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Author: Dinkelaker, Aline N. ×

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    Ultrafast laser inscription of asymmetric integrated waveguide 3 dB couplers for astronomical K-band interferometry at the CHARA array
    (Washington, DC : Soc., 2021) Benoît, Aurélien; Pike, Fraser A.; Sharma, Tarun K.; MacLachlan, David G.; Dinkelaker, Aline N.; Nayak, Abani S.; Madhav, Kalaga; Roth, Martin M.; Labadie, Lucas; Pedretti, Ettore; Brummelaar, Theo A. ten; Scott, Nic; Coudé du Foresto, Vincent; Thomson, Robert R.
    We present the fabrication and characterization of 3 dB asymmetric directional couplers for the astronomical K-band at wavelengths between 2.0 and 2.4 µm. The couplers were fabricated in commercial Infrasil silica glass using an ultrafast laser operating at 1030 nm. After optimizing the fabrication parameters, the insertion losses of straight single-mode waveguides were measured to be ∼1.2±0.5dB across the full K-band. We investigate the development of asymmetric 3 dB directional couplers by varying the coupler interaction lengths and by varying the width of one of the waveguide cores to detune the propagation constants of the coupled modes. In this manner, we demonstrate that ultrafast laser inscription is capable of fabricating asymmetric 3 dB directional couplers for future applications in K-band stellar interferometry. Finally, we demonstrate that our couplers exhibit an interferometric fringe contrast of >90%. This technology paves the path for the development of a two-telescope K-band integrated optic beam combiner for interferometry to replace the existing beam combiner (MONA) in Jouvence of the Fiber Linked Unit for Recombination (JouFLU) at the Center for High Angular Resolution Astronomy (CHARA) telescope array.
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    Ultracold atom interferometry in space
    ([London] : Nature Publishing Group UK, 2021) Lachmann, Maike D.; Ahlers, Holger; Becker, Dennis; Dinkelaker, Aline N.; Grosse, Jens; Hellmig, Ortwin; Müntinga, Hauke; Schkolnik, Vladimir; Seidel, Stephan T.; Wendrich, Thijs; Wenzlawski, André; Carrick, Benjamin; Gaaloul, Naceur; Lüdtke, Daniel; Braxmaier, Claus; Ertmer, Wolfgang; Krutzik, Markus; Lämmerzahl, Claus; Peters, Achim; Schleich, Wolfgang P.; Sengstock, Klaus; Wicht, Andreas; Windpassinger, Patrick; Rasel, Ernst M.
    Bose-Einstein condensates (BECs) in free fall constitute a promising source for space-borne interferometry. Indeed, BECs enjoy a slowly expanding wave function, display a large spatial coherence and can be engineered and probed by optical techniques. Here we explore matter-wave fringes of multiple spinor components of a BEC released in free fall employing light-pulses to drive Bragg processes and induce phase imprinting on a sounding rocket. The prevailing microgravity played a crucial role in the observation of these interferences which not only reveal the spatial coherence of the condensates but also allow us to measure differential forces. Our work marks the beginning of matter-wave interferometry in space with future applications in fundamental physics, navigation and earth observation.
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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.