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arXiv · 2604.26021

Near-field Meta-optics

Dongyoung Lee·Sehwan Kim·Jisoo Kyoung
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Abstract

Metasurfaces have revolutionized compact wavefront control using planar, subwavelength structures. However, conventional meta-optical devices predominantly operate within a far-field paradigm, assuming electromagnetic decoupling between the source and metasurface, which limits control to post-emission wavefront shaping. Here, we define and experimentally demonstrate near-field meta-optics - a regime where strong source - structure coupling enables simultaneous control of emission and radiation. By integrating an inverse-designed dielectric metasurface directly within the near field of a terahertz photoconductive antenna (PCA), we show that the metasurface co-defines the emission process itself. Our meta-PCA, incorporating a 50-um-high metasurface - one-third the thickness required by reciprocal far-field designs - collapses emission from ~60deg divergence to a sharp < 10deg forward beam, while enhancing on-axis intensity 50-fold compared to bare GaAs. Unlike far-field metasurfaces that typically trade efficiency for thinness while remaining laterally large, our device achieves extreme compactness in both dimensions. Remarkably, it exceeds the outcoupling efficiency of a bulky, millimeter-scale silicon lens by 10%, despite a volume reduction of over three orders of magnitude. These results establish near-field meta-optics as a transformative paradigm for developing high-efficiency, ultra-compact on-chip photonic systems across the electromagnetic spectrum.

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Dongyoung Lee, Sehwan Kim, Jisoo Kyoung. 2026-04-28. Near-field Meta-optics. https://arxiv.org/abs/2604.26021

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