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Join Dr Thierry Ruchon from CEA Saclay for a London for a Light & Matter Seminar entitled 'Extreme ultraviolet attosecond beams with orbital angular momentum: synthesis and applications.' 


Light beams may carry both a spin and an orbital angular momentum (OAM). While the former is associated to their polarization state, the latter stems from the geometrical properties of their wavefront. In their prototypical form, beams with OAM have “donuts-like” intensity profiles and helicoidal wavefronts, carrying integral multiples of ℏ as angular momenta. Since their “rediscovery” in the late 90’s, beams with OAM of visible wavelengths have found innumerable applications in quantum optics, atomic physics, microscopy or information transfer. A major recent development was the generation of such beams with much smaller wavelengths – in the extreme ultraviolet ( XUV) – using synchrotron sources, free electron lasers as well as high harmonic sources (HHG). In this latter case, it creates ultrashort XUV sources of light with OAM, suited for time-resolved applications at femtosecond and attosecond time scales.

In this seminar, we will summarize our recent progress on the synthesis of such beams with HHG [1, 2, 3, 4], and extensions to non-trivial light topologies such as polarization Möbius strip [5]. It offers an original tool to explore new kind of dichroisms, such as Magnetic Helicoidal Dichroism that we will introduce [6, 7].


[1] Géneaux, R. et al., 2016. Nature Communications, 7, 12583. http://­­10.1038/­ncomms12583

[2] Géneaux, R. et al., 2017. Phys Rev A, 95, 051801. http://­­10.1103/­PhysRevA.95.051801

[3] Gauthier, D. et al., 2017. Nature Communications, 8, 14971. http://­­10.1038/­ncomms14971

[4] Camper, A. et al., 2017. Optics Letters, 42(19), 3769. http://­­10.1364/­ol.42.003769

How to join:

Those external to King's should email this address to gain access to the building.

At this event

Alexey Krasavin

Research Associate

Amelle Zaïr

Senior Lecturer