Terahertz (THz) Science in Advanced Materials, Devices and Systems

A special issue of Photonics (ISSN 2304-6732).

Deadline for manuscript submissions: closed (31 July 2022) | Viewed by 33755

Special Issue Editors


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Guest Editor
Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan
Interests: teraherz propeties and physics; nanomaterials; terahertz microscopy; terahertz devices
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushimanaka, Kitaku, Okayama 700-8530, Japan
Interests: terahertz medical and biology; terahertz imaging; terahertz application

Special Issue Information

Dear Colleagues,

This Special Issue invites manuscripts that document the recent advances in “Terahertz Science in Advanced Materials, Devices and Systems”.

Terahertz science and technology, defined as the frequency range of 0.3–30 THz, has attracted a great deal of interest owing to its potential applications. Terahertz waves bridge electronics and photonics, as well as classical and quantum physics, located in an undeveloped research area. This Special Issue aims at highlighting recent advances in THz devices, THz functional materials, and THz application systems.

We will consider theoretical, numerical, and experimental papers that cover, but are not limited to, these topics:

(1) Advances in THz sources, detectors, and components;

(2) Advanced functional materials for THz devices;

(3) Ultrafast carrier dynamics and THz nonlinear science, and new quantum physics in advanced materials;

(4) Progress in THz systems for novel applications such as:

industrial inspection, and non-destructive evaluation,

defense and security,

imaging and spectroscopy for bio/medical diagnostics,

information processing and computing,

electronics/information/broadband communications.

Prof. Dr. Masayoshi Tonouchi
Prof. Dr. Toshihiko Kiwa
Guest Editors

Manuscript Submission Information

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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. Photonics is an international peer-reviewed open access monthly 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

  • terahertz chemistry
  • terahertz biology
  • terahertz medical applications
  • terahertz functional nano-materials
  • terahertz spectroscopy
  • terahertz microscopy
  • terahertz sources and detectors
  • application in industry
  • high-field terahertz and nonlinear terahertz optics

Published Papers (15 papers)

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Editorial

Jump to: Research, Review

2 pages, 171 KiB  
Editorial
Special Issue “Terahertz (THz) Science in Advanced Materials, Devices and Systems”
by Toshihiko Kiwa and Masayoshi Tonouchi
Photonics 2023, 10(9), 1024; https://doi.org/10.3390/photonics10091024 - 7 Sep 2023
Cited by 3 | Viewed by 807
Abstract
Terahertz (THz), a specific frequency region of electromagnetic wave laying between 0 [...] Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)

Research

Jump to: Editorial, Review

15 pages, 7174 KiB  
Article
275–305 GHz FM-CW Radar 3D Imaging for Walk-Through Security Body Scanner
by Tomofumi Ikari, Yoshiaki Sasaki and Chiko Otani
Photonics 2023, 10(3), 343; https://doi.org/10.3390/photonics10030343 - 22 Mar 2023
Cited by 5 | Viewed by 2151
Abstract
Imaging using millimeter waves (MMW) and terahertz (THz) waves can help inspect hazardous materials hidden beneath clothing in a non-contact and non-invasive manner. A 3D terahertz imaging system for security gate applications in the 275–305 GHz range was developed and experimentally demonstrated to [...] Read more.
Imaging using millimeter waves (MMW) and terahertz (THz) waves can help inspect hazardous materials hidden beneath clothing in a non-contact and non-invasive manner. A 3D terahertz imaging system for security gate applications in the 275–305 GHz range was developed and experimentally demonstrated to detect concealed objects carried by pedestrians. This system performs 3D measurements by combining depth detection using frequency-modulated continuous wave (FM-CW) radar, vertical scanning of the detection spot using a 1D high-speed mechanical beam scanner, and horizontal movement of the irradiated area and detection spot as the pedestrian walks. The high-speed beam scanner comprises an F-Theta telecentric lens and a polygon mirror. It has a vertical line scan rate of 142 lines/s and spatial resolution of ~10 mm, consistent with the design value, and a depth resolution of ~7 mm, which is 40% larger than the theoretical value estimated from the FM-CW radar principle. The depth-dependent lateral distortion in 3D images, known as telecentricity, measured using the body scanner imaging system, was also evaluated. Consequently, images with the same magnification were obtained at a range of more than 500 mm of focus depth. Finally, the detection of concealed objects carried by pedestrians was demonstrated, showing that the system can work for a pedestrian walking at speeds from 4 km/h to 7 km/h. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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11 pages, 2544 KiB  
Article
THz Pulse Generation and Detection in a Single Crystal Layout
by Moses Eshovo Ojo, Frederic Fauquet, Patrick Mounaix and Damien Bigourd
Photonics 2023, 10(3), 316; https://doi.org/10.3390/photonics10030316 - 15 Mar 2023
Cited by 2 | Viewed by 1879
Abstract
The THz pulse of a few picosecond durations have been generated and detected via optical rectification and electro-optic effect within the same ZnTe crystal. An unbalanced single-shot detection scheme was performed to characterize the signal. As a result, a multicycle signal was obtained, [...] Read more.
The THz pulse of a few picosecond durations have been generated and detected via optical rectification and electro-optic effect within the same ZnTe crystal. An unbalanced single-shot detection scheme was performed to characterize the signal. As a result, a multicycle signal was obtained, in which two-photon absorption and other associated nonlinear effects were reportedly negligible. The experimental set-up is compact, economical, easy to build and has the added simplicity of facilitating an independent analysis of the horizontal or vertical polarization arm of the THz-modulated chirped probe beam. This work finds a useful application in integrated THz devices, narrow-band THz phonon spectroscopy and spectroscopic investigation of fast-occurring processes. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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10 pages, 2089 KiB  
Communication
Simulated Studies of Polarization-Selectivity Multi-Band Perfect Absorber Based on Elliptical Metamaterial with Filtering and Sensing Effect
by Yinghua Wang, Yubo Kong, Shitong Xu, Jie Li and Guangqiang Liu
Photonics 2023, 10(3), 295; https://doi.org/10.3390/photonics10030295 - 11 Mar 2023
Cited by 2 | Viewed by 1355
Abstract
In this work, the Ag-SiO2-Ag metamaterial with elliptical nano-slits was proposed to investigate the multi-band polarization-dependent perfect absorber. It was found that multi-band perfect absorptions can be induced under TE and TM-polarized illuminations. Simulation results showed that the absorption peaks for [...] Read more.
In this work, the Ag-SiO2-Ag metamaterial with elliptical nano-slits was proposed to investigate the multi-band polarization-dependent perfect absorber. It was found that multi-band perfect absorptions can be induced under TE and TM-polarized illuminations. Simulation results showed that the absorption peaks for TE-polarized wave appeared at 337.6 THz and 360.0 THz with 98.5% and 97.6% absorbance, respectively. Conversely, the absorption peaks for TM-polarized wave appeared at 325.7 THz and 366.1 THz with 96.3% and 97.9% absorbance, respectively. As a result, the elliptical metamaterial presented polarization-selectivity property for perfect absorption, and so, the metamaterial can filter out different frequencies of TE- and TM-reflected waves, i.e., the elliptical metamaterial can be used as a reflecting filter. In addition, this work studied the sensing performance of the elliptical metamaterial and showed that the dual-band sensing performances were different at low and high frequencies. The sensitivities (S) to the refractive index reached up to 151.1 THz/RIU and 120.8 THz/RIU for the TE and TM-polarized waves around 337.6 THz and 325.7 THz, which provide promising potential in near-infrared photoelectric sensor and detector. However, both the absorption frequency and intensity of TM-polarized wave were insensitive to the refractive index of the medium around 366.1 THz, and so, the study provides a theoretical basis for infrared stealth of different media. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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10 pages, 3140 KiB  
Communication
A 245 GHz Real-Time Wideband Wireless Communication Link with 30 Gbps Data Rate
by Ting Zhang, Hao Zhang, Xiaojing Huang, Hajime Suzuki, Joseph Pathikulangara, Ken Smart, Jia Du and Jay Guo
Photonics 2022, 9(10), 683; https://doi.org/10.3390/photonics9100683 - 22 Sep 2022
Cited by 4 | Viewed by 1683
Abstract
This paper presents a 245 GHz wireless communications system with a data rate of 30 Giga bits per second (Gbps) at a 1.2 m distance, which proves the potential for future high-speed communications beyond 5G technology. The system consists of low-complexity and real-time [...] Read more.
This paper presents a 245 GHz wireless communications system with a data rate of 30 Giga bits per second (Gbps) at a 1.2 m distance, which proves the potential for future high-speed communications beyond 5G technology. The system consists of low-complexity and real-time base-band modules to provide the high-speed wideband signal processing capability. Multi-channel base-band signals are combined and converted to 15.65 ± 6.25 GHz wideband intermediate frequency (IF) signals. A novel 245 GHz waveguide bandpass filter (BPF) with low loss and high selectivity is designed and applied to a terahertz (THz) front-end for image rejection and noise suppression. Configuration of the base-band, IF, and THz front-end modules is also given in detail. The 245 GHz wireless communication link is demonstrated over a distance of 1.2 m. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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7 pages, 1726 KiB  
Communication
Ultrawideband and High-Resolution Terahertz Spectroscopy: Structural Identification of Glucose
by Katsuhiko Miyamoto, Tomohito Yamasaki, Shota Tsuji, Kazuma Inoue, Godeung Park, Hirohisa Uchida, Akira Matsuura, Peter Krüger and Takashige Omatsu
Photonics 2022, 9(9), 602; https://doi.org/10.3390/photonics9090602 - 25 Aug 2022
Cited by 4 | Viewed by 2670
Abstract
We report on the development of an ultrawideband and high-resolution THz spectroscopic system, which operates over a frequency range of 2–13.5 THz. This work goes beyond conventional THz spectroscopic measurements and demonstrates the capacity to differentiate D- and L-glucoses, which have the same [...] Read more.
We report on the development of an ultrawideband and high-resolution THz spectroscopic system, which operates over a frequency range of 2–13.5 THz. This work goes beyond conventional THz spectroscopic measurements and demonstrates the capacity to differentiate D- and L-glucoses, which have the same molecular conformation and crystal structure. Furthermore, this system facilitates the structural identification of glucose microcrystals, which exists in α- and β-forms, revealing that L-glucose microcrystals are formed of a mixture of α- and β-D-glucose with approximately equal weight. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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13 pages, 915 KiB  
Article
A Surface Plasmon–Polariton in a Symmetric Dielectric Waveguide with Active Graphene Plates
by Dmitry A. Evseev, Svetlana V. Eliseeva, Dmitry I. Sementsov and Anatolij M. Shutyi
Photonics 2022, 9(8), 587; https://doi.org/10.3390/photonics9080587 - 19 Aug 2022
Cited by 8 | Viewed by 1273
Abstract
A theoretical study of the plasmon modes’ characteristics is carried out in a structure consisting of two active graphene layers separated by a dielectric barrier layer. A general dispersion relation is obtained, the numerical analysis of which reveals the possibility of controlling the [...] Read more.
A theoretical study of the plasmon modes’ characteristics is carried out in a structure consisting of two active graphene layers separated by a dielectric barrier layer. A general dispersion relation is obtained, the numerical analysis of which reveals the possibility of controlling the parameters of amplified surface modes in the region of graphene negative conductivity. In particular, their dispersion is controlled by changing the chemical potential of the graphene layers. For antisymmetric plasmons, their dependence on the barrier layer parameters was revealed. An increase in the chemical potential makes it possible to expand the region of existence of the amplified plasmons, which is accompanied not only by an increase in the amplification coefficient but also by a shift to the region of higher frequencies of the amplified modes. For the first time, modal bistability was also demonstrated in a limited frequency range for antisymmetric plasmons, due to the appearance of additional modes, in which the phase velocity decreases sharply near the cutoff, and the group velocities of the modes entering the bistability turn out to be opposite in sign. The frequency dependences of the real and imaginary parts of the plasmon propagation constant are analyzed, the distributions of wave fields in the structure are plotted, and the frequency dependence of the depth of the plasmon–polariton is given. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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19 pages, 7199 KiB  
Article
Ultra-Low-Loss and Broadband All-Silicon Dielectric Waveguides for WR-1 Band (0.75–1.1 THz) Modules
by Ratmalgre Koala, Ryoma Maru, Kei Iyoda, Li Yi, Masayuki Fujita and Tadao Nagatsuma
Photonics 2022, 9(8), 515; https://doi.org/10.3390/photonics9080515 - 24 Jul 2022
Cited by 11 | Viewed by 3371
Abstract
This study presents ultra-low-loss and broadband all-silicon dielectric waveguides for the WR-1 band (0.75–1.1 THz). The waveguides are built in high-resistivity silicon (10 kΩ-cm) and integrated with supportive frames fabricated from the same silicon wafer in a single etch process to achieve a [...] Read more.
This study presents ultra-low-loss and broadband all-silicon dielectric waveguides for the WR-1 band (0.75–1.1 THz). The waveguides are built in high-resistivity silicon (10 kΩ-cm) and integrated with supportive frames fabricated from the same silicon wafer in a single etch process to achieve a compact design. We pursued low-loss, broadband, substrateless, unclad and effective medium waveguides. Smaller propagation losses of 0.3 dB/cm and 0.1 dB/cm were achieved for the unclad and effective medium waveguides, respectively. The 3 dB bandwidth was not encountered in the frequency range of interest and was as broad as 350 GHz. An unclad waveguide was employed to devise a Y-junction to demonstrate its practical applications in terahertz imaging. An integrated circuit card was successfully scanned. In addition, we developed unclad waveguide, effective medium waveguide, and Y-junction modules. The modules incorporated an input/output interface compatible with a standard WR-1 flange (254 μm × 127 μm). Unlike the conventional hollow waveguide modules, the unclad waveguide and effective medium waveguide modules reported total loss improvements of 6 dB and 8 dB, respectively, across the operation band. Our results provided a systematic way of achieving low-loss, compact, and versatile modules in the WR-1 band based on all-dielectric-waveguide platforms. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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10 pages, 986 KiB  
Communication
Instantaneous Photocarrier Transport at the Interface in Perovskite Solar Cells to Generate Photovoltage
by Toshimitsu Mochizuki, Iwao Kawayama, Masayoshi Tonouchi, Yoshihiko Nishihara, Msayuki Chikamatsu, Yuji Yoshida and Hidetaka Takato
Photonics 2022, 9(5), 316; https://doi.org/10.3390/photonics9050316 - 6 May 2022
Cited by 2 | Viewed by 3254
Abstract
The instantaneous photocarrier transport of perovskite solar cells was evaluated by assessing laser-induced terahertz (THz) emission to understand carrier dynamics in perovskite solar cells. The waveform of laser-induced THz radiation from an interface between the TiO2 electron transport layer and perovskite active [...] Read more.
The instantaneous photocarrier transport of perovskite solar cells was evaluated by assessing laser-induced terahertz (THz) emission to understand carrier dynamics in perovskite solar cells. The waveform of laser-induced THz radiation from an interface between the TiO2 electron transport layer and perovskite active layer of an n-i-p perovskite solar cell with varying external bias was measured using THz-time domain spectroscopy. The amplitude of the THz radiation decreased with increasing reverse bias voltage. The waveform of the THz radiation was inverted at a strong reverse bias. The measured bias voltage dependence suggests that the transient current generated at the interface between perovskite and TiO2 owing to the higher mobility of electrons than that of holes, namely the photo-Dember effect, is the dominant source of THz radiation and the destructive contribution of the interfacial electric field inverts the transient current when a reverse bias causes a strong interfacial electric field. The significant contribution of the interfacial electric field has not been previously reported in perovskite thin films and is unique to solar cells. We believe that band bending at interfaces in perovskite solar cells will be determined from the THz emission with proper modeling. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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10 pages, 3460 KiB  
Communication
Multi-Wavelength Terahertz Parametric Generator Using a Seed Laser Based on Four-Wave Mixing
by Sota Mine, Kodo Kawase and Kosuke Murate
Photonics 2022, 9(4), 258; https://doi.org/10.3390/photonics9040258 - 12 Apr 2022
Cited by 2 | Viewed by 2030
Abstract
In this study, we developed a multi-wavelength terahertz-wave parametric generator that operates with only one injection seeding laser. Tunable lasers used as an injection seeder must be single-frequency oscillators, and conventional multi-wavelength terahertz-wave parametric generator requires basically the same number of lasers as [...] Read more.
In this study, we developed a multi-wavelength terahertz-wave parametric generator that operates with only one injection seeding laser. Tunable lasers used as an injection seeder must be single-frequency oscillators, and conventional multi-wavelength terahertz-wave parametric generator requires basically the same number of lasers as the number of wavelengths. In order to solve this problem, we developed a new external cavity semiconductor laser that incorporates a DMD in its wavelength-selective mechanism. In this process, stable multi-wavelength oscillation from a single laser was made possible by efficiently causing four-wave mixing. This seed laser can be applied to practical real-time terahertz spectroscopy by arbitrarily switching the desired wavelength to be generated and the interval between multiple wavelengths. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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9 pages, 3450 KiB  
Communication
Non-Drude-Type Response of Photocarriers in Fe-Doped β-Ga2O3 Crystal
by Hao Jiang, Ke Wang, Hironaru Murakami and Masayoshi Tonouchi
Photonics 2022, 9(4), 233; https://doi.org/10.3390/photonics9040233 - 1 Apr 2022
Cited by 4 | Viewed by 2313
Abstract
Beta gallium oxide, β-Ga2O3, is one of the promising ultrawide bandgap semiconductors with a monoclinic (C2/m) β-phase structure showing strong anisotropic properties. To improve the performance of these devices, more optical characterization is required. Here, the anisotropic carrier dynamics [...] Read more.
Beta gallium oxide, β-Ga2O3, is one of the promising ultrawide bandgap semiconductors with a monoclinic (C2/m) β-phase structure showing strong anisotropic properties. To improve the performance of these devices, more optical characterization is required. Here, the anisotropic carrier dynamics in optically excited (010) oriented Fe-doped β-Ga2O3 was studied by terahertz time-domain spectroscopy. An 800 nm continuous-wave light source was employed to excite carriers from Fe acceptors to the conduction band and to probe an anisotropic interaction with the THz field. The complex THz conductivities fitted with the Drude and Drude–Smith models revealed that the optically excited carriers behave as nearly free carriers along the a-axis, whereas those along the c-axis show a non-Drude type response. The estimated mobility for the c-axis agrees with the reported values, whereas the results suggest much higher mobility along the a-axis. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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11 pages, 3328 KiB  
Communication
Distance Measurement of a Frequency-Shifted Sub-Terahertz Wave Source
by Minoru Honjo, Koji Suizu, Masaki Yamaguchi and Tomofumi Ikari
Photonics 2022, 9(3), 128; https://doi.org/10.3390/photonics9030128 - 24 Feb 2022
Cited by 2 | Viewed by 2017
Abstract
In this paper, we report the development of a frequency-shifted (FS) terahertz (THz) wave source for the non-destructive inspection of buildings. Currently, terahertz-time domain spectroscopy (THz-TDS) is the mainstream method for non-destructive inspection using THz waves. However, THz-TDS is limited by its measurement [...] Read more.
In this paper, we report the development of a frequency-shifted (FS) terahertz (THz) wave source for the non-destructive inspection of buildings. Currently, terahertz-time domain spectroscopy (THz-TDS) is the mainstream method for non-destructive inspection using THz waves. However, THz-TDS is limited by its measurement range and difficulties encountered when there is a strong frequency dependence in the absorption characteristics and refractive index of the measurement target. To address these issues, we developed a novel non-destructive approach for inspection applications using frequency-shifted THz waves. Our system uses a frequency-shifted feedback (FSF) laser as the pump light source to generate FS-THz waves; this allowed us to obtain precise distance measurements of objects over a broad range of distances. We tested a prototype FS-THz system and confirmed successful measurement of spatial distances inside a building material. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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13 pages, 3187 KiB  
Article
A Versatile Terahertz Chemical Microscope and Its Application for the Detection of Histamine
by Jin Wang, Kosuke Sato, Yuichi Yoshida, Kenji Sakai and Toshihiko Kiwa
Photonics 2022, 9(1), 26; https://doi.org/10.3390/photonics9010026 - 3 Jan 2022
Cited by 4 | Viewed by 3052
Abstract
Terahertz waves have gained increasingly more attention because of their unique characteristics and great potential in a variety of fields. In this study, we introduced the recent progress of our versatile terahertz chemical microscope (TCM) in the detection of small biomolecules, ions, cancer [...] Read more.
Terahertz waves have gained increasingly more attention because of their unique characteristics and great potential in a variety of fields. In this study, we introduced the recent progress of our versatile terahertz chemical microscope (TCM) in the detection of small biomolecules, ions, cancer cells, and antibody–antigen immunoassaying. We highlight the advantages of our TCM for chemical sensing and biosensing, such as label-free, high-sensitivity, rapid response, non-pretreatment, and minute amount sample consumption, compared with conventional methods. Furthermore, we demonstrated its new application in detection of allergic-related histamine at low concentration in buffer solutions. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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11 pages, 964 KiB  
Communication
Low-Frequency Content of THz Emission from Two-Color Femtosecond Filament
by Daniil E. Shipilo, Nikolay A. Panov, Irina A. Nikolaeva, Alexander A. Ushakov, Pavel A. Chizhov, Kseniia A. Mamaeva, Vladimir V. Bukin, Sergey V. Garnov and Olga G. Kosareva
Photonics 2022, 9(1), 17; https://doi.org/10.3390/photonics9010017 - 29 Dec 2021
Cited by 9 | Viewed by 1698
Abstract
We experimentally investigate the low-frequency (below 1 THz) spectral content of broadband terahertz (THz) emission from two-color femtosecond filament formed by the 2.7-mJ, 40-fs, 800+400-nm pulse focused into air. For incoherent detection, we screened the Golay cell by the bandpass [...] Read more.
We experimentally investigate the low-frequency (below 1 THz) spectral content of broadband terahertz (THz) emission from two-color femtosecond filament formed by the 2.7-mJ, 40-fs, 800+400-nm pulse focused into air. For incoherent detection, we screened the Golay cell by the bandpass filters and measured the THz angular distributions at the selected frequencies ν=0.5, 1, 2 and 3 THz. The measured distributions of THz fluence were integrated over the forward hemisphere taking into account the transmittance of the filters, thus providing the estimation of spectral power at the frequencies studied. The spectral power decreases monotonically with the frequency increasing from 0.5 to 3 THz, thus showing that the maximum of THz spectrum is attained at ν0.5 THz. The THz waveform measured by electro-optical sampling (EOS) based on ZnTe crystal and transformed into the spectral domain shows that there exists the local maximum of the THz spectral power at ν1 THz. This disagrees with monotonic decrease of THz spectral power obtained from the filter-based measurements. We have introduced the correction to the spectral power reconstructed from EOS measurements. This correction takes into account different focal spot size for different THz frequencies contained in the broadband electromagnetic pulse. The corrected EOS spectral power is in semi-quantitative agreement with the one measured by a set of filters. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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Review

Jump to: Editorial, Research

11 pages, 9891 KiB  
Review
Broadband Terahertz Metal-Wire Signal Processors: A Review
by Mohammad Ghazialsharif, Junliang Dong, Alaeddine Abbes and Roberto Morandotti
Photonics 2023, 10(1), 48; https://doi.org/10.3390/photonics10010048 - 3 Jan 2023
Cited by 6 | Viewed by 1976
Abstract
Communication links operating at terahertz frequencies are envisioned to provide a revolutionary enhancement of data transmission. As fundamental building blocks, waveguides play an indispensable role in future terahertz networks, not only transporting data streams with unprecedented data rates, but also serving as a [...] Read more.
Communication links operating at terahertz frequencies are envisioned to provide a revolutionary enhancement of data transmission. As fundamental building blocks, waveguides play an indispensable role in future terahertz networks, not only transporting data streams with unprecedented data rates, but also serving as a versatile platform for signal processing. Among various terahertz waveguides, metal-wire waveguides have attracted particular attention due to their distinct characteristics, such as structural simplicity, broad operating bandwidths, low transmission losses, and low dispersion, in turn making them promising candidates for signal processing. However, because of the tight confinement of modal energy within the wavelength-scale space, manipulating the propagating terahertz signals in-between the metal-wires is challenging. Here, we report the most recent advances in the realization of signal-processing functionalities within metal-wire waveguides. Based on these state-of-the-art methodologies, broadband signal processors that can function as filters, couplers, temporal integrators, as well as multiplexers, have been obtained. We expect this review to inspire new terahertz metal-wire signal processors with high potential for real-time tunability and reconfigurability. Full article
(This article belongs to the Special Issue Terahertz (THz) Science in Advanced Materials, Devices and Systems)
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