Third-order effects in the generation of femtosecond vortex beams

Spatially localized beams with orbital angular momentum (OAM) - so-called “vortex beams“ - are of interest for optical trapping, processing and data communications. We are interested in vortex beams with femtosecond pulse duration. For such short pulses, dispersion is a problem, as it leads to a temporal blur. Earlier, we reported about the generation of ultrashort wave packets with OAM using a refractive-diffractive compensation technique for group velocity dispersion [1]. Here, we consider the influence of higher order dispersion which may have an important influence on the pulse. In particular, 3rd order dispersion, transforms a temporal Gaussian profile into a temporal Airy profile. Airy profiles in the spatial domain are known from the phenomenon of Airy beams. In our presentation, we describe a theoretical analysis for 3rd order dispersion and discuss the generation of Airy-Bessel wave packets with OAM. Furthermore, by analogy we shall compare the situation in the temporal domain with the phenomenon of Airy beams in the spatial domain. [1] M. Musigmann, J. Jahns, M. Bock, R. Grunwald, 115. Jahrestagung der DGaO, 10.-14. Juni 2014, Karlsruhe.