Boosting optical nonlinearities of graphene oxide films by laser direct writing

In this work, we study the boosted optical nonlinearities of graphene oxide (GO) films by laser direct writing with femtosecond laser (532 nm, 330fs) excitation. We firstly prepare the uniform GO films by vacuum filtration method, which are then partly reduced by commercial carbon dioxide laser machine. The morphology, structure and luminescence traits of both the pristine and reduced GO are further characterized by SEM, XRD, Raman spectra, XPS, PL and UV-Vis absorption spectrum. Moreover, their third-order optical nonlinearities (TONs) are measured by the femtosecond laser Z-scan technique. The experimental results show that the reduced GO films take on stronger TONs and the related degree of enhancement depends on the spot size of laser processing. In particular, when the processed diameter is around 400 mu m, the optical nonlinear absorption and refraction coefficients of the reduced GO are-2.9 x 10(-7) m/W and 2.5 x 10(-15) m(2)/W, respectively, which are in turn 4 and 2 times higher than that of GO film. Our results provide powerful backing for the GO-based applications, such as ultra-fast optical devices, super-resolution imaging technology and photodetector.

Automated summary

In this work, we studied the boosted optical nonlinearities of graphene oxide (GO) films by laser direct writing. The films were prepared by vacuum filtration method and partly reduced using a commercial carbon dioxide laser machine. The morphology, structure, and luminescence traits of the films were characterized, and their third-order optical nonlinearities were measured. The results show that the reduced GO films exhibit stronger optical nonlinearities, and the degree of enhancement depends on the spot size of laser processing.