Polygonal vortex beams in quasi-frequency-degenerate states

TL;DR

This paper demonstrates the generation of polygonal vortex beams with large orbital angular momentum using a quasi-frequency-degenerate laser resonator, enabling novel beam shaping and particle trapping applications.

Contribution

It introduces a new method to produce polygonal vortex beams with controllable patterns and high OAM in a QFD laser resonator, expanding the capabilities of beam shaping technology.

Findings

Successfully generated triangular, square, and parallelogram vortex beams.

Beam patterns and OAM are controllable via cavity length and pump position.

Experimental results confirm the theoretical predictions.

Abstract

We originally demonstrate the vortex beams with patterns of closed polygons [namely polygonal vortex beams (PVBs)] generated by a quasi-frequency-degenerate (QFD) Yb:CALGO laser resonator with astigmatic transformation. The PVBs with peculiar patterns of triangular, square, and parallelogram shapes carrying large orbital angular momentums (OAMs) are theoretically investigated and experimentally obtained in the vicinity of the SU(2) degenerate states of laser resonator. The PVBs in QFD states are compared with the vortex beams with patterns of isolated spots arrays located on the triangle-, square-, and parallelogram-shaped routes [namely polygonalspots-array vortex beams (PSA-VBs)] under normal SU(2) degenerate states. Beam profile shape of PVB or PSA-VB and OAM can be controlled by adjusting the cavity length and the position of pump spot. The simulated and experimental results validate the performance of our method to generate PVB, which is of great potential for promoting novel technologies in particle trapping and beam shaping.