|
|
Semenov, A. D., Hübers, H. - W., Richter, H., Birk, M., Krocka, M., Mair, U., et al. (2003). Superconducting hot-electron bolometer mixer for terahertz heterodyne receivers. IEEE Trans. Appl. Supercond., 13(2), 168–171.
Abstract: We present recent results showing the development of superconducting NbN hot-electron bolometer mixer for German receiver for astronomy at terahertz frequencies and terahertz limb sounder. The mixer is incorporated into a planar feed antenna, which has either logarithmic spiral or double-slot configuration, and backed on a silicon lens. The hybrid antenna had almost frequency independent and symmetric radiation pattern slightly broader than expected for a diffraction limited antenna. At 2.5 THz the best 2200 K double side-band receiver noise temperature was achieved across a 1 GHz intermediate frequency bandwidth centred at 1.5 GHz. For this operation regime, a receiver conversion efficiency of -17 dB was directly measured and the loss budget was evaluated. The mixer response was linear at load temperatures smaller than 400 K. Implementation of the MgO buffer layer on Si resulted in an increased 5.2 GHz gain bandwidth. The receiver was tested in the laboratory environment by measuring a methanol emission line at 2.5 THz.
|
|
|
|
Angeluts, A. A., Bezotosnyi, V. V., Cheshev, E. A., Goltsman, G. N., Finkel, M. I., Seliverstov, S. V., et al. (2014). Compact 1.64 THz source based on a dual-wavelength diode end-pumped Nd:YLF laser with a nearly semiconfocal cavity. Laser Phys. Lett., 11(1), 015004 (1 to 4).
Abstract: We describe a compact dual-wavelength (1.047 and 1.053 μm) diode end-pumped Q-switched Nd:YLE laser source which has a number of applications in demand. In order to achieve its dual-wavelength operation it is suggested for the first time to use essentially nonmonotonous dependences of the threshold pump powers at these wavelengths on the cavity length in the region of the cavity semiconfocal configuration under a radius of the pump beam smaller than the radius of the zero Gaussian mode. Here we demonstrate one of the most interesting applications for this laser: difference frequency generation in a GaSe crystal at a frequency of 1.64 THz. A superconducting hot-electron bolometer is used to detect the THz power generated and to measure its pulse characteristics.
|
|
|
|
Smirnov, A. V., Baryshev, A. M., de Bernardis, P., Vdovin, V. F., Gol'tsman, G. N., Kardashev, N. S., et al. (2012). The current stage of development of the receiving complex of the millimetron space observatory. Radiophys. Quant. Electron., 54(8), 557–568.
Abstract: We present an overview of the state of the onboard receiving complex of the Millimetron space observatory in the development phase of its preliminary design. The basic parameters of the onboard equipment planned to create and required for astrophysical observations are considered. A review of coherent and incoherent detectors, which are central to each receiver of the observatory, is given. Their characteristics and limiting parameters feasible at the present level of technology are reported.
|
|
|
|
Ryabchun, S. A., Tretyakov, I. V., Pentin, I. V., Kaurova, N. S., Seleznev, V. A., Voronov, B. M., et al. (2009). Low-noise wide-band hot-electron bolometer mixer based on an NbN film. Radiophys. Quant. Electron., 52(8), 576–582.
Abstract: We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750 K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5 GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.
|
|
|
|
Kaurova, N. S., Finkel, M. I., Maslennikov, S. N., Vahtomin, Y. B., Antipov, S. V., Smirnov, K. V., et al. (2004). Submillimeter mixer based on YBa2Cu3O7-x thin film. In Proc. 1-st conf. Fundamental problems of high temperature superconductivity (291). Moscow-Zvenigorod.
|
|
|
|
Tretyakov, I. V., Ryabchun, S. A., Maslennikov, S. N., Finkel, M. I., Kaurova, N. S., Seleznev, V. A., et al. (2008). NbN HEB mixer: fabrication, noise temperature reduction and characterization. In Proc. Basic problems of superconductivity. Moscow-Zvenigorod.
Abstract: We demonstrate that in the terahertz region superconducting hot-electron mixers offer the lowest noise temperature, opening the possibility of using HTS's in the future to fabricate these devices. Specifically, a noise temperature of 950 K was measured for the receiver operating at 2.5 THz with a NbN HEB mixer, and a gain bandwidth of 6 GHz was measured at 300 GHz near Tc for the same mixer.
|
|
|
|
Kardakova, A. I., Coumou, P. C. J. J., Finkel, M. I., Morozov, D. V., An, P. P., Goltsman, G. N., et al. (2015). Electron–phonon energy relaxation time in thin strongly disordered titanium nitride films. IEEE Trans. Appl. Supercond., 25(3), 1–4.
Abstract: We have measured the energy relaxation times from the electron bath to the phonon bath in strongly disordered TiN films grown by atomic layer deposition. The measured values of τ eph vary from 12 to 91 ns. Over a temperature range from 3.4 to 1.7 K, they follow T -3 temperature dependence, which are consistent with values of τ eph reported previously for sputtered TiN films. For the most disordered film, with an effective elastic mean free path of 0.35 nm, we find a faster relaxation and a stronger temperature dependence, which may be an additional indication of the influence of strong disorder on a superconductor.
|
|
|
|
Tretyakov, I. V., Finkel, M. I., Ryabchun, S. A., Kardakova, A. I., Seliverstov, S. V., Petrenko, D. V., et al. (2014). Hot-electron bolometer mixers with in situ contacts. Radiophys. Quant. Electron., 56(8-9), 591–598.
Abstract: We report on the latest achievements in the development of superconducting hot-electron bolometer (HEB) mixers for terahertz superheterodyne receivers. We consider application ranges of such receivers and requirements for the basic characteristics of the mixers. Main features of the mixers, such as noise temperature, gain bandwidth, noise bandwidth, and required local-oscillator power, have been improved significantly over the past few years due to intense research work, both in terms of the element fabrication quality and in terms of understanding of the physics of the processes occurring in the HEB mixers. Contacts between the superconducting bridge and the planar antenna play a key role in the mixer operation. Improvement of the quality of the contacts leads simultaneously to a decrease in the noise temperature and an increase in the gain bandwidth of a mixer.
|
|
|
|
Tuchak, A. N., Gol’tsman, G. N., Kitaeva, G. K., Penin, A. N., Seliverstov, S. V., Finkel, M. I., et al. (2012). Generation of nanosecond terahertz pulses by the optical rectification method. JETP Lett., 96(2), 94–97.
Abstract: The possibility of the generation of quasi-cw terahertz radiation by the optical rectification method for broad-band Fourier unlimited nanosecond laser pulses has been experimentally demonstrated. The broadband radiation of a LiF dye-center laser is used as a pump source of a nonlinear optical oscillator. The energy efficiency of terahertz optical frequency conversion in a periodically polarized lithium niobate crystal is 4 × 10−9 at a pump power density of 7 MW/cm2.
|
|
|
|
Tret’yakov, I. V., Ryabchun, S. A., Kaurova, N. S., Larionov, P. A., Lobastova, A. A., Voronov, B. M., et al. (2010). Optimum absorbed heterodyne power for superconducting NbN hot-electron bolometer mixer. Tech. Phys. Lett., 36(12), 1103–1105.
Abstract: Absorbed heterodyne power has been measured in a low-noise broadband hot-electron bolometer (HEB) mixer for the terahertz range, operating on the effect of electron heating in the resistive state of an ultrathin superconducting NbN film. It is established that the optimum absorbed heterodyne power for the HEB mixer operating at 2.5 THz is about 100 nW.
|
|
