Lattice-mediated high-Q dielectric metasurface for near-infrared sensing

Achieving ultrahigh-Q resonances in all-dielectric metasurfaces remains challenging, as conventional electromagnetically induced transparency (EIT) designs rely primarily on intra-unit-cell bright-dark mode coupling and overlook the role of lattice-level interactions. Here, we demonstrate a lattice-mediated, phase-retarded coupling mechanism that introduces a previously unexplored channel for suppressing radiative loss and sharpening the transmission resonance. Tailoring the lattice constant and polarization direction reveals a strong lattice asymmetry effect, where the directional perturbation further enhances dark-mode reinforcement. The mechanism achieves an ultrahigh Q-factor of 1580, near-unit transmission, and a figure of merit of 284 in EIT-type dielectric metasurface sensors for near-infrared refractive-index sensing. This work establishes a distinct and generalizable design pathway for low-loss resonant metasurfaces, with broad implications for compact NIR photonics, biosensing, gas detection, LiDAR, and surveillance systems.