Browsing by Author "Singh, Dinesh Pratap"

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    Optical properties of millimeter-size metal-organic framework single crystals using THz techniques
    (2025) Wahaia, Faustino; Kasalynas, Irmantas; Pashnev, Daniil; Valusis, Gintaras; Urbanowicz, Andrzej; Karaliunas, Mindaugas; Singh, Dinesh Pratap; Wallentowitz, Sascha; Seifert, Birger
    Metal-organic frameworks (MOFs) crystals are promising emerging materials for terahertz (THz) photonics i.e., for THz wave generation through difference frequency or optical rectification and electrooptic detection, including optical components for THz beam steering. The present work reports optical properties of three different non-centrosymmetric single MOF crystals, grown by an innovative solvo-thermal technique with tunable morphology, termed MOF [Zn(3-ptz)2]n (MIRO-101). THz time-domain spectroscopy (TTDS) in the range of 0.25 - 1.5 THz has been used for the measurement of the transfer function, H(w) of these MOF crystals. Through this experimental function Hexp(w), optical parameters such as refractive index, nMOF(w) and absorption coefficient, aMOF(w) have been calculated for the analysis of the optical properties of this crystal. The results indicate that this MOF crystal offers opportunities for long-term exploration of properties toward the creation of novel nonlinear THz photonics materials, as a THz radiation emitter via Different Frequency Generation (DFG) or Optical Rectification (OR) and Electro-optic (EO) detection via optical sampling, including for its use in optoelectronics, and materials science.
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    Tailoring of titanium dioxide thin film in dual radiofrequency plasma enhanced pulsed laser deposition
    (2025) Villegas Dissett, Rodrigo Benjamín; Tomlinson Cornejo, Matías Paul; Ureta De La Fuente, Valentina Isidora; Carrasco Navarro, Camilo Antonio; Miranda, Maximiliano; Fernández Adell, José Ignacio; Saavedra, Daniel; Retamal, María José; Inestrosa-Izurieta, Maria Jose; Singh, Dinesh Pratap; Angel Figueroa, Felipe Alfonso; Volkmann, Ulrich Georg; Takamura, Yayoi; Bhuyan, Heman
    Efficient and cost-effective methods to create photovoltaic materials are constantly being sought, with metal oxides like TiO2 playing a key role in this field. In this study, TiO2 thin films were grown on glass substrates using a dual radiofrequency (RF) plasma-enhanced pulsed laser deposition (PLD) system with a thermal budget that remained below 400 °C. The physical, chemical, and optical properties of the deposited thin films were studied as a function of low- and high-RF powers as well as deposition time. These parameters were found to impact the proportion of anatase and rutile phase and their crystallinity, as well as the oxygen vacancy concentration and band gap energy. These findings demonstrated the utility of dual RF plasma-enhanced PLD for precise modulation of TiO2 thin-films, offering promising applications in photovoltaics and photocatalysis