Nonlinear absorption and refraction characteristics of reduced graphene oxide/polyurethane

In this research, the reduced graphene oxide (rGO) was synthesized by Hummer’s method and added to polyurethane (PU/G) with different weight percentages of rGO. Then, the optical phonon modes of the prepared compounds are studied using the Kramers-Kronig (KK) relations. As the results show, the optical phonon modes enhance with increasing the percentage of rGO nanosheets in the polyurethane (PU). Moreover, nonlinear optical (NLO) studies on the compound solutions were performed using the Z-scan method to determine their absorptive and refractive nonlinearities. The samples display saturable absorption (SA) based on Z-scan measurements taken at the open aperture. During the Z-scan measurements, thermal nonlinearity causes the samples to exhibit self-defocusing properties as evidenced by a negative sign of the nonlinear refractive index, n ₂ . Furthermore, the analysis of the figures of merit (FOM) for the prepared sample shows that T < 1 and W > 1. Consequently, there is potential for these samples to be used in lasers and optical switches, based on the results from the experiment.