Spatiotemporally Modulated Nonlocal Metasurfaces: Walking the Dispersion Curve.

Shilkin, Daniil A; Paniagua-Domínguez, Ramón; Ha, Son Tung; Kuznetsov, Arseniy I · Nano Lett · 2026

basic_science · Level V

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Abstract

Interaction of light with spatiotemporally modulated structures enables dynamic transformation of both the momentum and frequency of light. However, the efficiency of a single-step transformation is limited by the strength of the perturbation. Here, we use a nonlocal mode in a semiconductor metasurface, modulated by two pump beams shifted relative to each other in both space and time, to demonstrate a ladder process─momentum conversion followed by frequency conversion─thus allowing the system to walk along its dispersion curve. Our results highlight both the prospects and the challenges of realizing a multistep frequency conversion cascade in optics.