Tyndall National Institute - Journal Articles

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    Experimental analysis of variability in WS2-based devices for hardware security
    (Elsevier, 2023-06-24) Vatalaro, M.; Neill, Hazel; Gity, Farzan; Magnone, P.; Maccaronio, V.; Márquez, C.; Galdon, J. C.; Gamiz, F.; Crupi, F.; Hurley, Paul; De Rose, R.; Horizon 2020; Science Foundation Ireland; Ministero dell’Istruzione, dell’Università e della Ricerca
    This work investigates the variability of tungsten disulfide (WS2)-based devices by experimental characterization in view of possible application in the field of hardware security. To this aim, a preliminary analysis was performed by measurements across voltages and temperatures on a set of seven Si/SiO2/WS2 back-gated devices, also considering the effect of different stabilization conditions on their conductivity. Obtained results show appreciable variability in the conductivity, while also revealing similar dependence on bias and temperature across tested devices. Overall, our analysis demonstrates that WS2-based devices can be potentially exploited to ensure adequate randomness and robustness against environmental variations and then used as building blocks for hardware security primitives.
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    MORPHIC: MEMS enhanced silicon photonics for programmable photonics
    (Society of Photo-optical Instrumentation Engineers, SPIE, 2022-05-25) Khan, Muhammad Umar; Zand, Iman; Edinger, Pierre; Jo, Gaehun; Bleiker, Simon J.; Takabayashi, Alain Yuji; Antony, Cleitus; Jezzini, Moises; Talli, Giuseppe; Sattari, Hamed; Lee, Jun Su; Malik, Arun Kumar; Verheyen, Peter; Kumar, Saurav; Arce, Cristina Lerma; Garcia, Marco; Jonuzi, Tigers; Watte, Jan; Quack, Niels; Niklaus, Frank; Gylfason, Kristinn B.; Bogaerts, Wim; Baets, Roel G.; O'Brien, Peter; Vivien, Laurent; Horizon 2020 Framework Programme
    We present our work in the European project MORPHIC to extend an established silicon photonics platform with low-power and non-volatile micro-electromechanical (MEMS) actuators to demonstrate large-scale programmable photonic integrated circuits (PICs).
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    Monolithic InGaAs nanowire array lasers on silicon-on-insulator operating at room temperature
    (ACS Publications, 2017-05-23) Kim, Hyunseok; Lee, Wook-Jae; Farrell, Alan C.; Morales, Juan S. D.; Senanayake, Pradeep; Prikhodko, Sergey V.; Ochalski, Tomasz J.; Huffaker, Diana L.; Llywodraeth Cymru; Air Force Research Laboratory
    Chip-scale integrated light sources are a crucial component in a broad range of photonics applications. III–V semiconductor nanowire emitters have gained attention as a fascinating approach due to their superior material properties, extremely compact size, and capability to grow directly on lattice-mismatched silicon substrates. Although there have been remarkable advances in nanowire-based emitters, their practical applications are still in the early stages due to the difficulties in integrating nanowire emitters with photonic integrated circuits. Here, we demonstrate for the first time optically pumped III–V nanowire array lasers monolithically integrated on silicon-on-insulator (SOI) platform. Selective-area growth of InGaAs/InGaP core/shell nanowires on an SOI substrate enables the nanowire array to form a photonic crystal nanobeam cavity with superior optical and structural properties, resulting in the laser to operate at room temperature. We also show that the nanowire array lasers are effectively coupled with SOI waveguides by employing nanoepitaxy on a prepatterned SOI platform. These results represent a new platform for ultracompact and energy-efficient optical links and unambiguously point the way toward practical and functional nanowire lasers.
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    Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering
    (American Association for the Advancement of Science, 2017-06-23) Tsakmakidis, K. L.; Shen, L.; Schulz, Sebastian A.; Zheng, X.; Upham, J.; Deng, X.; Altug, H.; Vakakis, A. F.; Boyd, R. W.; Horizon 2020; National Natural Science Foundation of China; Max Planck Institute for the Science of Light; Government of Canada
    A century-old tenet in physics and engineering asserts that any type of system, having bandwidth Δω, can interact with a wave over only a constrained time period Δt inversely proportional to the bandwidth (Δt·Δω ~ 2π). This law severely limits the generic capabilities of all types of resonant and wave-guiding systems in photonics, cavity quantum electrodynamics and optomechanics, acoustics, continuum mechanics, and atomic and optical physics but is thought to be completely fundamental, arising from basic Fourier reciprocity. We propose that this “fundamental” limit can be overcome in systems where Lorentz reciprocity is broken. As a system becomes more asymmetric in its transport properties, the degree to which the limit can be surpassed becomes greater. By way of example, we theoretically demonstrate how, in an astutely designed magnetized semiconductor heterostructure, the above limit can be exceeded by orders of magnitude by using realistic material parameters. Our findings revise prevailing paradigms for linear, time-invariant resonant systems, challenging the doctrine that high-quality resonances must invariably be narrowband and providing the possibility of developing devices with unprecedentedly high time-bandwidth performance.
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    Principles and mechanisms of ultraviolet light emitting diode technology for food industry applications
    (Elsevier Ltd., 2019-07-16) Hinds, Laura M.; O'Donnell, Colm P.; Akhter, Mahbub; Tiwari, Brijesh K.; Department of Agriculture, Food and the Marine, Ireland
    The application of ultraviolet (UV) light to water, food contact surfaces and medical equipment for microbial inactivation is widely employed. To date, UV disinfection sources employed are primarily low-pressure and medium-pressure mercury lamps; emitting monochromatic and polychromatic light, respectively. Despite the widespread use of mercury lamps, there are multiple drawbacks associated with their use including; high energy consumption, large size which limits reactor design, high heat emission and the presence of mercury. Light emitting diodes (LEDs) have potential for use as a highly efficient UV decontamination technology. Recent advances in semiconductor development have resulted in UV-LEDs becoming more widely available. UV-LEDs emit monochromatic light, which enables customised UV-LED disinfection systems at specific wavelengths to be developed. The application of UV-LEDs for disinfection purposes has been studied in recent years, particularly with respect to water disinfections systems. In this review, studies relating to UV-LED food applications are discussed. Furthermore, the chemical changes induced in foods, as a result of UV treatment, together with advantages and limitations of the technology are outlined.