28 research outputs found

    Fluorescence imaging of lattice re-distribution on step-index direct laser written Nd:YAG waveguide lasers

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    The laser performance and crystalline micro-structural properties of near-infrared step-index channel waveguides fabricated inside Neodymium doped YAG laser ceramics by means of three-dimensional sub-picosecond pulse laser direct writing are reported. Fluorescence micro-mapping of the waveguide cross-sections reveals that an essential crystal lattice re-distribution has been induced after short pulse irradiation. Such lattice re-distribution is evidenced at the waveguide core corresponding to the laser written refractive index increased volume. The waveguides core surroundings also present diverse changes including slight lattice disorder and bi-axial strain fields. The step-index waveguide laser performance is compared with previous laser fabricated waveguides with a stress-optic guiding mechanism in absence of laser induced lattice re-distributionThis work was supported by the Spanish Government under Project Nos. MAT2013-47395-C4-1-R, TEC2010- 21574-C02-01/02, MAT2013-47395-C4, and MAT2011- 29255-C02-02 and by the Generalitat de Catalunya under Project No. 2014SGR1358. A. Benayas thanks Fonds de recherche du Quebec-Nature et technologies (FRQNT) for the Postdoctoral Fellowship given to him through Programme de Bourses d’Excellence (Merit Scholarship Program for Foreign Students)

    Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

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    PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

    Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

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    PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

    Femtosecond-laser microstructuring of ribs on active (Yb,Nb):RTP/RTP planar waveguides

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    We have produced rib waveguides by femtosecond-laser structuring of active (Yb,Nb):RbTiOPO4 /RbTiOPO4 epitaxial layers. The ribs were produced by the approximation scanning technique combined with beam multiplexing. The so-obtained waveguides are trapezoidal in shape and show propagation losses with an upper bound of ∿4 dB/cm. A simulation of the rib waveguides with real geometry parameters reveals high levels of light confinement at 632 and 972 nm. The near-field patterns of the fundamental modes have been obtained by exciting the waveguides at wavelengths of 632 and 972 nm. Micro-Raman spectroscopy study reveals that the damage to the crystalline structure in the rib boundaries, showing no amorphization traces, is around 3 ο m in length and depth, which is significantly shorter than the total width of the ribs. © 2012 IEEEThis work was supported by the Spanish Government under Projects TEC2010-21574-C02-02, TEC2011-22422, MAT2011-29255-C02-02, PI09/90527, and the Catalan Authority under Project 2009SGR235. This work was also supported in part by the European Commission under the Seventh Framework Programme under Project FP7-SPACE-2010-1-GA-263044. The work of J. Cugat was supported by the Spanish Government under the FPI fellowship BES-2009-024190.Peer Reviewe

    Mirrorless Yb3+-doped monoclinic double tungstate waveguide laser combining liquid phase epitaxy and multiplexed beam fs laser writing

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    In this paper, a mirrorless Yb-doped KYGdLu (WO) waveguide laser with cw operation at 981.5 and 1001 nm, fabricated by liquid phase epitaxy and femtosecond laser microstructuring, is reported. A planar waveguide was fabricated by growing an Yb-doped KYGdLu(WO) epitaxial layer by liquid phase epitaxy over a KY(WO) substrate. This planar waveguide was then microstructured by means of a multiplexed beam femtosecond laser writing technique in order to define ridge waveguides. Mirrorless laser action is demonstrated in ridge waveguides with different fabrication parameters, obtaining maximum slope efficiency of 78% versus absorbed power, which confirms the feasibility of this technique for the development of integrated laser devices.Peer Reviewe

    Mirrorless Yb 3+

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