Multimode and Programmable Deformation of Optical Fiber Taper‐Based Waveguide Photoactuators

Abstract Photoactuators with programmable and multimode deformations have attracted significant attention due to their potential applications in various soft devices. However, most existing photoactuators are triggered by free‐space illumination, which becomes problematic when direct optical access is restricted. Although using optical waveguides can overcome this limitation, achieving complex and programmable deformations in waveguide photoactuators remains challenging owing to difficulties in controlling the energy conversion within actuators. Here, a gradient‐loading strategy of photothermal material is reported to achieve programmable and multimode deformations in optical fiber taper (OFT)‐based waveguide photoactuator (OWPA), by analyzing light propagation behaviors, calculating fractions of various factors contributing to energy attenuation, and controlling the uniform photothermal conversion. The microscale OFT reduces the actuator thickness, thus improving the deformation amplitude and providing sufficient programmable space for designing complex deformations. Multimode deformations including S‐shaped, W‐shaped, and helical deformations are achieved, utilizing various patterning schemes. As a proof‐of‐concept, a single OWPA efficiently captures conical and cylindrical objects is demonstrated. It is posited that the proposed approach, which is based on the quantitative analysis of light propagation and employs a gradient‐loading strategy, could serve as a guiding principle for the development of other waveguide photoactuators with designable deformations.