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Nikoghosyan, A. S., Martirosyan, R. M., Hakhoumian, A. A., Makaryan, A. H., Tadevosyan, V. R., Goltsman, G. N., et al. (2018). Effect of absorption on the efficiency of THz radiation generation in a nonlinear crystal placed into a waveguide. Armenian J. Phys., 11(4), 257–262.
Abstract: The effect of THz radiation absorption on the efficiency of generation of coherent THz radiation in a nonlinear optical crystal placed into a metal rectangular waveguide is studied. The efficiency of the nonlinear conversion of optical laser radiation to the THz band is also a function of the phase-matching (PM) condition inside the nonlinear crystal. The method of partial filling of a metal waveguide with a nonlinear optical crystal is used to ensure phase matching. Phase matching was obtained by the proper choice of the thickness of the nonlinear crystal, namely the degree of partial filling of the waveguide. We have studied the THz radiation attenuation caused by the losses in both the metal walls of the waveguide and in the crystal, taking into account the dimension of the cross section of the waveguide, the degree of partial filling and its dielectric constant.
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Korneev, A., Finkel, M., Maslennikov, S., Korneeva, Y., Florya, I., Tarkhov, M., et al. (2010). Superconducting NbN terahertz detectors and infrared photon counters. Вестник НГУ. Серия: физ., 5(4), 68–72.
Abstract: We present our recent achievements in the development of sensitive and ultrafast thin-film superconducting sensors: hot-electron bolometers (HEB), HEB-mixers for terahertz range and infrared single-photon counters. These sensors have already demonstrated a performance that makes them devices-of-choice for many terahertz and optical applications. Keywords: Hot electron bolometer mixers, infrared single-photon detectors, superconducting device fabrication, superconducting NbN films.
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Iomdina, E. N., Seliverstov, S., Sianosyan, A., Teplyakova, K., Rusova, A., & Goltsman, G. (2016). The prospects of using the radiation for the assessment of corneal and scleral hydration. In Acta Ophthalmol. (Vol. 94).
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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Komrakova, S., Javadzade, J., Vorobyov, V., Bolshedvorskii, S., Soshenko, V., Akimov, A., et al. (2018). On-chip controlled placement of nanodiamonds with a nitrogen-vacancy color centers (NV). In J. Phys.: Conf. Ser. (Vol. 1124, 051046 (1 to 4)).
Abstract: Here we studied the fabrication technique of a kilopixel array of nanodiamonds with a nitrogen-vacancy color centers (NV) on top of the chip and measured the second-order correlation function deep, clearly demonstrated the presence of single-photon sources. The controlled position of nanodiamonds, determined from the measurement of second-order correlation fiction, was realize, as well as the yield of optimized technique equals 12.5% is shown.
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Elmanova, A., An, P., Kovalyuk, V., Golikov, A., Elmanov, I., & Goltsman, G. (2020). Study of silicon nitride O-ring resonator for gas-sensing applications. In J. Phys.: Conf. Ser. (Vol. 1695, 012124).
Abstract: In this work, we experimentally studied the influence of different gaseous surroundings on silicon nitride O-ring resonator transmission. We compared the obtained results with numerical calculations and theoretical analysis and found a good agreement between them. Our results have a great potential for gas sensing applications, where a compact footprint and high efficiency are desired simultaneously.
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