| Records |
| Author |
Schwaab, G. W.; Hübers, H.-W.; Schubert, J.; Erichsen, Patrik; Gol'tsman, G.; Semenov, A.; Verevkin, A.; Cherednichenko, S.; Gershenzon, E. |
| Title |
A high resolution spectrometer for the investigation of molecular structures in the THZ range |
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Conference Article |
| Year |
1999 |
Publication |
Proc. 10th Int. Symp. Space Terahertz Technol. |
Abbreviated Journal |
Proc. 10th Int. Symp. Space Terahertz Technol. |
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Pages |
530-538 |
| Keywords |
antireflection coatings, dielectric mirrors |
| Abstract |
A status report on the design study of a novel tunable far-infrared (TuFTR) spectrometer for the investigation of the structure of weakly bound molecular complexes is given. The goal is a sensitive TuFIR spectrometer with full frequency coverage from 1-6 THz. To hit the goal, advanced sources (e.g. p-Ge lasers) and detectors (e.g. superconducting hot electron bolometric (HEB) mixers) shall be employed to extend the technique of cavity ringdown spectroscopy, that is currently used at optical and infrared frequencies to the FIR spectral range. Critical for such a system are high-Q resonators that still allow good optical coupling, and wideband antireflection coatings to increase detector sensitivity and decrease optical path losses. 2 nd order effective media theory and an iterative multilayer algorithm have been employed to design wideband antireflection coatings for dielectrics with large dielectric constants like Ge or Si. Taking into account 6 layers, for Si bandwidths of 100% of the center frequency could be obtained with power reflectivities below 1% for both polarizations simultaneously. Wideband dielectric mirrors including absorption losses were also studied yielding a bandwidth of about 50% with reflectivities larger than 99.5%. |
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1577 |
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Schubert, J.; Semenov, A.; Hübers, H.-W.; Gol'tsman, G.; Schwaab, G.; Voronov, B.; Gershenzon, E. |
| Title |
Broad-band terahertz NbN hot-electron bolometric mixer |
Type |
Conference Article |
| Year |
1999 |
Publication |
Inst. Phys. Conf. |
Abbreviated Journal |
Inst. Phys. Conf. |
| Volume |
167 |
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Pages |
663-666 |
| Keywords |
NbN HEB mixers |
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4th Europ. Conf. on Appl. Superconductivity, Barcelona, Spain, 14-17 September 1999 |
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1578 |
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Gousev, Y. P.; Semenov, A. D.; Goghidze, I. G.; Pechen, E. V.; Varlashkin, A. V.; Gol'tsman, G. N.; Gershenzon, E. M.; Renk, K. F. |
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Current dependent noise in a YBa2Cu3O7-δ hot-electron bolometer |
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Journal Article |
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1997 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
7 |
Issue |
2 |
Pages |
3556-3559 |
| Keywords |
YBCO HTS HEB mixers |
| Abstract |
We investigated the output noise of a YBa2Cu3O7-δ (YBCO) superconducting hot-electron bolometer (HEB) in a large frequency range (10 kHz to 8 GHz); the bolometer either consisted of a structured 50 nm thick YBCO film on LaAlO/sub 3/ or a 30 nm thick film on a MgO substrate. We found that flicker noise dominated at low frequencies (below 1 MHz), while at higher frequencies Johnson noise and a current dependent noise were the main noise sources. |
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1051-8223 |
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1592 |
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Semenov, A. D.; Gousev, Y. P.; Renk, K. F.; Voronov, B. M.; Gol'tsman, G. N.; Gershenzon, E. M.; Schwaab, G.W.; Feinaugle, R. |
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Noise characteristics of a NbN hot-electron mixer at 2.5 THz |
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Journal Article |
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1997 |
Publication |
IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
7 |
Issue |
2 |
Pages |
3572-3575 |
| Keywords |
NbN HEB mixers |
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The noise temperature of a NbN phonon cooled hot-electron mixer has been measured at a frequency of 2.5 THz for various operating conditions. We obtained for optimal operation a double sideband mixer noise temperature of /spl ap/14000 K and a system conversion loss of /spl ap/23 dB at intermediate frequencies up to 1 GHz. The dependences of the mixer noise temperature on the bias voltage, local oscillator power, and intermediate frequency were consistent with the phenomenological description based on the effective temperature approximation. |
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1051-8223 |
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1594 |
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Svechnikov, S.; Gol'tsman, G.; Voronov, B.; Yagoubov, P.; Cherednichenko, S.; Gershenzon, E.; Belitsky, V.; Ekstrom, H.; Kollberg, E.; Semenov, A.; Gousev, Y.; Renk, K. |
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Spiral antenna NbN hot-electron bolometer mixer at submm frequencies |
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Journal Article |
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1997 |
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IEEE Trans. Appl. Supercond. |
Abbreviated Journal |
IEEE Trans. Appl. Supercond. |
| Volume |
7 |
Issue |
2 |
Pages |
3395-3398 |
| Keywords |
NbN HEB mixers |
| Abstract |
We have studied the phonon-cooled hot-electron bolometer (HEB) as a quasioptical mixer based on a spiral antenna designed for the 0.3-1 THz frequency band and fabricated on sapphire and high resistivity silicon substrates. HEB devices were produced from superconducting 3.5-5 nm thick NbN films with a critical temperature 10-12 K and a critical current density of approximately 10/sup 7/ A/cm/sup 2/ at 4.2 K. For these devices we reached a DSB receiver noise temperature below 1500 K, a total conversion loss of L/sub t/=16 dB in the 500-700 GHz frequency range, an IF bandwidth of 3-4 GHz and an optimal LO absorbed power of /spl sime/4 /spl mu/W. We experimentally analyzed various contributions to the conversion loss and obtained an RF coupling factor of about 5 dB, internal mixer loss of 10 dB and IF mismatch of 1 dB. |
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1051-8223 |
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1597 |
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