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State-of-the-art Terahertz Science and Technology

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (20 September 2021) | Viewed by 20800

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Special Issue Editor

Prof. Dr. Petrarca Massimo

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Guest Editor

Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, 00161 Rome, Italy
Interests: non-linear; optics; laser–matter interaction; THz
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

You are cordially invited to submit your original research or review papers to this Special Issue on “THz Science and Technology” in Applied Science.

This Special Issue is dedicated to the scientific request of a THz technology and therefore to the research and development activity that has been achieved in the past two decades and will continue.
The scientific interest in THz radiation (0.3–5 THz) derives from the many optical properties that many materials exhibit at these frequencies. That is, THz is sensitive to polar molecules such as water but at the same time interacts only very weakly with material composed of non-polar molecules such as plastic and ceramic and is reflected by most metals. It is less affected by scattering from atmospheric particulates compared to shorter-wavelength radiation, and at these frequencies many molecules have their fingerprints due to roto-vibrational motion, collective modes in crystal lattices, etc.

Some specific topics include:

1) Physics/Engineering science for the characterization of new materials to fulfill the increasing needs for electronics and photonics; security applications such as drug, weapon, and explosives recognition. Moreover, THz technology meets the 5G WCS network capacity requirements and is an appealing solution for emerging indoor short-range applications. As a consequence, the design, characterization, and fabrication of protection systems against THz electromagnetic (EM) interference have become subjects of actual EM compatibility research.

2) Biomedicine: the weak interactions including hydrogen and van der Waals bonds can be probed by THz spectroscopy. Moreover, due to its sensitivity to water, THz can monitor the hydration level allowing the differentiation between normal and cancer tissues, assessment of the living state of bacteria, and thanks to its non-ionizing properties, suitability for medical in vivo diagnosis without being harmful for the patient.

3) Climate and Environment: THz is of great interest for monitoring soil, water, and air pollutants.

4) Agri-food analysis and quality control: THz can be a competitive detection method for inspecting hidden physiological threats and defects through its capability of recognizing foreign bodies, determining pesticide and antibiotic residues in agri-food products, and characterizing edible oils and genetically modified food.

5) Cultural Heritage: non-destructive evaluation of the structures of targets or of hidden material and, therefore, suitability for non-invasive diagnostics for cultural heritage.

This Special Issue is an opportunity to further disseminate the scientific and technological development related to THz radiation.

Prof. Dr. Massimo Petrarca
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

THz sources and detectors
THz spectroscopy
THz optics
Linear and non-linear THz response of materials
Dust and pollution
Environmental science
Metamaterials
THz for communication
THz for transmission line and waveguide
THz applications
THz propagation
High field THz
THz for accelerator physics
THz for plasma diagnostic
Linear and non-linear optics…

Published Papers (7 papers)

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Research

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7 pages, 4162 KiB

Open AccessArticle

Polarization Imaging of Liquid Crystal Polymer Using Terahertz Difference-Frequency Generation Source

by Atsushi Nakanishi, Shohei Hayashi, Hiroshi Satozono and Kazuue Fujita

Appl. Sci. 2021, 11(21), 10260; https://0-doi-org.brum.beds.ac.uk/10.3390/app112110260 - 01 Nov 2021

Cited by 5 | Viewed by 1668

Abstract

We performed the polarization imaging of a liquid crystal polymer with a terahertz difference-frequency generation (THz DFG) source. The DFG source is an easy-to-operate and practical THz source. Liquid crystal polymers (LCPs) are suitable for applications such as fuel cell components, aircraft parts, and next-generation wireless communication materials. Accordingly, the demand for evaluating the orientation of liquid crystals, which affects the properties of the polymers, is set to increase. Since LCPs exhibit birefringence in the THz range due to the orientation of the liquid crystal molecules, we can determine the alignment of the molecules from the direction of the optical axis. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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Figure 1

15 pages, 4621 KiB

Open AccessArticle

THz Range Low-Noise SIS Receivers for Space and Ground-Based Radio Astronomy

by Kirill I. Rudakov, Andrey V. Khudchenko, Lyudmila V. Filippenko, Maxim E. Paramonov, Ronald Hesper, Daniele Aragão Ronsó da Costa Lima, Andrey M. Baryshev and Valery P. Koshelets

Appl. Sci. 2021, 11(21), 10087; https://0-doi-org.brum.beds.ac.uk/10.3390/app112110087 - 28 Oct 2021

Cited by 10 | Viewed by 2085

Abstract

We report on research in the field of low-noise receiving systems in the sub-terahertz (THz) range, carried out in recent years, aimed at developing receivers with quantum sensitivity for implementation in space and ground-based radio telescopes. Superconductor-Insulator-Superconductor (SIS) mixers based on high-quality tunnel junctions are the key elements of the most sensitive sub-THz heterodyne receivers. Motivations and physical background for technology improvement and optimization, as well as fabrication details, are described. This article presents the results of the SIS receiver developments for the 211–275 GHz and 790–950 GHz frequency ranges with a noise temperature in the double sideband (DSB) mode of approximTELY 20 K and 200 K, respectively. These designs and achievements are implemented in the development of the receiving systems for the Russian Space Agency mission “Millimetron”, and for the ground-based APEX (Atacama Pathfinder EXperiment) telescope. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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13 pages, 3807 KiB

Open AccessArticle

Terahertz and Microwave Optical Properties of Single-Crystal Quartz and Vitreous Silica and the Behavior of the Boson Peak

by Mira Naftaly and Andrew Gregory

Appl. Sci. 2021, 11(15), 6733; https://0-doi-org.brum.beds.ac.uk/10.3390/app11156733 - 22 Jul 2021

Cited by 31 | Viewed by 4784

Abstract

Z-cut single-crystal quartz and vitreous silica (silica glass or fused silica) were evaluated for use as reference materials for terahertz and microwave measurements of complex permittivity, with Z-cut quartz confirmed as being suitable. Measurements of refractive indices and absorption coefficients for o-ray and e-ray in quartz and for vitreous silica are reported at frequencies between 0.2 and 6 THz and at 36 and 144 GHz, and compared with data reported in the literature. A previously unreported broad band was seen in the extraordinary absorption of quartz. The Boson peak in silica glass absorption was examined, and for the first time, two negative relationships have been observed: between the refractive index and the Boson peak frequency, and between the Boson peak height and its frequency. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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13 pages, 6616 KiB

Open AccessArticle

Terahertz Rotational Spectroscopy of Greenhouse Gases Using Long Interaction Path-Lengths

by Arnaud Cuisset, Francis Hindle, Gaël Mouret, Robin Bocquet, Jonas Bruckhuisen, Jean Decker, Anastasiia Pienkina, Cédric Bray, Éric Fertein and Vincent Boudon

Appl. Sci. 2021, 11(3), 1229; https://0-doi-org.brum.beds.ac.uk/10.3390/app11031229 - 29 Jan 2021

Cited by 18 | Viewed by 3207

Abstract

Even if on-board mm-wave/THz heterodyne receivers have been developed to measure greenhouse gases (GHGs) atmospheric profiles, rotational spectroscopy rests under-exploited for their monitoring unlike IR rovibrational spectroscopy. The present study deals with the ability of THz spectroscopy using long interaction path-lengths for GHG laboratory investigations. High-resolution THz signatures of non-polar greenhouse molecules may be observed by probing very weak centrifugal distortion induced rotational transitions. To illustrate, new measurements on CH

_{4}

and CF

_{4}

have been carried out. For CH

_{4}

, pure rotational transitions, recorded by cw-THz photomixing up to 2.6 THz in a White type cell adjusted to 20 m, have allowed to update the methane line list of atmospheric databases. Concerning CF

_{4}

, Fabry-Perot THz absorption spectroscopy with a km effective pathlength was required to detect line intensities lower than 10

^{- 27}

^{- 1} / (molec {cm}^{- 2})

. Contrary to previous synchrotron-based FT-FIR measurements, the tetrahedral splitting of CF

_{4}

THz lines is fully resolved. Finally, quantitative measurements of N

_{2}

O and O

_{3}

gas traces have been performed in an atmospheric simulation chamber using a submm-wave amplified multiplier chain coupled to a Chernin type multi-pass cell on a 200 m path-length. The THz monitoring of these two polar GHGs at tropospheric and stratospheric concentrations may be now considered. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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17 pages, 3542 KiB

Open AccessArticle

THz Radiation Measurement with HTSC Josephson Junction Detector Matched to Planar Antenna

by Eldad Holdengreber, Aviv Glezer Moshe, Shmuel E. Schacham, Moshe Mizrahi, Dhasarathan Vigneswaran and Eliyahu Färber

Appl. Sci. 2020, 10(18), 6482; https://0-doi-org.brum.beds.ac.uk/10.3390/app10186482 - 17 Sep 2020

Cited by 4 | Viewed by 2387

Abstract

Superconducting Josephson junctions have major advantages as detectors of millimeter wave radiation. Frequency of the radiation can be easily derived from the Shapiro steps of the current-voltage characteristics. However, system performance is highly sensitive to impedance mismatch between the antenna and the junction; therefore, optimization is essential. We analyzed and implemented an improved antenna structure, in which the junction is displaced from the antenna center and placed between the ends of two matching strips. Based on theoretical analysis and advanced electromagnetic simulations, we optimized strip dimensions, which affect both the detection magnitude and the frequency of the reflection coefficient dip. Accordingly, two Au bow-tie antennas with different matching strip widths were fabricated. Superconducting Yttrium Barium Copper Oxide (YBCO) thin films were deposited exactly at the bicrystal substrate misorientation points, forming Josephson junctions at the ends of two matching strips. We found a very high correlation between the simulations and the response to Radio Frequency (RF) radiation in the range of 145–165 GHz. Experimental results agree extremely well with the design, showing best performance of both antennas around the frequency for which impedance matching was derived. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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Review

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23 pages, 134429 KiB

Open AccessReview

Arrays of Sub-Terahertz Cryogenic Metamaterial

by Mikhail Tarasov, Aleksandra Gunbina, Artem Chekushkin, Vyacheslav Vdovin and Aleksei Kalaboukhov

Appl. Sci. 2021, 11(20), 9649; https://0-doi-org.brum.beds.ac.uk/10.3390/app11209649 - 15 Oct 2021

Cited by 3 | Viewed by 1406

Abstract

Integrated quasi-optical cryogenic terahertz receivers contain arrays of detectors, quasi-optical filters, interferometers, and other metamaterials. Matrices of quasi-optical band-pass, low-pass, and high-pass filters, Fabry–Perot grid interferometers, and arrays of half-wave and electrically small antennas with superconductor-insulator-normal metal-insulator-superconductor (SINIS) sub-terahertz wavelength range detectors were fabricated and experimentally studied on the same computational, technological, and experimental platform. For the design of the filters, we used the periodic frequency-selective surfaces (FSS) approach, contrary to detector arrays that can be presented in a model of distributed absorbers. The structures were fabricated using direct electron beam lithography, thermal shadow evaporation, lift-off, alternatively magnetron sputtering, and chemical and plasma etching. The numerical simulation methods of such structures are sufficiently different: for the reactive matrices with low losses, the approximation of an infinite structure with periodic boundary conditions is applicable, and for the arrays of detectors with dissipative elements of absorbers, a complete analysis of the finite structure with hundreds of interacting ports is applicable. The difference is determined by the presence of dissipation in the detector arrays, the phase of the reflected or re-emitted signal turned out to be undefined and the Floquet periodic boundary conditions are correct only for a phased array antenna. The spectral characteristics of the created filters, interferometers, and antenna arrays were measured in the frequency range 50–600 GHz. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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31 pages, 17644 KiB

Open AccessFeature PaperReview

Towards Monolithic Indium Phosphide (InP)-Based Electronic Photonic Technologies for beyond 5G Communication Systems

by Chhandak Mukherjee, Marina Deng, Virginie Nodjiadjim, Muriel Riet, Colin Mismer, Djeber Guendouz, Christophe Caillaud, Hervé Bertin, Nicolas Vaissiere, Mathieu Luisier, Xin Wen, Magali De Matos, Patrick Mounaix and Cristell Maneux

Appl. Sci. 2021, 11(5), 2393; https://0-doi-org.brum.beds.ac.uk/10.3390/app11052393 - 08 Mar 2021

Cited by 11 | Viewed by 4276

Abstract

This review paper reports the prerequisites of a monolithic integrated terahertz (THz) technology capable of meeting the network capacity requirements of beyond-5G wireless communications system (WCS). Keeping in mind that the terahertz signal generation for the beyond-5G networks relies on the technology power loss management, we propose a single computationally efficient software design tool featuring cutting-edge optical devices and high speed III–V electronics for the design of optoelectronic integrated circuits (OEICs) monolithically integrated on a single Indium-Phosphide (InP) die. Through the implementation of accurate and SPICE (Simulation Program with Integrated Circuit Emphasis)-compatible compact models of uni-traveling carrier photodiodes (UTC-PDs) and InP double heterojunction bipolar transistors (DHBTs), we demonstrated that the next generation of THz technologies for beyond-5G networks requires (i) a multi-physical understanding of their operation described through electrical, photonic and thermal equations, (ii) dedicated test structures for characterization in the frequency range higher than 110 GHz, (iii) a dedicated parameter extraction procedure, along with (iv) a circuit reliability assessment methodology. Developed on the research and development activities achieved in the past two decades, we detailed each part of the multiphysics design optimization approach while ensuring technology power loss management through a holistic procedure compatible with existing software tools and design flow for the timely and cost-effective achievement of THz OEICs. Full article

(This article belongs to the Special Issue State-of-the-art Terahertz Science and Technology)

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