Chip-integrated metasurface with double-helix point spread functions for ultra-large dynamic range wavefront sensing.

Area of Science:

• Optical Engineering
• Metasurface Technology
• Integrated Photonics

Background:

• Wavefront sensing is crucial for optical technologies but faces limitations in sensor size, dynamic range, and integration.
• Conventional Shack-Hartmann sensors have limited dynamic range and sampling density, and cannot resolve polarization.
• Current metasurface sensors require external optics, hindering on-chip integration and creating a dynamic range vs. sampling density trade-off.

Purpose of the Study:

• To present the first chip-integrated metasurface Shack-Hartmann sensor operating directly on a CMOS image sensor.
• To overcome the trade-off between dynamic range and sampling density in wavefront sensing.
• To enable vectorial wavefront sensing and on-chip optical metrology.

Main Methods:

• Developed a chip-integrated metasurface Shack-Hartmann sensor.
• Implemented a dual-encoding strategy using orientation-encoded double-helix point spread functions.
• Utilized orthogonal circular polarization channels with distinct lobe separations.

Main Results:

• Achieved an extended dynamic range of ±9.4° per channel without degrading sampling density.
• Doubled the sampling density using orthogonal polarization channels without sacrificing dynamic range.
• Demonstrated vectorial wavefront sensing capabilities.
• Successfully performed 3D point source localization, lens profilometry, and video-rate dynamic wavefront monitoring.

Conclusions:

• The presented sensor is the first chip-integrated metasurface Shack-Hartmann sensor operating directly on a CMOS image sensor.
• The dual-encoding strategy effectively extends dynamic range and enhances sampling density, overcoming previous limitations.
• This scalable platform enables alignment-free, high-performance metrology for diverse optical applications.