Generation of a sub-diffracted Bessel beam via diffraction interference in a combined amplitude structure.

Abstract

We have theoretically investigated the use of a simple combined amplitude structure to produce a sub-diffracted Bessel beam via diffraction interference. This powerful structure is composed of a spiral slit and radial grating. When a vortex beam illuminates this combined amplitude structure, a subwavelength Bessel beam with a size of 0.39λ and a long working distance of approximately 100 µm is numerically realized. By tailoring the parameters of the spiral slit, we can obtain a longer sub-diffracted Bessel beam. Moreover, the observed Bessel beam has low-energy side-lobes. The peculiar features of our theoretically generated Bessel beam have numerous potential applications, such as in nanoparticles manipulation, super-resolution imaging, and lithography.