Strong coupling of double resonance designs and epsilon-near-zero modes for mode-matching enhancement of second-harmonic generation.

ABSTRACT: We investigate the coupling effects between a double-resonance split-ring resonators (SRRs) design and the epsilon-near-zero (ENZ) guided mode of ultrathin indium tin oxide (ITO) films on second-harmonic generation (SHG). The optimized SRRs with an aspect ratio of 0.3 support a magnetic dipole (MD) resonance within the ENZ regime of ITO and a higher-order resonance at the SH frequency to achieve mode matching under cross-polarized excitation. The SRR-ITO coupled system (as opposed to the nanorod-ITO coupled system) was found to perform constructive (destructive) polarization interference between the nonlinear polarization currents at the upper hybridized modes (ω⁺) and the linear electric field at SH frequency (2ω⁺), resulting in a 1218-fold SHG enhancement outperform

SUBMITTER: Liu AY 

PROVIDER: S-EPMC12714063 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature