Unveiling Talbot Effect under Fresnel Diffraction at a Fork‐Shaped Grating

Abstract

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.

Gain Assisted Raman Induced Classical and Quantum Talbot Imaging

“…Fresnel diffraction at an amplitude periodic grating with dislocation has been described, resulting in the generation of a spatially ordered intensity distribution in the near‐field, similar to the Talbot effect for periodic structures. [ 32 ] Recently, researchers investigated superimposed amplitude masks superposed by periodic spatially evolving functions. They discovered a periodic spatial distribution of light intensity in the near‐field, which is interpreted as the Talbot effect at stacked structures.…”