NIKLAUS URSUS WETTER

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Niklaus Ursus Wetter holds a BA in Physics from the Eidgenössische Technische Hochschule Zürich - ETH (1988 - Switzerland) and a Ph.D. in Nuclear Technology from the Institute for Energy and Nuclear Research (1993). He is currently a senior researcher at the National Nuclear Energy Commission at IPEN / SP and a postgraduate professor at the University of São Paulo ? USP, where he regularly teaches a subject. From 2009 to 2013 he was deputy manager of the Center for Lasers and Applications at IPEN / SP. From 2013 to 2018 he held the position of manager of the Center for Lasers and Applications at IPEN / SP. From 2014 to 2020 he held the position of CEO of FAFITPE, IPEN's Foundation for Support and Promotion of Technological Innovation in Research and Education. Since 2019 he has held the position of Deputy Director of Research and Internationalization Manager at IPEN. As manager of Internationalization, he has so far implemented 14 bilateral agreements with universities and institutes around the world, including the Battelle Energy Alliance, which encompasses eight of the largest federal research institutions in the US. In 2018 he was responsible for organizing the André Swieca Summer School and the São Paulo School of Advanced Science FAPESP "Laserfrontiers.com" with 141 students, 40 of whom came from outside Latin America. He specializes in laser development and operates in the main segments: Diode lasers, waveguides, solid state lasers, laser applications in life sciences, lasers in nuclear applications, optical spectroscopy and materials for laser media in general. Since 2008 he has been developing light sources in disordered materials, or "Random Lasers", for the purpose of applications in optical devices. In 2017, he acquired, through a FAPESP project, a Raman-TERS (AFM) multiuser equipment with STM and SNOM, focused on measurements and development of nanomaterials. He has 4 patent letters and 7 applications in total, 190 international articles with over 2000 citations and an h factor of 26 (Scopus). (Text obtained from the Currículo Lattes on October 14th 2021)


Niklaus Ursus Wetter é bacharel em Física pela Eidgenössische Technische Hochschule Zürich - ETH (1988 - Suíça) e Doutor em Tecnologia Nuclear pelo Instituto de Pesquisas Energéticas e Nucleares (1993). Atualmente é pesquisador titular da Comissão Nacional de Energia Nuclear no IPEN/SP-USP e docente de pós-graduação da Universidade de São Paulo ? USP, onde ministra regularmente uma disciplina. De 2009 a 2013 foi gerente adjunto do Centro de Lasers e Aplicações do IPEN/SP. De 2013 até 2018 ocupou o cargo de gerente do Centro de Lasers e Aplicações do IPEN/SP. De 2014 até 2020 ocupou o cargo de diretor-presidente da FAFITPE, Fundação de Apoio e Fomento a Inovação Tecnológica a Pesquisa e ao Ensino do IPEN. Desde 2019 ocupa o cargo de Vice-diretor de Pesquisa e gerente de Internacionalização do IPEN. Na função de gerente da Internacionalização, ele implementou até agora 14 acordos bilaterais com universidades e institutos de toda parte do mundo, entre estes a Battelle Energy Alliance que engloba oito das maiores instituições federais de pesquisa dos EUA. Em 2018 foi o responsável pela organização da Escola de Verão André Swieca e a Escola São Paulo de Ciencia Avançada FAPESP "Laserfrontiers.com" com 141 alunos dos quais 40 de fora da america latina. Foi editor associado das revistas Optics Express e Optical Materials Express e atualmente atua como editor associado da revista Frontiers, especialidade Optical Nanostructures. É especialista em desenvolvimento de lasers e atua nos principais segmentos: Lasers de diodo, Guias de onda, Lasers de estado sólido, Aplicações de lasers nas ciências da vida, Lasers em aplicações nucleares, Espectroscopia ótica e materiais para meios Laser em geral. Desde 2008 desenvolve fontes de luz em materiais desordenados, ou "Lasers Randômicos", para fins de aplicações em dispositivos ópticos. Possui 4 cartas de patente e 7 pedidos no total, 190 artigos internacionais com mais de 2000 citações e fator h de 26 (Scopus). (Texto extraído do Currículo Lattes em 14 out. 2021)

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2020 - 202466
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Data inicial: 2020 × Data final: 2024 × Âmbito: Internacional ×

Resultados de Busca

Agora exibindo 1 - 10 de 66
  • Imagem de Miniatura
    Artigo IPEN-doc 30452
    Strong Raman enhancement in structured colloids
    2024 - DIPOLD, JASSICA; WETTER, NIKLAUS U.; MARQUES, FRANCISCO C.; FREITAS, ANDERSON Z.; DOGARIU, ARISTIDE; JIMENES-VILLAR, ERNESTO
    Raman spectroscopy is a powerful technique for studying the interaction between light and matter. Here we show a significant enhancement of Raman emission over a broad range of pumping wavelengths from strongly scattering media comprising spatially correlated photonic structures of core–shell TiO2@Silica scatterers mixed with silica nanoparticles and suspended in ethanol. Long-range Coulomb interactions between nanoparticles inside these photonic colloidal structures induce a correlation in the scatterers’ positions (TiO2@Silica), affecting local and global photonic properties. The anomalous enhancement in Raman signal increases as the scattering strength is increased (through either scatterer concentration or pumping wavelength); however, the signal strength continues to behave linearly with excitation power, ruling out classical nonlinear and interferential phenomena. These observations may indicate strong photon correlation in strongly localized electromagnetic modes, inducing successive photon interactions with the atoms or molecules. Aside from the fundamental relevance to understanding measurable properties in this regime of strongly localized electromagnetic modes, our demonstration of strongly enhanced Raman emission over a broad range of pumping wavelengths provides new opportunities for the development of advanced photonic materials and devices.
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    Artigo IPEN-doc 30450
    Improved relative gain in Nd3+doped GeO2-PbO glass with double waveguides irradiated by femtosecond laser micromachining and decorated with Au nanoparticles
    2024 - BORDON, CAMILA D.S.; DIPOLD, JESSICA; VECCHI, THIAGO F.; WETTER, NIKLAUS U.; ROSSI, WAGNER de; FEITAS, ANDERSON Z.; KASSAB, LUCIANA R.P.
    The paper explores the effects of Au nanoparticle (NP) islands deposited by sputtering technique on the surface of Nd3+-doped GeO2-PbO glasses, with double-line waveguides, produced via femtosecond laser processing for photonics. A Ti:sapphire femtosecond laser operating at 800 nm was employed to inscribe the waveguides directly into the glass, 0.7 mm beneath the surface. These waveguides were structured as pairs of parallel lines separated 10 μm. Additional procedures were undertaken to position the waveguides on the glass surface where Au NPs were deposited. Refractive index change of 10− 3 at 632 nm was observed in both horizontal and vertical directions. Similar results for the beam quality factors (Mx2 and My2) at 632 nm and 1064 nm indicated x, y-symmetrical guiding. Photoluminescence and relative gain growth were observed due to Au NP islands. The relative gain reached 3.0 dB/cm representing an increase of approximately 450 % when compared to samples without the Au NP islands, and was attributed to the local field growth in their vicinities. This study highlights the potential to change Nd3+-doped GeO2-PbO glasses optical properties with Au nanoparticle islands, opening up new and promising prospects for photonics and 1064 nm optical amplifiers.
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    Artigo IPEN-doc 30231
    Tunable visible light and energy transfer mechanism in Tm3+ and silver nanoclusters within co-doped GeO2-PbO glasses
    2023 - NISHIMURA, MARCOS V. de M.; AMARO, AUGUSTO A.; BORDON, CAMILA D. da S.; DIPOLD, JESSICA; WETTER, NIKLAUS U.; KASSAB, LUCIANA R.P.
    This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.
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    Artigo IPEN-doc 30193
    Random lasers
    2023 - WETTER, NIKLAUS U.; VIEIRA, RENATO J.R.; SILVA, DANILO M. da; JORGE, KELLY C.; JIMENEZ-VILLAR, ERNESTO; GIEHL, JULIA M.; MIRANDA, ADRIANA R. de; DIPOLD, JESSICA
    Random lasers offer advantages such as low-cost fabrication and robustness in harsh environments and have applications in sensing, imaging, communications, and security. Our current research focuses on advanced materials, active control techniques, integration with other photonic structures, and exploration of Anderson localization and polydisperse effects. Coherent feedback in cavity-enhanced random lasers is discussed as means to achieve specific emission characteristics, and emission at 1300 nm is shown for the first time.
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    Artigo IPEN-doc 30191
    Transverse electromagnetic modes simulation and experimental measurement technique for a single stripe laser diode
    2023 - ROMANO, FERNANDO C.; WETTER, NIKLAUS U.
    A single stripe multimode laser diode software model has been developed. In addition, a method for measuring the transverse electromagnetic modes (TEM) in the RF spectrum through a frequency beating process was also developed. For supporting the TEM readings, a spectrum analyzer was applied and converted the temporal signals to the frequency domain using the fast Fourier transform (FFT) method.
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    Artigo IPEN-doc 30190
    Photoelastic dispersion coefficient by holographic reconstruction with neural networks and the Fresnel method
    2023 - PRADO, FELIPE M.; SOUZA, PEDRO H.M. de; SILVA, SIDNEY L. da; WETTER, NIKLAUS U.
    Here we report the characterization of the photoelastic dispersion coefficient using digital holography with two distinct reconstruction methods: one based on the Fresnel method and the other utilizing convolutional neural networks (CNN). The CNN was trained with reconstruction from the Fresnel method and was able to provide reconstructions with an average Mean Squared Error of 0.006.
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    Artigo IPEN-doc 30189
    Highly-efficient, dual-wavelength Nd:YLF laser emitting at 1314 nm and 1047 nm
    2023 - PRADO, FELIPE M.; FRANCO, TOMAS J.; WETTER, NIKLAUS U.
    We report a record optical-to-optical efficiency of 43% and a slope efficiency of 48% for a Nd: YLF laser emitting at 1314 nm. The crystal was side-pumped by a VBG-equipped diode emitting at 797 mn, with a peak power of 1545 W. We also report simultaneous dual-wavelength emission, at 1313 nm and 1047 nm.
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    Artigo IPEN-doc 30185
    Random laser emission in Nd3+ doped tellurite glass
    2023 - DIPOLD, JESSICA; BORDON, CAMILA D.S.; MAGALHAES, EVELLYN S.; KASSAB, LUCIANA R.P.; JIMENEZ-VILLAR, ERNESTO; WETTER, NIKLAUS U.
    Random lasers are easier and cheaper to manufacture than regular ones, being made of several materials such as polymers, powders or dyes. Glass random lasers have been rarely studied due to their inhomogeneous broadened emission and low damage threshold. Here, we study Nd 3 +doped Te0 2 -ZnO-Al 2 0 3 glasses with different concentrations of rare-earth doping (4 wt.%, 8 wt.% and 16 wt.%). Emission intensity per pump fluence and fluorescence decay time measurements showed the potential of these glasses for random laser applications in the near-infrared region.
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    Artigo IPEN-doc 30184
    Sub-nanosecond microchip oscillator for a MOPA system tailored for tattoo removal
    2023 - CATARINA, MARCUS V.; BERECZKI, ALLAN; WETTER, NIKLAUS U.
    In this work we study a microchip laser designed to function as an oscillator in a Master-Oscillator Power-Amplifier (MOPA) system targeted for laser tattoo removal. Different configurations of the Nd: YAG resonator were used by changing the output coupler mirror reflectivities and the initial transmission of the Q-switch. The quasi-CW resonator provided 55.4 W of output with 51.31% and 78.2% optical and slope efficiencies, respectively. For Q-switched operation, the best configuration resulted in a peak output power of 3.6 MW with 588 ps pulse width.
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    Artigo IPEN-doc 30183
    Compact, high power CW ring laser resonator
    2023 - BERECZKI, ALLAN; MENEZES, FELIPE C. de; WETTER, NIKLAUS U.
    We demonstrated the dynamically stable operation of aNd: YAG ring laser with 51.8 W of linearly polarized, continuous output power. The laser was based on laser modules side-pumped by diode bars. The resonator, aimed at single-frequency operation, is a design improvement from a previous work with the resonator length 4.3 times smaller than the previous design, thus resulting in a larger free spectral range, favoring for operation at single-frequency.