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Author Kataoka, T; Kajikawa, K.; Kitagawa, J.; Kadoya, Y; Takemura, Y.
Title Improved sensitivity of terahertz detection by GaAs photoconductive antennas excited at 1560 nm Type (up) Journal Article
Year 2010 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 97 Issue Pages 201110 (1-3)
Keywords photoconductive antenna (PCA)
Abstract The terahertz detection by photoconductive antennas (PCAs) based on low-temperature grown (LTG) GaAs with 1.5 μm pulse excitation was revisited. We found that the detection efficiency can be improved by a factor of 10 (20 dB) by reducing the excitation spot size and the gap length of the PCA, maintaining the low noise feature of the PCA on LTG GaAs. As a result, the signal-to-noise ratio higher than 50 dB was obtained at a reasonable incident power of 9.5 mW, suggesting that the scheme is promising for the detection of terahertz waves in practical time domain systems.
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Call Number Serial 904
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Author Gao, J. R.; Hovenier, J. N.; Yang, Z. Q.; Baselmans, J. J. A.; Baryshev, A.; Hajenius, M.; Klapwijk, T. M.; Adam, A. J. L.; Klaassen, T. O.; Williams, B. S.; Kumar, S.; Hu, Q.; Reno, J. L.
Title Terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer Type (up) Journal Article
Year 2005 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 86 Issue Pages 244104 (1 to 3)
Keywords HEB, QCL
Abstract We report the first demonstration of an all solid-stateheterodyne receiver that can be used for high-resolution spectroscopy above 2THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8THz as local oscillator. We measure a double sideband receiver noise temperature of 1400K at 2.8THz and 4.2K, and find that the free-running QCL has sufficient power stability for a practical receiver, demonstrating an unprecedented combination of sensitivity and stability.
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Notes Approved no
Call Number Serial 905
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Author Yagoubov, P.; Kroug, M.; Merkel, H.; Kollberg, E.; Gol'tsman, G.; Svechnikov, S.; Gershenzon, E.
Title Noise temperature and local oscillator power requirement of NbN phonon-cooled hot electron bolometric mixers at terahertz frequencies Type (up) Journal Article
Year 1998 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 73 Issue 19 Pages 2814-2816
Keywords NbN HEB mixers, noise temperature, local oscillator power
Abstract In this letter, the noise performance of NbN-based phonon-cooled hot electron bolometric quasioptical mixers is investigated in the 0.55–1.1 THz frequency range. The best results of the double-sideband <cd><2018>DSB<cd><2019> noise temperature are: 500 K at 640 GHz, 600 K at 750 GHz, 850 K at 910 GHz, and 1250 K at 1.1 THz. The water vapor in the signal path causes significant contribution to the measured receiver noise temperature around 1.1 THz. The devices are made from 3-nm-thick NbN film on high-resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are typically 0.2Ï«2 um. The amount of local oscillator power absorbed in the bolometer is less than 100 nW.
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Notes Approved no
Call Number Serial 911
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Author Bennett, Douglas A.; Schmidt, Daniel R.; Swetz, Daniel S.; Ullom, Joel N.
Title Phase-slip lines as a resistance mechanism in transition-edge sensors Type (up) Journal Article
Year 2014 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 104 Issue Pages 042602
Keywords microbolometers, TES, phase-slip lines, PSL
Abstract The fundamental mechanism of resistance in voltage-biased superconducting films is poorly understood despite its importance as the basis of transition-edge sensors (TESs). TESs are utilized in state-of-the-art microbolometers and microcalorimeters covering a wide range of energies and applications. We present a model for the resistance of a TES based on phase-slip lines (PSLs) and compare the model to data. One of the model's predictions, discrete changes in the number of PSLs, is a possible explanation for the observed switching between discrete current states in localized regions of bias.
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Notes Recommended by Klapwijk Approved no
Call Number Serial 929
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Author Swetz, D. S.; Bennett, D. A.; Irwin, K. D.; Schmidt, D. R.; Ullom, J. N.
Title Current distribution and transition width in superconducting transition-edge sensors Type (up) Journal Article
Year 2012 Publication Appl. Phys. Lett. Abbreviated Journal Appl. Phys. Lett.
Volume 101 Issue Pages 242603
Keywords
Abstract Present models of the superconducting-to-normal transition in transition-edge sensors (TESs) do not describe the current distribution within a biased TES. This distribution is complicated by normal-metal features that are integral to TES design. We present a model with one free parameter that describes the evolution of the current distribution with bias. To probe the current distribution experimentally, we fabricated TES devices with different current return geometries. Devices where the current return geometry mirrors current flow within the device have sharper transitions, thus allowing for a direct test of the current-flow model.Measurements from these devices show that current meanders through a TES low in the resistivetransition but flows across the normal-metal features by 40% of the normal-state resistance. Comparison of transition sharpness between device designs reveals that self-induced magnetic fields play an important role in determining the width of the superconducting transition.
Address TES, current distribution
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Notes Recommended by Klapwijk Approved no
Call Number Serial 930
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