Open AccessSpectral anomalies and Gouy rotation around the singularity of ultrashort vortex pulses
Author(s) -
Max Liebmann,
Alexander Treffer,
Martin Böck,
Thomas Elsaesser,
R. Grünwald
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.026076
Subject(s) - optics , physics , optical vortex , angular momentum , wavefront , femtosecond , wavelength , rotation (mathematics) , dispersion (optics) , spectral resolution , vortex , bessel function , phase (matter) , spectral width , laser , spectral line , beam (structure) , geometry , mathematics , quantum mechanics , astronomy , thermodynamics
Spectral anomalies of femtosecond pulses with orbital angular momentum were studied in the vicinity of singularities. Bessel-Gauss (BG) beams were generated with mode-locked Ti:sapphire oscillators and dispersion-compensated diffractive axicons acting as spiral phase plates (SPPs). High-resolution two-dimensional spectral mapping was performed with a scanning fiber probe. Progressive rotation of the most pronounced features, known as "spectral eyes", in the maps of spectral moments was found at increasing propagation distance. The phenomenon is explained by a wavelength-dependent Gouy phase shift of interfering spectral components in the twisted wavefront. Spatial "spectral switching" was detected for few-cycle pulses. Possible improvements of selectivity are proposed.