| Records |
| Author |
Lobanov, Y.V.; Tong, C.-Y.E.; Hedden, A.S.; Blundell, R.; Voronov, B.M.; Gol'tsman, G.N. |
| Title |
Direct measurement of the gain and noise bandwidths of HEB mixers |
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Journal Article |
| Year |
2011 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
21 |
Issue |
3 |
Pages |
645-648 |
| Keywords |
waveguide NbN HEB mixers |
| Abstract |
The intermediate frequency (IF) bandwidth of a hot electron bolometer (HEB) mixer is an important parameter of the mixer, in that it helps to determine its suitability for a given application. With the availability of wideband low noise amplifiers, it is simple to measure the performance of an HEB mixer over a wide range of IF at a fixed LO frequency using the standard Y-factor method. This in-situ method allows us to measure both the gain and noise bandwidths simultaneously. We have also measured mixer output impedance with a vector network analyser. Intrinsic time constant has been extracted from the impedance data and compared to the mixer's bandwidths determined from receiver Y-factor measurement. |
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RPLAB @ gujma @ |
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720 |
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Васильева, И. А.; Компанеец, В. В.; Красная, Ж. А.; Чижикова, З. А. |
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Проявление внутримолекулярных вибронных взаимодействий в тонкоструктурных спектрах флуоресценции и возбуждения флуоресценции полиеновых δ-диметиламинокетонов |
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Journal Article |
| Year |
2011 |
Publication |
Оптический журнал |
Abbreviated Journal |
Опт. ж. |
| Volume |
78 |
Issue |
5 |
Pages |
3-8 |
| Keywords |
спектры флуоресценции; вибрационный анализ; адиабатическое гармоническое приближение; бесфононная линия; фононное крыло |
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Проведен вибрационный анализ спектров флуоресценции и возбуждения флуоресценции, полученных методом Шпольского при 4,2 K. Рассчитаны параметры внутримолекулярных взаимодействий двух δ-диметиламинокетонов. Для определения интегральных интенсивностей вибронных полос в спектрах с тонкой структурой на интенсивном сплошном фоне выполнено моделирование спектров путем представления полосы каждого из вибронных переходов бесфононной линией и фононным крылом с определенными параметрами (полуширинами, фактором Дебая–Валлера). Показано, что нарушение зеркальной симметрии в сопряженных спектрах флуоресценции и возбуждения флуоресценции этих двух соединений может быть обÑŠяснено интерференцией франк-кондоновского и герцберг-теллеровского взаимодействий. |
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RPLAB @ gujma @ |
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721 |
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Seleznev, V. A.; Tarkhov, M. A.; Voronov, B. M.; Milostnaya, I. I.; Lyakhno, V. Yu; Garbuz, A. S.; Mikhailov, M. Yu; Zhigalina, O. M.; Gol'tsman, G. N. |
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Deposition and characterization of few-nanometers-thick superconducting Mo-Re films |
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Journal Article |
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2008 |
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Supercond. Sci. Technol. |
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Supercond. Sci. Technol. |
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21 |
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11 |
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115006 (1 to 6) |
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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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RPLAB @ gujma @ |
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723 |
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Ожегов, Р.В.; Окунев, О.В.; Гольцман, Г.Н. |
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Флуктуационная чувствительность сверхпроводящего болометрического смесителя на эффекте разогрева электронного газа |
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Journal Article |
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2009 |
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Радиотехника |
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3 |
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120-124 |
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смеситель на горячих электронах; флуктуационная чувствительность; тепловизор терагерцевого диапазона частот; hot-electron bolometer mixer; Imaging system; Noise equivalent temperature difference; Heterodyne receiver; Terahertz range |
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Interest in research in the terahertz range is driven by a great number of various applications, where terahertz instruments may play a leading role. To name just a few, such applications include study of the cosmic microwave background radiation and the distribution of the dark matter, medicine, navigation, fire alarm, security systems and environmental monitoring. The paper discusses the possibility of using a receiver based on the hot-electron effect in superconducting films as an imaging system. We present the results of the noise equivalent temperature difference (NETD) measurements performed with a hot-electron bolometer mixer made from a thin superconducting film. The receiver with a noise temperature of ~ 3800 K at a local oscillator frequency of 300 GHz a bandwidth of 500 MHz and an integration time of 1 s has offered an NETD of 0.5 K. We have also developed a technique that enabled us to reduce the contribution of the mixer gain fluctuations to the overall system instability. As of this writing, the above value of the NETD is the lowest value offered for this type of receiver, which indicates the possibility to use such receivers in real-time imaging systems. The technique offered in the paper for achieving the limiting value of the NETD offers an alternative to the phase-locking scheme.
Представены результаты измерения флуктуационной чувствительности (NETD – noise equivalent temperature difference) болометрического смесителя на эффекте разогрева электронного газа в тонких сверхпроводящих пленках. Получено предельное значение NETD, равное 0,5 К, при шумовой температуре приемника 3800 К, ширине полосы преобразования 500 МГц, постоянной времени 1 с и частоте гетеродина 300 ГГц. Разработана методика достижения предельной флуктуационной чувствительности, позволяющая избежать влияния нестабильности коэффициента преобразования смесителя. |
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RPLAB @ gujma @ |
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728 |
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| Author |
Ожегов, Роман Викторович |
| Title |
Флуктуационная чувствительность и стабильность приемников с СИС и HEB смесителями для терагерцового тепловидения |
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Journal Article |
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2011 |
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Радиофизика |
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135 |
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HEB |
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RPLAB @ gujma @ |
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