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Optical wavefront phase-tilt measurement using Si-photonic waveguide grating couplers
Optics Letters
|December 1, 2023
Summary
Silicon photonic sensors use grating arrays to monitor wavefront tilt and phase. These compact sensors offer high sensitivity for adaptive optics in communications and astronomy.
Area of Science:
- Photonics and Optical Engineering
- Adaptive Optics Systems
Background:
- Wavefront monitoring is crucial for adaptive optics (AO) systems.
- Existing wavefront sensors often rely on bulky optical components.
Purpose of the Study:
- To demonstrate silicon photonic sensors for wavefront phase and tilt monitoring.
- To develop compact, chip-based sensor elements for AO applications.
Main Methods:
- Utilizing surface coupling grating arrays on silicon photonic chips.
- Employing grating coupling efficiency's angle dependence for tilt sensing (7 dB/° sensitivity).
- Integrating gratings in an interferometric waveguide circuit for phase variation measurement (2° tilt per fringe).
Main Results:
- Demonstrated silicon photonic wavefront phase-tilt sensors with high sensitivity.
- Achieved compact sensor elements (<60 µm) suitable for large arrays.
- Eliminated the need for bulk optics, fiber arrays, or imaging arrays.
Conclusions:
- These silicon photonic sensors are effective for wavefront monitoring.
- They are suitable as unit cells for large-scale wavefront sensing in AO systems.
- Potential applications include free-space optical communications, astronomy, and beam pointing.

