A fabrication-friendly graphene-based polarization insensitive optical modulator

Graphene is a suitable material for high efficient optical modulator. However, graphene-based modulators are of strong polarization dependence. Here a fabrication-friendly structure for graphene-based polarization insensitive electro-absorption modulator (EAM) is reported. The modulator consists of two adiabatic tapers (ATs), two asymmetric directional couplers (ADCs) and an active region. The ATs and ADCs are used to realize mode conversion and mode coupling. The theoretical analysis of the modulator was performed. The device can operate at the spectrum of 1.5 mu m-1.6 mu m. The extinction ratio (ER) is of > 24dB and the insertion loss is of < 6dB for both modes. The 3dB modulation bandwidth is about 80GHz based on theoretical calculation at the cost of 300 mu m device length.