Optical data storage in a graphene oxide thin film integrated with upconversion nanoparticles (Conference Presentation)

The huge volume of digital information generated across the world represents an insuperable challenge for the currently-available data storage devices and compels for the development of novel techniques and storage media. Nanomaterials, which have unique mechanical, electronic and optical properties owing to the strong confinement of electrons, photons and phonons at the nanoscale, are enabling the development of disruptive methods for optical data storage with ultra-high capacity, ultra-long lifetime and ultra-low energy consumption. In this context, upconversion nanoparticles, which feature the interesting property of photon upconversion and emit in a range from ultraviolet to near-infrared, have attracted considerable attention for optical data storage applications through the modulation of their upconversion fluorescence emission. However, it has been difficult to find an effective quencher for upconversion nanoparticles to entirely quench their anti-Stokes type of emission. Graphene oxide (GO) and reduced graphene oxide (r-GO) have proved useful as effective quenchers due to their strong broadband absorption. Herein, we demonstrate optical data storage in a GO and upconversion nanoparticles thin film. Core-shell nanoparticles were prepared via co-precipitation method and measurements of upconversion fluorescence emission intensity and fluorescence lifetime have been performed. Subsequently, the upconversion nanoparticles have been conjugated to GO and deposited through vacuum filtration to form a thin film. The nanocomposite was then irradiated using laser at different powers to produce the reduction of GO to r-GO. The encoded optical data bits were readout through the variation of fluorescence intensity from the upconversion nanoparticles accompanied by the reduction of the GO to r-GO.