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Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect.

Lu X, Wu Z, Zhang W, Chen L - Sci Rep (2014)

Bottom Line: Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect.We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands.It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics and Laboratory of Nanoscale Condensed Matter Physics, Xiamen University, Xiamen 361005, China [2] Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005, China.

ABSTRACT
The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

No MeSH data available.


The 3D structures of C lines (blue) and L surfaces (red).Different electric fields are applied: (a) E0 = 0, (b) E0 = 5.31 kV/cm, (c) E0 = 6.90 kV/cm and (d) E0 = 10.62 kV/cm. All coordinates are in unit of μm. See also the Supplemental information video 1.
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f2: The 3D structures of C lines (blue) and L surfaces (red).Different electric fields are applied: (a) E0 = 0, (b) E0 = 5.31 kV/cm, (c) E0 = 6.90 kV/cm and (d) E0 = 10.62 kV/cm. All coordinates are in unit of μm. See also the Supplemental information video 1.

Mentions: We plot in Figure 2 our numerical solution of the 3D polarization singularities embedded in the emerging light. It is found that when the KDP crystal is undergoing the Pockels effect, C lines and L surfaces attain different morphologies. Figure 2(a) demonstrate the simple case when E0 is absent. It looks like a right circular cone with the conical surface being L surface and the axis of the cone being C line. As the light propagates, the C line is stretching along the propagation direction coinciding with optical axis. While E0 is switched on, however, the C line is quickly bifurcated into two ones, appearing like a pair of compasses with both arms being left-handed circular polarization and deflecting from the optic axis. Besides, the L surface is then gradually cleaved into two separate sleeves and each encircles one C line. By a comparison of Figure 2(a)–2(d), we find that applying a larger E0 accelerates the cleavage of L surface. As E0 increases from 5.31 kV/cm to 10.62 kV/cm, the cleavage point is brought forward from z = 6000 μm to 3000 μm or so.


Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect.

Lu X, Wu Z, Zhang W, Chen L - Sci Rep (2014)

The 3D structures of C lines (blue) and L surfaces (red).Different electric fields are applied: (a) E0 = 0, (b) E0 = 5.31 kV/cm, (c) E0 = 6.90 kV/cm and (d) E0 = 10.62 kV/cm. All coordinates are in unit of μm. See also the Supplemental information video 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4007095&req=5

f2: The 3D structures of C lines (blue) and L surfaces (red).Different electric fields are applied: (a) E0 = 0, (b) E0 = 5.31 kV/cm, (c) E0 = 6.90 kV/cm and (d) E0 = 10.62 kV/cm. All coordinates are in unit of μm. See also the Supplemental information video 1.
Mentions: We plot in Figure 2 our numerical solution of the 3D polarization singularities embedded in the emerging light. It is found that when the KDP crystal is undergoing the Pockels effect, C lines and L surfaces attain different morphologies. Figure 2(a) demonstrate the simple case when E0 is absent. It looks like a right circular cone with the conical surface being L surface and the axis of the cone being C line. As the light propagates, the C line is stretching along the propagation direction coinciding with optical axis. While E0 is switched on, however, the C line is quickly bifurcated into two ones, appearing like a pair of compasses with both arms being left-handed circular polarization and deflecting from the optic axis. Besides, the L surface is then gradually cleaved into two separate sleeves and each encircles one C line. By a comparison of Figure 2(a)–2(d), we find that applying a larger E0 accelerates the cleavage of L surface. As E0 increases from 5.31 kV/cm to 10.62 kV/cm, the cleavage point is brought forward from z = 6000 μm to 3000 μm or so.

Bottom Line: Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect.We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands.It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics and Laboratory of Nanoscale Condensed Matter Physics, Xiamen University, Xiamen 361005, China [2] Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005, China.

ABSTRACT
The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.

No MeSH data available.