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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Data inicial: 2020 × Data final: 2024 × Percentil: 75.00 - 100.00 ×

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Agora exibindo 1 - 8 de 8
  • Imagem de Miniatura
    Artigo IPEN-doc 30037
    Sub-10 nm nanoparticle detection using multi-technique-based micro-raman spectroscopy
    2023 - BERECZKI, ALLAN; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUS U.
    Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nanosized pollutants and the possibility of interactions with organisms at the sub cellular level, with many risks still being unknown, there are only a few publications on this topic due to the lack of reliable techniques for nanoparticle characterization. We propose a multi-technique approach for the characterization of nanoparticles down to the 10 nm level using standard micro-Raman spectroscopy combined with standard atomic force microscopy. We successfully obtained single-particle spectra from 25 nm sized polystyrene and 9 nm sized TiO2 nanoparticles with corresponding mass limits of detection of 8.6 ag (attogram) and 1.6 ag, respectively, thus demonstrating the possibility of achieving an unambiguous Raman signal from a single, small nanoparticle with a resolution comparable to more complex and time-consuming technologies such as Tip-Enhanced Raman Spectroscopy and Photo-Induced Force Microscopy
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    Artigo IPEN-doc 30036
    (U)SAXS characterization of porous microstructure of chert: insights into organic matter preservation
    2023 - MUNOZ, PATRICIO; ILAVSKY, JAN; NEWVILLE, MATTHEW; WETTER, NIKLAUS U.; LOURENÇO, RAFAEL A.; ANDRADE, MARCELO B. de; MARTINS, TEREZA S.; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; SILVA, LUIS C.C. da; OLIVEIRA, CRISTIANO L.P.
    This study characterizes the microstructure and mineralogy of 132 (ODP sample), 1000 and 1880 million-year-old chert samples. By using ultra-smallangle X-ray scattering (USAXS), wide-angle X-ray scattering and other techniques, the preservation of organic matter (OM) in these samples is studied. The scarce microstructural data reported on chert contrast with many studies addressing porosity evolution in other sedimentary rocks. The aim of this work is to solve the distribution of OM and silica in chert by characterizing samples before and after combustion to pinpoint the OM distribution inside the porous silica matrix. The samples are predominantly composed of alpha quartz and show increasing crystallite sizes up to 33 5 nm (1 standard deviation or SD). In older samples, low water abundances (0.03%) suggest progressive dehydration. (U)SAXS data reveal a porous matrix that evolves over geological time, including, from younger to older samples, (1) a decreasing pore volume down to 1%, (2) greater pore sizes hosting OM, (3) decreasing specific surface area values from younger (9.3 0.1 m2 g 1 ) to older samples (0.63 0.07 m2 g 1 , 1 SD) and (4) a lower background intensity correlated to decreasing hydrogen abundances. The pore-volume distributions (PVDs) show that pores ranging from 4 to 100 nm accumulate the greater volume fraction of OM. Raman data show aromatic organic clusters up to 20 nm in older samples. Raman and PVD data suggest that OM is located mostly in mesopores. Observed structural changes, silica–OM interactions and the hydrophobicity of the OM could explain the OM preservation in chert.
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    Artigo IPEN-doc 29621
    Sub-nanosecond, 41 mJ pulse energy, passively Q-switched Nd:YLF laser
    2023 - PRADO, FELIPE M.; FRANCO, TOMAS J.; WETTER, NIKLAUS U.
    A sub-nanosecond, diode-stack side-pumped, passively Q-switched Nd3+:YLF4/Cr4+:YAG Laser is reported in a compact cavity design, generating one pulse of 41 mJ with a pulse width of 894 ps, achieving a peak output power of 46 MW and beam quality M2 of 5.4 × 5.9 (HxV). The number of pulses in the pulse train could be adjusted from one pulse to ten pulses of 111 mJ total output energy and 23.7 % optical efficiency by adjusting the focus distance while maintaining sub-nanosecond pulse duration. This resonator can also be used for high-power simultaneous Q-switched laser emission at 1047 nm and 1053 nm.
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    Artigo IPEN-doc 28683
    Nd:YLF laser at 1053 nm diode side pumped at 863 nm with a near quantum-defect slope efficiency
    2022 - VIEIRA, TARCIO de A.; PRADO, FELIPE M.; WETTER, NIKLAUS U.
    Laser emission at the 1053 nm transition of Nd:YLF4 is demonstrated using diode-side-pumping at 863 nm directly into the emitting level. The laser configuration uses one total internal reflection at the pump face and provides the highest slope efficiency reported for the Nd:YLF4 medium, close to the quantum limit. In quasi-continuous mode, the laser operates with diffraction-limited beam quality and 78.2% slope efficiency with 14.4 W of output power. In continuous mode, 75.7% slope efficiency in both single-mode and multimode operation is achieved, with 13.5 W output power.
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    Resumo IPEN-doc 27820
    Focus issue introduction
    2021 - PETERSEN, ALAN; TACCHEO, STEFANO; MIROV, SERGEY; NILSSON, JOHAN; PASK, HELEN; SARACENO, CLARA; WETTER, NIKLAUS; WU, RUIFEN
    This Joint Issue of Optics Express and Optical Materials Express features 15 articles written by authors who participated in the international online conference Advanced Solid State Lasers held 13–16 October, 2020. This review provides a summary of the conference and these articles from the conference which sample the spectrum of solid state laser theory and experiment, from materials research to sources and from design innovation to applications.
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    Artigo IPEN-doc 27817
    Localization of light induced in ordered colloidal suspensions
    2021 - ERMAKOV, VIKTOR A.; MARTINS, WELITON S.; WETTER, NIKLAUS U.; MARQUES, FRANCISCO C.; JIMENEZ-VILLAR, ERNESTO
    We study the light–matter coupling by Raman scattering in colloidal suspensions composed by core–shell TiO2@Silica (Rutile@Silica) nanoparticles suspended in ethanol and water solutions. Strong enhancement of the Raman signal per particle is observed as [TiO2@Silica] is increased above a threshold, being stronger in ethanol suspensions. Moreover, above this [TiO2@Silica] threshold, the optical transmittance of the ethanol suspension starts to be considerably lower than in water, despite scattering strength being higher in water. These results are attributed to localization of light induced by strong correlation in the scatterers’ position as a consequence of the long-range Coulomb interaction between the TiO2@Silica nanoparticles. Light diffraction in TiO2@Silica suspensions (water and ethanol) shows strong correlation in the scatterers’ position (structure seemingly cubic), being stronger in ethanol than in water (longer-range Coulomb interaction). As a result, we demonstrate in these colloidal suspensions for the first time, to our knowledge, strongly enhanced light–matter coupling through correlation-induced localization with klT much higher than unity and in an ordered colloidal-photonic structure. This strong enhancement of light–matter coupling by localization of light opens an avenue for manufacturing powerful sensing tools.
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    Artigo IPEN-doc 26431
    Double line waveguide amplifiers written by femtosecond laser irradiation in rare-earth doped germanate glasses
    2020 - SILVA, DIEGO S. da; WETTER, NIKLAUS U.; KASSAB, LUCIANA R.P.; ROSSI, WAGNER de; ARAUJO, MARIANA S. de
    We report the production of active double waveguides in Er/Yb doped GeO2-PbO glasses, by direct femtosecond laser writing. The glasses were produced using the melt-quenching technique and the active waveguides were written using 30 fs laser pulses, at 800 nm, with writing speed of 0.06 mm/s and pulse energy of 32 μJ. The photo-induced negative refractive index change was of 􀀀 7.4 � 10􀀀 3. The Er/Yb doped sample showed a relative gain (signal enhancement of 7.5 dB/cm, for 105 mW of 980 nm pump power. The relative gain compensates both, the propagation losses and the absorption losses, and a positive maximum internal gain of 4.6 dB/cm can be obtained at the signal wavelength of 1550 nm. The results obtained in present work demonstrate that Er/Yb glasses are promising materials for the fabrication of integrated amplifiers, lossless components and lasers based on germanate glasses.
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    Artigo IPEN-doc 23928
    Yb:KGW self-Raman laser with 89 cm(−1) Stokes shift and more than 32% diode-to-Stokes optical efficiency
    2020 - FERREIRA, MERILYN S.; WETTER, NIKLAUS U.
    We report on a Yb3+:KGW self-Raman laser operating at 1096 nm. A 100 μm fiber-coupled diode end-pumped configuration is used to generate a fundamental emission wavelength that strongly depends on internal resonator losses. Stokes emission at 1096 nm is achieved with a slope efficiency of 42 ± 8%, an optical conversion efficiency of more than 32% and a maximum output power of 4.5W for quasi-continuous operation (1 ms pulses). The explored Stokes conversion of 89 cm−1 shows excellent laser characteristics, indicating that this still little explored Stokes shift could pave the way to continuous-wave Raman frequency-comb lasers.