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

Abstract

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.