Fresnel diffraction on periodic gratings results in a two‐dimensional periodic distribution of light intensity, also known as the Talbot effect. Here this approach is extended to the family of superimposed structures with translational symmetry, which consist of superposed spatial harmonics. The Talbot effect is demonstrated to be valid for superimposed gratings. The considered superimposed gratings provide a wide range of textures of optical super‐lattices. These texture super‐lattices represent a Talbot carpets with a complex motif, which can be varied by choosing structure parameters. These results provide a new functionality for structuring optical lattices and can find potential applications in a wide range of light–matter interactions.
The near‐field effect of diffraction image self‐reproduction or self‐imaging of a periodic grating illuminated by quasi‐monochromatic wave is well‐known as the Talbot effect. Introducing a dislocation to a periodic structure provides a fork‐shaped modulation of the phase/amplitude, which produces discrete diffraction pattern in a far‐field consisting of optical vortices. In this paper, Fresnel diffraction at amplitude fork‐shaped grating is theoretically and experimentally studied. The coexistence of spatial ordering and local violation of translational symmetry of the structure manifests itself in a strict diffraction pattern consisting of optical vortices in the far‐field, which is shown to be accompanied by formation of a spatially ordered intensity distribution in the near‐field, reminiscent the Talbot carpets for periodic structures. These results demonstrate the first evidence of Talbot effect occurred under light diffraction at fork‐shaped gratings, being promising for deep understanding of near‐field singular optics phenomena.
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