Spatial frequency response of nanocomposite holographic gratings

We investigate the spatial frequency response of a volume grating recorded in a ZrO₂ nanoparticle-dispersed nanocomposite. We experimentally find that there exists the optimum recording intensity to maximize the saturated refractive index modulation amplitude of a nanocomposite grating recorded at short and long grating spacing. A strong parametric relationship between grating spacing and recording intensity is seen and an increase in the saturated refractive index modulation amplitude at shorter grating spacing (< 0.5 μm)can be obtained by using higher recording intensities than those at longer grating spacing. Such a trend can be qualitatively explained by a phenomenological model used for holographic polymer-dispersed liquid crystal gratings. We also describe another method for the improvement of the high spatial frequency response by co-doping of thiol monomer that acts as a chain-transfer agent.