2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/24493We have derived the local electric field inside graded metal-dielectric composite films with weak nonlinearity analytically, which further yields the effective linear dielectric constant and third-order nonlinear susceptibility of the graded structures. As a result, the composition-dependent gradation can produce a broad resonant plasmon band in the optical region, resulting in a large enhancement of the optical nonlinearity and hence a large figure of merit.11 pages, 2 figures. To be published in Europhysics LettersMaterials ScienceOpticstext