Metasurfaces for Bulk Suppression and Wavelength-Dependent Mid-Infrared Imaging

Metasurfaces have emerged as powerful platforms for manipulating light at the subwavelength scale, with promising applications in imaging, sensing, and on-chip photonics. However, extending their functionality into the mid-infrared (MIR) region remains challenging due to the strong phonon absorption of silicon dioxide (SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>). In this work, we present a grating-engineered metal-insulator-metal (MIM) metasurface that effectively suppresses the bulk absorption of SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and enhances plasmonic resonance in the MIR range. By introducing a grating structure into the nanorod antennas, we mitigate SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> phonon loss and achieve tunable, high-efficiency plasmonic absorption. This design not only preserves the advantages of wafer-scale fabrication but also enables wavelength-selective infrared imaging, as demonstrated through letter-pattern visualization. Our results provide a practical and scalable route for the development of high-performance MIR metasurfaces using standard semiconductor processes.