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Three different graphene nanostructure suspensions of graphene oxide nanosheets (GONSs), graphene oxide nanoribbons (GONRs), and graphene oxide quantum dots (GOQDs) are prepared and characterized. Using a typical two-step method, the GONSs, GONRs, and GOQDs are incorporated into a polyimide (PI) matrix to synthesize graphene/PI composite films, whose nonlinear optical (NLO) and optical limiting (OL) properties are investigated at 532 nm in the nanosecond regime. The GONR suspension exhibits superior NLO and OL effects compared with those of GONSs and GOQDs because of its stronger nonlinear scattering and excited-state absorption. The graphene/PI composite films exhibit NLO and OL performance superior to that of their corresponding suspensions, which is attributed primarily to a combination of nonlinear mechanisms, charge transfer between graphene materials and PI, and the matrix effect.

The nonlinear optical (NLO) and optical limiting (OL) properties of graphene families, including graphene oxide nanosheets, graphene nanosheets (GNSs), graphene oxide nanoribbons (GONRs), and graphene nanoribbons (GNRs), were investigated at 532 and 1064 nm using a nanosecond regime. GNSs, GONRs, and GNRs exhibited broadband NLO and OL properties. Reduced graphene samples exhibited stronger NLO and OL responses than their graphene oxide precursors because of their increased crystallinity and conjugation. Nonlinear scattering and two-photon-absorption were found to have strong effects on the NLO and OL responses of the graphene nanostructures.

Nanostructured Ag in shapes of nanoplate, nanowire, and nanoparticle, as well as their silica gel glass composites have been prepared and characterized. Nonlinear optical (NLO) properties were measured at 532 and 1064 nm using open aperture z-scan technique and studied from the view of shape effect. NLO behaviors of the nanostructured Ag are found to be shape dependent in suspensions at both the investigated wavelengths, although they originate differently. Comparing to the mother suspensions, the Ag/silica gel glass nanocomposites present rather dissimilar NLO behaviors, which is quite interesting for further studies.