Effects of various misalignments and beam impurities on creation of optical needle using Pancharatnam–Berry phase elements

Abstract

A combination of beams exhibiting long focal lines and small focal spot sizes is desired in a variety of applications. A good example is laser micromachining of structures with dimensions comparable to the wavelength of incident light. Optical beams exhibiting this property are called optical needles, with Bessel beam being a common example [1] . Conical prisms are commonly used to generate Bessel beams, so a combination of axicons together with passive optical apodization components flattens the on-axis intensity profile and reduces on-axis oscillations. A good example of such alteration is known as the logarithmical axicon, which is usually designed employing principles of geometrical optics [2] . Recent advancements in this approach have enabled not only the polarization control in the individual optical needle [3] , but also position control inside a spatial array [4] and also have introduced elliptically and parabolically [5] .