Effect of Orbital Angular Momentum on Nondiffracting Ultrashort Optical Pulses

Abstract

We introduce a new class of nondiffracting optical pulses possessing orbital angular momentum. By generalizing the X-wave solution of the Maxwell equation, we discover the coupling between angular momentum and the temporal degrees of freedom of ultrashort pulses. The spatial twist of propagation invariant light pulse turns out to be directly related to the number of optical cycles. Our results may trigger the development of novel multilevel classical and quantum transmission channels free of dispersion and diffraction. They may also find application in the manipulation of nanostructured objects by ultrashort pulses and for novel approaches to the spatiotemporal measurements in ultrafast photonics.

Effects of orbital angular momentum on few-cycle and sub-cycle pulse shapes: coupling between the temporal and angular momentum degrees of freedom

“…It is then fundamental to acquire an accurate knowledge of their propagation properties. Interestingly, the number of experimental works [6][7][8][9][10][11] far exceeds theoretical studies [18][19][20][21][22].…”

Effects of the Coupling between the Orbital Angular Momentum and the Temporal Degrees of Freedom in the Most Intense Ring of Ultrafast Vortices

“…Withω(ρ F ) ≈ω independent of the topological charge l, the approximate lower bound ∆t(ρ F ) |l|/ω with the right hand side growing monotonously with |l|, the duration at the bright ring of the synthesized ultrafast vortex must necessarily increase with |l| [5], if the laser source spectrumâ ω is fixed. These effects of the coupling between the OAM and the temporal degrees of freedom at the most energetic ring have been recently reviewed in [36], where they are also demonstrated to be substantially the same for other types of ultrafast vortices, as OAMcarrying nondiffracting X-waves [4,6,36].…”

“…OAM-temporal coupling is a particular case of spatiotemporal coupling, say an azimuthal-temporal coupling, which seems to be rather more pronounced than the radial-temporal coupling in ultrashort Gaussian beams. In [3][4][5][6] the effects of OAM-temporal coupling have been described for the first time in ultrafast vortices shaped as pulsed Laguerre-Gauss (LG) beams, commonly used in the experiments, and also shaped as pulsed Bessel beams, or diffractionfree X-waves. These effects are reviewed in [36], where it turns out that the OAM-temporal coupling manifests itself with different effects in different parts of the vortex.…”

Attosecond helical pulses

“…The real quadratic term r 2 /2cR(z) represents a time delay for the whole helical pulse structure to reach the distance z at a radius r due to the spherical pulse fronts of radius R(z) when the pulse is converging to or diverging from the waist, as for the fundamental pulsed Gaussian beam [10,13]. The dependence of the imaginary part on l 0 reflects the coupling between the OAM and temporal degrees of freedom, as recently described [8,17]. If the phases ofã j are approximately constant, a(t) represents a train of pulses with repetition period δt = 2π/δjδω, where δj is the step in the index j, e. g., δj = 2 in high harmonic generation experiments.…”