Abstract
Graphene plasmons with enhanced localized electric field have been used for boosting the light-matter interaction in linear optical nano-devices. Meanwhile, graphene is an excellent nonlinear material for several third-order nonlinear processes. We present a theoretical investigation of the mechanism of plasmon-enhanced third-order nonlinearity susceptibility of graphene nanoribbons. It is demonstrated that the third-order nonlinearity susceptibility of graphene nanoribbons with excited graphene surface plasmon polaritons can be an order of magnitude larger than the intrinsic susceptibility of a continuous graphene sheet. Combining these properties with the relaxed phase matching condition due to the ultrathin graphene, we propose a novel plasmon-enhanced mid-infrared wavelength converter with arrays of graphene nanoribbons. The wavelength of sig-nal light is in mid-infrared range, which can excite the tunable surface plasmon polaritons in arrays of graphene nanoribbons. The efficiency of the converter from mid-infrared to near-infrared wavelength can be remarkably improved by 60 times compared with the graphene sheet without graphene plasmons. This work provides a novel idea for the efficient application of graphene in the nonlinear optical nano-devices. The proposed mid-infrared wavelength converter is compact, tunable and has promising potential in graphene-based mid-infrared detector with high detection efficiency.
Modeling of dark current in mid-infrared quantum-well infrared photodetectors