Quadratic phase matching in nonlinear plasmonic nanoscale waveguides

Area of Science:

• * Photonics and Plasmonics
• * Nonlinear Optics

Background:

• * Metal-dielectric nanostructures support highly localized surface plasmon polariton (SPP) modes.
• * Achieving efficient nonlinear optical processes like second-harmonic generation (SHG) often requires phase matching.
• * Traditional phase matching methods are challenging in plasmonic systems due to strong mode confinement and dispersion.

Purpose of the Study:

• * To investigate the feasibility of quadratic phase matching in metal-dielectric nonlinear structures supporting SPP modes.
• * To explore the potential for achieving efficient second-harmonic generation (SHG) in planar waveguide geometries.
• * To analyze the interaction of plasmon modes with different symmetries for nonlinear frequency conversion.

Main Methods:

• * Theoretical analysis of phase matching conditions in metal-dielectric waveguide structures.
• * Modeling of highly localized plasmon polariton modes.
• * Simulation of nonlinear optical processes, specifically second-harmonic generation (SHG).

Main Results:

• * Quadratic phase matching is shown to be achievable between plasmon modes of different symmetries in planar waveguide configurations.
• * Demonstration of second-harmonic generation (SHG) using interacting plasmonic modes within a nonlinear LiNbO(3) waveguide sandwiched between silver plates.
• * Identification of specific waveguide geometries that facilitate efficient nonlinear frequency conversion via SPP modes.

Conclusions:

• * Planar metal-dielectric waveguide structures offer a viable platform for achieving quadratic phase matching in plasmonic systems.
• * Efficient second-harmonic generation (SHG) is possible through the interaction of tailored plasmon polariton modes.
• * This work opens avenues for novel nonlinear photonic devices based on plasmonics.