Full-wave nonlinear optical analyses of graphene-based optoelectronic devices

Graphene has drawn strong interest and intensive study because of its remarkable electromagnetic, thermal, and mechanical properties. As a crucial property, graphene´s nonlinear optical performance is an emerging topic in theoretical and experimental studies. Recent investigations shows that despite its one-atom thickness, single layer graphene´s nonlinear optical response is particularly strong. Due to the centrosymmetric structure, the ideal floating single layer graphene forbids the emission of second harmonic generation (SHG) of optical fields. However, in practical designs, the symmetric property may be broken by its adjacent materials, which makes the induced SHG optical behavior interesting. On the contrary, the third order nonlinear optical effects in graphene are reported as remarkably strong. Originated from the resonant nature of the light-graphene interaction, the effective third-order susceptibility arrives on the order of |χ⁽³⁾| ∼ 10⁻¹⁵m²/V². This strong third order optical interaction generates a third harmonic signal with a significant contrast between graphene and the background material in most optoelectronic designs.