Experimental Analysis of Optical Trapping System Using Tapered Hemispherically Lensed Optical Fiber

摘要

We describe the operation and performance of an optical fiber trap realized using a tapered hemispherically lensed optical fiber. Axial and transverse trapping forces exerted on a microsphere are experimentally analyzed to corroborate the optical trapping using an optical fiber. Experimental results are as follows. (i) Transverse force F_(tr) acting on a sphere is a restoring force that acts to pull the microsphere back to the center of trap. (ii) Axial force F_(ax) always acts to push a sphere in the direction of the beam away from the trapping fiber end. (iii) Vector sum of F_(tr) and F_(ax) acting on a sphere gives a restoring force directed back to the stable point. (iv)Transverse for F_(tr) plays a significant role in trapping a micro-sized object by means of an optical fiber.