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Ozhegov RV, Smirnov AV, Vakhtomin YB, Smirnov KV, Divochiy AV, Goltsman GN. Ultrafast superconducting bolometer receivers for terahertz applications [abstract]. In: Proc. PIERS. 777 Concord Avenue, Suite 207 Cambridge, MA 02138: The Electromagnetics Academy; 2009. 867.
Abstract: The research by the group of Moscow State Pedagogical University into the hot-electron phenomena in thin superconducting films has led to the development of new types of detectors and their use both in fundamental and applied studies. In this paper, we present the results of testing the terahertz HEB receiver systems based on ultrathin (∼ 4 nm) NbN and MoRe detectors with a response time of 50 ps and 1 ns, respectively. We have developed three types of devices which differ in the way a terahertz signal is coupled to the detector and cover the following ranges: 0.3–3 THz, 0.1–30 THz and 25–70 THz. In the case of the receiving system optimized for 0.3–3 THz, the sensitive element (a strip of asuperconductor with planar dimensions of 0.2μm (length) by 1.7μm (width)) was integrated witha planar broadband log-spiral antenna. For additional focusing ofthe incident radiation a silicon hyperhemispherical lens was used. For the 0.1–30 THz receivingsystem, the sensitive element was patterned as parallel strips(2μm wide each) filling an area of 500×500μm2with a filling factor of 0.5. In the receivingsystem of this type we used direct coupling of the incident radiation to the sensitive element. Inthe 25–70 THz range (detector type 2/2a in Table 1) we used a square-shaped superconductingdetector with planar dimensions of 10×10μm2. Incident radiation was coupled to the detectorwith the use of a germanium hyperhemispherical lens.The response time of the above receiving systems is determined by the cooling rate of the hotelectrons in the film. That depends on the electron-phonon interaction time, which is less forultrathin NbN than in MoRe.
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Gol'tsman G, Maslennikov S, Finkel M, Antipov S, Kaurova N, Grishina E, et al. Nanostructured ultrathin NbN film as a terahertz hot-electron bolometer mixer. In: Proc. MRS. Vol 935.; 2006. 210 (1 to 6).
Abstract: Planar spiral antenna coupled and directly lens coupled NbN HEB mixer structures are studied. An additional MgO buffer layer between the superconducting film and Si substrate is introduced. The buffer layer enables us to increase the gain bandwidth of a HEB mixer due to better acoustic transparency. The gain bandwidth is widened as NbN film thickness decreases and amounts to 5.2 GHz. The noise temperature of antenna coupled mixer is 1300 and 3100 K at 2.5 and 3.8 THz respectively. The structure and composition of NbN films is investigated by X-ray diffraction spectroscopy methods. Noise performance degradation at LO frequencies more than 3 THz is due to the use of a planar antenna and signal loss in contacts between the antenna and the sensitive NbN bridge. The mixer is reconfigured for operation at higher frequencies in a manner that receiver’s noise temperature is only 2300 K (3 times of quantum limit) at LO frequency of 30 THz.
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Ryabchun S, Smirnov A, Pentin I, Vakhtomin Y, Smirnov K, Kaurova N, et al. Superconducting single photon detector integrated with optical cavity. In: Proc. MLPLIT. Modern laser physics and laser-information technologies for science and manufacture; 2011. p. 143–5.
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Maslennikova A, Larionov P, Ryabchun S, Smirnov A, Pentin I, Vakhtomin Y, et al. Noise equivalent power and dynamic range of NBN hot-electron bolometers. In: Proc. MLPLIT. Modern laser physics and laser-information technologies for science and manufacture; 2011. p. 146–8.
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Semenov AD, Hübers H-W, Gol’tsman GN, Smirnov K. Superconducting quantum detector for astronomy and X-ray spectroscopy. In: Pekola J, Ruggiero B, Silvestrini P, editors. Proc. Int. Workshop on Supercond. Nano-Electronics Devices. : Springer; 2002. p. 201–10.
Abstract: We propose the novel concept of ultra-sensitive energy-dispersive superconducting quantum detectors prospective for applications in astronomy and X-ray spectroscopy. Depending on the superconducting material and operation conditions, such detector may allow realizing background limited noise equivalent power 10−21 W Hz−1/2 in the terahertz range when exposed to 4-K background radiation or counting of 6-keV photon with almost 10—4 energy resolution. Planar layout and relatively simple technology favor integration of elementary detectors into a detector array.
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Maslennikov S, Antipov S, Shishkov A, Svechnikov S, Voronov B, Smirnov K, et al. NbN HEB mixer noise temperature measurements with hot/cold load mounted inside the helium cryostat at 300 GHz. In: Proc. Int. Student Seminar on Microwave Appl. of Novel Physical Phenomena supported by IEEE. St.-Petersburg: LETI; 2002.
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Kuznetsov KA, Kornienko VV, Vakhtomin YB, Pentin IV, Smirnov KV, Kitaeva GK. Generation and detection of optical-terahertz biphotons via spontaneous parametric downconversion. In: Proc. ICLO.; 2018. 303.
Abstract: We study spontaneous parametric downconversion (SPDC) in the strongly non-degenerate regime when the idler wave hits the terahertz range. By using the hot-electron bolometer, for the first time the SPDC-generated idler-wave photons were directly detected in the terahertz frequency range. Spectrum of corresponding signal photons was measured using standard technique by the CCD camera. Possible applications of correlated optical-terahertz biphotons are discussed.
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Hübers H-W, Semenov A, Richter H, Birk M, Krocka M, Mair U, et al. Terahertz heterodyne receiver with a hot-electron bolometer mixer. In: Wold J, Davidson J, editors. Proc. Far-IR, Sub-mm, and mm Detector Technology Workshop.; 2002.
Abstract: During the past decade major advances have been made regarding low noise mixers for terahertz (THz) heterodyne receivers. State of the art hot-electron-bolometer (HEB) mixers have noise temperatures close to the quantum limit and require less than a µW power from the local oscillator (LO). The technology is now at a point where the performance of a practical receiver employing such mixer, rather than the figures of merit of the mixer itself, are of major concern. We have incorporated a phonon-cooled NbN HEB mixer in a 2.5 THz heterodyne receiver and investigated the performance of the receiver. This yields important information for the development of heterodyne receivers such as GREAT (German receiver for astronomy at THz frequencies aboard SOFIA)[1] and TELIS (Terahertz limb sounder), a balloon borne heterodyne receiver for atmospheric research [2]. Both are currently under development at DLR.
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Zolotov P, Divochiy A, Vakhtomin Y, Moshkova M, Morozov P, Seleznev V, et al. Photon-number-resolving SSPDs with system detection efficiency over 50% at telecom range. In: Proc. AIP Conf. Vol 1936.; 2018. 020019.
Abstract: We used technology of making high-efficiency superconducting single-photon detectors as a basis for improvement of photon-number-resolving devices. By adding optical cavity and using an improved NbN superconducting film, we enhanced previously reported system detection efficiency at telecom range for such detectors. Our results show that implementation of optical cavity helps to develop four-section device with quantum efficiency over 50% at 1.55 µm. Performed experimental studies of detecting multi-photon optical pulses showed irregularities over defining multi-photon through single-photon quantum efficiency.
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Romanov NR, Zolotov PI, Smirnov KV. Development of disordered ultra-thin superconducting vanadium nitride films. In: Proc. 8th Int. Conf. Photonics and Information Optics.; 2019. p. 425–6.
Abstract: We present the results of development and research of superconducting vanadium nitride VN films ~10 nm thick having different level of disorder. It is showed that both silicon substrate temperature T sub in process of magnetron sputtering and total gas pressure P affect superconducting transition temperature of sputtered films and R 300 /R 20 ratio defining their level of disorder. VN films suitable for development of superconducting single-photon detectors on their basis are obtained.
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