Investigation of the Pancharatnam–Berry phase element for the generation of the top-hat beam

Abstract

Within optics, the Pancharatnam-Berry phase enables the design and creation of various flat special optical elements such as top-hat converters. We present a study on engineering efficient vectorial top-hat converters inscribed in glass by high-power femtosecond laser pulses. We phase-encode a top-hat converter and demonstrate how its quality is influenced by various parameters. We investigate theoretically the generation of the top-hat beam under imperfect conditions such as the mismatch of the incident beam width or the misalignment of the center of the converter. Experimental verification of the concept is also presented.

Light Engineering and Silicon Diffractive Optics Assisted Nonparaxial Terahertz Imaging

“…Another implementation is based on the concept of metasurfaces, where diffractive gratings are realized by local changes in the geometric phase of the structure consisting of individual metaatoms. [42,43] This advancement has resulted in a greatly reduced mass and thickness of Fresnel lenses, [35,44] top-hat converters, [45] and axicons. [9,46] An axicon became especially interesting, as it has enabled the generation of the so-called non-diffracting Bessel beam, [46][47][48] which can be further engineered using a flat geometrical phase element.…”

“…This advancement has resulted in a greatly reduced mass and thickness of Fresnel lenses, [ 35,44 ] top‐hat converters, [ 45 ] and axicons. [ 9,46 ] An axicon became especially interesting, as it has enabled the generation of the so‐called non‐diffracting Bessel beam, [ 46–48 ] which can be further engineered using a flat geometrical phase element.…”