Design and Optimization of a Graphene-On-Silicon Nitride Integrated Waveguide Dual-Mode Electro-Absorption Modulator

We present the design, simulation and optimization of a graphene-on-silicon nitride (GOSiN) integrated waveguide dual-mode electro-absorption modulator operating with a speed between 27-109 GHz and an energy consumption below 6 pJ/bit. This device individually modulates the TE$_0$ and TE$_1$ modes in a single-arm dual-mode waveguide with modulation depths up to 316 dB/cm and 273 dB/cm, respectively. It has promising applications in Multimode Division Multiplexing (MDM) systems, where single-mode modulation induces high losses and costs. We have started from the design of GOSiN TE$_0$ and TE$_1$ passive low-loss mode filters. Then, applying a gate voltage to graphene via transparent IHO electrodes, we have combined both filters and shown that the light absorption can be modulated to obtain four logical values in transmission: (0,0), (0,1), (1,0) and (1,1). Our proposed devices can potentially boost the development of efficient MDM systems for ultra-fast on-chip interconnections.