Nonlocal optical response in asymmetric IMI plasmonic waveguides.

In this paper, we investigate the nonlocal optical response of surface-plasmon polaritons (SPPs) in an asymmetric insulator-metal-insulator (A-IMI) waveguide, in which the two insulator materials have different permittivities. A nonlocal dispersion relation of SPPs in A-IMI waveguides is derived based on the generalized nonlocal response (GNOR) model including quantum pressure effects and induced charge diffusion kinetics in metal film, from which one can see that the nonlocal effects result in not only the disappearance of double-peak and step-like behaviors in the dispersion relation of A-IMI waveguides occurring at local response approximation, but also an obvious frequency blueshift and a loss enhancement. Furthermore, the influence of electron diffusion on the dispersion relation under different diffusion constants in the GNOR model as well as the variation in propagation length and penetration depth of SPPs with metal film thickness and frequency are provided, which are helpful to the future development of plasmonic waveguides. • A nonlocal dispersion relation of SPPs in A-IMI waveguides has been derived based on the GNOR model including quantum pressure effects and induced charge diffusion kinetics in metal film. • The nonlocal effects result in not only the disappearance of double-peak and step-like behaviors in the dispersion relation of A-IMI waveguides occurring at local response approximation, but also an obvious frequency blueshift and a loss enhancement. • The influence of electron diffusion on the dispersion relation under different diffusion constants in the GNOR model as well as the variation in propagation length and penetration depth of SPPs with metal film thickness and frequency are provided, which are helpful to the development of ultra-compact plasmonic waveguides. [ABSTRACT FROM AUTHOR]