Abstract
Plasmonic structures have been revealed as efficient units to enhance localized nonlinear phenomena generated at dielectric–metal interfaces. However, their effect on the nonlinear interactions provided by quasi-phase matching processes in χ(2) modulated dielectric crystals have been scarcely addressed, mainly due to the complexity in manufacturing appropriate periodic plasmonic structures overlying the χ(2) dielectric structure. Here, by a simple method we have fabricated a periodic structure based on the combination of two commensurate lattices: a periodic lattice of chains of Ag nanoparticles and a periodic lattice of χ(2)-modulation based on a ferroelectric domains structure. The hybrid system supports multiple surface plasmon lattice resonances (SLRs) at the technologically relevant NIR spectral region, which yield the enhancement of the nonlinear diffraction pattern generated by the χ(2) structure. The superposition of the plasmonic and the χ(2)-modulation lattice results in a 20-fold enhancement of the directional SHG due to the excitation of SLRs by the interacting waves involved in the nonlinear process. The results are obtained in lithium niobate, a widely used crystal in optoelectronics, and demonstrate the potential of the approach to design integrated solid-state platforms for on-chip optical steering, multiplexing or quantum technologies.
Highlights
Plasmonic structures have been revealed as efficient units to enhance localized nonlinear phenomena generated at dielectric−metal interfaces
In addition to the localized enhancement of the NL response at the metal−nonlinear dielectric interface, plasmonic lattices placed on the surface of ferroelectric domain patterns can allow the interaction of plasmonic surface lattice resonances (SLRs) with the waves participating in the NL processes generated at the χ(2) dielectric crystal
We investigate the effect of surface plasmon lattice resonances (SLRs) supported by periodic arrays of linear chains and hexagonal necklaces of Ag NPs on the NL diffraction pattern of nonlinear photonic crystals (NLPC) based on periodically poled lithium niobate, a widespread used dielectric material in advanced photonics and optoelectronics.[33−36] On the one hand, we experimentally and theoretically demonstrate the presence of multiple SLRs in the near-infrared (NIR) spectral region due to the collective optical response sustained by periodical arrays of linear chains of interacting Ag NPs
Summary
Plasmonic structures have been revealed as efficient units to enhance localized nonlinear phenomena generated at dielectric−metal interfaces. In addition to the localized enhancement of the NL response at the metal−nonlinear dielectric interface, plasmonic lattices placed on the surface of ferroelectric domain patterns can allow the interaction of plasmonic surface lattice resonances (SLRs) with the waves participating in the NL processes generated at the χ(2) dielectric crystal. This can lead to new integrated NL platforms for enhancing and shaping light in specific directions, as required for scientific and technological applications. The experiments were carried out at normal incidence for a fundamental beam of 800 nm
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