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Author Mohan, N.; Minaeva, O.; Gol'tsman, G. N.; Nasr, M. B.; Saleh, B. E.; Sergienko, A. V.; Teich, M. C. url  doi
openurl 
  Title Photon-counting optical coherence-domain reflectometry using superconducting single-photon detectors Type Journal Article
  Year 2008 Publication Opt. Express Abbreviated Journal Opt. Express  
  Volume (down) 16 Issue 22 Pages 18118-18130  
  Keywords SSPD, SNSPD  
  Abstract We consider the use of single-photon counting detectors in coherence-domain imaging. Detectors operated in this mode exhibit reduced noise, which leads to increased sensitivity for weak light sources and weakly reflecting samples. In particular, we experimentally demonstrate the possibility of using superconducting single-photon detectors (SSPDs) for optical coherence-domain reflectometry (OCDR). These detectors are sensitive over the full spectral range that is useful for carrying out such imaging in biological samples. With counting rates as high as 100 MHz, SSPDs also offer a high rate of data acquisition if the light flux is sufficient.  
  Address Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA. nm82@bu.edu  
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  ISSN 1094-4087 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:18958090 Approved no  
  Call Number Serial 1407  
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Author Nasr, M. B.; Minaeva, O.; Goltsman, G. N.; Sergienko, A. V.; Saleh, B. E.; Teich, M. C. url  doi
openurl 
  Title Submicron axial resolution in an ultrabroadband two-photon interferometer using superconducting single-photon detectors Type Journal Article
  Year 2008 Publication Opt. Express Abbreviated Journal Opt. Express  
  Volume (down) 16 Issue 19 Pages 15104-15108  
  Keywords SSPD, SNSPD  
  Abstract We generate ultrabroadband biphotons via the process of spontaneous parametric down-conversion in a quasi-phase-matched nonlinear grating that has a linearly chirped poling period. Using these biphotons in conjunction with superconducting single-photon detectors (SSPDs), we measure the narrowest Hong-Ou-Mandel dip to date in a two-photon interferometer, having a full width at half maximum (FWHM) of approximately 5.7 fsec. This FWHM corresponds to a quantum optical coherence tomography (QOCT) axial resolution of 0.85 µm. Our results indicate that a high flux of nonoverlapping biphotons may be generated, as required in many applications of nonclassical light.  
  Address Departments of Electrical & Computer Engineering and Physics, Quantum Imaging Laboratory, Boston University, Boston, MA 02215, USA. boshra@bu.edu  
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  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1094-4087 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:18795048 Approved no  
  Call Number Serial 1408  
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Author Ozhegov, R. V.; Gorshkov, K. N.; Smirnov, K. V.; Gol’tsman, G. N.; Filippenko, L. V.; Koshelets, V. P. url  openurl
  Title Terahertz imaging system based on superconducting integrated receiver Type Conference Article
  Year 2010 Publication Proc. 2-nd Int. Conf. Terahertz and Microwave radiation: Generation, Detection and Applications Abbreviated Journal Proc. 2-nd Int. Conf. Terahertz and Microwave radiation: Generation, Detection and Applications  
  Volume (down) Issue Pages 20-22  
  Keywords SIS mixer, SIR  
  Abstract The development of terahertz imaging instruments for security systems is on the cutting edge of terahertz technology. We are developing a THz imaging system based on a superconducting integrated receiver (SIR). An SIR is a new type of heterodyne receiver based on an SIS mixer integrated with a flux-flow oscillator (FFO) and a harmonic mixer which is used for phase-locking the FFO. Developing an array of SIRs would allow obtaining amplitude and phase characteristics of incident radiation in the plane of the receiver. Employing an SIR in an imaging system means building an entirely new instrument with many advantages compare to traditional systems: i) high temperature resolution, comparable to the best results for incoherent receivers; ii) high spectral resolution allowing spectral analysis of various substances; iii) the local oscillator frequency can be varied to obtain images at different frequencies, effectively providing “color” images; iv) since a heterodyne receiver preserves the phase of the radiation, it is possible to construct 3D images. The paper presents a prototype THz imaging system using an 1 pixel SIR. We have studied the dependence of the noise equivalent temperature difference (NETD) on the integration time and also possible ways of achieving best possible sensitivity. An NETD of 13 mK was obtained with an integration time of 1 sec a detection bandwidth of 4 GHz at a local oscillator frequency of 520 GHz. An important advantage of an FFO is its wide operation range: 300-700 GHz.  
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  Call Number ozhegov2010terahertz Serial 1397  
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Author Maslennikova, Anna; Tretyakov, Ivan; Ryabchun, Sergey; Finkel, Matvey; Kaurova, Natalia; Voronov, Boris; Gol’tsman, Gregory url  openurl
  Title Gain bandwidth and noise temperature of NbN HEB mixers with simultaneous phonon and diffusion cooling Type Abstract
  Year 2010 Publication Proc. 21th Int. Symp. Space Terahertz Technol. Abbreviated Journal Proc. 21th Int. Symp. Space Terahertz Technol.  
  Volume (down) Issue Pages 218-219  
  Keywords  
  Abstract The space observatory Millimetron will be operating in the millimeter, sub-millimeter and infrared ranges using a 12-m cryogenic telescope in a single-dish mode, and as an interferometer with the space-earth and space-space baselines (the latter after the launch of the second identical space telescope). The observatory will allow performing astronomical observations with an unprecedented sensitivity (down to nJy level) in the single-dish mode, and observations with a high angular resolution in the interferometer mode. The total spectral range 20 μm – 2 cm is separated into 10 bands. HEB mixers with two cooling channels (diffusion and phonon) have been chosen to be the detectors of choice of the system covering the range from 1 THz to 6 THz as the best detectors in terahertz receivers. This type of HEB has already shown good work in the terahertz range. A gain bandwidth of 6 GHz at an LO frequency of 300 GHz and a noise temperature of 750 K at an LO frequency of 2.5 THz are the best values for HEB mixers with two cooling channels [1]. Theoretical estimations predict a bandwidth up to 12 GHz. Reaching such good result demands more systematic and thorough research. We present the results of the gain bandwidth and noise temperature measurements for superconducting hot- electron bolometer mixers with two cooling channels. These characteristics of the devices of lengths varying from 50 to 200 nm were measured for the purposes of Millimetron at frequencies of 600 GHz, 2.5 THz, and 3.8 THz. For gain bandwidth measurements we use two BWO’s operating at 600 GHz: one as the signal and the second as the LO. The noise temperature measurements were performed using a gas discharge laser as the LO and blackbodies at 77 K and 295 K as input signals. The devices studied consist of 3.5-nm-thick NbN bridges connected to thick (10 nm) high conductivity Au leads fabricated in situ. This method of fabricating devices has already proved promising by opening the diffusion cooling channel. [2] Fig. 1 shows a SEM photograph of a log-spiral antenna with an HEB at its apex. Fig. 1. Left: a SEM photograph of a log-spiral antenna with an HEB at its apex; right: a close-up of the HEB at the antenna apex. [1] S. A. Ryabchun, I. V. Tretyakov, M. I. Finkel, S. N. Maslennikov, N. S. Kaurova, V. A. Seleznev, B. M. Voronov, and G. N. Gol’tsman, NbN phonon-cooled hot-electron bolometer mixer with additional diffusion cooling, Proc. of the 20 th Int. Symp. Space. Technol., Charlottesville, Virginia, USA, April 20 – 22, 2009. 218[2] S. A. Ryabchun * , I. V. Tretyakov, M. I. Finkel, S. N. Maslennikov, N. S. Kaurova, V. A. Seleznev, B. M. Voronov and G. N. Goltsman, Fabrication and characterisation of NbN HEB mixers with in situ gold contacts, Proc. of the 19 th Int. Symp. Space. Technol., Groningen, The Netherlands, April 28-30, 2008  
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  Notes Approved no  
  Call Number Serial 1393  
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Author Palma, F.; Teppe, F.; Fatimy, A. E.; Green, R.; Xu, J.; Vachontin, Y.; Tredicucci, A.; Goltsman, G.; Knap, W. url  doi
openurl 
  Title THz communication system based on a THz quantum cascade laser and a hot electron bolometer Type Conference Article
  Year 2010 Publication 35th Int. Conf. Infrared, Millimeter, and Terahertz Waves Abbreviated Journal 35th Int. Conf. Infrared, Millimeter, and Terahertz Waves  
  Volume (down) Issue Pages 11623798 (1 to 2)  
  Keywords QCL, HEB detector  
  Abstract We present the experimental study of the direct emission – detection system based on the THz Quantum Cascade Laser as a source and Hot Electron Bolometer (HEB) detector – in view of its application as an optical communication system. We show that the system can efficiently transmit the QCL Terahertz pulses. We estimate the maximal modulation speed of the system to be about several GHz and show that it is limited only by the QCL pulse power supply, detector amplifier and connection line/wires parameters.  
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  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number Serial 1391  
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