Work

Evanescent field-induced breakdown of quasi-static nonlinear effective medium theory at deep-subwavelength scales

Year: 2026

Type: article

Abstract: Deep-subwavelength, dilute, weakly nonlinear dielectric composites are widely assumed to obey the nonlinear Maxwell-Garnett effective medium theory (NMGT). Here, we demonstrate that evanescent fields can cause NMGT breakdown at deep-subwavelength scales. We show that strong evanescent fields near linear dielectric components, even at λ 0 /100 scale, create local optical hotspots and zero-field regions. When nonlinear components are positioned within these regions, the composite’s nonlinear response becomes highly sensitive to component placement, a behavior that conventional NMGT fails to capture due to its averaging approximation. We overcome this limitation by developing a semi-analytic corrected NMGT that incorporates evanescent-field effects in dilute, weakly nonlinear composites. By harnessing these evanescent fields, we further demonstrate a nonlinear quenching effect and design a metamaterial with extreme nonlinear anisotropy. Our findings unveil the mechanisms underlying NMGT breakdown at deep-subwavelength scales and enable new strategies for nonlinear optical engineering.

Source: Optics Express

DOI: 10.1364/oe.586618

Authors: Fengchuan Xu, Chenglin Wang, Lei Gao, Andrey Novitsky, Jie Luo

Institutions: Belarusian State University, Soochow University

Language: English

Topic: Metamaterials and Metasurfaces Applications

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,270

Funders: National Natural Science Foundation of China, Natural Science Foundation of Jiangsu Province