Enhanced optical transmission of non-coaxial double-layer gold nano-slit with slanted sidewall arrays

► We study the optical transmission on a slit with slanted sidewall arrays. ► There mainly exist three resonant peaks. ► The transmission spectra are strongly influenced by configuration parameters. ► The two short wavelength resonant peaks are characterized as the surface plasmon resonance. ► The long wavelength resonant peak is characterized as the localized waveguide resonance.