Next colloquium
Wednesday, 8 February at 3 pm
Emilio Pisanty (KCL)
Knotted topologies in the polarization state of bichromatic light
The fundamental polarization singularities of light are generally symmetric under coordinated rotations: that is, transformations which rotate the spatial dependence of the fields by an angle θ and the field polarization by a fraction γθ of that angle, as generated by 'mixed' angular momenta of the form L + γ S. Generically, the coordination parameter γ has been thought to be restricted to integer or half-integer values. In this talk I will show that this constraint is an artifact of the restriction to monochromatic fields, and that a much wider variety of optical singularities is available when one considers polychromatic beam combinations that contain more than one frequency.
Building upon this I will show that these new optical singularities present novel field topologies, isomorphic to torus knots, and I will show how they can be characterized both analytically and experimentally. I will also show that the generator for the symmetry group of these singularities, whose algebraic structure is deeply related to the torus-knot topology of the beams, is conserved in nonlinear optical interactions. Finally, I will report on recent work that constructs explicit three-dimensional versions of these topologies, providing an explicit embedding in real space.
Main references:
- E. Pisanty et al. Knotting fractional-order knots with the polarization state of light. Nature Photonics 13 569 (2019).
- E. Pisanty et al. Conservation of torus-knot angular momentum in high-order harmonic generation. Physical Review Letters 122 203201 (2019).
Colloquia 2022/23
2022
Date |
Time |
Speaker |
Title |
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2023
Date |
Time |
Speaker |
Title |
---|---|---|---|
8/2/2022 |
3 pm GMT |
Emilio Pisanty (KCL) |
Knotted topologies in the polarization state of bichromatic light |
22/2/2023 |
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|
|
8/3/23 |
3 pm GMT |
TBA |
TBA |
22/3/23 |
3 pm GMT |
Thierry Ruchon (Saclay) |
Extreme ultraviolet attosecond beams with orbital angular momentum: synthesis and applications |
19/4/23 |
3 PM BST |
Tessa Baker (QMUL) |
TBA |
General information
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All are welcome!
PhAs Seminars
Date | Speaker | Title |
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29 March 2023 | Dave Sutherland | Turning off the Higgs vacuum |
Contact
Questions? Comments? Speaker suggestions?
Please use the dedicated padlet to leave your comment or contact Dr Jörg Götte
Joerg.Goette@Glasgow.ac.uk
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Room 523
Ext 7563