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Three-dimensional (3D) plasmonic metamaterials, featuring well-arranged subwavelength nanostructures, facilitate effective coupling between electrical dipoles and incident electromagnetic waves. This coupling allows for unique optical responses including localized surface plasmon resonance (LSPR) and quasi-bound states in the continuum (q-BIC). While 3D plasmonic metamaterials with LSPR and q-BIC have been independently explored for sensors, achieving simultaneous optical responses in the near-infrared region remains challenging. Here, we present 3D plasmonic metamaterials that integrate LSPR and q-BIC within a single π-shaped plasmonic structure, fabricated using a 3D aerosol nanoprinting technique. This printing technique controls the local electrostatic field to precisely position charged metallic nanoaerosols, enabling parallel printing of π-shaped plasmonic structures under ambient conditions. The printed π-shaped plasmonic structures exhibit two distinct optical modes: x-polarization-sensitive LSPR and transverse magnetic mode-sensitive q-BIC within the near-infrared region. Exploiting these dual optical responses, we demonstrate simultaneous polarization detection and incident angle analysis by integrating the π-shaped plasmonic structures into commercial Fourier-transform infrared spectroscopy, termed "numerical aperture-detective polarimetry". This approach holds promise for evaluating alignment in optical and imaging systems with light distribution analysis. Furthermore, the 3D aerosol nanoprinting technique provides an avenue for fabricating 3D plasmonic metamaterials with intricate geometries and optical properties, expanding their potential applications in nano-optics.
Yang et al. (Mon,) studied this question.