High‐Density Pixelated Metasurfaces for Terahertz Hyperspectral Imaging

Metasurface-enabled terahertz imaging and spectroscopy are moving toward compact, high-throughput systems, but current approaches remain limited by discrete spectral sampling, computational reconstruction, and the trade-off between spatial resolution and resonance quality in nonlocal designs. Here, we introduce a fundamentally different paradigm based on photonic crystal heterojunction-enabled pixelated metasurfaces that directly encode spatial information into spectrally resolved, high-quality-factor resonances. By embedding bound-state-in-the-continuum metapixels within a bandgap-engineered heterostructure, we simultaneously suppress lateral leakage and control vertical radiation, enabling effective three-dimensional photon confinement in finite metasurfaces. This mechanism overcomes the conventional dependence of resonance quality on pixel size, yielding enhanced quality factors and figure of merit without increasing the device footprint, and enabling metapixels with lateral dimensions of ∼2λ that retain high spectral fidelity and signal-to-noise ratio. Leveraging this capability, we realize a 3 × 3 pixelated metasurface supporting nine independently addressable resonances, all retrieved in a single-shot broadband terahertz measurement. The resulting spectral-spatial encoding strategy establishes a direct one-to-one mapping between resonance signatures and spatial pixels, enabling hyperspectral imaging with a single-pixel detector and a THz pulse, without raster scanning or algorithmic inversion. These results provide a scalable route toward real-time terahertz imaging and integrated photonic sensing.