Integrated astrophotonic phase control for high resolution optical interferometry

Ross Cheriton; Siegfried Janz; Glen Herriot; Jean-Pierre Véran; Brent Carlson

doi:10.1117/12.2630449

29 August 2022 Integrated astrophotonic phase control for high resolution optical interferometry

Ross Cheriton, Siegfried Janz, Glen Herriot, Jean-Pierre Véran, Brent Carlson

Proceedings Volume 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V; 121883J (2022) https://doi.org/10.1117/12.2630449
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

Long baseline optical interferometry and aperture synthesis using ground-based telescopes can enable unprecedented angular resolution astronomy in the optical domain. However, atmospheric turbulence leads to large, dynamic phase errors between participating apertures that limit fringe visibility using telescopes arrays or subaperture configurations in a single large telescope. Diffraction limited optics or adaptive optics can be used to ensure coherence at each aperture, but correlating the phase between apertures requires high speed, high stroke phase correction and recombination that is extremely challenging and costly. As a solution, we show an alternative phase correction and beam combination method using a centimeter-scale silicon astrophotonic chip optimized for H-band operation. The 4.7x10mm silicon photonic chip is fabricated using electron beam lithography with devices with 2 up to 32 independent channels. Light is coupled into the chip using single mode fiber ribbons. An array of microheaters is used to individually tune the effective index of each spiral delay waveguides. Narrowband spectral splitters at each spatial channel divert a modulated digital reference signal from an artificial guide star off-chip for phase measurement. Science light from other wavelengths is coherently combined using on-chip beam combiners and outputted to a single waveguide. We described the role, design, fabrication and characterization of the photonic chip. This photonic phase control scheme can be applied in astronomical interferometry or optical satellite communications.

Citation Download Citation

Ross Cheriton, Siegfried Janz, Glen Herriot, Jean-Pierre Véran, and Brent Carlson "Integrated astrophotonic phase control for high resolution optical interferometry", Proc. SPIE 12188, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V, 121883J (29 August 2022); https://doi.org/10.1117/12.2630449

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