Imaging of exposed and occluded objects with dark-state resonant photonic lattices

Resonant photonic lattices are implemented as subwavelength periodic structures in low-loss dielectric media. Often referenced as metamaterials or metasurfaces, resonant lattices support lateral Bloch modes and prominent field signatures with propagative and evanescent diffraction channels controlling their response. With proper lattice geometry and dielectric properties, there appear resonant bright channels and non-resonant dark channels in the spectra. The bright channel corresponds to a guided-mode resonance (GMR), whereas the dark channel represents a bound state in the continuum (BIC). Characteristic dark-state resonance signatures appear with primary emission in reflection or in transmission. Here, we present new, to the best of our knowledge, imaging concepts enabled by dark-state photonic lattices that are non-resonant in the absence of signal illumination. Dark-state photonic lattices imaging works by object-induced imbalance that generates local asymmetric guided-mode resonance (aGMR) populating pertinent radiation channels. We refer to this principle as "edge-mode resonance" [Opt. Lett.50, 81 (2025)10.1364/OL.541674]. By numerical modeling, we demonstrate dark-lattice imaging of metallic amplitude objects and dielectric phase objects. Moreover, imaging of an occluded phase object under a metal shield is shown. These conceptual studies and results may stimulate new modalities of imaging and feature extraction with metamaterials based on modal resonance state transitions.