Nonlinearity modulation based multiple Fano resonance and multi-spectral switching in a nanoplasmonic waveguide-coupled cavity system

Abstract

Dual and multiple asymmetric Fano resonance are theoretically explored in a subwavelength plasmonic cavity-coupled waveguide system incorporated with a third order Kerr nonlinear medium. The degree of asymmetry and the number of multiple resonances are controlled by an external pump beam which modulates the Kerr permittivity thereby dictating the resonant behavior. Electromagnetically induced transparency in plasmonic systems, referred to as plasmon induced transparency, is a special case of Fano resonance and plays a key role for the occurrence of multiple Fano excitations. Plasmon induced transparency appears as induced reflectance dips when analyzed in reflection mode. Though geometrical dependency of dual and multiple Fano effect is demonstrated, the main interest and importance is focused on the generation and manipulation of multiple Fano resonances by intensity modulation of the pump beam and its application in multispectral switching and quality factor tuning at a fixed operating frequency.