Experimental demonstration of photonic phase correctors based on grating coupler arrays and thermo-optic shifters

In ground-based astronomy, the ability to couple light into single-mode fibers (SMFs) is limited by atmospheric turbulence, which prohibits the use of many astrophotonic instruments. We propose a silicon-on-insulator photonic chip capable of coherently coupling the out-of-phase beamlets from the sub...

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Bibliographic Details
Published in:arXiv.org 2024-08
Main Authors: Diab, Momen, Cheriton, Ross, Taylor, Jacob, Patel, Dhwanil, Rojas, Libertad, Barnet, Mark, Zavyalova, Polina, Dan-Xia, Xu, Cheben, Pavel, Janz, Siegfried, Schmid, Jens H, Sivanandam, Suresh
Format: Article
Language:English
Subjects:
Adaptive optics
Arrays
Astronomical instruments
Astronomy
Atmospheric turbulence
Couplers
Deformable mirrors
Formability
Integrated circuits
Phase measurement
Photonics
Propagation modes
Refractivity
Wave front sensors
Wave fronts
Wave propagation
Waveguides
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Summary:In ground-based astronomy, the ability to couple light into single-mode fibers (SMFs) is limited by atmospheric turbulence, which prohibits the use of many astrophotonic instruments. We propose a silicon-on-insulator photonic chip capable of coherently coupling the out-of-phase beamlets from the subapertures of a telescope pupil into an SMF. The photonic integrated circuit (PIC) consists of an array of grating couplers that are used to inject light from free space into single-mode waveguides on the chip. Metallic heaters modulate the refractive index of a coiled section of the waveguides, facilitating the co-phasing of the propagating modes. The phased beamlets can then be coherently combined to efficiently deliver the light to an output SMF. In an adaptive optics (AO) system, the phase corrector acts as a deformable mirror (DM) commanded by a controller that takes phase measurements from a wavefront sensor (WFS). We present experimental results for the PIC tested on an AO testbed and compare the performance to simulations.
ISSN:2331-8422