Production-Ready Double-Sided Fabrication of Dual-Band Infrared Metaoptics Using Deep-Ultraviolet Lithography

Metaoptics, the application of metasurfaces into optical systems, is seeing an accelerating development owing to advantages in size, weight, and cost and the ability to program optical functions beyond traditional refractive optics. The transition of metaoptics from the laboratory into applications is enabled by scalable production methods based on highly reproducible semiconductor process technology. Here, we introduce a method for the fabrication of double-sided metasurfaces through deep-UV lithography as a production-ready method for achieving high-quality metaoptics. We achieve patterning of a silicon wafer on both sides with mutual alignment of around 10 μm based on tool accuracy without requiring through-wafer alignment markers other than the wafer notch. An application highlighting the benefits of double-sided design is demonstrated in the form of a dual-band metalens with independent control over focal lengths in mid- and long-wavelength infrared bands. Using multireticle stitching, we demonstrate a 40 mm diameter, large-area metalens with excellent broadband imaging performance, showing partial canceling of chromatic dispersion when used in a hybrid configuration with a BaF₂ refractive lens. Our work establishes a production-ready approach to infrared metaoptics designs and double-sided metaoptics fabrication with direct potential for translation into scalable technology for real-world applications.