Diffraction of relativistic vortex harmonics with fractional average orbital angular momentum
Vortex harmonics with fractional average orbital angular momentum are generated when a relativistic fractional vortex beam incidents on and reflects from an overdense plane plasma target. A two-step model is presented to explain the far-field patterns of the harmonics. In the first step, a fundamental spot-shaped hole is produced during the hole-boring (HB) stage, and harmonics are generated simultaneously. In the second step, different order harmonics are diffracted by the hole and propagate to the far-field. This process can be accurately described by Fraunhofer diffraction theory. This work facilitates a basic recognition of fractional vortex beams.
Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences
Li Shasha,Shen Baifei,Wang Wenpeng,Bu Zhigang,Zhang Hao,Zhang Hui,Zhai Shuhua. Diffraction of relativistic vortex harmonics with fractional average orbital angular momentum[J].Chinese Optics Letters,2019,17(5):05.