Volume 129, Number 6, March 2020
|Number of page(s)||6|
|Section||Electromagnetism, Optics, Acoustics, Heat Transfer, Classical Mechanics, and Fluid Dynamics|
|Published online||27 April 2020|
Self-phase modulation and superfluidity in twisted fluids of light
IPFN, Instituto Superior Técnico, Universidade de Lisboa - 1049-001 Lisboa, Portugal
Received: 20 December 2019
Accepted: 14 April 2020
We study superfluidity of laser pulses with a finite duration, propagating in a nonlinear Kerr medium. For such pulses, self-phase modulation (SPM) is also present. Usually, superfluidity is assumed independent of SPM, because the elementary excitations of the photon fluid are observed in the transverse plane, while SPM takes place along the propagation direction. But, as shown here, for sufficiently short pulses and sufficiently long propagation distances, SPM can eventually modify the Landau criterium for the occurrence of superfluidity due to the associated frequency shifts, which modify the threshold for superfluid behaviour. Instead of plane wave or Gaussian beams, we consider twisted laser beams, with a finite amount of orbital angular momentum (OAM), because they provide the necessary transverse velocity for the photon fluid.
PACS: 42.65.Jx – Beam trapping, self-focusing and defocusing; self-phase modulation / 67.85.De – Dynamic properties of condensates; excitations, and superfluid flow
© EPLA, 2020
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