A programmable fiber laser with full spatiotemporal reconfigurability

A structured light laser that enables on-demand generation of arbitrary optical field patterns and operates seamlessly across diverse lasing regimes constitutes a transformative platform, offering unprecedented flexibility in high-dimensional optical communications, ultrafast precision machining, and novel strong-field physics experiments. Here, we demonstrate a programmable structured light fiber ring laser capable of generating arbitrary structured beams and supporting multiple operational regimes. This is achieved by integrating a spatial light modulator (SLM) inside the resonant cavity: the left half of the SLM converts a Gaussian beam into structured light and partially extracts it, while the right half performs the reverse conversion. Spatial beam shaping is governed by the SLM, whereas temporal control of the laser is realized by inserting an optical modulator inside the cavity. Experimentally, we have successfully generated vortex beams with topological charges ℓ = 1, 3, 5, 10, and 15 in both Q-switched and mode-locking regimes, as well as user-defined patterns such as the letters “A,” “H,” and “U” in the continuous wave regime. To the best of our knowledge, this work demonstrates for the first time a fiber laser system that directly integrates in situ on-demand structured light generation within resonators while offering controllable operational states. It thus provides a novel, integrated solution for the research and application of dynamically programmable structured laser fields.