Light‐Induced In‐Plane Rotation of Microobjects on Microfibers

Abstract The transfer of momentum carried by photons into a microobject has been widely used to actuate the microobject. However, this scheme is defective in nonliquid environments due to the scale gap between friction force (N) and optical force (pN). To overcome this problem, the researchers have recently proposed to take advantage of elastic waves induced by optical absorption. Grounded on this insight, here, the in‐plane rotation of a gold microplate in its surface contacting with a microfiber is demonstrated and characterized. The in‐plane rotation is actuated by laser pulses guided into the microfiber, and its speed increases with laser power. Furthermore, the underlying physical mechanisms supported with numerical simulations are examined, highlighting the joint role of the spatial gradient of optical absorption and the asymmetry in two wings of the plate. The combined experimental and theoretical results offer new insights into the study of the light‐induced actuation of the microobjects in nonliquid environments, an emerging field far from being mature in both comprehensive understanding and practical applications.