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Svechnikov SI, Finkel MI, Maslennikov SN, Vachtomin YB, Smirnov KV, Seleznev VA, et al. Superconducting hot electron bolometer mixer for middle IR range. In: Proc. 16th Int. Crimean Microwave and Telecommunication Technology. Vol 2.; 2006. p. 686–7.
Abstract: The developed directly lens coupled hot electron bolometer (HEB) mixer was based on 5 nm superconducting NbN deposited on GaAs substrate. The layout of the structure, including 30x20 mcm^2 active area coupled with a 50 Ohm coplanar line, was patterned by photolithography. The responsivity of the mixer was measured in a direct detection mode in the 25-64 THz frequency range. The noise performance of the mixer and the directivity of the receiver were investigated in a heterodyne mode. A 10.6 mum wavelength CW CO2 laser was utilized as a local oscillator.
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Svechnikov SI, Okunev OV, Yagoubov PA, Gol'tsman GN, Voronov BM, Cherednichenko SI, et al. 2.5 THz NbN hot electron mixer with integrated tapered slot antenna. IEEE Trans Appl Supercond. 1997;7(2):3548–51.
Abstract: A Hot Electron Bolometer (HEB) mixer for 2.5 THz utilizing a NbN thin film device, integrated with a Broken Linearly Tapered Slot Antenna (BLTSA), has been fabricated and is presently being tested. The NbN HEB device and the antenna were fabricated on a SiO2membrane. A 0.5 micrometer thick SiO2layer was grown by rf magnetron reactive sputtering on a GaAs wafer. The HEB device (phonon-cooled type) was produced as several parallel strips, 1 micrometer wide, from an ultrathin NbN film 4-7 nm thick, that was deposited onto the SiO2layer by dc magnetron reactive sputtering. The BLTSA was photoetched in a multilayer Ti-Au metallization. In order to strengthen the membrane, the front-side of the wafer was coated with a 5 micrometer thick polyimide layer just before the membrane formation. The last operation was anisotropic etching of the GaAs in a mixture of HNO3and H2O2.
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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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Tong C-YE, Trifonov A, Shurakov A, Blundell R, Gol’tsman G. A microwave-operated hot-electron-bolometric power detector for terahertz radiation. IEEE Trans Appl Supercond. 2015;25(3):2300604 (1 to 4).
Abstract: A new class of microwave-operated THz power detectors based on the NbN hot-electron-bolometer (HEB) mixer is proposed. The injected microwave signal ( 1 GHz) serves the dual purpose of pumping the HEB element and enabling the read-out of the internal state of the device. A cryogenic amplifier amplifies the reflected microwave signal from the device and a homodyne scheme recovers the effects of the incident THz radiation. Two modes of operation have been identified, depending on the level of incident radiation. For weak signals, we use a chopper to chop the incident radiation against a black body reference and a lock-in amplifier to perform synchronous detection of the homodyne readout. The voltage measured is proportional to the incident power, and we estimate an optical noise equivalent power of 5pW/ √Hz at 0.83 THz. At higher signal levels, the homodyne circuit recovers the stream of steady relaxation oscillation pulses from the HEB device. The frequency of these pulses is in the MHz frequency range and bears a linear relationship with the incident THz radiation over an input power range of 15 dB. A digital frequency counter is used to measure THz power. The applicable power range is between 1 nW and 1 μW.
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Tong C-YE, Kawamura J, Todd RH, Papa DC, Blundell R, Smith M, et al. Successful operation of a 1 THz NbN hot-electron bolometer receiver. In: Proc. 11th Int. Symp. Space Terahertz Technol.; 2000. p. 49–59.
Abstract: A phonon-cooled NbN superconductive hot-electron bolometer receiver covering the frequency range 0.8-1.04 THz has successfully been used for astronomical observation at the Sub-Millimeter Telescope Observatory on Mount Graham, Arizona. This waveguide heterodyne receiver is a modified version of our fixed-tuned 800 GHz HEB receiver to allow for operation beyond 1 THz. The measured noise temperature of this receiver is about 1250 K at 0.81 THz, 560 K at 0.84 THz, and 1600 K at 1.035 THz. It has a 1 GHz wide IF bandwidth, centered at 1.8 GHz. This receiver has recently been used to detect the CO (9-8) molecular line emission at 1.037 THz in the Orion nebula. This is the first time a ground-based heterodyne receiver has been used to detect a celestial source above 1 THz.
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