Ring-shaped Talbot effect

Abstract

We report an unusual type of Talbot effect. Unlike the traditional Talbot effect taking place in the lateral direction, this ring-shaped Talbot effect takes place for beams with certain topological charges. A rigorous theoretical derivation for this phenomenon is provided based on the Fresnel diffraction theory. Experimental demonstration is conducted by periodically modulating a spatial light modulator to create beams with the ring-shaped periodical phase distribution. With a properly adjusted phase pattern, the beam will exhibit equally spaced ring intensity distribution at the fractional Talbot length.