Analogy of plasmon induced transparency in detuned U-resonators coupling to MDM plasmonic waveguide

• A simplified Coupled-Mode theory model is used to demonstrate the PIT-like effect in coupled MDM waveguide system theoretically.
• The wavelength detuning δ for detuned U-resonators is introduced qualitatively to discuss the optical property.
• The sensitivity of wavelength and the trade-off between Q-factor and transmission maxima resulting from the structure detuning are observed.
• The observed group index guarantees a slow light effect and may have potential application in optical buffer.

We provide an investigation on the analogy of plasmon induced transparency (PIT) in plasmonic waveguide numerically and theoretically. A simplified Coupled-Mode theory model is used to demonstrate the PIT-like effect in a system consisting of two detuned U-resonators (DURs) back coupled to a metal–dielectric–metal (MDM) waveguide. The detuned wavelength δ is introduced by the simplified model qualitatively due to the structural design. The sensitivity of wavelength and the trade-off between Q-factor and transmission maxima are considered. Finally, the observed slow light effect in our system guarantees a low group velocity which has potential application in nano-filter and optical buffer.