GLINT South: A photonic nulling interferometer pathfinder at the Anglo-Australian Telescope for high contrast imaging of substellar companions

Lagadec, Tiphaine; Norris, Barnaby; Gross, Simon; Arriola, Alexander; Gretzinger, Thomas; Cvetojevic, Nick; Lawrence, Jon; Withford, Michael J.; Tuthill, P. G.

doi:10.1117/12.2313171

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…The GLINT programme has two prototype instruments. One is now permanently installed at the 8-m Subaru Telescope in Hawaii, (Norris et al 2020; Martinod et al 2021a) referred as GLINT (or GLINT North), and one as a testbed in Australia, referred to as GLINT South (Lagadec et al 2018). This paper concentrates on the latter.…”

Section: The Glint South Instrumentmentioning

confidence: 99%

The GLINT South testbed for nulling interferometry with photonics: Design and on-sky results at the Anglo-Australian Telescope

Lagadec

Norris

Gross

et al. 2021

Publ. Astron. Soc. Aust.

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In 1978, Bracewell suggested the technique of nulling interferometry to directly image exoplanets which would enable characterisation of their surfaces, atmospheres, weather, and possibly determine their capacity to host life. The contrast needed to discriminate starlight reflected by a terrestrial-type planet from the glare of its host star lies at or beyond a forbidding $10^{-10}$ for an exo-Earth in the habitable zone around a Sun-like star at near-infrared wavelengths, necessitating instrumentation with extremely precise control of the light. Guided Light Interferometric Nulling Technology (GLINT) is a testbed for new photonic devices conceived to overcome the challenges posed by nulling interferometry. At its heart, GLINT employs a single-mode nulling photonic chip fabricated by direct-write technology to coherently combine starlight from an arbitrarily large telescope at 1 550 nm. It operates in combination with an actuated segmented mirror in a closed-loop control system, to produce and sustain a deep null throughout observations. The GLINT South prototype interfaces the 3.9-m Anglo-Australian Telescope and was tested on a sample of bright Mira variable stars. Successful and continuous starlight injection into the photonic chip was achieved. A statistical model of the data was constructed, enabling a data reduction algorithm to retrieve contrast ratios of about $10^{-3}$ . As a byproduct of this analysis, stellar angular diameters that were below the telescope diffraction limit ( $\sim$ 100 mas) were recovered with 1 $\sigma$ accuracy and shown to be in agreement with literature values despite working in the seeing-limited regime. GLINT South serves as a demonstration of the capability of direct-write photonic technology for achieving coherent, stable nulling of starlight, which will encourage further technological developments towards the goal of directly imaging exoplanets with future large ground based and space telescopes.

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Section: The Glint South Instrumentmentioning

confidence: 99%

The GLINT South testbed for nulling interferometry with photonics: Design and on-sky results at the Anglo-Australian Telescope

Lagadec

Norris

Gross

et al. 2021

Publ. Astron. Soc. Aust.

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“…A nulling interferometer is an offshoot of the technique described above, where an extra phase delay of π is added to one of the two combining beams to create destructive interference of the central source (e.g., a bright star), making any off-center source visible (e.g., a planet). A photonic nulling interferometer called GLINT has recently been demonstrated which can be used for observing exoplanets, possibly able to measure their spectra in the future [53]. A current analogue which offers these functionalities (R ∼ 20, 500, 4000 and angular resolution of tens of milliarcseconds in the K-band) is the GRAVITY instrument-a VLT interferometer [54][55][56].…”

Section: Interferometrymentioning

confidence: 99%

Astrophotonic Spectrographs

2019

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Astrophotonics is the application of photonic technologies to channel, manipulate, and disperse light from one or more telescopes to achieve scientific objectives in astronomy in an efficient and cost-effective way. Utilizing photonic advantage for astronomical spectroscopy is a promising approach to miniaturizing the next generation of spectrometers for large telescopes. It can be primarily attained by leveraging the two-dimensional nature of photonic structures on a chip or a set of fibers, thus reducing the size of spectroscopic instrumentation to a few centimeters and the weight to a few hundred grams. A wide variety of astrophotonic spectrometers is currently being developed, including arrayed waveguide gratings (AWGs), photonic echelle gratings (PEGs), and Fourier-transform spectrometer (FTS). These astrophotonic devices are flexible, cheaper to mass produce, easier to control, and much less susceptible to vibrations and flexure than conventional astronomical spectrographs. The applications of these spectrographs range from astronomy to biomedical analysis. This paper provides a brief review of this new class of astronomical spectrographs.Appl. Sci. 2019, xx, 5 2 of 18 of the telescope), creating new challenges for instrumentation [7]. At the same time, there is an explosion in the number of large astronomical surveys discovering a multitude of new transients, exoplanets, and galaxies. This necessitates development of new instruments for large telescopes that are compact and cost-effective while providing the flexibility to address the challenge of high-throughput characterization for these large surveys.Photonic technologies provide a promising platform for building next-generation instruments that are flexible (in terms of light manipulation), compact (volumes of a few tens of cubic centimetres) and lightweight (a few hundreds of grams), thanks to manipulation of guided light [8,9]. In addition, they are cost-effective, due to the advantages of mass-fabrication. Therefore, the astronomical community has pursued this direction very positively and built a wide variety of instruments from the near-ultraviolet (NUV) [10] to mid-infrared (MIR) wavebands [11]. As an example of the growth of astrophotonics, Figure 1 shows the number of citations of papers related to astrophotonic spectrographs. However, the current technical know-how is still far from complete or ideal, leaving many challenges that will likely be addressed in the near future.In this paper, we focus on the recent developments in the field of astrophotonic spectrographs. To paint a complete picture, in Sections 2 and 3, respectively, we briefly discuss the steps to channel the light from the telescope to the spectrograph and condition it. Photonic dispersion concepts, and their implementation and challenges are described in Section 4. In Section 5, we discuss new developments in calibration and detection that are particularly of interest to astrophotonic spectrographs. Lastly, in Section 6, we summarize and discuss the impact of photonic spectrogr...

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“…The application of this technique to high contrast imaging has previously been demonstrated in conventional (non-nulling) interferometry in the Dragonfly project (Jovanovic et al 2012;Norris et al 2014) upon which this new instrument builds. The GLINT instrument presented here is closely linked to its sister project 'GLINT South' (Lagadec et al 2018), which is demonstrating the same photonic nulling technology on a non-AO corrected telescope (the 3.9 m Anglo-Australian Telescope in Australia).…”

Section: Introductionmentioning

confidence: 96%

First on-sky demonstration of an integrated-photonic nulling interferometer: the GLINT instrument

Norris

Cvetojevic

Lagadec

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The characterisation of exoplanets is critical to understanding planet diversity and formation, their atmospheric composition and the potential for life. This endeavour is greatly enhanced when light from the planet can be spatially separated from that of the host star. One potential method is nulling interferometry, where the contaminating starlight is removed via destructive interference. The GLINT instrument is a photonic nulling interferometer with novel capabilities that has now been demonstrated in onsky testing. The instrument fragments the telescope pupil into sub-apertures that are injected into waveguides within a single-mode photonic chip. Here, all requisite beam splitting, routing and recombination is performed using integrated photonic components. We describe the design, construction and laboratory testing of our GLINT pathfinder instrument. We then demonstrate the efficacy of this method on sky at the Subaru Telescope, achieving a null-depth precision on sky of ∼ 10 −4 and successfully determining the angular diameter of stars (via their null-depth measurements) to milliarcsecond accuracy. A statistical method for analysing such data is described, along with an outline of the next steps required to deploy this technique for cutting-edge science.

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GLINT South: A photonic nulling interferometer pathfinder at the Anglo-Australian Telescope for high contrast imaging of substellar companions

Cited by 11 publications

References 10 publications

The GLINT South testbed for nulling interferometry with photonics: Design and on-sky results at the Anglo-Australian Telescope

The GLINT South testbed for nulling interferometry with photonics: Design and on-sky results at the Anglo-Australian Telescope

Astrophotonic Spectrographs

First on-sky demonstration of an integrated-photonic nulling interferometer: the GLINT instrument

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