Index-Tunable Structured-Light Beams from a Laser with an Intracavity Astigmatic Mode Converter

Abstract

Structured-light lasers are highly topical due to not only their ability to tailor customized distribution of intensity, phase, orbital angular momentum (OAM), and other optical properties, but also the compact and simple at-the-source generation scheme. Here we propose a form of structured-light laser, intracavity mode convertor laser, with the ability to generate two-dimensional (2D) tunable high-order Hermite-Gaussian (HG) modes with a large indice range (up to 15). The mode convertor constituted by two cylindrical lenses is always used for external OAM conversion, but here we show that it can be inserted into a laser cavity as an intracavity element for symmetry-breaking control, which we also demonstrate with a complete matrix optics theory. The generated 2D HG modes can also be converted into Laguerre-Gaussian (LG) vortex beams with both tunable OAM and radial momentum. Moreover, we also show the ability to directly generate vortex beam from our laser cavity. Our approach meets the urgent necessity for a practical laser device for more versatile light, providing more alternative parametric space for structure control and fostering extended applications.