Graphene-Based Photodetectors for Silicon Photonic Optical Communications: Progress, Challenges, and Outlook

Graphene-based photodetectors have emerged as an interesting alternative to conventional semiconductor photodiodes for integrated silicon photonic systems. This perspective reviews the evolution of waveguide-integrated graphene photodetectors from their first demonstrations in 2013 to recent devices achieving responsivities up to 0.65 A/W and bandwidths exceeding 180 GHz, with experimentally proven potential to surpass 500 GHz. These advances highlight graphene’s unique potential for ultrahigh-speed optical communication and microwave photonic applications. We discuss the underlying photodetection mechanisms, key performance metrics, and integration strategies that enable efficient coupling between graphene and silicon photonic waveguides. Despite impressive progress, graphene photodetectors currently do not surpass state-of-the-art germanium photodiodes in responsivity, noise-equivalent power, or manufacturing maturity. Consequently, graphene is unlikely to replace established technologies in standard telecom receivers in the coming years. Instead, its greatest impact is expected in applications requiring extreme bandwidth, broadband wavelength operation, and heterogeneous integration across diverse photonic platforms.