High-Speed Optical Modulation Using a Double-Layer Graphene-Based Device

In 2019, Giambra et al. [47] presented a study on a high-speed double-layer graphene-based optical modulator. The device's length was optimized to be 120 μm, achieving a modulation efficiency of approximately 0.137 dB μm−1. To minimize series resistance, top contacts were fabricated using a stack of Nickel (Ni) and Gold (Au), resulting in a contact resistance of less than 10 Ω. The device also exhibited an electrical capacitor of 204 fF, contributing to a 3-dB bandwidth of approximately 29 GHz. Notably, the device attained a modulation speed of 50 Gb s−1 with an extinction ratio (ER) of 1.3 dB, as confirmed by the presented eye diagram.