Waveguide Photoactuators: Materials, Fabrication, and Applications

Waveguide photoactuators direct light through optical fibers or planar waveguides to stimuli‐responsive materials, converting optical energy into precise mechanical motion without the alignment constraints or undesired scattering of free‐space illumination. Their tethered yet flexible architecture promises applications in minimally invasive surgical tools, soft robotic grippers for confined spaces, and reconfigurable elements for integrated photonic circuits. This review contrasts the major actuation pathways, namely photothermal, photochemical, and optical‐force mechanisms, and identifies representative material platforms that enable them. It then surveys principal waveguide geometries and summarizes fabrication and integration approaches that join waveguides with active films while maintaining optical coupling efficiency and mechanical robustness. Deformation concepts are organized around stress‐mismatch bilayers and asymmetric illumination, which provide a unified account of bending, hooking, coiling, and pumping behaviors. A comparative performance analysis highlights thickness reduction, interface durability, and liquid‐phase operation as key levers for future improvement, and outlines how programmable alignment or patterned inert layers can further expand functionality. By connecting these elements into a coherent framework, the review aims to guide materials selection, device design, and system integration, accelerating the transition of waveguide photoactuators from laboratory prototypes to versatile microscale tools for complex real‐world environments.