Open AccessConical third-harmonic generation of optical vortex through ultrashort laser filamentation in air
Author(s) -
YanCheng Lin,
Yasuo Nabekawa,
Katsumi Midorikawa
Publication year - 2016
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.24.014857
Subject(s) - filamentation , optics , conical surface , vortex , physics , femtosecond , optical vortex , laser , axicon , high harmonic generation , materials science , beam (structure) , laser beams , composite material , thermodynamics
We experimentally generate third-harmonic (TH) vortex beams in air by the filamentation of femtosecond pulses produced in a lab-built Ti:sapphire chirped pulse amplifier. The generated TH beam profile is shown to evolve with increasing pump energy. At a sufficiently high pump energy, we observe a conical TH emission of the fundamental vortex and confirm that the conical radiation follows the conservation law for orbital angular momentum. We further investigate the far-field angularly resolved spectra of the TH wave to analyze the conical emission angle. We theoretically verify that the formation of the conical TH vortex results from the phase-matching between the fundamental and TH waves during the filamentation process.