Building hybridized 28-baseline pupil-remapping photonic interferometers for future high resolution imaging

TL;DR

This paper presents the development of a novel hybridized 8-input photonic interferometer, 'Dragonfly', capable of high-resolution imaging with stable closure-phase, suitable for future large telescopes and high-contrast astronomical observations.

Contribution

The paper introduces the first hybridized 8-input photonic interferometer with 28 baselines, integrating 3D pupil remapping and planar beam combining in a monolithic device.

Findings

Achieved a raw closure-phase stability of 0.9 degrees

Demonstrated detection contrast of approximately 6.5×10^{-4}

Successfully integrated complex photonic components into a single device

Abstract

One key advantage of single-mode photonic technologies for interferometric use is their ability to easily scale to an ever increasing number of inputs without a major increase in the overall device size, compared to traditional bulk optics. This is particularly important for the upcoming ELT generation of telescopes currently under construction. We demonstrate the fabrication and characterization of a novel hybridized photonic interferometer, with 8 simultaneous inputs, forming 28 baselines, the largest amount to-date. Utilizing different photonic fabrication technologies, we combine a 3D pupil remapper with a planar 8-port ABCD pairwise beam combiner, along with the injection optics necessary for telescope use, into a single integrated monolithic device. We successfully realized a combined device called Dragonfly, which demonstrates a raw instrumental closure-phase stability down to $0.9^{\circ}$ over $8\pi$ phase piston error, relating to a detection contrast of $\sim6.5\times 10^{-4}$ on an Adaptive-Optics corrected 8-m telescope. This prototype successfully demonstrates advanced hybridization and packaging techniques necessary for on-sky use for high-contrast detection at small inner working angles, ideally complementing what can currently be achieved using coronagraphs.