All-optical tunable notch filter by use of Kerr nonlinearity in the graphene microribbon array

We report a numerical study on the optical tuning of a notch filter comprised of an array of engineered graphene microribbons. The notch on the normal incidence transmission spectra is created due to light-plasmon coupling in graphene. Besides investigating the effect of structural parameters and electrostatic gating on the graphene plasmon excitation, we particularly examine the modulation of transmission with incident light intensity based on the significant optical Kerr effect in graphene. Our numerical simulation with the finite difference time domain numerical method reveals that considerable variation in the transmission up to 12.15 dB can be effectively achieved by increasing the irradiance intensity up to 0.68 MW/cm(2), which is adequately below the graphene threshold damage. The presence of well-known techniques to fabricate and characterize graphene sheets such as chemical vapor deposition and Raman spectroscopy makes such a one-atom-thick terahertz filter feasible. (C) 2014 Optical Society of America