Standoff Detection of Hidden Explosives and Cold and Fire Arms by Terahertz Time-Domain Spectroscopy and Active Spectral Imaging (Review)

Skvortsov, L A

doi:10.1007/s10812-014-9998-2

Cited by 29 publications

(9 citation statements)

References 116 publications

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“…Please note that for fair comparison, the individual layer thicknesses are properly chosen such that the InSb-SiO 2 multilayers have exactly the same total thicknesses for these different values of t m /t d . To understand this interesting phenomenon, we turn to the effective relative permittivities expressed by Equations (2) and (3). As we have shown in Figure 1c, the InSb-SiO 2 multilayers with t m /t d = 1:1 have hyperbolic dispersion relationship since ε ε ⊥ < 0 at f = 1.6 THz.…”

Section: Resultsmentioning

confidence: 99%

“…Terahertz (THz) wave refers to electromagnetic radiation with a frequency of 0.1-10 × 10 12 Hz (corresponding to wavelength of 3 mm-30 µm). Because of its unique characteristics such as superior spatial resolution, perspective, and spectroscopic fingerprints, terahertz wave has been widely used in security or industrial inspection [1,2], material composition identification [3,4], and biosensing [5]. Since commercially available high-power terahertz sources are expensive, it is crucial to enhance the localized field intensity, thus enabling strong light-matter interactions in diverse exciting applications such as detection [6], sensing [7], absorption [8], spectral filtering [9], and emission [10], and significantly improving the performance of the corresponding devices.…”

Section: Introductionmentioning

confidence: 99%

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Large Near-Field Enhancement in Terahertz Antennas by Using Hyperbolic Metamaterials with Hole Arrays

Cheng

Chen

et al. 2019

Applied Sciences

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Terahertz antennas can greatly enhance the near fields and enable strong light–matter interactions, and thus have been widely used in applications such as terahertz sensing and detection. Here we propose a novel approach to further enhance the near fields in terahertz antennas. We show that by sandwiching hyperbolic metamaterials that are composed of InSb and SiO 2 multilayer and that are dressed with hole arrays, between a terahertz dipole antenna and the substrate, the near-field electric field intensities in the antenna can be further enhanced by more than three times. Simulations reveal that this enhancement originates from the doubly enhanced in-plane electric field component and the significantly enhanced out-of-plane electric field component. We expect this work will advance the design of terahertz antennas that are widely used in sensors and detectors.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large Near-Field Enhancement in Terahertz Antennas by Using Hyperbolic Metamaterials with Hole Arrays

Cheng

Chen

et al. 2019

Applied Sciences

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“…Terahertz (THz) imaging has potential applications in a variety of fields, such as non-destructive detection [1,2], security inspection [3,4], and biomedicine [5,6]. Despite great progress, commercially available terahertz focal plane array detectors are still too expensive for most researchers.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Single-Pixel Imaging Improved by Using Silicon Wafer with SiO2 Passivation

et al. 2020

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We demonstrate terahertz single-pixel imaging is improved by using a photomodulator based on silicon passivated with SiO 2 . By exploring various SiO 2 thicknesses, we show that the modulation factor of the as-fabricated terahertz photomodulator can reach 0.9, three times that based on bare silicon. This improvement originates from chemical passivation, as well as anti-reflection. Single-pixel imaging experiments based on the compressed sensing method show that reconstructed images adopting the new photomodulator have better quality than the conventional terahertz modulator based on bare silicon. Since the passivation process is routine and low cost, we expect this work will reduce the cost of terahertz photomodulator and single-pixel THz imaging, and advance their applications.

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“…Current THz technology has given birth to a new wave of applications in important fields such as medicine, security, telecommunications and industry, but, specifically, THz radiation has gained special importance for science and the industrial sector to recognize and characterize non-polar materials, plastics and gases [1][2][3][4][5][6][7][8]. To achieve this, it mainly required a spectrometer capable of interrogating samples to extract information like the real and imaginary parts of the refractive index [9]. In this respect, we now have commercially available frequency sweep-based THz spectroscopy devices at our disposal, however, they are not suited for applications requiring real time measurement.…”

Section: Introductionmentioning

confidence: 99%

Design of a Multipurpose Photonic Chip Architecture for THz Dual-Comb Spectrometers

Betancur-Pérez

Martín-Mateos

Dios

et al. 2020

Sensors

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In this work, we present a multipurpose photonic integrated circuit capable of generating multiheterodyne complex Dual-Combs (DC) THz signals. Our work focuses on translating the functionality of an electro-optic tunable DC system into a photonic chip employing standard building blocks to ensure the scalability and cost efficiency of the integrated device. The architecture we analyze for integration is based on three stages: a seed comb, a mode selection stage and a DC stage. This final DC stage includes a frequency shifter, a key element to improve the final detection of the THz signals and obtain real-time operation. This investigation covers three key aspects: (1) a solution for comb line selection on GHz spaced combs using OIL or OPLL on photonic chips is studied and evaluated, (2) a simple and versatile scheme to produce a frequency shift using the double sideband suppressed carrier modulation technique and an asymmetric Mach Zehnder Interferometer to filter one of the sidebands is proposed, and (3) a multipurpose architecture that can offer a versatile effective device, moving from application-specific PICs to general-purpose PICs. Using the building blocks (BBs) available from an InP-based foundry, we obtained simulations that offer a high-quality Dual-Comb frequency shifted signal with a side mode suppression ratio around 21 dB, and 41 dB after photodetection with an intermediate frequency of 1 MHz. We tested our system to generate a Dual-Comb with 10 kHz of frequency spacing and an OOK modulation with 5 Gbps which can be down-converted to the THz range by a square law detector. It is also important to note that the presented architecture is multipurpose and can also be applied to THz communications. This design is a step to enable a commercial THz photonic chip for multiple applications such as THz spectroscopy, THz multispectral imaging and THz telecommunications and offers the possibility of being fabricated in a multi-project wafer.

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Standoff Detection of Hidden Explosives and Cold and Fire Arms by Terahertz Time-Domain Spectroscopy and Active Spectral Imaging (Review)

Cited by 29 publications

References 116 publications

Large Near-Field Enhancement in Terahertz Antennas by Using Hyperbolic Metamaterials with Hole Arrays

Large Near-Field Enhancement in Terahertz Antennas by Using Hyperbolic Metamaterials with Hole Arrays

Terahertz Single-Pixel Imaging Improved by Using Silicon Wafer with SiO2 Passivation

Design of a Multipurpose Photonic Chip Architecture for THz Dual-Comb Spectrometers

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