Photonics / Fotonik

Permanent URI for this collectionhttps://hdl.handle.net/11147/2590

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Author: search.filters.author.Kocabaş, ÇoşkunCOAR Access Rights: search.filters.coarAccessRights.embargoed access

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  • Article
    Citation - WoS: 84
    Citation - Scopus: 82
    Topological Engineering of Terahertz Light Using Electrically Tunable Exceptional Point Singularities
    (American Association for the Advancement of Science, 2022) Ergöktaş, M. Said; Soleymani, Sina; Kakenov, Nurbek; Wang, Kaiyuan; Smith, Thomas B.; Bakan, Gökhan; Balcı, Sinan; Principi, Alessandro; Novoselov, Kostya S.; Özdemir, Şahin K.; Kocabaş, Çoşkun
    The topological structure associated with the branch point singularity around an exceptional point (EP) can provide tools for controlling the propagation of light. Through use of graphene-based devices, we demonstrate the emergence of EPs in an electrically controlled interaction between light and a collection of organic molecules in the terahertz regime at room temperature. We show that the intensity and phase of terahertz pulses can be controlled by a gate voltage, which drives the device across the EP. Our electrically tunable system allows reconstruction of the Riemann surface associated with the complex energy landscape and provides topological control of light by tuning the loss imbalance and frequency detuning of interacting modes. Our approach provides a platform for developing topological optoelectronics and studying the manifestations of EP physics in light-matter interactions.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 1
    Transition Metal Salt Promoted, Green, and High-Yield Synthesis of Silver Nanowires for Flexible Transparent Conductive Electrodes
    (Wiley-Blackwell, 2021) Sarısözen, Sema; Tertemiz, Necip Ayhan; Arıca, Tuğçe Aybüke; Polat, Nahit; Kocabaş, Çoşkun; Mert Balcı, Fadime; Balcı, Sinan
    Silver nanowires (AgNWs) have attracted considerable interest from both academia and industry owing to their excellent electrical, optical, and chemical properties. For large-scale synthesis of AgNWs, the polyol method involving ethylene glycol, a toxic alcohol, has been widely used. We herein report on a facile, green, high yield, transition metal salt promoted, open atmosphere method for the synthesis of high quality AgNWs in a glycerol-water mixture. We have shown that transition metal salts have a strong influence on the morphology of AgNWs. Importantly, in the presence of copper(II) chloride, AgNWs with a high aspect ratio of around 400 (length, 36 μm; diameter, 90 nm) were obtained. Additionally, for the first time, we have demonstrated AgNWs based flexible transparent conductive electrodes (TCEs) on poly(sodium 4-styrenesulfonate) (PSS) treated polyethylene terephthalate (PET) substrate with a sheet resistance of 34 Ω/sq and transmittance of 91 % at 550 nm. The PSS layer on the PET substrate generated a highly hydrophilic surface, which boosts interaction of AgNWs with the PET surface. We envision that our results would play a significant role both in the synthesis of AgNWs with high aspect ratio and also in designing new rigid and flexible TCEs having high transmittance and low sheet resistance for applications especially in printable solar cells, organic light emitting diodes, and high performance flexible electronics.