|
|
Finkel MI, Maslennikov SN, Vachtomin YB, Svechnikov SI, Smirnov KV, Seleznev VA, et al. Hot electron bolometer mixer for 20 – 40 THz frequency range. In: Proc. 16th Int. Symp. Space Terahertz Technol. Göteborg, Sweden; 2005. p. 393–7.
Abstract: The developed HEB mixer was based on a 5 nm thick NbN film deposited on a GaAs substrate. The active area of the film was patterned as a 30×20 μm 2 strip and coupled with a 50 Ohm coplanar line deposited in situ. An extended hemispherical germanium lens was used to focus the LO radiation on the mixer. 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 μm wavelength CW CO 2 laser was utilized as a local oscillator.
|
|
|
|
Baselmans JJA, Hajenius M, Gao JR, Baryshev A, Kooi J, Klapwijk TM, et al. Hot electron bolometer mixers with improved interfaces: sensitivity, LO power and stability. In: Proc. 15th Int. Symp. Space Terahertz Technol.; 2004. p. 17–24.
Abstract: We study twin slot antenna coupled NbN hot electron bolometer mixers with an improved contact structure and a small volume, ranging from 1 µm × 0.1 µm to 2 × 0.3 µm. We obtain a DSB receiver noise temperature of 900 K at 1.6 THz and 940 K at 1.9 THz. To explore the practical usability of such small HEB mixers we evaluate the LO power requirement, the sensitivity and the stability. We find that the LO power requirement of the smallest mixers is reduced to about 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. The stability of these receivers is characterized using a measurement of the Allan Variance. We find an Allan time of 0.5 sec. in an 80 MHz bandwidth. A small increase in stability can be reached by using a higher bias at the expense of a significant amount of sensitivity. The stability is sufficient for spectroscopic applications in a 1 MHz bandwidth at a 1 Hz chopping frequency.
|
|
|
|
Gol'tsman GN. Hot electron bolometric mixers: new terahertz technology. Infrared Physics & Technology. 1999;40(3):199–206.
Abstract: This paper presents an overview of recent results for NbN phonon-cooled hot electron bolometric (HEB) mixers. The noise temperature of the receivers based on both quasioptical and waveguide versions of HEB mixers has crossed the level of 1 K GHz−1 at 430 GHz (410 K), 600–650 GHz (480 K), 750 GHz (600 K), 810 GHz (780 K) and is close to that level at 1.1 THz (1250 K) and 2.5 THz (4500 K). The gain bandwidth measured for quasioptical HEB mixer at 620 GHz reached 4 GHz and the noise temperature bandwidth was almost 8 GHz. Local oscillator power requirements are about 1 μW for mixers made by photolithography and about 100 nW for mixers made by e-beam lithography. A waveguide version of 800 GHz receiver was installed at the Submillimeter Telescope Observatory on Mt. Graham, AZ, to conduct astronomical observations of known submillimeter lines (CO, J=7→6, CI, J=2→1). It was proved that the receiver works as a practical instrument.
|
|
|
|
Gerecht E, Musante CF, Schuch R, Lutz CR, Jr., Yngvesson KS, et al. Hot electron detection and mixing experiments in NbN at 119 micrometer wavelength. In: Proc. 6th Int. Symp. Space Terahertz Technol.; 1995. p. 284–93.
Abstract: We have performed preliminary experiments with the goal of demonstrating a Hot Electron Bolometric (HEB) mixer for a 119 micrometer wavelength (2.5 THz). We have chosen a NbN device of size 700 x 350 micrometers. This device can easily be coupled to a laser LO source, which is advantageous for performing a prototype experiment. The relatively large size of the device means that the LO power required is in the mW range; this power can be easily obtained from a THz laser source. We have measured the amount of laser power actually absorbed in the device, and from this have estimated the best optical coupling loss to be about 10 di . We are developing methods for improving the optical coupling further. Preliminary measurements of the response of the device to a chopped black-body have not yet resulted in a measured receiver noise temperature. We expect to be able to complete this measurement in the near future.
|
|
|
|
Ekström H, Kroug M, Belitsky V, Kollberg E, Olsson H, Goltsman G, et al. Hot electron mixers for THz applications. In: Rolfe EJ, Pilbratt G, editors. Proc. 30th ESLAB.; 1996. p. 207–10.
Abstract: We have measured the noise performance of 35 A thin NbN HEB devices integrated with spiral antennas on antireflection coated silicon substrate lenses at 620 GHz. From the noise measurements we have determined a total conversion gain of the receiver of—16 dB, and an intrinsic conversion of about-10 dB. The IF bandwidth of the 35 A thick NbN devices is at least 3 GHz. The DSB receiver noise temperature is less than 1450 K. Without mismatch losses, which is possible to obtain with a shorter device, and with reduced loss from the beamsplitter, we expect to achieve a DSB receiver noise temperature of less ‘than 700 K.
|
|
|
|
Kollberg EL, Gershenzon E, Goltsman G, Yngvesson KS. Hot electron mixers, the potential competition. In: Proc. ESA Symp. on Photon Detectors for Space Instrumentation.; 1992. p. 201–6.
Abstract: There is an urgent need in radio astronomy for low noise heterodyne receivers for frequencies above about 500 GHz. It is not certain that mixers based on superconducting quasiparticle tunnelling (SIS mixers) may turn out to be the answer to this need. In order to try to find an alternative way for realizing low noise heterodyne receivers for submillimeter waves, so called hot electron bolometric effects for mixing are now being investigated. Two basically different approaches are tried, one based on semiconductors and one on superconductors. Both methods are briefly discussed in this overview paper.
|
|
|
|
Karasik BS, Gol'tsman GN, Voronov BM, Svechnikov SI, Gershenzon EM, Ekstrom H, et al. Hot electron quasioptical NbN superconducting mixer. IEEE Trans Appl Supercond. 1995;5(2):2232–5.
Abstract: Hot electron superconductor mixer devices made of thin NbN films on SiO/sub 2/-Si/sub 3/N/sub 4/-Si membrane have been fabricated for 300-350 GHz operation. The device consists of 5-10 parallel strips each 5 /spl mu/m long by 1 /spl mu/m wide which are coupled to a tapered slot-line antenna. The I-V characteristics and position of optimum bias point were studied in the temperature range 4.5-8 K. The performance of the mixer at higher temperatures is closer to that predicted by theory for uniform electron heating. The intermediate frequency bandwidth versus bias has also been investigated. At the operating temperature 4.2 K a bandwidth as wide as 0.8 GHz has been measured for a mixer made of 6 nm thick film. The bandwidth tends to increase with operating temperature. The performance of the NbN mixer is expected to be better for higher frequencies where the absorption of radiation should be more uniform.
|
|
|
|
Gershenzon EM, Gol'tsman GN. Hot electron superconductive mixers. In: Proc. 4th Int. Symp. Space Terahertz Technol.; 1993. p. 618–22.
|
|
|
|
Yagoubov P, Hübers H-W, Gol’tsman G, Semenov A, Gao J, Hoogeveen R, et al. Hot-electron bolometer mixers – technology for far-infrared heterodyne instruments in future atmospheric chemistry missions. In: Buehler S, Berlin, editors. Proc. 3rd Int. Symp. Submillimeter Wave Earth Observation From Space. Logos-Verlag; 2001. p. 57–69.
|
|
|
|
Tretyakov IV, Finkel MI, Ryabchun SA, Kardakova AI, Seliverstov SV, Petrenko DV, et al. Hot-electron bolometer mixers with in situ contacts. Radiophys Quant Electron. 2014;56(8-9):591–8.
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.
|
|
