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Tong CE, Blundell R, Papa DC, Smith M, Kawamura J, Gol'tsman G, et al. An all solid-state superconducting heterodyne receiver at terahertz frequencies. IEEE Microw Guid Wave Lett. 1999;9(9):366–8.
Abstract: A superconducting hot-electron bolometer mixer-receiver operating from 1 to 1.26 THz has been developed. This heterodyne receiver employs two solid-state local oscillators each consisting of a Gunn oscillator followed by two stages of varactor frequency multiplication. The measured receiver noise temperature is 1350 K at 1.035 THz and 2700 K at 1.26 THz. This receiver demonstrates that tunable solid-state local oscillators, supplying only a few micro-watts of output power, can be used in terahertz receiver applications.
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Meledin D, Tong C-YE, Blundell R, Goltsman G. Measurement of intermediate frequency bandwidth of hot electron bolometer mixers at terahertz frequency range. IEEE Microw Wireless Compon Lett. 2003;13(11):493–5.
Abstract: We have developed a new experimental setup for measuring the IF bandwidth of superconducting hot electron bolometer mixers. In our measurement system we use a chopped hot filament as a broadband signal source, and can perform a high-speed IF scan with no loss of accuracy when compared to coherent methods. Using this technique we have measured the 3 dB IF bandwidth of hot electron bolometer mixers, designed for THz frequency operation, and made from 3-4 nm thick NbN film deposited on an MgO buffer layer over crystalline quartz.
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Tong C-YE, Meledin D, Loudkov D, Blundell R, Erickson N, Kawamura J, et al. A 1.5 THz Hot-Electron Bolometer mixer operated by a planar diode based local oscillator. In: IEEE MTT-S Int. Microwave Symp. Digest. Vol 2.; 2003. p. 751–4.
Abstract: We have developed a 1.5 THz superconducting NbN Hot-Electron Bolometer mixer. It is operated by an all-solid-state Local Oscillator comprising of a cascade of 4 planar doublers following an MMIC based W-band power amplifier. The threshold available pump power is estimated to be 1 /spl mu/W.
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Gol'tsman GN, Karasik BS, Okunev OV, Dzardanov AL, Gershenzon EM, Ekstrom H, et al. NbN hot electron superconducting mixers for 100 GHz operation. IEEE Trans Appl Supercond. 1995;5(2):3065–8.
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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Kawamura JH, Tong C-YE, Blundell R, Cosmo Papa D, Hunter TR, Gol'tsman G, et al. An 800 GHz NbN phonon-cooled hot-electron bolometer mixer receiver. IEEE Trans Appl Supercond. 1999;9(2):3753–6.
Abstract: We describe a heterodyne receiver developed for astronomical applications to operate in the 350 /spl mu/m atmospheric window. The waveguide receiver employs a superconductive NbN phonon-cooled hot-electron bolometer mixer. The double sideband receiver noise temperature closely follows 1 kGHz/sup -1/ across 780-870 GHz, with the intermediate frequency centered at 1.4 GHz. The conversion loss is about 15 dB. The receiver was installed for operation at the University of Arizona/Max Planck Institute for Radio Astronomy Submillimeter Telescope facility. The instrument was successfully used to conduct test observations of a number of celestial sources in a number of astronomically important spectral lines.
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