We investigate spatial differentiation of optical beams using guided mode resonances in suspended dielectric one-dimensional photonic crystals. Various SiN grating structures are characterized under various incidence, polarization and beam size illuminations. We first observe first- and second-order spatial differentiation in transmission of Gaussian beams impinging at oblique and normal incidence, respectively, on gratings designed to be resonant for either TE- or TM-polarized incident light. Polarization-independent first-order spatial differentiation is then demonstrated with a specifically designed, doubly-resonant, one-dimensional and symmetric grating structure. Such ultrathin and essentially lossfree nanostructured dielectric films are promising for various optical processing, optomechanics and sensing applications.
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