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Zhang, W.; Li, N.; Jiang, L.; Ren, Y.; Yao, Q.-J.; Lin, Z.-H.; Shi, S.-C.; Voronov, B. M.; Gol’tsman, G. N. |
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Title |
Dependence of noise temperature of quasi-optical superconducting hot-electron bolometer mixers on bath temperature and optical-axis displacement |
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Conference Article |
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Year |
2008 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
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Volume  |
6840 |
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684007 (1 to 8) |
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Keywords |
NbN HEB mixers, noise temperature, LO power |
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Abstract |
It is known that the increase of bath temperature results in the decrease of critical current of superconducting hot-electron bolometer (HEB) mixers owing to the depression of superconductivity, thus leading to the degradation of the mixer’s sensitivity. Here we report our study on the effect of bath temperature on the heterodyne mixing performance of quasi-optical superconducting NbN HEB mixers incorporated with a two-arm log-spiral antenna. The correlation between the bath temperature, critical current, LO power requirement and noise temperature is investigated at 0.5 THz. Furthermore, the heterodyne mixing performance of quasi-optical superconducting NbN HEB mixers is examined while there is an optical-axis displacement between the center of the extended hemispherical silicon lens and the superconducting NbN HEB device, which is placed on the back of the lens. Detailed experimental results and analysis are presented. |
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Spie |
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Zhang, C.; Zhang, X.-C. |
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Terahertz Photonics |
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1415 |
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Author |
Kopp, Victor I.; Churikov, Victor M.; Zhang, Guoyin; Singer, Jonathan; Draper, Christopher W.; Chao, Norman; Neugroschl, Daniel; Genack, Azriel Z. |
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Title |
Chiral fiber gratings: perspectives and challenges for sensing applications |
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Conference Article |
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Year |
2007 |
Publication |
Proceedings of Third european workshop on optical fibre sensors |
Abbreviated Journal |
Proc. 3rd European Workshop on Opt. Fibre Sensors |
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6619 |
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66190B-(1-8) |
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Keywords |
optical fiber gratings, chiral fiber gratings applications, chiral gratings applications, from chiralphotonics |
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Abstract |
Chiral fiber gratings are produced in a microforming process in which optical fibers with noncircular or nonconcentric cores are twisted as they pass though a miniature oven. Periodic glass structures as stable as the glass material itself are produced with helical pitch that ranges from under a micron to hundreds of microns. The geometry of the fiber cross section determines the symmetry of the resulting structure which in turn determines its polarization selectivity. Single helix structures are polarization insensitive while double helix gratings interact only with a single optical polarization. Both single and double helix gratings may act as a fiber long period grating, coupling the core and cladding modes. The coupling is manifested in a series of narrow dips in the transmission spectrum. The dip position is sensitive to fiber elongation, twist and temperature, and to the refractive index of the surrounding medium. The suitability of chiral gratings for sensing pressure, temperature and liquid levels is investigated. Polarization insensitive single helix silica glass gratings display excellent stability up to temperatures of 6000C, while a pressure sensor with dynamic range of nearly 40 dB is demonstrated in polarization selective double helix gratings. |
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855 |
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Korneev, A.; Minaeva, O.; Divochiy, A.; Antipov, A.; Kaurova, N.; Seleznev, V.; Voronov, B.; Gol’tsman, G.; Pan, D.; Kitaygorsky, J.; Slysz, W.; Sobolewski, R. |
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Title |
Ultrafast and high quantum efficiency large-area superconducting single-photon detectors |
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Conference Article |
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Year |
2007 |
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Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
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Volume |
6583 |
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65830I (1 to 9) |
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Keywords |
SSPD, SNSPD, superconducting NbN films, infrared single-photon detectors |
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We present our latest generation of superconducting single-photon detectors (SSPDs) patterned from 4-nm-thick NbN films, as meander-shaped 0.5-mm-long and 100-nm-wide stripes. The SSPDs exhibit excellent performance parameters in the visible-to-near-infrared radiation wavelengths: quantum efficiency (QE) of our best devices approaches a saturation level of 30% even at 4.2 K (limited by the NbN film optical absorption) and dark counts as low as 2x10-4 Hz. The presented SSPDs were designed to maintain the QE of large-active-area devices, but, unless our earlier SSPDs, hampered by a significant kinetic inductance and a nanosecond response time, they are characterized by a low inductance and GHz counting rates. We have designed, simulated, and tested the structures consisting of several, connected in parallel, meander sections, each having a resistor connected in series. Such new, multi-element geometry led to a significant decrease of the device kinetic inductance without the decrease of its active area and QE. The presented improvement in the SSPD performance makes our detectors most attractive for high-speed quantum communications and quantum cryptography applications. |
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Spie |
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Dusek, M.; Hillery, M.S.; Schleich, W.P.; Prochazka, I.; Migdall, A.L.; Pauchard, A. |
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1249 |
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Slysz, W.; Wegrzecki, M.; Bar, J.; Grabiec, P.; Gorska, M.; Rieger, E.; Dorenbos, P.; Zwiller, V.; Milostnaya, I.; Minaeva, O.; Antipov, A.; Okunev, O.; Korneev, A.; Smirnov, K.; Voronov, B.; Kaurova, N.; Gol’tsman, G.N.; Kitaygorsky, J.; Pan, D.; Pearlman, A.; Cross, A.; Komissarov, I.; Sobolewski, R. |
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Title |
Fiber-coupled NbN superconducting single-photon detectors for quantum correlation measurements |
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Conference Article |
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Year |
2007 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
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Volume |
6583 |
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65830J (1 to 11) |
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Keywords |
NbN SSPD, SNSPD, superconducting single-photon detectors, single-photon detectors, fiber-coupled optical detectors, quantum correlations, superconducting devices |
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Abstract |
We have fabricated fiber-coupled superconducting single-photon detectors (SSPDs), designed for quantum-correlationtype experiments. The SSPDs are nanostructured ( 100-nm wide and 4-nm thick) NbN superconducting meandering stripes, operated in the 2 to 4.2 K temperature range, and known for ultrafast and efficient detection of visible to nearinfrared photons with almost negligible dark counts. Our latest devices are pigtailed structures with coupling between the SSPD structure and a single-mode optical fiber achieved using a micromechanical photoresist ring placed directly over the meander. The above arrangement withstands repetitive thermal cycling between liquid helium and room temperature, and we can reach the coupling efficiency of up to 33%. The system quantum efficiency, measured as the ratio of the photons counted by SSPD to the total number of photons coupled into the fiber, in our early devices was found to be around 0.3 % and 1% for 1.55 &mgr;m and 0.9 &mgr;m photon wavelengths, respectively. The photon counting rate exceeded 250 MHz. The receiver with two SSPDs, each individually biased, was placed inside a transport, 60-liter liquid helium Dewar, assuring uninterrupted operation for over 2 months. Since the receiver’s optical and electrical connections are at room temperature, the set-up is suitable for any applications, where single-photon counting capability and fast count rates are desired. In our case, it was implemented for photon correlation experiments. The receiver response time, measured as a second-order photon cross-correlation function, was found to be below 400 ps, with timing jitter of less than 40 ps. |
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Spie |
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Dusek, M.; Hillery, M.S.; Schleich, W.P.; Prochazka, I.; Migdall, A.L.; Pauchard, A. |
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Photon Counting Applications, Quantum Optics, and Quantum Cryptography |
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1431 |
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Ryabchun, S.; Tong, C.-yu E.; Blundell, R.; Kimberk, R.; Gol’tsman, G. |
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Title |
Effect of microwave radiation on the stability of terahertz hot-electron bolometer mixers |
Type |
Conference Article |
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Year |
2006 |
Publication |
Proc. SPIE |
Abbreviated Journal |
Proc. SPIE |
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Volume |
6373 |
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63730J (1 to 5) |
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Keywords |
NbN HEB mixers, hot-electron bolometer mixers, stability, Allan variance, LO power fluctuations |
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Abstract |
We report our studies of the effect of microwave radiation, with a frequency much lower than that corresponding to the energy gap of the superconductor, on the performance of the NbN hot-electron bolometer (HEB) mixer incorporated into a THz heterodyne receiver. It is shown that exposing the HEB mixer to microwave radiation does not result in a significant rise of the receiver noise temperature and degradation of the mixer conversion gain so long as the level of microwave power is small compared to the local oscillator drive. Hence the injection of a small, but controlled amount of microwave radiation enables active compensation of local oscillator power and coupling fluctuations which can significantly degrade the stability of HEB mixer receivers. |
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SPIE |
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Anwar, M.; DeMaria, A.J.; Shur, M.S. |
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Terahertz Physics, Devices, and Systems |
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Call Number |
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1441 |
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