Experimental investigations of underwater laser propulsion microspheres based on a tapered fiber propulsion system

Abstract

An underwater propulsion microsystem is proposed in this work, which employing a nanosecond laser pulse out from the tapered fiber tip. Noteworthily, the system can generate a directional shock wave (or plasma) to propel the polystyrene (PS) microsphere. Through simulation, the shock wave propagation characteristics and the bubble dynamic are investigated. Experimentally, high-speed photography method is employed to obtain the motion image of microsphere. The results show that the propulsion efficiency is dependent on the laser energy. Meanwhile, we explain the role of the bubble dynamic process in propelling microsphere, and find that the bubble diameter increases with the laser energy. In addition, an experiment is performed to separating and removing the PS microsphere clusters in water at fixed point. Our findings make the tapered fiber propulsion system promising for applications in the underwater directional manipulation of microstructures and the removal of the contaminate microsphere in water environment.