Hartmann wavefront sensor characterization of a high charge vortex beam in the extreme ultraviolet spectral range

Abstract

We demonstrate for the first time, to the best of our knowledge, the ability of extreme ultraviolet (XUV) Hartmann wavefront sensors to characterize high charge vortex beams produced by high-order harmonic generation up to the order of 25. We also show that phase matched absorption limited high harmonic generation is able to maintain the high charge vortex structure of the XUV beam even in a rather long (1 cm) generation medium.

Conservation of Torus-knot Angular Momentum in High-order Harmonic Generation

“…Finally, it is important to note that this configuration also allows for the production of XUV radiation with controllable OAM, as recently pointed out in Refs. 41, 50, 60. In single-color collinear experiments the OAM scales linearly [16][17][18], with the qth harmonic carrying OAM q = q [15,17]; for high q, this OAM is often too big to be useful, and it is challenging to detect and characterize in the first place [16,61]. One solution is to use a noncollinear perturbing beam [16,19,20], but that spreads the harmonic yield over a range of different OAM modes.…”

Ptychographic amplitude and phase reconstruction of bichromatic vortex beams

“…To test the fidelity of ptychographic CDI as a high spatial resolution wavefront sensor, possible beam profiles at the imaging plane of the experiment were simulated and compared to the experimentally reconstructed beams. The simulation involved (1) applying the SPP and the focusing lens phase to an input TEM00 Gaussian beam with adjustable radius and phase curvature, and then (2) propagating the field to the imaging plane (i.e., the location of the target) using the transfer function of free space method. The SPP phase was applied as a discrete 32 stepped phase spiral in two ramps, and the lens phase was approximated as a thin lens without any aberrations.…”

“…Exciting recent advances have made it possible to achieve full control over the wavefront, polarization, and orbital angular momentum of light fields spanning from the THz, through the visible, and also the extreme ultraviolet spectral regions [1,2]. As a result, it is now possible to generate three-dimensional, structured optical fields [3].…”

“…However, many of these methods often only retrieve the average value of the OAM charge and are inadequate when measurements of both the amplitude and phase profile of the field are required with a high spatial resolution, especially if the field is hyperspectral. Wavefront sensing schemes based on Shack-Hartmann wavefront sensors can characterize both the amplitude and phase of wavefronts, and some variants are also able to handle hyperspectral fields [2,22]. However, since these methods use an array of microlenses or apertures to sample the wavefront, the spatial resolution of the reconstruction is limited by the manufacturing precision of the array.…”

Single-shot wavefront characterization of high topological charge extreme-ultraviolet vortex

“…Owing to the numerous applications of optical vortices, the generation, and characterization of light beams carrying topological singularities has received increasing attention in the recent past [4]. Besides, high harmonic generation (HHG) in rare gases has proven to be a handy way to generate extreme-ultraviolet (EUV) vortices of low and high topological charges [5][6][7]. HHG, when driven by a driver of topological charge 1 , follows the perturbative energy conversion law = 1 , where is the topological charge of ℎ harmonic [5,7].…”