-Re films. Supercond. Sci. Technol., 21(11), 115006 (1 to 6).
Abstract: We report on the fabrication and investigation of few-nanometers-thick superconducting molybdenum-rhenium (Mo-Re) films intended for use in nanowire single-photon superconducting detectors (SSPDs). Mo-Re films were deposited on sapphire substrates by DC magnetron sputtering of an Mo(60)-Re(40) alloy target in an atmosphere of argon. The films 2-10 nm thick had critical temperatures (Tc) from 5.6 to 9.7 K. HRTEM (high-resolution transmission electron microscopy) analysis showed that the films had a homogeneous structure. XPS (x-ray photoelectron spectroscopy) analysis showed the Mo to Re atom ratio to be 0.575/0.425, oxygen concentration to be 10%, and concentration of other elements to be 1%.
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