Nonlocal Electro-Optic Metasurface Modulator using <em>Q</em>-Tuned Dimerized Nanometallic Grating

Electro-optic metasurface modulators are attracting increasing interest for spatiotemporal applications, including high-speed imaging, free-space optical communication, and diffractive computing. In this paper, we demonstrate high-speed nonlocal metasurface modulators utilizing a single-layer dimerized nanometallic grating integrated with an organic electro-optic material. By introducing a symmetry-breaking perturbation to the grating spacings, we achieve systematic tuning of the resonance quality (Q) factor across a broad spectral range from 1350 to 1450 nm. As a result, we obtain a record-high Q factor of 570, along with a large modulation depth exceeding 50% through precise Q tuning to satisfy the critical-coupling condition. The measured 3-dB modulation bandwidth reaches 650 MHz for a 150-μm-square device, which is currently limited by the RC time constant and should scale to tens-of-GHz regime with reduced device dimensions. Owing to its simple single-layer structure and spatially scalable surface-normal configuration, the demonstrated platform offers a promising pathway toward compact and high-speed free-space electro-optic modulators.