| 1. |
- Acharya, Narendra, 1982, et al.
(författare)
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Analysis of the broad IF-band performance of MgB2 HEB mixers
- 2019
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 9:6, s. 565-571
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Tidskriftsartikel (refereegranskat)abstract
- We present an experimental study of gain and noise bandwidths in superconducting MgB2 hot-electron bolometer (HEB) terahertz mixers in a 0.1-20 GHz intermediate frequency (IF) range. At an elevated temperature and with a 90-GHz local oscillator (LO), we measure a gain bandwidth of 13-14 GHz, which is the first accurate data for ultrathin MgB2 films. The output noise spectrum has its maximum in the 100-200 K range, depending on the temperature (or the LO power) and the bias point, and its spectrum also confirms the gain bandwidth data obtained with the mixing experiment. Using both the gain and the output noise spectra, we obtain the mixer input noise temperature, which is nearly constant up to 20 GHz. Using the measured data and the HEB mixer theory, we argue that noise bandwidth in the current MgB2 HEB mixers is ∼30 GHz.
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| 2. |
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| 3. |
- Balbekin, N.S., et al.
(författare)
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Nondestructive monitoring of aircraft composites using terahertz radiation
- 2014
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Ingår i: Progress in Biomedical Optics and Imaging - Proceedings of SPIE. - : SPIE. - 1605-7422. - 9781628415643 ; 9448, s. 94482D-
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider using the terahertz (THz) time domain spectroscopy (TDS) for non destructive testing and determining the chemical composition of the vanes and rotor-blade spars. A versatile terahertz spectrometer for reflection and transmission has been used for experiments. We consider the features of measured terahertz signal in temporal and spectral domains during propagation through and reflecting from various defects in investigated objects, such as voids and foliation. We discuss requirements are applicable to the setup and are necessary to produce an image of these defects, such as signal-to-noise ratio and a method for registration THz radiation. Obtained results indicated the prospects of the THz TDS method for the inspection of defects and determination of the particularities of chemical composition of aircraft parts.
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| 4. |
- Bevilacqua, Stella, 1981, et al.
(författare)
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Characterisation and Modeling of MgB2 HEBs IF impedance
- 2016
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Ingår i: Swedish Microwave Days March 15-16, 2016, Linköping, Sweden. ; , s. 55-
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Konferensbidrag (refereegranskat)abstract
- Here we present the method which allows to measure quiteaccurately the HEB impedance employing just one cooling.By knowing the HEB IF impedance a coupling matchingnetwork can be designed for a possible packaged receiver.
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| 5. |
- Bevilacqua, Stella, 1981, et al.
(författare)
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MgB2 Hot-Electron Bolometer Mixers at Terahertz Frequencies
- 2015
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 25:3, s. 2301104-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we compare the performance of MgB2 Hot-Electron Bolometer Mixers operating at Local Oscillator frequencies of 0.6 and 1.63 THz. The minimum noise temperatures that were obtained are 700 and 1150 K for 0.6 and 1.63 THz, respectively. The receiver noise bandwidth is of the order of 2.2-3 GHz for 10-nm-thick HEB devices with a Tc of 8.5 K. Sub-micrometer size HEBs were also fabricated with no degradation of the initial film quality when a 20-nm MgB2 film with a Tc of 22 K was used. In the direct detection mode, the maximum voltage responsivity is in the range of 1-2 kV/W at 1.63 THz and the optimal bias current is around 1/4-1/3 of the Ic at 4.2 K.
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| 6. |
- Bevilacqua, Stella, 1981, et al.
(författare)
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Wideband MgB2 Hot-Electron Bolometer Mixers: IF Impedance Characterisation and Modeling
- 2016
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 26:3, s. 2300105-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a method for low signal S11 parameter vector measurements of a cryogenic device in the microwave frequency range. In particular, the intermediate frequency (IF) impedance of MgB2 Hot-electron Bolometer (HEB) mixers was investigated over a frequency range of 100 MHz to 10 GHz. A new cryogenic calibration technique, which employs the HEB as a calibration kitandrequires two consecutive thermal cycles, was developed for this purpose.The real part of measured IF impedance showed a strong correlationwith the differential resistance (dV/dI) obtained from the dc I-V curves while the imaginary partwas capacitive for almost the entire frequency range.
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| 7. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Low kinetic inductance superconducting MgB2 nanowires with a 130-picosecond relaxation time for single-photon detection applications
- 2021
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Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 34:4
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Tidskriftsartikel (refereegranskat)abstract
- Properties of superconducting nanowires set the performance level for Superconducting Nanowire Single Photon Detectors (SNSPD). Reset time in commonly employed large area SNSPDs, 1-10ns, is known to be limited by the nanowire's kinetic inductance to the load impedance ratio. On the other hand, reduction of the kinetic inductance in small area (waveguide integrated) SNSPDs prevents biasing them close to the critical current due to latching into a permanent resistive state. In order to reduce the reset time in SNSPDs, superconducting nanowires with both low kinetic inductance and fast electron energy relaxation are required. In this paper, we report on a study of kinetic inductance in narrow (15-100nm) and long (up to 120m) superconducting MgB2 nanowires made from 5 nm-thick films, offering such combination of properties. Such films were grown using Hybrid Physical Chemical Vapor Deposition, resulting in a critical temperature of 32K, and a switch current density of 5107A/cm2 (at 4.8K). Using microwave reflectometry, we measured a kinetic inductance of Lk0(4.8K)=1.3-1.6 pH/ regardless of the nanowire width, which results in a magnetic field penetration depth of 90 nm. These values are very close to those in pristine MgB2. We showed that after excitations by a 50 fs pulsed laser the reset time in 35nm120m MgB2 nanowires is 130 ps, which is more than a factor of 10 shorter than in NbN nanowires of similar length-to-width ratios. Depending on the bias current, such MgB2 nanowires function as single-, double , or triple- photon detectors for both visible (= 630 nm) and infrared (= 1550 nm) photons, with a dark count rate of <10 cps. Although the apparent photon detection efficiency seems so far to be low, further technological advances (uniform nanowire width, smaller thickness, increasing the switching current closer to the pair-breaking current) may improve this figure of merit.
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| 8. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Study of MgB2 HEB mixers vs the LO frequency and the bath temperature
- 2015
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Ingår i: 26th International Symposium on Space Terahertz Technology March 16-18, 2015, Cambridge, United States. ; , s. M2-1
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Konferensbidrag (refereegranskat)abstract
- We investigate the noise and the gain of MgB2 Hot-Electron Bolometer (HEB) mixers at 1.63THz LO. The critical temperature of the HEB was 22K and the film thickness was 20nm. At 4.2K and 12K bath temperatures the lowest obtained receiver noise temperatures are 1700K and 2100K,respectively, with a noise bandwidth of about 4.6GHz. The gain bandwidth is about 3GHz in both cases.
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| 9. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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THz Hot-Electron Bolometer Mixers
- 2014
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781479938773
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Konferensbidrag (refereegranskat)abstract
- We overview the technology of superconductingHot-Electron Bolometer mixers in the field of terahertzheterodyne detection. HEB mixer performance is analyzed vs competing technologies and application fields, with emphasize on radio astronomy. We discuss materials which have been reported in the past to be used for such devices with both phonon-substrate and electron-diffusion cooling mechanisms. It caused a splash of interesting theories with attempts of describing both dc and RF characteristics of HEB mixers. Development of HEB mixers made possible to extend high spectral resolution radio astronomy beyond 1THz.
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| 10. |
- Novoselov, Evgenii, 1988, et al.
(författare)
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Broadband MgB2 Hot-Electron Bolometer THz Mixers operating up to 20K
- 2017
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- We discuss performance of submicron size hot-electron bolometer (HEB) mixers made from thin MgB2 superconducting films. With a superconducting transition temperature of 30K, such THz mixers can operate with high sensitivity at temperatures up to 20K. Due to very small dimensions local oscillator (LO) power requirements are rather low. In the intermediate frequency (IF) band of 1-3GHz the double sideband receiver noise temperature is 1600K at 10K operation temperature, 2000K at 15K, 2500-3000K at 20K. The gain bandwidth of such devices is 6GHz and the noise bandwidth is estimated to be 6-8GHz
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