Abstract

Visible vortex beams are demanded in a range of applications, including micromachining, vortex induced laser printing [1], and quantum technologies. The diversity of applications requires an equally diverse set of source requirements for wavelength, power, pulse characteristics, and mechanical form factor. These demands will need to be met for successful scientific and commercial exploitation of these techniques. Typical methods to obtain visible vortex beams involve converting Gaussian laser sources with bespoke optics, for example spiral phase plates or spatial light modulators. The visible laser sources are typically nonlinear frequency converted infrared lasers. The multiple steps required to obtain the eventual vortex output highlights the likely cost and complexity of these systems, which will be a barrier to widespread adoption. Direct output of a vortex from a laser is desirable to tackle both issues, amongst others. There has been some prior work on visible vortex emission with the Pr:LiYF₄ crystalline gain medium, with off-axis pumping or spherical aberration cavities [2].

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