Towards a photonic mid-infrared nulling interferometer in chalcogenide glass

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Nulling interferometry enables astronomers to advance beyond the resolving power of ground-based telescopes with the goal of directly detecting exo-planets. By diminishing the overwhelming emission of the host star through destructive interference, radiation from young companions can be observed. The atmospheric transmission window centered around 4 µm wavelength is of particular interest because it has a favorable contrast between star and planet as well as a reduced atmospheric disturbance. For robustness and high stability, it is desirable to employ integrated devices based on optical waveguide technology. Their development is hindered at this wavelength range due to the lack of suitable host materials and compatible fabrication techniques to create low-loss photonic devices. This paper details our work on femtosecond laser direct-written optical waveguides and key components for an on-chip nulling interferometer inside gallium lanthanum sulphur glass. By combining cumulative heating fabrication with the multiscan technique, single-mode optical waveguides with propagation losses as low as 0.22 ± 0.02 dB/cm at 4 µm and polarization-dependent losses of < 0.1 dB/cm were realized. Furthermore, S-bends with negligible bending loss and broadband Y-splitters with 50/50 power division across a 600 nm wavelength window (3.6 - 4.2 µm) and low losses of < 0.5 dB are demonstrated. Directional couplers with an equal splitting ratio complement these main building blocks to create a future compact nulling interferometer with a total projected intrinsic loss of < 1 dB, a value that is sufficient to perform future on-sky experiments in relatively short observation runs on ground-based telescopes.

LanguageEnglish
Pages8626-8638
Number of pages13
JournalOptics Express
Volume27
Issue number6
DOIs
Publication statusPublished - 18 Mar 2019

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infrared interferometers
photonics
glass
optical waveguides
planets
interferometers
wavelengths
telescopes
stars
fabrication
directional couplers
lanthanum
complement
division
gallium
sky
interferometry
disturbances
sulfur
chips

Bibliographical note

Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Cite this

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abstract = "Nulling interferometry enables astronomers to advance beyond the resolving power of ground-based telescopes with the goal of directly detecting exo-planets. By diminishing the overwhelming emission of the host star through destructive interference, radiation from young companions can be observed. The atmospheric transmission window centered around 4 µm wavelength is of particular interest because it has a favorable contrast between star and planet as well as a reduced atmospheric disturbance. For robustness and high stability, it is desirable to employ integrated devices based on optical waveguide technology. Their development is hindered at this wavelength range due to the lack of suitable host materials and compatible fabrication techniques to create low-loss photonic devices. This paper details our work on femtosecond laser direct-written optical waveguides and key components for an on-chip nulling interferometer inside gallium lanthanum sulphur glass. By combining cumulative heating fabrication with the multiscan technique, single-mode optical waveguides with propagation losses as low as 0.22 ± 0.02 dB/cm at 4 µm and polarization-dependent losses of < 0.1 dB/cm were realized. Furthermore, S-bends with negligible bending loss and broadband Y-splitters with 50/50 power division across a 600 nm wavelength window (3.6 - 4.2 µm) and low losses of < 0.5 dB are demonstrated. Directional couplers with an equal splitting ratio complement these main building blocks to create a future compact nulling interferometer with a total projected intrinsic loss of < 1 dB, a value that is sufficient to perform future on-sky experiments in relatively short observation runs on ground-based telescopes.",
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Towards a photonic mid-infrared nulling interferometer in chalcogenide glass. / Gretzinger, Thomas; Gross, Simon; Arriola, Alexander; Withford, Michael J.

In: Optics Express, Vol. 27, No. 6, 18.03.2019, p. 8626-8638.

Research output: Contribution to journalArticleResearchpeer-review

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AU - Gretzinger, Thomas

AU - Gross, Simon

AU - Arriola, Alexander

AU - Withford, Michael J.

N1 - Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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Y1 - 2019/3/18

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