Records |
Author |
Nebosis, R. S.; Heusinger, M. A.; Schatz, W.; Renk, K. F.; Gol’tsman, G. N.; Karasik, B. S.; Semenov, A. D.; Gershenzon, E. M. |
Title |
Ultrafast photoresponse of a structured YBa2Cu3O7-δ thin film to ultrashort FIR laser pulses |
Type |
Journal Article |
Year |
1993 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
3 |
Issue |
1 |
Pages |
2160-2162 |
Keywords |
YBCO HTS detectors |
Abstract |
The authors have investigated the photoinduced voltage response of a current-carrying structured YBa2Cu3O7-δ thin film to ultrashort far-infrared (FIR) laser pulses in the frequency range from 0.7 THz to 7 THz. The detector has shown an almost constant sensitivity of 1 mV/W and a noise equivalent power of less than 5*10/sup -7/ W/ square root Hz. The temperature dependence of the decay time of the detector signal was studied for temperatures around the transition temperature of the film ( approximately 80 K). For a detector temperature where dR/dT had its maximum, the authors observed bolometric signals with decay times of about 2 ns, and for lower temperatures they observed nonbolometric signals with decay times of approximately 120 ps; the duration of the nonbolometric signals was limited by the time resolution of the electronic registration equipment. |
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1658 |
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Semenov, A. D.; Goghidze, I. G.; Gol’tsman, G. N.; Sergeev, A. V.; Aksaev, E. E.; Gershenzon, E. M. |
Title |
Non-equilibrium quasiparticle response to radiation and bolometric effect in YBaCuO films |
Type |
Journal Article |
Year |
1993 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
3 |
Issue |
1 |
Pages |
2132-2135 |
Keywords |
YBCO HTS HEB detectors |
Abstract |
The voltage photoresponse of structured current biased YBCO films on different substrates to 20-ps laser pulses of 0.63- mu m and 1.54- mu m wavelengths and to continuously modulated radiation of 2-mm wavelength is measured to temperatures around Tc. Fast picosecond decay of the response to pulsed radiation is followed by slow exponential relaxation with a nanosecond characteristic time depending on the substrate material and film dimensions. The slow component does not depend on wavelength and is attributed to the bolometric effect, while the magnitude of the fast component associated with nonequilibrium response rises with wavelength. More than an order-of-magnitude increase of the nonequilibrium response is seen from near-infrared to millimeter-wave range. This dependence plausibly reflects the low efficiency of multiplication of photoexcited electrons in YBaCuO compared to conventional superconductors. |
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1558-2515 |
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1659 |
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Gol'tsman, G. N.; Karasik, B. S.; Okunev, O. V.; Dzardanov, A. L.; Gershenzon, E. M.; Ekstrom, H.; Jacobsson, S.; Kollberg, E. |
Title |
NbN hot electron superconducting mixers for 100 GHz operation |
Type |
Journal Article |
Year |
1995 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
5 |
Issue |
2 |
Pages |
3065-3068 |
Keywords |
NbN HEB mixers |
Abstract |
NbN is a promising superconducting material for hot-electron superconducting mixers with an IF bandwidth larger than 1 GHz. In the 1OO GHz frequency range, the following parameters were obtained for 50 /spl Aring/ thick NbN films at 4.2 K: receiver noise temperature (DSB) /spl sim/1000 K; conversion loss /spl sim/10 dB; IF bandwidth /spl sim/1 GHz; and local oscillator power /spl sim/1 /spl mu/W. An increase of the critical current of the NbN film, increased working temperature, and a better mixer matching may allow a broader IF bandwidth up to 2 GHz, reduced conversion losses down to 3-5 dB and a receiver noise temperature (DSB) down to 200-300 K. |
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1051-8223 |
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About LO power required |
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255 |
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Zorin, M.; Gol'tsman, G.N.; Karasik, B.S.; Elantev, A.I.; Gershenzon, E.M.; Lindgren, M.; Danerud, M.; Winkler, D. |
Title |
Optical mixing in thin YBa2Cu3O7-x films |
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Journal Article |
Year |
1995 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
5 |
Issue |
2 |
Pages |
2431-2434 |
Keywords |
YBCO HTS HEB mixers |
Abstract |
High quality, j/sub c/ (77 K)>10/sup 6/ A/cm/sup 2/, epitaxial YBa2Cu3O7-x films of 50 nm thickness were patterned into ten parallel 1 /spl mu/m wide strips. The film structure was coupled to a single-mode fiber. Mixer response was obtained at 0.78 /spl mu/m using laser frequency modulation and an optical delay line. Using two semiconductor lasers at 1.55 /spl mu/m wavelength the beating signal was used to measure the photoresponse up to 18 GHz. Nonequilibrium photoresponse in the resistive state of the superconductor was observed. Bolometric response dominates up to 3 GHz, after which the nonequilibrium response is constant up to the frequency limit of our registration system. Using an electron heating model the influence of different thermal processes on the conversion loss has been analyzed. Ways of increasing the sensitivity are also discussed. |
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1051-8223 |
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1619 |
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Karasik, B. S.; Milostnaya, I. I.; Zorin, M. A.; Elantev, A. I.; Gol'tsman, G. N.; Gershenzon, E. M. |
Title |
High speed current switching of homogeneous YBaCuO film between superconducting and resistive states |
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Journal Article |
Year |
1995 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
Volume |
5 |
Issue |
2 |
Pages |
3042-3045 |
Keywords |
YBCO HTS HEB switches |
Abstract |
Transitions of thin structured YBaCuO films from superconducting (S) to normal (N) state and back induced by a supercritical current pulse has been studied. A subnanosecond stage in the film resistance dynamic has been observed. A more gradual (nanosecond) ramp in the time dependence of the resistance follows the fast stage. The fraction of the film resistance which is attained during the fast S-N stage rises with the current amplitude. Subnanosecond N-S switching is more pronounced for smaller amplitudes of driving current and for shorter pulses. The phenomena observed are viewed within the framework of an electron heating model. The expected switching time and repetition rate of an optimized current controlling device are estimated to be 1-2 ps and 80 GHz respectively. |
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1051-8223 |
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Call Number |
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1620 |
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