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 its 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 indices range (up to 15). The mode convertor constituted by two cylindrical lenses was 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 of practical laser device for more versatile light, providing new parametric space for structure control and fostering extended applications.

Advances of Yb:CALGO Laser Crystals

“…Under this premise, we successfully explored vortex lattices with transverse-modelocking states [80], periodic-trajectory-controlled and wavelength-tunable SU(2) geometric modes [81] as well as polygonal vortex beams [82]. Not long ago, a new Yb:CALGO laser scheme was proposed by inserting two cylindrical lenses into the cavity to surprisingly obtain two-dimensional tunable high order HG modes as shown in Figure 3b [83]. This is significant because the elegant scheme was able to directly control two indices of HG modes at the source and after an astigmatic converter, the LG modes were tunable likewise.…”

“…(a) Wavelength-and OAM-tunable Yb:CALGO laser[77]. (b) Two-dimensional tunable high order mode laser[83]. (c) Mode-tunable laser based on a mirror curvature dynamically controlled Z-shaped resonator[85].…”

Intra-Cavity Astigmatic Mode Converting VECSEL

“…Intra-cavity astigmatic mode conversion using pump power dependent thermal lensing in a solid state bounce laser has been reported [26]. First order OAM beams have also been directly generated using intra-cavity cylindrical lenses [29]. Lastly, intra-cavity generation of OAM modes in vertical external cavity surface emitting lasers (VECSEL) was first reported by Fresnel number manipulation [30].…”

Orbital angular momentum of structurally stable laser beams

“…Имеется несколько обзорных работ, в которых описываются генерация и детектирование такого света [1,2]. Такой свет можно генерировать как с помощью лазеров [3,4], так и с помощью оптических компонент вне резонатора (например, с помощью астигматического конвертора [5]). Структурированный свет -это свет, имеющий пространственную поперечную (например, пучки Эрмита-Гаусса (ЭГ) или Лагерра-Гаусса [6]), продольную (например, пучки Эйри [7]), поляризационную (например, пучки с радиальной или азимутальной поляризацией [8]) и временную (например, пространственно-временные оптические вихри [9,10]) структуру.…”