Formation of optical needles by Pancharatnam-Berry phase element for laser-induced modifications in transparent materials

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

“…The actual optical elements with custom orientation of the nanograting and with custom retardance are usually called geometric phase optical elements (GPOEs). Those nanogratings act as meta-atoms and are applied for the spatial manipulation of amplitude, phase or polarization of the incoming beam [27][28][29][30][31][32][33][34]. The main advantage of such elements over other implementations is a high optical damage threshold, reaching 2.2 J cm −2 at 1030 nm wavelength (212 fs regime) or 63.4 J cm −2 at 1064 nm wavelength (10 ns regime) [35,36].…”

“…Here, we are interested in beam shaping elements for high-power laser microprocessing applications. It was already shown that it is beneficial to have a non-Gaussian irradiance profile in the microprocessing of transparent materials, such as Bessel beams [51], optical needles [32], knives [52] and shovels [53]. Most high-power interactions of laser light and matter are threshold-based [54].…”