High speed graphene-silicon electro-absorption modulators for the O-band and C-band

In the past few years, graphene has drawn interest for applications in optoelectronic devices. Due to its extraordinary properties, i.e. wide optical bandwidth, tunable absorption, high carrier mobility, and CMOS compatibility, it is a candidate to improve current state-of-the-art high-speed optoelectronic devices, such as modulators. In this work, we present a model that describes the DC and high-speed behaviour of single-layer graphene-oxide-silicon electro-absorption modulators (EAM). We compare the theoretical analysis with experimental results, and we find that p-doped graphene combined with p-doped silicon enables high-speed operation at low DC bias. Using this configuration, we demonstrate 75 μm long TM EAMs operating in the O-band and in the C-band. The O-band EAM exhibits 3.1 dB extinction ratio (ER) and 16.0 GHz 3 dB bandwidth at 1 V DC bias. With the C-band EAM we achieve 6.5 dB ER and 14.2 GHz 3 dB bandwidth at 0 V DC bias. Open eye diagrams up to 50 Gbit s−1 are measured using 2.5 Vpp and −0.5 V DC bias at a wavelength of 1560 nm.