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| Author |
Siddiqi, I.; Prober, D. E. |
| Title |
Nb–Au bilayer hot-electron bolometers for low-noise THz heterodyne detection |
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Journal Article |
| Year |
2004 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
84 |
Issue |
8 |
Pages  |
1404 |
| Keywords |
HEB, mixers, dynamic range, saturation, LO power, local oscillator power, Nb |
| Abstract |
The sensitivity of present Nb diffusion-cooled hot-electron bolometer (HEB) mixers is not quantum limited, and can be improved by reducing the superconducting transition temperature TC. Lowering TC reduces thermal fluctuations, resulting in a decrease of the mixer noise temperature TM. However, lower TC mixers have reduced dynamic range and saturate more easily due to background noise. We present 30 GHz microwave measurements on a bilayer HEB system, Nb–Au, in which TC can be tuned with Au layer thickness to obtain the maximum sensitivity for a given noise background. These measurements are intended as a guide for the optimization of THz mixers. Using a Nb–Au mixer with TC = 1.6 K, we obtain TM = 50 K with 2 nW of local oscillator (LO) power. Good mixer performance is observed over a wide range of LO power and bias voltage and such a device should not exhibit saturation in a THz receiver. |
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0003-6951 |
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571 |
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Semenov, A. D.; Gol’tsman, G. N.; Gogidze, I. G.; Sergeev, A. V.; Gershenzon, E. M.; Lang, P. T.; Renk, K. F. |
| Title |
Subnanosecond photoresponse of a YBaCuO thin film to infrared and visible radiation by quasiparticle induced suppression of superconductivity |
Type |
Journal Article |
| Year |
1992 |
Publication |
Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
60 |
Issue |
7 |
Pages |
903-905 |
| Keywords |
YBCO HTS detectors |
| Abstract |
We observed subnanosecond photoresponse of a structured superconducting YBa2Cu3O7−δ thin film to infrared and visible radiation. We measured the voltage response of a current biased film (thickness 700 Å) in a resistive state to radiation pulses. From our results we conclude a response time of about 90 ps and a responsivity of about 4×1010 Ω/J. We attribute the response to Cooper pair breaking and suppression of the superconducting energy gap induced by nonequilibrium quasiparticles. |
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0003-6951 |
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1672 |
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Karasik, B. S.; Elantiev, A. I. |
| Title |
Noise temperature limit of a superconducting hot-electron bolometer mixer |
Type |
Journal Article |
| Year |
1996 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
68 |
Issue |
6 |
Pages |
853-855 |
| Keywords |
HEB mixer noise temperature, Johnson noise, thermal fluctuation noise, noise bandwidth |
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0003-6951 |
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260 |
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Gol’tsman, G. N.; Okunev, O.; Chulkova, G.; Lipatov, A.; Semenov, A.; Smirnov, K.; Voronov, B.; Dzardanov, A.; Williams, C.; Sobolewski, R. |
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Picosecond superconducting single-photon optical detector |
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Journal Article |
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2001 |
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Appl. Phys. Lett. |
Abbreviated Journal |
Appl. Phys. Lett. |
| Volume |
79 |
Issue |
6 |
Pages |
705-707 |
| Keywords |
NbN SSPD, SNSPD |
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We experimentally demonstrate a supercurrent-assisted, hotspot-formation mechanism for ultrafast detection and counting of visible and infrared photons. A photon-induced hotspot leads to a temporary formation of a resistive barrier across the superconducting sensor strip and results in an easily measurable voltage pulse. Subsequent hotspot healing in ∼30 ps time frame, restores the superconductivity (zero-voltage state), and the detector is ready to register another photon. Our device consists of an ultrathin, very narrow NbN strip, maintained at 4.2 K and current-biased close to the critical current. It exhibits an experimentally measured quantum efficiency of ∼20% for 0.81 μm wavelength photons and negligible dark counts. |
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0003-6951 |
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1543 |
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Gousev, Yu. P.; Semenov, A. D.; Pechen, E. V.; Varlashkin, A. V.; Nebosis, R. S.; Renk K. F |
| Title |
Coupling of terahertz radiation to a high-Т(с) superconducting hot electron bolometer mixer |
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Journal Article |
| Year |
1996 |
Publication |
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Appl. Phys. Lett., |
| Volume |
69 |
Issue |
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Pages |
691-693 |
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We report on efficient coupling of THz radiation to a high-T(c) superconducting hot electron bolometer that is suitable for heterodyne detection. Our quasioptical system consisted of a planar self-complementary spiral antenna on a dielectric substrate clamped to an extended hyperhemispherical lens. The antenna was integrated into a co-planar line for broadband intermediate frequency matching. Measurements in the homodyne regime at a frequency of 2.5 THz showed a radiation pattern with a beam width of 1° and a coupling efficiency of 0.1. We measured, at an intermediate frequency of 1.5 GHz, an output noise temperature of'160 K and estimated for the device, operated in the heterodyne regime, a system noise temperature of 30 000 K. We also discuss possibilities of significant improvement of the sensitivity. |
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RPLAB @ atomics90 @ |
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958 |
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