Figure 3: Localized phase modulation produced by the refractive-index change of GOs through the tunable extent of the photoreduction.
From: Athermally photoreduced graphene oxides for three-dimensional holographic images
(a) Wide-field image of one typical phase grating composed of arrays of refractive-index modulation pixels through the athermal photoreduction with a parallel digitalization objective. Scale bar, 6 μm. (b) Example of diffraction images of ±1st and 0th orders. (c) Phase modulation strength as a function of the pulse fluence of the fs beam. The circles are experimental data and the blue curve is the guide for eyes. The colour levels indicate digitalized phase modulations by judicious control of the intensity of the fs beam. (d) Microscopic images of a section of a rGO hologram through 4-, 8- and 16-level digitalized photoreduction processes of GO polymers and their statistics of strengths of randomly selected refractive-index pixels. The table shows the comparison of the first-order diffraction efficiency of rGO holograms with different levels of modulation.
