Matter manipulation with extreme terahertz light: Progress in the enabling THz technology

Terahertz (THz) light has proven to be a fine tool to probe and control quasi-particles and collective excitations in solids, to drive phase transitions and associated changes in material properties, and to study rotations and vibrations in molecular systems. In contrast to visible light, which usually carries excessive photon energy for collective excitations in condensed matter systems, THz light allows for direct coupling to low-energy (meV scale) excitations of interest, The development of light sources of strong-field few-cycle THz pulses in the 2000s opened the door to controlled manipulation of reactions and processes. Such THz pulses can drive new dynamic states of matter, in which materials exhibit properties entirely different from that of the equilibrium. In this review, we first systematically analyze known studies on matter manipulation with strong-field few-cycle THz light and outline some anticipated new results. We focus on how properties of materials can be manipulated by driving the dynamics of different excitations and how molecules and particles can be controlled in useful ways by extreme THz light. Around 200 studies are examined, most of which were done during the last five years. Secondly, we discuss available and proposed sources of strong-field few-cycle THz pulses and their state-of-the-art operation parameters. Finally, we review current approaches to guiding, focusing, reshaping and diagnostics of THz pulses. (C) 2019 The Author(s). Published by Elsevier B.V

Not Available

Not AvailableThe effects of ultrasonication and drying method on particle size and other product characteristics of bio-calcium powder from Asian sea bass (Lates calcarifer) backbone were investigated. Ultrasonication was performed at different amplitudes (60 %, 70 %, and 8 0% ) for varying periods (15 and 30 min). Ultrasonication at higher amplitudes for a longer time reduced the powder particle size more effectively, but had no impact on zeta potential. The bio-calcium powder ultrasonicated at 70% amplitude for 15 min had the smallest particle size (3.38 µm) when compared to the control (28.85 µm). When the ultrasonicated bio-calcium was subjected to drying, freeze - drying produced powders with higher calcium solubility but lower whiteness than hot air (tray) drying. The results suggest that the ultrasonication is a potential suitable method to reduce the size of bio-calcium powders, while the drying method slightly affected the product characteristics. The bio-calcium powder could serve as a suitable functional ingredient for food fortification aimed at improving the calcium bioavailability. Particle size of bio-calcium powder from fishbone could affect the mouth feel and calcium solubility when used for food product fortification. This work showed that ultrasonication could be used to obtain up to 10 - fold reduction in the particle size of fishbone bio - calcium powders, which promotes increased calcium solubility when subjected to simulated gastrointestinal tract digestion. Few differences in characteristics of the bio-calcium powder were observed for freeze - dried and hot air- dried samples. Thus, an economical, safe, and fast process can be implemented for the production of small particle size bio - calcium powder from fishbone.Not Availabl

Strain-Engineered SiGe Nanomembrane Quantum-Well Infrared Photodetectors

Conference on Lasers and Electro-Optics (CLEO) -- MAY 14-19, 2017 -- San Jose, CAWOS: 000427296202357SiGe quantum-well nanomembranes, where stress from lattice mismatch is relaxed via elastic strain sharing rather than defect formation, are used to develop intersubband photodetectors showing improved performance compared to identical devices grown on rigid substrates.IEEEAFOSRUnited States Department of DefenseAir Force Office of Scientific Research (AFOSR) [FA9550-14-1-0361]This work was supported by AFOSR under Grant FA9550-14-1-0361

SiGe Nanomembrane Quantum-Well Infrared Photodetectors

SiGe quantum wells are promising candidates for the development of intersubband light emitters and photodetectors operating at mid- and far-infrared wavelengths. By virtue of their inherent compatibility with the Si microelectronics platform, these devices may be integrated seamlessly within complex optoelectronic systems for sensing and imaging applications. However, the development of high-quality SiGe intersubband active layers is complicated by the large lattice mismatch between Si and Ge, which limits the number of quantum wells that can be grown on bulk Si substrates before the onset of structural degradation due to inelastic strain relaxation. To address this issue, we investigate the use of lattice matched growth templates consisting of quantum-well nanomembrane stacks that were at one point free-standing, allowing for the internal stress to be relaxed via elastic strain sharing rather than defect formation. SiGe quantum-well infrared photodetectors (QWIPs) based on this approach are developed and characterized. Efficient current extraction from these ultrathin devices is obtained by bonding the nanomembranes directly on a doped Si substrate. Pronounced photocurrent peaks at mid-infrared wavelengths are measured, with improved responsivity compared to otherwise identical devices grown simultaneously on the supporting Si substrate

Electronic Transport Properties of Epitaxial Si/SiGe Heterostructures Grown on Single-Crystal SiGe Nanomembranes

To assess possible improvements in the electronic performance of two-dimensional electron gases (2DEGs) in silicon, SiGe/Si/SiGe heterostructures are grown on fully elastically relaxed single-crystal SiGe nanomembranes produced through a strain engineering approach. This procedure eliminates the formation of dislocations in the heterostructure. Top-gated Hall bar devices are fabricated to enable magnetoresistivity and Hall effect measurements. Both Shubnikov-de Haas oscillations and the quantum Hall effect are observed at low temperatures, demonstrating the formation of high-quality 2DEGs. Values of charge carrier mobility as a function of carrier density extracted from these measurements are at least as high or higher than those obtained from companion measurements made on heterostructures grown on conventional strain graded substrates. In all samples, impurity scattering appears to limit the mobility