Analysis of Tunable Flat-Top Bandpass Filters Based on Graphene

A multilayer graphene-based tunable bandpass filter is proposed by using cascaded silicon microring resonators. Six graphene layers are embedded in the silicon-on-insulator waveguide to enhance the influence on the effective mode index, and a pretreatment has also been implemented to compensate the coupling-induced resonance frequency shifts. By tuning the Fermi level of the graphene, the position of the pass band can be dynamically modulated in the whole communication
$C$
-band. The out-of-band extinction ratio of drop port can be larger than 40 dB; the 3-dB bandwidths of the pass bands are over 2.8 nm, and the insertion loss is less than 1.5 dB.