Abstract-The Role of Scattering in Quasi-Ordered Structures for Terahertz Imaging: Local Order Can Increase an Image Quality

Irina N. Dolganova, Kirill I. Zaytsev,  Stanislav O. Yurchenko, Valeriy E. Karasik, Valery V. Tuchin

https://ieeexplore.ieee.org/document/8371640/

In this paper, we propose a computational approach for description of radiation transfer in a quasi-ordered medium and study the impact of scattering on electromagnetic wave propagation and image formation. It combines finite-difference time-domain method, Monte Carlo simulations, and radiative transfer theory. Using as an example terahertz imaging, we analyze modulation transfer function (MTF) of imaging system operated at 0.25 THz for scattering material layers placed between the object and the imaging plane. We experimentally study imaging of bar-pattern test-objects through a quasi-ordered scattering medium. Both numerical and experimental results are in good agreement and demonstrate an impact of quasi-ordered scatterers on quality of THz images, i.e. particular combination of the electromagnetic wavelength and parameters of scattering materials could enhance MTF compared with ones with random particle structures.

Abstract-Technological aspects of manufacturing terahertz photonic crystal waveguides based on sapphire shaped crystals

Gleb M. Katyba; Kirill I. Zaytsev; Sergey N. Rossolenko, Irina A. Shikunova, Sergey L. Shikunov,  Dmitriy O. Stryukov,  Stanislav O. Yurchenko, Vladimir N. Kurlov

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10333/103331C/Technological-aspects-of-manufacturing-terahertz-photonic-crystal-waveguides-based-on/10.1117/12.2270168.short?SSO=1

Recently, terahertz (THz) photonic crystal waveguides based on sapphire shaped crystals have been proposed. These waveguides combine unique properties of sapphire with advantages of the edge-defined film-fed growth (EFG) or Stepanov technique of shaped crystal growth and allow guiding THz waves in a wide spectral range with small dispersion and losses. The sapphire photonic crystal waveguides are capable for operation in aggressive environment, which makes possible to perform high-temperature and high-pressure THz measurements, as well as THz measurements of aggressive chemicals. In this paper, the technological aspects of sapphire THz photonic crystal waveguide manufacturing by the EFG/Stepanov technique (including, the problems of seeding and automated control of multichannel shaped crystal growth) have been described. Prospective applications of sapphire photonic crystal waveguides in various branches of THz science and technology have been discussed.

© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-Technological aspects of manufacturing terahertz photonic crystal waveguides based on sapphire shaped crystals

Gleb M. Katyba, Sergey N. Rossolenko, Irina A. Shikunova, Sergey L. Shikunov, Dmitriy O. Stryukov, Vladimir N. Kurlov

Institute of the Solid State Physics (Russian Federation)

Kirill I. Zaytsev, Stanislav O. Yurchenko

Bauman Moscow State Technical Univ. (Russian Federation)

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2635665

Recently, terahertz (THz) photonic crystal waveguides based on sapphire shaped crystals have been proposed. These waveguides combine unique properties of sapphire with advantages of the edge-defined film-fed growth (EFG) or Stepanov technique of shaped crystal growth and allow guiding THz waves in a wide spectral range with small dispersion and losses. The sapphire photonic crystal waveguides are capable for operation in aggressive environment, which makes possible to perform high-temperature and high-pressure THz measurements, as well as THz measurements of aggressive chemicals. In this paper, the technological aspects of sapphire THz photonic crystal waveguide manufacturing by the EFG/Stepanov technique (including, the problems of seeding and automated control of multichannel shaped crystal growth) have been described. Prospective applications of sapphire photonic crystal waveguides in various branches of THz science and technology have been discussed. 

© (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-A hybrid continuous-wave terahertz imaging system

Irina N. Dolganova^1,a), Kirill I. Zaytsev^1,b), Anna A. Metelkina¹,Valeriy E. Karasik¹ and Stanislav O. Yurchenko^1,c)
http://scitation.aip.org/content/aip/journal/rsi/86/11/10.1063/1.4935495
1 Bauman Moscow State Technical University, 2nd Baumanskaya str. 5, Moscow 105005, Russia
a) Electronic mail: in.dolganova@gmail.com
b) Electronic mail: kirzay@gmail.ru
c) Electronic mail: st.yurchenko@mail.ru
Rev. Sci. Instrum. 86, 113704 (2015); http://dx.doi.org/10.1063/1.4935495

A hybrid (active-passive mode) terahertz (THz) imagingsystem and an algorithm for imagingsynthesis are proposed to enhance the THz image quality. The concept of imagecontrast is used to compare active and passive THz imaging. Combining the measurement of the self-emitted radiation of the object with the back-scattered source radiation measurement, it becomes possible to use the THz image to retrieve maximum information about the object. The experimental results confirm the advantages of hybrid THz imagingsystems, which can be generalized for a wide range of applications in the material sciences, chemical physics, bio-systems, etc.

Abstract-Spectroscopy of Nafion in terahertz frequency range

Stanislav O. Yurchenko^1,a) and Kirill I. Zaytsev^1,b)
http://scitation.aip.org/content/aip/journal/jap/116/11/10.1063/1.4896194
1 Bauman Moscow State Technical University, 105005, 2nd Baumanskaya str. 5, Moscow, Russia
a) Electronic mail: st.yurchenko@mail.ru
b) Electronic mail: kirzay@gmail.com
J. Appl. Ph

We report results on the terahertz (THz) spectroscopy of polymer Nafion. Using THz pulsespectroscopy and refined post-processing algorithms based on the ill-posed spectroscopicinverse problem analysis, we find the complex dielectric permittivity of Nafion to be in the range 0.15–1.5 THz. The results in the low-frequency (gigahertz) range agree well with known measurements. We find that the complex dielectric permittivity can be described well using the double-Debye model with relaxation times of 7.20 ± 0.05 ps and 0.12 ± 0.05 ps. This result is discussed briefly from the viewpoint of the appearance of a segregated structure in the “Nafion–water” system.