All-optical intensity modulation based on graphene-coated microfibre waveguides

Abstract We investigate graphene-covered microfibre (GCM) waveguides, and analyse the microfibres’ evanescent field distributions in different diameters and lengths by numerically simulation. According to the simulation results, we designed a graphene-based all-optical modulator using 980 nm and Amplified Spontaneous Emission (ASE) lasers, employing the microfibre’s evanescent field induced light–graphene interaction. We studied the modulation effect that is influenced by the microfibre’s diameter, number of graphene layers, and effective graphene length. Compared to a single graphene layer of shorter length, the double graphene layer with longer length presents stronger absorption and higher modulation depth. Using a 2- μ m diameter microfibre covered by ∼ 0.3 cm double graphene sheets, we achieved a modulation depth of 8.45 dB. This modulator features ease of fabrication, low cost, and a controllable modulation depth.