There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Increasing customer demand for durable and functional apparel manufactured in a sustainable manner has created an opportunity for nanomaterials to be integrated into textile substrates. Nanomoieties can induce stain repellence, wrinkle-freeness, static elimination, and electrical conductivity to fibers without compromising their comfort and flexibility. Nanomaterials also offer a wider application potential to create connected garments that can sense and respond to external stimuli via electrical, color, or physiological signals. This review discusses electronic and photonic nanotechnologies that are integrated with textiles and shows their applications in displays, sensing, and drug release within the context of performance, durability, and connectivity. Risk factors including nanotoxicity, nanomaterial release during washing, and environmental impact of nanotextiles based on life cycle assessments have been evaluated. This review also provides an analysis of nanotechnology consolidation in the textiles ...

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Nanotechnology in Textiles

Bibliometric data set the scene by illustrating the growth of terahertz work and the present interest in terahertz science and technology. After locating terahertz sources within the broader context of terahertz systems, an overview is given of the range of available sources, emphasizing recent developments. The focus then narrows to terahertz sources that rely on surface phenomena. Three are highlighted. Optical rectification, usually thought of as a bulk process, may in addition exhibit a surface contribution, which, in some cases, predominates. Transient surface currents, for convenience often separated into drift and diffusion currents, are well understood according to Monte Carlo modelling. Finally, terahertz surface emission by mechanical means—in the absence of photoexcitation—is described.

https://iopscience.iop.org/article/10.1088/0022-3727/47/37/374001/pdf

A review of terahertz sources

Theory of complex spectra.

Recently, a large number of experimental and theoretical works have revealed a variety of plasmonic nanostructures with the capabilities of Fano resonance (FR) generation. Among these structures, plasmonic oligomers consisting of packed metallic nanoelements with certain configurations have been of significant interest. Oligomers can exhibit FR independently of the polarization direction based on dipole–dipole antiparallel modes without the need to excite challenging high-order modes. The purpose of this review article is to provide an overview of recent achievements on FR of plasmonic nanostructures in recent years. Meanwhile, more attention is given to the optical properties of plasmonic oligomers due to the high potential of such structures in optical spectra engineering.

Fano resonance in novel plasmonic nanostructures

3D printing opens up an inexpensive, rapid, and versatile path to the fabrication of optical elements suited to the terahertz regime. The transmission of the plastics used in 3D printers, while generally decreasing with frequency, is usable over the range 0.1–2 THz. We have designed, fabricated, and tested regular and blazed gratings and aspherical lenses for operation at terahertz frequencies. We find that the measured performance matches our theoretical predictions.

/pdf/3d-printed-terahertz-diffraction-gratings-and-lenses-36lw9vhoyw.pdf

3D Printed Terahertz Diffraction Gratings And Lenses

We present a novel method for producing drawn metamaterials containing slotted metallic cylinder resonators, possessing strong magnetic resonances in the terahertz range. The resulting structures are either spooled to produce a 2-dimensional metamaterial monolayer, or stacked to produce three-dimensional multi-layered metamaterials. We experimentally investigate the effects of the resonator size and number of metamaterial layers on transmittance, observing magnetic resonances between 0.1 and 0.4 THz, in good agreement with simulations. Such fibers promise future applications in mass-produced stacked or woven metamaterials.

/pdf/stacked-and-drawn-metamaterials-with-magnetic-resonances-in-z8d96uzt6w.pdf

Stacked-and-drawn metamaterials with magnetic resonances in the terahertz range

The dielectric properties of nematic liquid crystal (LC) mixtures are measured from 300 GHz to 1500 GHz. Measurements are performed in a standard THz TDS setup. Refractive index and extinction coefficient for parallel and perpendicular orientation are calculated and compared to results obtained at 19 GHz. The investigated mixtures are of interest for Terahertz devices as their properties stay almost constant from 19 GHz to 1500 GHz.

/pdf/time-domain-spectroscopy-of-novel-nematic-liquid-crystals-in-4cwozwadfl.pdf

Time-domain spectroscopy of novel nematic liquid crystals in the terahertz range

Infrared reflection and transmission as a function of temperature have been measured on single crystals of Cu3Bi(SeO3)(2)O2Cl. The complex dielectric function and optical properties along all three principal axes of the orthorhombic cell were obtained via Kramers-Kronig analysis and by fits to a Drude-Lorentz model. Below 115 K, 16 additional modes [8(E parallel to(a) over cap)+ 6(E parallel to(b) over cap)+ 2(E parallel to(c) over cap)] appear in the phonon spectra; however, powder x-ray diffraction measurements do not detect a new structure at 85 K. Potential explanations for the new phonon modes are discussed. Transmission in the far infrared as a function of temperature has revealed magnetic excitations originating below the magnetic ordering temperature (T-c similar to 24 K). The origin of the excitations in the magnetically ordered state will be discussed in terms of their response to different polarizations of incident light, behavior in externally applied magnetic fields, and the anisotropic magnetic properties of Cu3Bi(SeO3)(2)O2Cl as determined by dc susceptibility measurements.

http://www.physics.ufl.edu/~tanner/PDFS/Miller12prb-CBSCO.pdf

Infrared phonon anomaly and magnetic excitations in single-crystal Cu3Bi(SeO3)2O2Cl

We employ a combination of pulsed- and continuous-wave polarized terahertz spectroscopy techniques to probe temperature-dependent spin waves in the antiferromagnet $\mathrm{Nd}\mathrm{Fe}{\mathrm{O}}_{3}$. Our optical data span 1.6--467 K and reveal a conspicuous spin reorientation between 110 and 170 K, during which the lower-energy mode softens completely. Complementary inelastic neutron scattering reveals that the frequencies of the optically excited spin waves are consistent with a temperature-variable spin gap in the low-energy spin-wave dispersion of $\mathrm{Nd}\mathrm{Fe}{\mathrm{O}}_{3}$. The result links the temperature dependence of the spin waves to a dynamic in-plane anisotropy. The magnetic anisotropy is calculated based on the results of the optical measurements. The change observed in the anisotropy energy along the $a$ and $c$ crystal axes suggests that the spin reorientation evident in $\mathrm{Nd}\mathrm{Fe}{\mathrm{O}}_{3}$ is driven by temperature-dependent in-plane anisotropy.

/pdf/complementary-terahertz-absorption-and-inelastic-neutron-43mfshd74u.pdf

Complementary terahertz absorption and inelastic neutron study of the dynamic anisotropy contribution to zone-center spin waves in a canted antiferromagnet NdFeO3

E. Constable

Papers

3D Printed Terahertz Diffraction Gratings And Lenses

Stacked-and-drawn metamaterials with magnetic resonances in the terahertz range

Time-domain spectroscopy of novel nematic liquid crystals in the terahertz range

Infrared phonon anomaly and magnetic excitations in single-crystal Cu3Bi(SeO3)2O2Cl

Complementary terahertz absorption and inelastic neutron study of the dynamic anisotropy contribution to zone-center spin waves in a canted antiferromagnet NdFeO3