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| Author | Bandurin, Denis; Svintsov, Dmitry; Gayduchenko, Igor; Xu, Shuigang; Principi, Alessandro; Moskotin, Maksim; Tretyakov, Ivan; Yagodkin, Denis; Zhukov, Sergey; Taniguchi, Takashi; Watanabe, Kenji; Grigorieva, Irina; Polini, Marco; Goltsman, Gregory; Geim, Andre; Fedorov, Georgy | ||||
| Title | Resonant terahertz photoresponse and superlattice plasmons in graphene field-effect transistors | Type  |
Abstract | ||
| Year | 2019 | Publication | APS March Meeting | Abbreviated Journal | APS March Meeting |
| Volume | Issue | Pages | F14.015 | ||
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| Abstract | Plasmons, collective oscillations of electron systems, can couple light and electric current, and thus can be used to create compact photodetectors, radiation mixers, and spectrometers. Despite the effort, it has proven challenging to implement plasmonic devices operating at THz frequencies. The material capable to meet this challenge is graphene as it supports long-lived electrically-tunable plasmons. In this talk, we will demonstrate plasmon-assisted resonant detection of THz radiation by antenna-coupled graphene FETs that act as both rectifying elements and plasmonic Fabry-Perot cavities amplifying the photoresponse. We will show that by varying the plasmon velocity using gate voltage, our detectors can be tuned between multiple resonant modes, a functionality that we apply to measure plasmons' wavelength and lifetime in graphene as well as to probe collective modes in its moire minibands. Our approach offers a convenient tool for further plasmonic research that is often difficult under non-ambient conditions and promises a viable route for various THz applications. We acknowledge Leverhulme Trust, Russian Science Foundation Grants N18-72-00234 and 17-72-30036, Russian Foundation for Basic Research No. 18-57-06001 and 16-29-03402. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 1290 | |||
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| Author | Tretyakov, Ivan; Kaurova, N.; Voronov, B. M.; Goltsman, G. N. | ||||
| Title | About effect of the temperature operating conditions on the noise temperature and noise bandwidth of the terahertz range NbN hot-electron bolometers | Type |
Abstract | ||
| Year | 2018 | Publication | Proc. 29th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 29th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 113 | ||
| Keywords | NbN HEB mixer | ||||
| Abstract | Results of an experimental study of the noise temperature (Tn) and noise bandwidth (NBW) of the superconductor NbN hot-electron bolometer (HEB) mixer as a function of its temperature (Tb) and NbN bridge length are presented. It was determined that the NBW of the mixer is significantly wider at temperatures close to the critical ones (Tc) than are values measured at 4.2 K. The NBW of the mixer measured at the heterodyne frequency of 2.5 THz at temperature Tb close to Tc was ~13 GHz, as compared with 6 GHz at Tb = 4.2 K. This experiment clearly demonstrates the limitation of the thermal flow from the NbN bridge at Tb ≪ Tc for mixers manufactured by the in situ technique. This limitation is close in its nature to the Andreev reflection on the superconductor/metal boundary. In this case, the noise temperature of the studied mixer increased from 1100 to 3800 K. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 1313 | |||
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| Author | Iomdina, E. N.; Seliverstov, S.; Sianosyan, A.; Teplyakova, K.; Rusova, A.; Goltsman, G. | ||||
| Title | The prospects of using the radiation for the assessment of corneal and scleral hydration | Type |
Abstract | ||
| Year | 2016 | Publication | Acta Ophthalmol. | Abbreviated Journal | Acta Ophthalmol. |
| Volume | 94 | Issue | Pages | ||
| Keywords | BWO, avalanche transit‐time diode, medicine, biology | ||||
| Abstract | Purpose An adequate water balance (hydration extent) is one of the basic factors of normal eye function, including its external shells – the cornea and the sclera. THz systems creating images in reflected beams are likely to become ideal instruments of noninvasive testing of corneal and scleral hydration degree as THz radiation is highly sensitive to water content. The paper aims at studying the transmittance and reflectance spectra of the cornea and the sclera of rabbit and human eyes, as well as those of the whole rabbit eye, in the frequency range of 0.13–0.32 THz. Methods The experiments were carried out on 3 corneas and 3 rabbit scleras, 2 whole rabbit eyes, and 3 human healthy adult scleras using a specially developed THz system based on reliable and easy‐to‐use continuous wave sources: a backward‐wave oscillator and an avalanche transit‐time diode. Results The transmittance spectra of the cornea and the sclera and the dependence of the reflection coefficient of these tissues in THz range on water percentage content were determined. Comparison of the rabbit cornea hydrated from 73.2% to 76.3% concentration by mass demonstrated an approximately linear relationship between THz reflectivity and water concentration. The decrease of free water concentration by 1% leads to a drop of the reflectance coefficient by 13%. The parameters studied displayed noticeable differences between the sclera and the cornea of rabbits and between rabbit sclera and human sclera. Conclusions Preliminary results demonstrate that the proposed technique, based on continuous THz radiation, may be used to create a device for noninvasive testing of corneal and scleral hydration, which has good potential of wide‐scale practical application. The work was supported by the Russian Foundation of Basic Research (grant No.15‐29‐03843) |
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| ISSN | 1755375X | ISBN | Medium | ||
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| Notes | Approved | no | |||
| Call Number | Serial | 1333 | |||
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| Author | Baselmans, J. J. A.; de Visser, P. J.; Yates, S. J. C.; Bueno, J.; Jansen, R. M. J.; Endo, A.; Thoen, D. J.; Baryshev, A. M.; Ferrari, L.; Klapwijk, T. M. | ||||
| Title | Large format, background limited arrays of kinetic inductance detectors for sub-mm astronomy | Type |
Abstract | ||
| Year | 2014 | Publication | Proc. 25th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 25th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 64 | ||
| Keywords | KID | ||||
| Abstract | Kinetic Inductance detectors have held a promise for the last decade to enable very large arrays, in excess of 10.000 pixels, with background limited sensitivity for ground- and Space Based sub-mm observatories. First we present the development of the detector chips of the A-MKID instrument: These chips contain up to 5400 detector pixel divided over up to 5 readout lines for the 350 GHz and 850 GHz atmospheric windows. The individual detectors are lens antenna coupled KIDs made of NbTiN and Aluminium that reach photon noise limited sensitivity at sky loading levels in excess of a few fW per pixel using either phase readout or amplitude readout. The ability to use phase readout is crucial as it reduces the requirements on the readout electronics of the instrument. Cross coupling between the KID resonators was mitigated by a combination of numerical simulations and a suitable position encoding of the readout resonance frequencies of the individual pixels. Beam pattern measurements are performed to demonstrate the absence of any cross talk due to resonator- resonator cross coupling. Second we present experiments on individual lens-antenna coupled detectors at 1.5 THz that are made out of aluminium. With these devices we have observed, as a function of the irradiated power at 1.5 THz, the crossover from photon noise limited performance to detector-limited performance at loading powers less than 0.1 fW. In the latter limit the device is limited by intrinsic fluctuations in the Cooper pair and quasiparticle number, i.e. Generation-Recombination noise. This results in a sensitivity corresponding to a NEP = 3.8·10 -19 W/√(Hz). | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 1360 | |||
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| Author | Fedorov, G.; Kardakova, A.; Gayduchenko, I.; Voronov, B. M.; Finkel, M.; Klapwijk, T. M.; Goltsman, G. | ||||
| Title | Photothermoelectric response in asymmetric carbon nanotube devices exposed to sub-THz radiation | Type |
Abstract | ||
| Year | 2014 | Publication | Proc. 25th Int. Symp. Space Terahertz Technol. | Abbreviated Journal | Proc. 25th Int. Symp. Space Terahertz Technol. |
| Volume | Issue | Pages | 71 | ||
| Keywords | carbon nanotubes, CNT | ||||
| Abstract | This work reports on the voltage response of asymmetric carbon nanotube devices to sub-THz radiation at the frequency of 140 GHz. The devices contain CNT’s, which are over their length partially suspended and partially Van der Waals bonded to a SiO 2 substrate, causing a difference in thermal contact. Different heat sinking of CNTs by source and drain gives rise to temperature gradient and consequent thermoelectric power (TEP) as such a device is exposed to the sub-THz radiation. Sign of the DC signal, its power and gate voltage dependence observed at room temperature are consistent with this scenario. At liquid helium temperature the observed response is more complex. DC voltage signal of an opposite sign is observed in a narrow range of gate voltages at low temperatures and under low radiation power. We argue that this may indicate a true photovoltaic response from small gap (less than 10meV) CNT’s, an effect never reported before. While it is not clear if the observed effects can be used to develop efficient THz detectors we note that the responsivity of our devices exceeds that of CNT based devices in microwave or THz range reported before at room temperature. Besides at 4.2 K notable increase of the sample conductance (at least four-fold) is observed. Our recent results with asymmetric carbon nanotube devices response to THz radiation (2.5 THz) will also be presented. | ||||
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| Notes | Approved | no | |||
| Call Number | Serial | 1361 | |||
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