Generation of ultrashort vortex pulses by spiral array

The ultrashort orbital angular momentum pulses, or the ultrashort optical vortex pulses, with the properties of the ultrashort duration and broadband spectrum, open significant applications in various contexts. The controllability of the orbital angular momentum in ultrashort vortex pulses crucially affects its capabilities. We put forward an approach for orbital angular momentum mode selection in an ultrashort laser pulse. This approach depends on an optical mask with multiple spirals rotationally and symmetrically arranged in a model of the spiral array. Both theoretical analyses and experimental work in the context of ultrashort vortex pulses demonstrate that the spiral array enables flexible generation of the structured orbital angular momentum modes. This optical mask shows the advantages of damage resistance, without medium-dispersion, and ease of handling in an ultrafast optical field. Furthermore, the spiral array can be applied to analyzing and generating other matter vortex beams within an axially scalar system.