Electromagnetic theory of helicoidal dichroism in reflection from magnetic structures

Shack-Hartmann Wavefront Sensing of Ultrashort Optical Vortices

“…The characterized wavefronts reveal the topological charge as well as its sign. However, for applications such as quantum communication, information processing, and appropriate quantification of all light–matter interactions studies [ 19 , 20 , 21 , 22 ], including highly nonlinear frequency upconversion [ 70 , 71 ], it is imperative to deduce their full modal composition. Due to the Shack-Hartmann wavefront sensing, we can utilize the reconstructed complex field of the vortex beams to reveal their modal composition.…”

“…Structured light beams have emerged as a versatile tool for a wide range of applications [ 1 , 2 , 3 ]. In particular, light beams manifesting Orbital Angular Momentum (OAM) [ 4 ] have propelled exciting new developments in the field of optical communication and quantum information [ 5 , 6 , 7 , 8 ], super-resolution microscopy [ 9 , 10 ], optical trapping and tweezing [ 11 , 12 ], material processing [ 13 , 14 ], astronomy [ 15 , 16 ], induction of topological current in semiconductors [ 17 , 18 ], and light–matter interaction [ 19 , 20 , 21 , 22 ]. These helically-phased beams, also known as optical vortices (OV), are characterized by their twisted wavefront resulting from an azimuthally varying phase given by around the beam propagation axis [ 4 ].…”

Observation of magnetic helicoidal dichroism with extreme ultraviolet light vortices

“…Upon interaction (reflection or transmission) of a pure Laguerre-Gaussian mode of topological charge with a magnetic surface, MHD consists in an intensity redistribution into all modes + n in the outgoing beam, where n represents all the azimuthal decomposition coefficients of the magnetic structure topological symmetry. [36]. Differently from MCD, MHD is sensitive to the overall topology of the spin texture, it vanishes for homogeneous structures, and is not self-similar if one inverts either the helicity of the beam or the magnetization direction.…”

“…Over the last decade, the development of highly coherent sources and tailored optical schemes has opened new possibilities for generating structured light vortices in the extreme ultraviolet (XUV) [12][13][14][15][16][17][18][19] and x-ray [20][21][22][23][24][25] regimes, paving the way to their spectroscopic applications. In this context, magnetic helicoidal dichroism (MHD) has been recently predicted [36], in analogy to the SAM dependent magnetic circular dichroism (MCD). Upon interaction (reflection or transmission) of a pure Laguerre-Gaussian mode of topological charge with a magnetic surface, MHD consists in an intensity redistribution into all modes + n in the outgoing beam, where n represents all the azimuthal decomposition coefficients of the magnetic structure topological symmetry.…”

“…They have been shown to be particularly robust against perturbations [42] and present a rich sub-nanosecond dynamics [43]. Because of their symmetry, MVs are also a particularly simple test case for MHD, since they only present n = ±1 [36].…”