DESHIMA 2.0: Development of an Integrated Superconducting Spectrometer for Science-Grade Astronomical Observations

Taniguchi, Akio; Bakx, Tom J. L. C.; Baselmans, J. J. A.; Huiting, Robert; Karatsu, K.; Llombart, Nuria; Rybak, Matus; Takekoshi, Tatsuya; Tamura, Yoichi; Akamatsu, Hiroki; Brackenhoff, Stefanie; Bueno, J.; Buijtendorp, Bruno T.; Dabironezare, Shahab Oddin; Doing, Anne-Kee; Fujii, Yasunori; Fujita, Kazuyuki; Gouwerok, Matthijs; Hähnle, Sebastian; Ishida, Tsuyoshi; Ishii, Shun; Kawabe, Ryohei; Kitayama, Tetsu; Kohno, Kotaro; Kouchi, Akira; Maekawa, Jun; Matsuda, Keiichi; Murugesan, Vignesh; Nakatsubo, Shunichi; Oshima, Tai; Laguna, Alejandro Pascual; Thoen, David J.; Werf, P. P. van der; Yates, S. J. C.; Endo, Akira

doi:10.1007/s10909-022-02888-5

Cited by 10 publications

(1 citation statement)

References 24 publications

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“…We demonstrate a method for adjusting the position of an optical component to correct for misalignment in a submm quasi-optical system, which uses a pair of reflectors mounted on a motorised hexapod, a novel phase-and-amplitude beampattern measurement technique, and an optimisation algorithm. We apply the alignment method to the DESHIMA 2.0 (Taniguchi et al 2022) submm ISS. DESHIMA 2.0 uses a wide-band leakylens antenna (Neto 2010;Neto et al 2010;Hähnle et al 2020), in combination with a superconducting filterbank (Laguna et al 2021;Thoen et al 2022) coupled to an array of NbTiN-hybrid MKIDs (Janssen et al 2013), to observe the electromagnetic spectrum between 220 and 440 GHz.…”

Section: Introductionmentioning

confidence: 99%

Optimisation-based alignment of wide-band integrated superconducting spectrometers for submillimeter astronomy

Moerman,

Karatsu,

Yates

et al. 2024

A&A

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Integrated superconducting spectrometers (ISSs) for wide-band submillimeter (submm) astronomy use quasi-optical systems for coupling radiation from the telescope to the instrument. Misalignment in these systems is detrimental to the system performance. The common method of using an optical laser to align the quasi-optical components requires an accurate alignment of the laser to the submm beam from the instrument, which is not always guaranteed to a sufficient accuracy. We develop an alignment strategy for wide-band ISSs that directly uses the submm beam of the wide-band ISS. The strategy should be applicable in both telescope and laboratory environments. Moreover, the strategy should deliver similar quality of the alignment across the spectral range of the wide-band ISS. We measured the misalignment in a quasi-optical system operating at submm wavelengths using a novel phase and amplitude measurement scheme that is capable of simultaneously measuring the complex beam patterns of a direct-detecting ISS across a harmonic range of frequencies. The direct detection nature of the microwave kinetic inductance detectors in our device-under-test, DESHIMA 2.0, necessitates the use of this measurement scheme. Using geometrical optics, the measured misalignment, a mechanical hexapod, and an optimisation algorithm, we followed a numerical approach to optimise the positioning of corrective optics with respect to a given cost function. Laboratory measurements of the complex beam patterns were taken across a harmonic range between 205 and 391 GHz and were simulated through a model of the ASTE telescope in order to assess the performance of the optimisation at the ASTE telescope. Laboratory measurements show that the optimised optical setup corrects for tilts and offsets of the submm beam. Moreover, we find that the simulated telescope aperture efficiency is increased across the frequency range of the ISS after the optimisation.

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Section: Introductionmentioning

confidence: 99%

Optimisation-based alignment of wide-band integrated superconducting spectrometers for submillimeter astronomy

Moerman,

Karatsu,

Yates

et al. 2024

A&A

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Deshima 2.0: Rapid Redshift Surveys and Multi-line Spectroscopy of Dusty Galaxies

et al. 2022

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We present a feasibility study for the high-redshift galaxy part of the Science Verification Campaign with the 220–440 GHz deshima 2.0 integrated superconducting spectrometer on the ASTE telescope. The first version of the deshima 2.0 chip has been recently manufactured and tested in the lab. Based on these realistic performance measurements, we evaluate potential target samples and prospects for detecting the [CII] and CO emission lines. The planned observations comprise two distinct, but complementary objectives: (1) acquiring spectroscopic redshifts for dusty galaxies selected in far-infrared/mm-wave surveys; (2) multi-line observations to infer physical conditions in dusty galaxies.

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Directional Filter Design and Simulation for Superconducting On-Chip Filter-Banks

Marting,

Karatsu,

Endo

et al. 2024

J Low Temp Phys

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Many superconducting on-chip filter-banks suffer from poor coupling to the detectors behind each filter. This is a problem intrinsic to the commonly used half-wavelength filter, which has a maximum theoretical coupling of 50 %. In this paper, we introduce a phase-coherent filter, called a directional filter, which has a theoretical coupling of 100 %. In order to study and compare different types of filter-banks, we first analyze the measured filter frequency scatter, losses, and spectral resolution of a DESHIMA 2.0 filter-bank chip. Based on measured fabrication tolerances and losses, we adapt the input parameters for our circuit simulations, quantitatively reproducing the measurements. We find that the frequency scatter is caused by nanometer-scale line width variations and that variances in the spectral resolution is caused by losses in the dielectric only. Finally, we include these realistic parameters in a full filter-bank model and simulate a wide range of spectral resolutions and oversampling values. For all cases, the directional filter-bank has significantly higher coupling to the detectors than the half-wave resonator filter-bank. The directional filter eliminates the need to use oversampling as a method to improve the total efficiency, instead capturing nearly all the power remaining after dielectric losses.

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DESHIMA 2.0: Development of an Integrated Superconducting Spectrometer for Science-Grade Astronomical Observations

Cited by 10 publications

References 24 publications

Optimisation-based alignment of wide-band integrated superconducting spectrometers for submillimeter astronomy

Optimisation-based alignment of wide-band integrated superconducting spectrometers for submillimeter astronomy

Deshima 2.0: Rapid Redshift Surveys and Multi-line Spectroscopy of Dusty Galaxies

Directional Filter Design and Simulation for Superconducting On-Chip Filter-Banks

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