Design and Optimization of a Graphene Modulator Based on Hybrid Plasmonic Waveguide with Double Low-Index Slots

Graphene modulators based on surface plasmonic waveguides enable a strong interaction between light and graphene because great electric field enhancement occurs in the sub-wavelength region. However, a tight field confinement will cause a large metal absorption of light. Thus, graphene modulator base on hybrid plasmonic waveguide has a tradeoff between the propagation loss and the modulation depth. Here, we achieved a good balance between them by designing and optimizing an electro-optic modulator based on hybrid plasmonic waveguide with four graphene layers. The structure of the waveguide is metal/insulator/Si/insulator/metal. The modulation depth and the propagation loss of the modulator are 0.524 and 0.05dB/m respectively, which make a relatively high figure of merit about 10.5. Also the obtained modulation bandwidth and power consumption are 150GHz and 0.607pJ/bit, respectively.