▎ 摘　　要

We explore the effects of crystallite size (L-a) on the linear and non-linear optical properties of chemical vapor deposition grown polycrystalline graphene. The pi-plasmon resonance present at similar to 4.75 eV (similar to 260 nm) in the optical absorption spectrum of graphene follows the empirical relationship lambda(pi) 250.5 nm + 89.5 nm(2)/L-a, where lambda(pi) represents the pi-plasmon wavelength. Furthermore, our Z-scan studies reveal that the crystallite size significantly changes the saturation intensity in CVD grown graphene. Notably, in comparison to epitaxial graphene layers grown on SiC wafers which exhibit a photogenerated carrier lifetime of few picoseconds, we find that the photogenerated carriers in our CVD grown graphene can exhibit lifetimes as long as nanoseconds.