Enhanced saturable absorption of the graphene oxide film via photonic nanojets

A novel solid-state film system comprising of the Graphene Oxide (GO) and particle lens is studied for its enhanced saturable absorption and tunable optical nonlinearity. A silica microsphere, which functions as a particle lens, can redistribute the light through the focusing effect and generate a high intensity focusing beam known as the photonic nanojet (PNJ). By applying the local field enhancement of the PNJ, the normalized peak transmittance of the GO film can be enhanced around 38% after hybridizing it with silica microspheres. The tunable nonlinearity is investigated by varying the concentration of silica microspheres. Meanwhile, such ultrathin solid-state hybrid system can be easily fabricated and coated on various types of substrates, which can be a promising candidate for applications on integrated photonics and ultrafast laser devices. (C) 2016 Optical Society of America