On-chip integration of achromatic metalens arrays.
basic_science · Level V
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- Record sourced from PubMed, PMID 40796744.
- Also identified by DOI 10.1038/s41467-025-62539-7 and PMC identifier 12343996.
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Abstract
Broadband achromatic metalenses and metalens arrays hold promise for enabling high-performance optical imaging in a compact form factor. Conventional visible-light achromatic metalenses are composed of transparent and high-refractive-index TiO<sub>2</sub> or GaN nanopillars, but are strongly limited in mainstream silicon-based complementary metal-oxide-semiconductor (CMOS) processes. Herein, we report the realization of high-efficiency Si<sub>3</sub>N<sub>4</sub> achromatic metalenses in the visible range and demonstrate their integration onto a commercial imaging chip. By improving nanofabrication techniques, we have dramatically increased the aspect ratio of Si<sub>3</sub>N<sub>4</sub> nanostructures from ~17 to a high value of 43.33. Consequently, the group delay of the Si<sub>3</sub>N<sub>4</sub> nanostructures is significantly increased and the averaged focusing efficiency of a Si<sub>3</sub>N<sub>4</sub> metalens with a numerical aperture of 0.155 reaches 80.39%. Owing to the CMOS-compatibility of Si<sub>3</sub>N<sub>4</sub>, such high-quality metalenses have been integrated with commercial imaging sensors and demonstrated the capability of full-color optical imaging. This research paves a critical step towards chip-integrated meta-devices.