Intrapulse multimodal four-wave sum mixing in the visible range from high contrast index grating with PMMA layer.

ABSTRACT: Nonlinear metasurfaces have emerged as powerful platforms for enhancing and controlling light-matter interactions at the nanoscale, enabling versatile and compact design of devices for frequency conversion processes. In this work, we report on the experimental observation and theoretical analysis of intrapulse four-wave sum mixing (FWSM) in a high-index contrast grating (HCG) supporting quasi-bound states in the continuum (q-BIC). By engineering a one-dimensional silicon-based HCG with an additional poly(methyl methacrylate) (PMMA) cladding layer, we achieve the simultaneous excitation of a q-BIC and a guided-mode resonance (GMR), enabling nonlinear coupling between the two modes. Broadband femtosecond excitation reveals multiple distinct spectral peaks in the visible range, attributed to

SUBMITTER: Franceschini P 

PROVIDER: S-EPMC12765861 | biostudies-literature | 2026 Jan

REPOSITORIES: biostudies-literature