RICARDO ELGUL SAMAD

Resumo

Has graduation at Bacharelado Em Física by Instituto de Física da Usp (1993) , specialization at V Escola Jorge André Swieca de Óptica Quântica by Centro Brasileiro de Pesquisas Físicas (1996) , specialization at 1a Escola de Óptica Aplicada by Instituto de Física da Usp (1998) , specialization at Training Course On Instrumentation For Ultrashort by International Centre For Science And High Technology (2002) , specialization at An Introduction to Femtosecond Laser Techniques by The International Society For Optical Engineering (2005) , specialization at IV Escola Jorge André Swieca de Óptica Quântica by Universidade Estadual de Campinas (1994) , specialization at Workshop On Thin Films by International Centre For Theoretical Physics (1999) , specialization at Winter College On Optics by International Centre For Theoretical Physics (1998) , specialization at Winter College On Ultrafast Non Linear Optics by International Centre For Theoretical Physics (2002) , master's at Física do Estado Sólido by Instituto de Física da Usp (1997) and Ph.D. at Física do Estado Sólido by Instituto de Física da Usp (2006) . Currently is of Instituto de Pesquisas Energéticas e Nucleares, Revisor de periódico of Applied Optics, Revisor de periódico of Optics Letters, of Universidade de São Paulo, Revisor de periódico of Journal of Applied Physics, of Comissão Nacional de Energia Nuclear, Revisor de periódico of OPTICS EXPRESS, Revisor de periódico of OPTICS AND LASERS IN ENGINEERING, Revisor de periódico of JOURNAL OF APPLIED PHYSICS, Revisor de projeto de fomento of Conselho Nacional de Desenvolvimento Científico e Tecnológico, Revisor de projeto de fomento of Fundação de Amparo à Pesquisa do Estado de São Paulo, Revisor de projeto de fomento of Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Revisor de periódico of Papers in Physics, Revisor de periódico of Optics and Laser Technology, Membro de corpo editorial of SBFoton Newsletter, of University of Nebraska/Lincoln e of Centro Tecnológico da Marinha Em Sao Paulo. Has experience in the area of Physics , with emphasis on Física da Matéria Condensada. Focused, mainly, in the subjects: femtossegundos, Terawatt, Cr:LiSAF, Amplificacao de Pulsos Laser, Lasers. (Text obtained from the Currículo Lattes on November 25th 2021)


Ricardo Elgul Samad bacharelou-se em Física em 1993, obteve o seu mestrado em Física do Estado Sólido em 1997, e concluiu o doutorado também em Física do Estado Sólido em 2006, todos pelo Instituto de Física da USP. Atualmente é Pesquisador do Centro de Lasers e Aplicações Instituto de Pesquisas Energéticas e Nucleares (IPEN-CNEN/SP). Publicou 69 artigos em periódicos especializados que possuem mais de 550 citações, 3 capítulos de livros e mais de 90 trabalhos em anais de eventos, além de ter submetido 2 pedidos de patente. Desde a sua Iniciação Científica trabalha no desenvolvimento e em aplicações de lasers de estado sólido, e no seu doutorado iniciou atividades de pesquisa com lasers de pulsos ultracurtos. Atualmente trabalha com aplicações de pulsos ultracurtos e a interação destes com a matéria, como na ablação e usinagem de sólidos por laser, geração de plasma induzida por pulsos ultracurtos e modificação de materiais resultante de estados extremos de temperatura e pressão gerados pelos pulsos ultracurtos, e técnicas de geração de harmônicos para viabilizar novas fontes de luz na região do UV profundo e raios X moles. Recentemente tem trabalhado com aceleração de partículas por pulsos laser ultracurtos. (Texto extraído do Currículo Lattes em 25 nov. 2021)

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Agora exibindo 1 - 7 de 7
  • Artigo IPEN-doc 27543
    Femtosecond Ti: Sa ultra short-pulse laser irradiation effects on the properties and morphology of the zirconia surface after ageing
    2021 - KIYAN, VANESSA H.; RODRIGUES, FLAVIA P.; SAMAD, RICARDO E.; ZEZELL, DENISE M.; BOTTINO, MARCO A.; LIMA, NELSON B. de; SARACENI, CINTIA H.C.
    Femtosecond pulses from a Ti:Sapphire laser were used to irradiate specimens of yttria-stabilised (35% mol) tetragonal zirconia (Y-TZP) with the purpose of studying the effects of the irradiations on their surface properties and morphology after ageing. Zirconia disks were divided into eight groups (n = 32) according to their surface treatment and subsequent ageing: Control: no treatment; sandblasting: Al2O3 sandblasting 50 μm; and ultrashort laser pulses irradiation with 25 μJ pulses, considering two different scanning steps based on the width between two grooves. These groups were duplicated and submitted to ageing. The surfaces were analysed using scanning electron microscopy (SEM), and X-ray diffraction. A finite element analysis, a biaxial flexure test, as well as fractographic and Weibull analyses, were performed. The strengths of the disks were statistically different for the treatment factor, and the principal stresses seemed to be concentrated at the centre of the specimens, as predicted by the computer simulations. Ageing decreased the strengths for all groups and increased the Weibull modulus for the laser group with the 40 μm-width between two grooves. The sandblasting group presented the highest monoclinic phase peak. Although the most significant strength was found within the sandblasting group, the phase transformation was favourable to the laser groups. The Weibull modulus was higher for the laser group with the 60 μm-width between two grooves, confirming the highest homogeneity of its failure distribution. Regardless of the surface treatment, strength was decreased with ageing in all groups. The femtosecond Ti:Sa ultra-short pulse laser irradiation can be suggested as an alternative to the gold standard sandblasting in longterm Y-TZP zirconia rehabilitations, such as crowns and veneers.
  • Artigo IPEN-doc 26669
    Low-loss pedestal Ta2O5 nonlinear optical waveguides
    2019 - SIERRA, JULIAN H.; RANGEL, RICARDO C.; SAMAD, RICARDO E.; VIEIRA JUNIOR, NILSON D.; ALAYO, MARCO I.; CARVALHO, DANIEL O.
    In this work, we investigate a pedestal tantalum oxide (Ta2O5) material platform for integrated nonlinear optics (NLO). In order to achieve low propagation losses with this material, pedestal waveguides with Ta2O5 cores were designed. The nonlinear refractive index n2 of this new platform was obtained by measuring the amount of spectral broadening due to self-phase modulation (SPM) of 23 fs optical pulses at 785 nm propagating through the waveguides. In this manner, a nonlinear index of (5.8 2.0) 10􀀀19 m2W􀀀1 was found for this material, which is in good agreement with values reported in related works where strip waveguides were used for a similar purpose. Furthermore, due to the pedestal configuration, propagation losses as low as 1.6 dB cm􀀀1 for narrow waveguides and 0.1 dB cm􀀀1 for large waveguides were obtained. Finite element method (FEM) mode analysis was performed to calculate the mode characteristics, as well as the effective areas of the waveguides. The high nonlinear and linear refractive indices, wide bandgap and low propagation losses make this platform ideal for applications extending from the visible into the mid-IR regions of the optical spectrum. Due the large gap, Ta2O5 should have low two photon absorption at the near-IR as well.
  • Artigo IPEN-doc 25796
    Modifying the second order dispersion of femtosecond laser pulses to crack silver nanoparticles and control their dimensions
    2019 - CORDEIRO, THIAGO da S.; AMARAL, MARCELLO M.; MATOS, RICARDO A. de; SILVA, FLAVIA R.O.; VIEIRA JUNIOR, NILSON D.; COURROL LILIA C.; ROSSI, WAGNER de; SAMAD, RICARDO E.
    The potential application of metallic nanoparticles had been attracting attention and interest from different areas of academia and industry. The nanoparticles properties and applications depend heavily on their dimension and shape, thus special interest is aimed to controlling the nanoparticles sizes. Ultrashort laser pulses are known to change metallic nanoparticles characteristics, but the interaction mechanism is still not completely understood. In this work we reduced the dimension of silver nanoparticles with ultrashort pulses and demonstrated that there is a dependence of the particles size on the second order dispersion introduced in the pulses, which became smaller as the dispersion becomes more negative. Based on the results, we propose that the Coulomb explosion that reduces the nanoparticles size is predominantly initiated by multiphotonic ionization for the intensities used (1014 W/cm2).
  • Artigo IPEN-doc 25775
    Focus tracking system for femtosecond laser machining using low coherence interferometry
    2019 - RAELE, MARCUS P.; DE PRETTO, LUCAS R.; ROSSI, WAGNER de; VIEIRA JUNIOR, NILSON D.; SAMAD, RICARDO E.
    We designed a real time, single-laser focus tracking system using low coherence properties of the machining femtosecond laser itself in order to monitor and correct the sample position relative to the focal plane. Using a Michelson Interferometer, the system collects data arising from part of the beam backscattered at the ablation spot. The data is analyzed by a custom software for position correction (employing an XYZ automated translation stage). With the focus tracking enabled we were able to etch channels with a stable cross-section profile on a bovine tooth with relief amplitude tens of times greater than the Rayleigh length of the system, keeping the sample inside the confocal parameter during most of the processing time. Moreover, the system is also capable of monitoring crater depth evolution during the ablation process, allowing for material removal assessment.
  • Artigo IPEN-doc 24673
    Optical properties and antimicrobial effects of silver nanoparticles synthesized by femtosecond laser photoreduction
    2018 - COURROL, DANIELLA dos S.; LOPES, CARLA R.B.; CORDEIRO, THIAGO da S.; FRANZOLIN, MARCIA R.; VIEIRA JUNIOR, NILSON D.; SAMAD, RICARDO E.; COURROL, LILIA C.
    Silver nanoparticles exhibit a powerful antimicrobial action showing a pronounced potential to be widely used against drug resistance bacteria. The present work describes the optical properties and antimicrobial effect of silver nanoparticles produced by femtosecond laser photoreduction of AgNO3 in the presence of tryptophan water solution. The advantages of this method are the absence of hazardous chemical reducing agents in the solution, and the versatile dimensional control achieved. The synthesized silver nanoparticles were characterized by absorption and fluorescence spectroscopy and their antibacterial activity were determined by monitoring the cell viability of Escherichia coli. The effects of the silver nanoparticles concentration and laser parameters (exposure time and pulse energy), on the formation of the nanoparticles, and its influence on the bacteria growth inhibition were studied. The prepared silver nanoparticles exhibited suitable antimicrobial properties. The results demonstrated that the nanoparticles concentration plays an important role in their bactericidal efficacy. The increase in the laser energy caused an increase in E. coli growth inhibition. Irradiations with energies around 300 mu j for 60 min presented high antimicrobial activity due to the presence of kynurenine, sub product of tryptophan photolysis. The first-time formation mechanism of tryptophan silver nanoparticles in high optical intensities was also discussed.
  • Artigo IPEN-doc 22896
    Multimodal evaluation of ultra-short laser pulses treatment for skin burn injuries
    2017 - SANTOS, MOISES O. dos; LATRIVE, ANNE; CASTRO, PEDRO A.A. de; ROSSI, WAGNER de; ZORN, TELMA M.T.; SAMAD, RICARDO E.; FREITAS, ANDERSON Z.; CESAR, CARLOS L.; VIEIRA JUNIOR, NILSON D.; ZEZELL, DENISE M.
    Thousands of people die every year from burn injuries. The aim of this study is to evaluate the feasibility of high intensity femtosecond lasers as an auxiliary treatment of skin burns. We used an in vivo animal model and monitored the healing process using 4 different imaging modalities: histology, Optical Coherence Tomography (OCT), Second Harmonic Generation (SHG), and Fourier Transform Infrared (FTIR) spectroscopy. 3 dorsal areas of 20 anesthetized Wistar rats were burned by water vapor exposure and subsequently treated either by classical surgical debridement, by laser ablation, or left without treatment. Skin burn tissues were noninvasively characterized by OCT images and biopsied for further histopathology analysis, SHG imaging and FTIR spectroscopy at 3, 5, 7 and 14 days after burn. The laser protocol was found as efficient as the classical treatment for promoting the healing process. The study concludes to the validation of femtosecond ultra-short pulses laser treatment for skinburns, with the advantage of minimizing operatory trauma.
  • Artigo IPEN-doc 20930
    Synthesis of diamond-like phase from graphite by ultrafast laser driven dynamical compression
    2015 - MAIA, FRANCISCO C.B.; SAMAD, RICARDO E.; BETTINI, JEFFERSON; FREITAS, RAUL O.; VIEIRA JUNIOR, NILSON D.; SOUZA-NETO, NARCIZO M.