Optical Limiter Device Based on Innovative Graphene Derived Materials (OLIDIGRAPH)

OLIDIGRAPH aims to develop and validate a laboratory scale technology for synthesis of an innovative class of graphene based nonlinear optical materials in visible and infrared domains, and to build a device that incorporate the synthesized materials. Our research approach involves development of homogeneous and transparent films of graphene materials (graphene oxide (GO) and reduced graphene oxide (rGO)) and their composite films with silica-based materials on glass. The films should show sufficient optical limiting properties without significantly influence the light transmittance. Functionalization will be conducted in order to obtain homogeneous distribution of GO/rGO in the films. When incident laser beam intensities increase above a threshold value, the thin film can lower the optical transmittance and prevent the damages to human eye. During the project period, the most important parameters that have effect on stability and homogeneity of GO and rGO dispersions have been determined. Synthesized chemically converted graphene showed better stability over the time than rGO. Functionalization of GO and rGO via covalent bonding was achieved and facilitated homogeneous distribution of GO the sol-gel derived coating matrix. The obtained GO/rGO films and their composite films with hybrid silica showed promising optical limiting capability.

- The most important parameters that have effect on stability and homogeneity of GO and rGO dispersions have been determined. - Synthesized chemically converted graphene showed better stability over the time than rGO. - Functionalization of GO and rGO via covalent bonding via amine chemistry was achieved. - Dispersion of GO in isopropanol with enhanced stability was obtained after functionalization, this facilitated formation of homogeneous dispersion of GO in the sol-gel coating matrix. - Several graphene coatings, together with inorganic-organic hybrid coatings with GO and RGO were obtained, the coatings show promising optical limiting capability. - A joint 1st-stage proposal titled "Improved graphene ­based optical limiting device" on was submitted to ERA-Net Manunet in March 2020. - The interesting results further strengthen the knowledge and competencies for ABALONYX and SINTEF, promoting GO/rGO as new additive materials for other applications.

Lasers are currently indispensable for many military and civil applications and there is a considerable need for a material to be included into a device for laser damage prevention of optoelectronic devices and for people protection. The overall objectives of this project are: (1) to validate a laboratory scale technology for synthesis of an innovative class of graphene based nonlinear optical materials in visible and infrared domains; (2) to build a device that incorporate the synthesized materials. A composite material graphene oxide (GO)­ silicophosphate (SP) as bulk/films and GO/rGO (reduced GO) films, prepared by sol­gel, will be investigated. These materials have the role to lower their optical transmittance when incident laser beam intensities are increasing above a threshold value, ensuring a constant intensity of the transmitted laser beam and preventing thus the damages to human eye and different optical sensors. Z­scan investigations will explore the nonlinear optical properties and optical limiting performances of these materials all along with the technological chain and will allow the selection of the best performing material to be used in the final prototype device. The project involves complementary competence from four partners from Romania and Norway, 2 research institutes and 2 SMEs.