Regenerative oscillation and four-wave mixing in graphene optoelectronics

The unique linear and massless band structure of graphene in a purely two-dimensional Dirac fermionic structure has led to intense research in fields ranging from condensed matter physics to nanoscale device applications covering the electrical, thermal, mechanical and optical domains. Here, we report three consecutive first observations in graphene-silicon hybrid optoelectronic devices-ultralow-power resonant optical bistability, self-induced regenerative oscillations and coherent four-wave mixing-all at few-femtojoule cavity recirculating energies. These observations, in comparison with control measurements on solely monolithic silicon cavities, are enabled only by the dramatically large and ultrafast Ï ‡ (3) nonlinearities in graphene and the large Q/V ratios in wavelength-localized photonic crystal cavities. These third-order nonlinear results demonstrate the feasibility and versatility of hybrid two-dimensional graphene-silicon nanophotonic devices for next-generation chip-scale high-speed optical communications, radiofrequency optoelectronics and all-optical signal processing.