Fig. 4
Characterization of the operation speed of the fabricated photodetector. The beams from two wavelength-tunable DFB lasers at frequencies of f1 and f2 are focused onto the gold-patched graphene nano-stripes to generate a photocurrent, Iph, at the optical beating frequency, f1–f2. The measured photoresponse values exhibit no roll-off up to 50 GHz, which is the frequency limitation of the utilized experimental setup. The dashed lines show the estimated frequency response for the graphene photodetector calculated from the device electrical model
