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Start date: 2020 × DDC: 530 × Subject: Photons × Subject: Ultrafast lasers ×

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    High-order parametric generation of coherent XUV radiation
    (Washington, DC : Soc., 2021) Hort, O.; Dubrouil, A.; Khokhlova, M.A.; Descamps, D.; Petit, S.; Burgy, F.; Mével, E.; Constant, E.; Strelkov, V.V.
    Extreme ultraviolet (XUV) radiation finds numerous applications in spectroscopy. When the XUV light is generated via high-order harmonic generation (HHG), it may be produced in the form of attosecond pulses, allowing access to unprecedented ultrafast phenomena. However, the HHG efficiency remains limited. Here we present an observation of a new regime of coherent XUV emission which has a potential to provide higher XUV intensity, vital for applications. We explain the process by high-order parametric generation, involving the combined emission of THz and XUV photons, where the phase matching is very robust against ionization. This introduces a way to use higher-energy driving pulses, thus generating more XUV photons.
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    First stellar photons for an integrated optics discrete beam combiner at the William Herschel Telescope
    (Washington, DC : The Optical Society, 2021) Nayak, Abani Shankar; Labadie, Lucas; Sharma, Tarun Kumar; Piacentini, Simone; Corrielli, Giacomo; Osellame, Roberto; Gendron, Éric; Buey, Jean-Tristan M.; Chemla, Fanny; Cohen, Mathieu; Bharmal, Nazim A.; Bardou, Lisa F.; Staykov, Lazar; Osborn, James; Morris, Timothy J.; Pedretti, Ettore; Dinkelaker, Aline N.; Madhav, Kalaga V.; Roth, Martin M.
    We present the first on-sky results of a four-telescope integrated optics discrete beam combiner (DBC) tested at the 4.2mWilliamHerschel Telescope. The device consists of a four-input pupil remapper followed by a DBC and a 23-output reformatter. The whole device was written monolithically in a single alumino-borosilicate substrate using ultrafast laser inscription. The device was operated at astronomical H-band (1.6 μm), and a deformable mirror along with a microlens array was used to inject stellar photons into the device. We report the measured visibility amplitudes and closure phases obtained on Vega and Altair that are retrieved using the calibrated transfer matrix of the device. While the coherence function can be reconstructed, the on-sky results show significant dispersion from the expected values. Based on the analysis of comparable simulations, we find that such dispersion is largely caused by the limited signal-to-noise ratio of our observations. This constitutes a first step toward an improved validation of theDBCas a possible beam combination scheme for long-baseline interferometry. © 2021 Optical Society of America.