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Waveguide-Integrated Broadband Spectrometer Based on Tailored Disorder
2020, Hartmann, Wladick, Varytis, Paris, Gehring, Helge, Walter, Nicolai, Beutel, Fabian, Busch, Kurt, Pernice, Wolfram
Compact, on-chip spectrometers exploiting tailored disorder for broadband light scattering enable high-resolution signal analysis while maintaining a small device footprint. Due to multiple scattering events of light in the disordered medium, the effective path length of the device is significantly enhanced. Here, on-chip spectrometers are realized for visible and near-infrared wavelengths by combining an efficient broadband fiber-to-chip coupling approach with a scattering area in a broadband transparent silicon nitride waveguiding structure. Air holes etched into a structured silicon nitride slab terminated with multiple waveguides enable multipath light scattering in a diffusive regime. Spectral-to-spatial mapping is performed by determining the transmission matrix at the waveguide outputs, which is then used to reconstruct the probe signals. Direct comparison with theoretical analyses shows that such devices can be used for high-resolution spectroscopy from the visible up to the telecom wavelength regime. © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
First stellar photons for an integrated optics discrete beam combiner at the William Herschel Telescope
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.