Application of optical trapping to beam manipulation in optofluidics.

We introduce a novel method of attaining all-optical beam control in an optofluidic device by displacing an optically trapped microsphere through a light beam. The micro-sphere causes the beam to be refracted by various degrees as a function of the sphere position, providing tunable attenuation and beam-steering in the device. The device itself consists of the manipulated light beam extending between two buried waveguides which are on either side of a microfluidic channel. This channel contains the micro-spheres which are suspended in water. We simulate this geometry using the Finite Difference Time Domain method and find good agreement between simulation and experiment.