In Situ Third‐Order Non‐linear Responses During Laser Reduction of Graphene Oxide Thin Films Towards On‐Chip Non‐linear Photonic Devices

High-quality continuous (GO) thin films are prepared by a self-assembly method. Z-scan measurements during the laser-induced reduction process unveil in situ nonlinear responses in the GO film. Third-order nonlinear responses of the GO film can be tuned dynamically by varying the laser input fluence. GO thin films with tunable nonlinear responses and versatile patterning opportunities by using direct laser writing may serve as promising solid-state materials for novel nonlinear functional devices.