4 research outputs found

    SiO2-P2O5-HfO2-Al2O3-Na2O glasses activated by Er3+ ions: From bulk sample to planar waveguide fabricated by rf-sputtering

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    0.4 Er3+-doped 90.7 SiO2 – 4.4 P2O5 – 2.3 HfO2 – 1.7 Al2O3 – 0.7 Na2O planar waveguide was fabricated by multi-target rf-sputtering technique starting by massive Er3+-activated P2O5-SiO2-Al2O3-Na2O glass. The optical parameters were measured by m-line apparatus operating at 632.8, 1319 and 1542 nm. The waveguide compositions were investigated by Energy Dispersive X-ray Spectroscopy and its morphology analyzed by Atomic Force Microscopy. The waveguide exhibits a single propagation mode at 1319 and 1542 nm with an attenuation coefficient of 0.2 dB/cm in the infrared. The emission of 4I13/2 → 4I15/2 transition of Er3+ ion, with a 28.5 nm bandwidth was observed upon TE0 mode excitation at 514.5 nm. The optical and spectroscopic features of the Er3+-activated parent P2O5-SiO2-Al2O3-Na2O glass were also investigated

    Multi-messenger Observations of a Binary Neutron Star Merger

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    International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∌1.7 s\sim 1.7\,{\rm{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of 40−8+8{40}_{-8}^{+8} Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26  M⊙\,{M}_{\odot }. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∌40 Mpc\sim 40\,{\rm{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∌10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∌9\sim 9 and ∌16\sim 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
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