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Slysz, W., Wegrzecki, M., Bar, J., Grabiec, P., Gol'tsman, G. N., Verevkin, M., et al. (2004). NbN superconducting single-photon detectors coupled with a communication fiber (Vol. 37).
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Slysz, W., Wegrzecki, M., Papis, E., Gol'tsman, G. N., Verevkin, A., & Sobolewski, R. (2004). A method of optimization of the NbN superconducting single-photon detector (Vol. 36).
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Il'in, K., Siegel, M., Semenov, A., Engel, A., Hübers, H. - W., Hollmann, E., et al. (2004). Thickness dependence of superconducting properties of ultrathin Nb and NbN films. In AKF-Frühjahrstagung.
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Hubers, H. - W., Semenov, A., Richter, H., Schwarz, M., Gunther, B., Smirnov, K., et al. (2004). Heterodyne receiver for 3-5 THz with hot-electron bolometer mixer. In J. Zmuidzinas, W. S. Holland, & S. Withington (Eds.), Proc. SPIE (Vol. 5498, pp. 579–586). SPIE.
Abstract: Heterodyne receivers for applications in astronomy and planetary research need quantum limited sensitivity. In instruments which are currently build for SOFIA and Herschel superconducting hot electron bolometers (HEB) will be used to achieve this goal at frequencies above 1.4 THz. The local oscillator and the mixer are the most critical components for a heterodyne receiver operating at 3-5 THz. The design and performance of an optically pumped THz gas laser optimized for this frequency band will be presented. In order to optimize the performance for this frequency hot electron bolometer mixers with different in-plane dimensions and logarithmic-spiral feed antennas have been investigated. Their noise temperatures and beam patterns were measured. Above 3 THz the best performance was achieved with a superconducting bridge of 2.0 x 0.2 μm2 incorporated in a logarithmic spiral antenna. The DSB noise temperatures were 2700 K, 4700 K and 6400 K at 3.1 THz, 4.3 THz and 5.2 THz, respectively. The results demonstrate that the NbN HEB is very well suited as a mixer for THz heterodyne receivers up to at least 5 THz.
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Baselmans, J. J. A., Hajenius, M., Gao, J., de Korte, P., Klapwijk, T. M., Voronov, B., et al. (2004). Doubling of sensitivity and bandwidth in phonon-cooled hot-electron bolometer mixers. In J. Zmuidzinas, W. S. Holland, & S. Withington (Eds.), Proc. SPIE (Vol. 5498, pp. 168–176). SPIE.
Abstract: NbN hot electron bolometer (HEB) mixers are at this moment the best heterodyne detectors for frequencies above 1 THz. However, the fabrication procedure of these devices is such that the quality of the interface between the NbN superconducting film and the contact structure is not under good control. This results in a contact resistance between the NbN bolometer and the contact pad. We compare identical bolometers, with different NbN – contact pad interfaces, coupled with a spiral antenna. We find that cleaning the NbN interface and adding a thin additional superconductor prior to the gold contact deposition improves the noise temperature and the bandwidth of the HEB mixers with more than a factor of 2. We obtain a DSB noise temperature of 950 K at 2.5 THz and a Gain bandwidth of 5-6 GHz. For use in real receiver systems we design small volume (0.15x1 micron) HEB mixers with a twin slot antenna. We find that these mixers combine good sensitivity (900 K at 1.6 THz) with low LO power requirement, which is 160 – 240 nW at the Si lens of the mixer. This value is larger than expected from the isothermal technique and the known losses in the lens by a factor of 3-3.5.
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Antipov, S. V., Vachtomin, Y. B., Maslennikov, S. N., Smirnov, K. V., Kaurova, N. S., Grishina, E. V., et al. (2004). Noise performance of quasioptical ultrathin NbN hot electron bolometer mixer at 2.5 and 3.8 THz. In Proc. 5-th MSMW (Vol. 2, pp. 592–594). Kharkov, Ukraine.
Abstract: To put space-based and airborne heterodyne instruments into operation at frequencies above 1 THz the superconducting NbN hot-electron bolometer (HEB) will be incorporated into heterodyne receiver as a mixer. At frequencies above 1.3 THz the sensitivity of the NbN HEB mixers outperform the one of the Schottky diodes and SIS-mixers, and the receiver noise temperature of the NbN HEB mixers increase with frequency. In this paper we present the results of the noise temperature measurements within one batch of NbN HEB mixers based on 3.5 mn thick superconducting NbN film grown on Si substrate with MgO buffer layer at the LO frequencies 2.5 THz and 3.8 THz.
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Maslennikov, S. N., Morozov, D. V., Ozhegov, R. V., Smirnov, K. V., Okunev, O. V., & Gol’tsman, G. N. (2004). Imaging system for submillimeter wave range based on AlGaAs/GaAs hot electron bolometer mixers. In Proc. 5-th MSMW (Vol. 2, pp. 558–560).
Abstract: Electromagnetic radiation of the submillimeter (SMM) range is dispersed and absorbed significantly less than infrared (IR) radiation when passing through different objects. That is the reason for the development of an SMM imaging system. In this paper, we discuss the design of an SMM heterodyne imager, based on a matrix of AlGaAs/GaAs heterostructure hot electron bolometer mixers (HEB) with relatively high (about 77 K) operating temperature. The predicted double side band (DSB) noise temperature is about 1000 K and optimal local oscillator (LO) power is about 1 /spl mu/W for such mixers, which seems to be quite prospective for an SMM heterodyne imager.
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Rubtsova, I., Korneev, A., Matvienko, V., Chulkova, G., Milostnaya, I., Goltsman, G., et al. (2004). Spectral sensitivity, quantum efficiency, and noise equivalent power of NbN superconducting single-photon detectors in the IR range. In Proc. 29th IRMMW / 12th THz (pp. 461–462).
Abstract: We have developed nanostructured NbN superconducting single-photon detectors capable of GHz-rate photon counting in the 0.4 to 5 /spl mu/m wavelength range. Quantum efficiency of 30%, dark count rate 3/spl times/10/sup -4/ s/sup -1/, and NEP=10/sup -20/ W/Hz/sup -1/2/ have been measured at the 1.3-/spl mu/m wavelength for the device operating at 2.0 K.
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Richter, H., Semenov, A., Hubers, H. - W., Smirnov, K., Gol’tsman, G., & Voronov, B. (2004). Phonon cooled hot-electron bolometric mixer for 1-5 THz. In Proc. 29th IRMMW / 12th THz (pp. 241–242).
Abstract: Heterodyne receivers for applications in astronomy and planetary research need quantum limited sensitivity. In instruments which are currently built for SOFIA and Herschel, superconducting hot electron bolometers (HEB) are used to achieve this goal at frequencies above 1.4 THz. In order to optimize the performance for this frequency of hot electron bolometer mixers with different in-plane dimensions and logarithmic-spiral feed antennas have been investigated. Their noise temperatures and beam patterns were measured. Above 3 THz the best performance was achieved with a superconducting bridge of 2.0/spl times/0.2 /spl mu/m/sup 2/ incorporated in a logarithmic spiral antenna. The DSB noise temperatures were 2700 K, 4700 and 6400 K at 3.1 THz, 4.3 THz and 5.2 THz, respectively. The results demonstrate that the NbN HEB is very well suited as a mixer for THz heterodyne receivers up to at least 5 THz.
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Sobolewski, R., Verevkin, A., & Gol’tsman, G. N. (2004). Superconducting optical single-photon detectors. In CLEO/QELS (IThD1). Optical Society of America.
Abstract: We review the development of superconducting single-photon detectors. The devices are characterized by experimental quantum efficiency of ~8% for infrared photons, counting rate ~2 GHz, 18 ps jitter, and <0.01 per second dark counts.
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