AlCoCrCuFeNi-Based High-Entropy Alloys: Correlation Between Molar Density and Enthalpy of Mixing in the Liquid State

The density of the liquid equiatomic high-entropy alloys, namely, AlCoCrCuFeNi, AlCoCuFeNi, and CrCoCuFeNi, as well as quaternary alloys AlCoCuFe and AlCoCrNi was determined over a wide temperature range. The measurements were performed by a non-contact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependencies of the density were analyzed and the molar excess volumes were calculated. The integral enthalpy of mixing of multi-component alloys was predicted using extended Kohler model, while the model of Miedema was used for binary sub-system alloys. It has been found that a negative excess volume of the investigated Al-containing liquid alloys correlates with a negative enthalpy of mixing. In contrast, a positive excess volume and an endothermic reaction have been estimated for the liquid CoCrCuFeNi alloy. The change of the excess volume in the Al-containing liquid alloys is affected by two basic effects, namely, compression of the Al matrix and formation of compounds in the melt

Scalable Functionalization of Optical Fibers Using Atomically Thin Semiconductors

Atomically thin transition metal dichalcogenides are highly promising for integrated optoelectronic and photonic systems due to their exciton-driven linear and nonlinear interactions with light. Integrating them into optical fibers yields novel opportunities in optical communication, remote sensing, and all-fiber optoelectronics. However, the scalable and reproducible deposition of high-quality monolayers on optical fibers is a challenge. Here, the chemical vapor deposition of monolayer MoS2 and WS2 crystals on the core of microstructured exposed-core optical fibers and their interaction with the fibers’ guided modes are reported. Two distinct application possibilities of 2D-functionalized waveguides to exemplify their potential are demonstrated. First, the excitonic 2D material photoluminescence is simultaneously excited and collected with the fiber modes, opening a novel route to remote sensing. Then it is shown that third-harmonic generation is modified by the highly localized nonlinear polarization of the monolayers, yielding a new avenue to tailor nonlinear optical processes in fibers. It is anticipated that the results may lead to significant advances in optical-fiber-based technologies. © 2020 The Authors. Published by Wiley-VCH Gmb

Scalable functionalization of optical fibers using atomically thin semiconductors

Published online: October 6, 2020Atomically thin transition metal dichalcogenides are highly promising for integrated optoelectronic and photonic systems due to their exciton-driven linear and nonlinear interactions with light. Integrating them into optical fibers yields novel opportunities in optical communication, remote sensing, and all-fiber optoelectronics. However, the scalable and reproducible deposition of high-quality monolayers on optical fibers is a challenge. Here, the chemical vapor deposition of monolayer MoS2 and WS2 crystals on the core of microstructured exposed-core optical fibers and their interaction with the fibers' guided modes are reported. Two distinct application possibilities of 2D-functionalized waveguides to exemplify their potential are demonstrated. First, the excitonic 2D material photoluminescence is simultaneously excited and collected with the fiber modes, opening a novel route to remote sensing. Then it is shown that third-harmonic generation is modified by the highly localized nonlinear polarization of the monolayers, yielding a new avenue to tailor nonlinear optical processes in fibers. It is anticipated that the results may lead to significant advances in optical-fiber-based technologies.Gia Quyet Ngo, Antony George, Robin Tristan Klaus Schock, Alessandro Tuniz, Emad Najafidehaghani, Ziyang Gan, Nils C. Geib, Tobias Bucher, Heiko Knopf, Sina Saravi, Christof Neumann, Tilman Lühder, Erik P. Schartner, Stephen C. Warren-Smith, Heike Ebendorff-Heidepriem, Thomas Pertsch, Markus A. Schmidt, Andrey Turchanin, and Falk Eilenberge