Polarization-independent infrared micro-lens array based on all-silicon metasurfaces

Area of Science:

• Optics and Photonics
• Metamaterials
• Infrared Technology

Background:

• Micro-lens arrays are crucial for long-wavelength infrared (LWIR) thermal optics applications like wavefront sensing and beam shaping.
• Electromagnetic metasurfaces offer a novel approach for creating high-performance, compact optical elements.

Purpose of the Study:

• To experimentally demonstrate a polarization-independent LWIR micro-lens array using all-silicon metasurfaces.
• To evaluate the performance of individual micro-metalenses in terms of focusing capabilities.

Main Methods:

• Fabrication of a 60 × 60 transmissive micro-lens array using all-silicon metasurfaces.
• Characterization of individual micro-metalenses with a pitch of 100 μm and focal length of 100 μm at a wavelength of 10.6 μm.
• Utilizing single-step photolithography and integrated circuit (IC) compatible processes.

Main Results:

• Demonstration of a polarization-independent LWIR micro-lens array with a fill factor near 100%.
• Each micro-metalens achieved focusing to a spot with a full-width at half-maximum (FWHM) of approximately 1.2λ (12.7 μm) at the focal plane.
• The fabrication process is compatible with standard integrated circuit manufacturing.

Conclusions:

• Metasurface-based LWIR micro-lens arrays are a viable technology for advanced optical systems.
• The demonstrated arrays show significant potential for integration into compact thermal imaging systems.
• The polarization-independent nature and fabrication compatibility enhance their practical applicability.