Generation of Intense High-Order Vortex Harmonics

TL;DR

This paper introduces a novel method to generate intense high-order optical vortex harmonics in the extreme ultraviolet region, enabling new applications in quantum information and high-resolution detection.

Contribution

It is the first to demonstrate the generation of intense high-order vortex harmonics with orbital angular momentum in the EUV region using particle-in-cell simulations.

Findings

High-order LG harmonic modes scale with their order.

Generated vortex harmonics have intensities near the relativistic region.

Pulse durations can reach attosecond scales.

Abstract

This paper presents the method for the first time to generate intense high-order optical vortices that carry orbital angular momentum in the extreme ultraviolet region. In three-dimensional particle-in-cell simulation, both the reflected and transmitted light beams include high-order harmonics of the Laguerre-Gaussian (LG) mode when a linearly polarized LG laser pulse impinges on a solid foil. The mode of the generated LG harmonic scales with its order, in good agreement with our theoretical analysis. The intensity of the generated high-order vortex harmonics is close to the relativistic region, and the pulse duration can be in attosecond scale. The obtained intense vortex beam possesses the combined properties of fine transversal structure due to the high-order mode and the fine longitudinal structure due to the short wavelength of the high-order harmonics. Thus, the obtained intense vortex beam may have extraordinarily promising applications for high-capacity quantum information and for high-resolution detection in both spatial and temporal scales because of the addition of a new degree of freedom.