Si-Photonic Waveguide Grating Coupler Arrays for Wavefront Monitoring

A silicon photonic wavefront monitoring chip may be designed using arrays of surface grating couplers. Such a chip can monitor wavefront distortion across a pupil plane in adaptive optics systems for free space optical communications and astronomy. This paper reports experimental results for grating pair wavefront monitor elements intended as building blocks for such an array. Wavefront tilt signals of 6 dB/degree and 10 dB/degree, respectively, are measured for grating pairs arranged in power ratio and interferometric configurations.