NIKLAUS URSUS WETTER

NIKLAUS URSUS WETTER

(Fonte: Lattes)

Resumo

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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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.
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.
1337 nm emission of a Nd3+-doped TZA glass random laser
2023 - DIPOLD, JESSICA; BORDON, CAMILA D.S.; MAGALHAES, EVELLYN S.; KASSAB, LUCIANA R.P.; JIMENEZ-VILLAR, ERNESTO; WETTER, NIKLAUS U.
Random lasers have been studied using many materials, but only a couple have used glass matrices. Here, we present a study of zinc tellurite and aluminum oxide doped with different percentages of neodymium oxide (4 wt.%, 8 wt.%, and 16 wt.%) and demonstrate for the first time random laser action at 1337 nm. Laser emission was verified and the laser pulse’s rise time and input–output power slope were obtained. A cavity composed of the sample’s pump surface and an effective mirror formed by a second, parallel layer at the gain-loss boundary was probably the main lasing mechanism of this random laser system. The reason for the absence of emission at 1064 nm is thought to be a measured temperature rise in the samples’ active volume.
Silver nanoclusters tunable visible emission and energy transfer to Yb3+ Ions in co-doped GeO2-PbO glasses for photonic applications
2023 - AMARO, AUGUSTO A.; MATTOS, GUILHERME R. da S.; NISHIMURA, MARCOS V. de M.; DIPOLD, JESSICA; WETTER, NIKLAUS U.; KASSAB, LUCIANA R.P.
This work investigates the optical properties of Yb3+ ions doped GeO2 -PbO glasses containing Ag nanoclusters (NCs), produced by the melt-quenching technique. The lack in the literature regarding the energy transfer (ET) between these species in these glasses motivated the present work. Tunable visible emission occurs from blue to orange depending on the Yb3+ concentration which affects the size of the Ag NCs, as observed by transmission electron microscopy. The ET mechanism from Ag NCs to Yb3+ ions (2F7/2 → 2F5/2) was attributed to the S1→T1 decay (spin-forbidden electronic transition between singlet–triplet states) and was corroborated by fast and slow lifetime decrease (at 550 nm) of Ag NCs and photoluminescence (PL) growth at 980 nm, for excitations at 355 and 405 nm. The sample with the highest Yb3+ concentration exhibits the highest PL growth under 355 nm excitation, whereas at 410 nm it is the sample with the lowest concentration. The restriction of Yb3+ ions to the growth of NCs is responsible for these effects. Thus, higher Yb3+ concentration forms smaller Ag NCs, whose excitation at 355 nm leads to more efficient ET to Yb3+ ions compared to 410 nm. These findings have potential applications in the visible to near-infrared regions, such as tunable CW laser sources and photovoltaic devices.
Effect of silver nanoparticles on the optical properties of double line waveguides written by fs laser in Nd3+-doped GeO2-PbO glasses
2023 - BORDON, CAMILA D. da S.; DIPOLD, JESSICA; WETTER, NIKLAUS U.; ROSSI, WAGNER de; FREITAS, ANDERSON Z.; KASSAB, LUCIANA R.P.
Nd3+-doped GeO2-PbO glass with silver (Ag) nanoparticles (NPs) are produced with double line waveguides through fs laser processing for photonic applications. A Ti:sapphire fs laser at 800 nm was used to write the waveguides directly into the glass 0.7 mm beneath the surface. This platform is based on pairs of parallel lines with spacing of 10 µm, each pair being formed by two identical written lines but in two different configurations of 4 or 8 separately processed lines, which are coincident. The results of optical microscopy, absorbance measurements, refractive index change, beam quality factor (at 632 and 1064 nm), photoluminescence, propagation losses, and relative gain at 1064 nm are presented. The structural changes in the glass due to the presence of Ag NPs were investigated by Raman spectroscopy. At 632 and 1064 nm, x,y-symmetrical guiding was observed, and for both kinds of overlapping pulses, a refractive index alteration of 10−3 was found in both directions. Photoluminescence growth of ~47% at 1064 nm was observed due to the plasmonic effect of Ag NPs. In dual waveguides containing Ag NPs, the relative gain obtained increased by 40% and 30% for four and eight overlapping lines, respectively, at 600 mW of 808 nm pump power, when compared to waveguides without those metallic NPs. We highlight the resultant positive internal gains of 5.11 and 7.12 dB/cm that showed a growth of ~40% and ~30%, respectively, with respect to the samples without Ag NPs. The increase in photoluminescence and relative gain were related to the local field growth produced by Ag NPs. The present results show that the addition of Ag NPs impacts positively on the optical performance at 1064 nm of double line waveguides processed by fs laser writing in Nd3+-doped GeO2-PbO glass, opening news perspectives for photonics.
A new double-line waveguide architecture for photonic applications using fs laser writing in Nd3+ doped GeO2-PbO glasses
2022 - BORDON, CAMILA D.S.; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUS U.; ROSSI, WAGNER de; KASSAB, LUCIANA R.P.
A new double-line waveguide architecture produced in Nd3+ doped GeO2-PbO glasses is presented for photonic applications. The waveguides are written directly into Nd3+ doped GeO2-PbO glasses using a Ti:Sapphire femtosecond (fs) laser, operating at 800 nm, delivering 30 fs pulses at 10 kHz repetition rate and writing speed of 0.5 mm/s. Two parallel lines form a dual-waveguide each line being a result of either 4 or 8 superimposed lines. Results of propagation losses, M2 beam quality factor at 632 and 1064 nm, refractive index change, and relative gain at the signal wavelength (1064 nm) are presented. Structural changes, due to laser writing process were investigated by Raman spectroscopy. The observed near-field pattern image showed good waveguiding quality, consisting of a single, circular lobe. X,y-symmetrical guiding for both waveguides was observed. The relative gain reached 4.5 and 6.0 dB/cm for 4 and 8 superimposed lines, respectively, for 420 mW of 808 nm pumping. Propagation losses were 0.89 and 0.44 dB/cm, for 4 and 8 superimposed lines, respectively, leading to positive internal gain of 3.6 and 5.56 dB/cm. The results obtained in the present work demonstrate that this new double line architecture for Nd3+ doped GeO2-PbO glasses is promising for the fabrication of integrated amplifiers, lossless components and lasers.
Dynamically stable single frequency ring resonator from diode pumped Nd:YAG modules with 55.6 W of output power
2021 - BERECZKI, ALLAN; FERREIRA, AMAURI A.; WETTER, NIKLAUS U.
A Nd:YAG rod single-frequency ring laser based on side-pumped commercial modules is presented. Thermally induced birefringence compensation was applied in a dynamically stable resonator providing 55.6 W of continuous, linearly polarized, TEM00 output. The particular case of a symmetric ring resonator containing one or two focusing rods and a pair of curved mirrors was analyzed and a design technique is presented, allowing for easy, continuous shaping of the stability limits by changing only the distances in the resonator.
Random lasing at localization induced in correlated colloidal system
2021 - DOMINGUEZ, CHRISTIAN T.; GOMES, ANDERSON A.V.; WETTER, NIKLAUS U.; DIPOLD, JESSICA; MESTRE, VALDECI; MARTINS, WELITON S.; JIMENEZ-VILLAR, ERNESTO
Random lasers have the potential for cheap and coherent light sources which, in the particular case of colloidal suspensions, are completely flexible and can take on any desired shape. Here, we studied random lasing in correlated colloidal systems composed by TiO2@Silica nanoparticles suspended in ethanol solutions of Rhodamine 6G. TiO2 particles with two different silica layers (thicknesses of 40 nm and 70 nm) were prepared. The Random laser performance improves when the silica shell is thicker (70 nm), which was attributed to a stronger localization of light (higher density of localized states) induced by stronger correlation in the scatterers' (TiO2@Silica) position as a consequence of a stronger and longer-range Coulomb interaction between the scatterers. Light diffraction patterns in both TiO2@Silica suspensions showed a stronger correlation in the scatterers’ position, being stronger when the silica shell is thicker.
Diode-side-pumped, intracavity Nd:YLF/KGW/LBO Raman laser at 573 nm for retinal photocoagulation
2021 - FERREIRA, MERILYN S.; WETTER, NIKLAUS U.
Wavelengths in the yellow-orange range are of significant interest for retinal photocoagulation and are especially important in the case of diabetic retinopathy, which can cause blindness and affects 3.3% of all working-age adults. This work presents a highly-efficient, compact, and cost-efficient side-pumped, intracavity Raman configuration to achieve this objective. A side-pumped Nd:YLF/KGW/LBO frequency-doubled Raman laser producing 11.7 W of output power at 1147 nm with 21% of slope efficiency and 6 W of output power at 573.5 nm with 12% slope efficiency is demonstrated.
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.