Browsing by Author "Wheatley, Robert"

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    Multiple-reflections single-shot dispersion scan for fast ultrashort-pulse measurements
    (2024) Capdeville, Francisco; Villanueva, Fernando; Hidalgo Rojas, Diego Mauricio; Wahaia, Faustino; Wheatley, Robert; Wallentowitz, Sascha; Volkmann, Ulrich; Seifert, Birger
    A single-shot non-interferometric ultrashort-pulse measurement method based on the dispersion scan (d-scan) technique with a substantially extended time span for the pulses to be measured is presented. While single-shot d-scan is typically used for rather short femtosecond pulses, the presented multiple-reflections d-scan (MR d-scan) technique allows measurement of both short and long femtosecond pulses. Single-shot d-scan is currently limited to pulses with a maximum duration of 60 fs using a chromatic dispersion, i.e., a group delay dispersion (GDD) of 4400 fs2 at 840 nm provided by customized random nonlinear crystals. MR d-scan achieves a GDD of 31100 fs2 at 820 nm in this work, but can generally achieve an increase in GDD of up to two orders of magnitude. MR d-scan works with commonly available output couplers, does not rely on a homogeneous, precisely imaged beam profile and has an in-line configuration. As an example, long femtosecond double pulses are measured and reconstructed.
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    Wrinkled TiNAgNW Nanocomposites for High-Performance Flexible Electrodes on TEMPO-Oxidized Nanocellulose
    (2024) Gence Loik, Herve Patrick; Quero, Franck; Escalona Álvarez, Miguel Benito; Wheatley, Robert; Seifert, Birger; Díaz Droguett, Donovan Enrique; Retamal, María José; Wallentowitz, Sascha; Volkmann, Ulrich Georg; Bhuyan, Heman
    Flexible electrodes are essential for the development of future wearable such as implantable medicaldevices. While silver nanowire (AgNW) networks are promising candidates for transparent conductive electrodes (TCEs), they suffer from issues such as high roughness, low adhesion, and atmospheric corrosion sensitivity. Many flexible electrodes are made of a wrinkled conductive layer on top of a compliant s ubstrates. Wrinkles provide a way to maintain the integrity and conductivity of the electrode while it is being stretched or bent. In this study, we report on the characterization ofFE-SEMi-transparent electrodes produced by a novel plasma-enhanced pulsed laser deposition (PE-PLD) technique compatible with cellulose nanopaper (CNP) substrates. We combined AgNW with titanium nitride (TiN) layers to form wrinkled conducting nano-composite coatings with excellent electro-mechanical properties. Our results show that the incorporation of AgNW into TiN coatings improves the electrode’s electro-mechanical robustness. Additionally, our data show that CNP/TiNAgNW electrodesexhibit improved stability in air compared to bare AgNW coatings with improved adhesion. These findings have important implications for the development of bio-compatible flexible electronics and could pave the way for the creation of new wearable and implantable medical devices.