Tunable plasmon-induced absorption in an integrated graphene nanoribbon side-coupled waveguide.

By designing a novel graphene plasmonic band-pass filter with two gold ribbons, we have numerically and analytically investigated the transmission properties of plasmon-induced absorption (PIA) in a compact graphene nanoribbon side-coupled waveguide. The formation and evolution of the PIA window are dependent on the superposition of super resonances and the near-field coupling intensity between the designed two resonators. Interestingly, the induced absorption window not only can be engineered longitudinally in intensity, but also dynamically tuned horizontally in the resonant wavelength by changing the Fermi energy of the graphene layers. Optical time delay near 1.0 ps can be realized in the PIA window, which exhibits excellent slow light features. Double PIA resonance is also discussed. This result may have potential applications in graphene plasmonic switching and buffering.