Toward a practical Laguerre–Gaussian mode laser

The Laguerre–Gaussian (LG) mode is viewed as an important cornerstone for constructing fascinating topological light fields, including optical skyrmions and optical Möbius strips, which have been extensively investigated in optical communications, super-resolution imaging, and quantum information process. However, it still lacks a reliable LG-mode light source, featuring high purity, high efficiency, high power, high order, and tunable mode, to meet the requirements of advanced applications. Here, we present a high-performance solid-state LG-mode laser system. Based on our Janus cavity design, the mode distortion and cavity loss due to non-perfect intracavity mode conversion are significantly suppressed. The mode purities are >92%, the optical-to-optical conversion efficiencies reach >12%, and the output powers are >500 mW. In particular, these laser parameters do not degrade for high-order LG mode (up to 50 in our experiment). In addition, we show an example application of our system in a direct laser output of an arbitrary higher-order Poincaré sphere state. Our LG-mode laser system provides a powerful support to advance the applications of topological photonics.