Optical Manipulation of Micro / Nanoparticles Using Fiber-Based Optical Tweezers

Abstract

Over forty years, the optical tweezers have been used to facilitate new scientific findings and benchmark single-molecule studies. One of the next steps, as far as applications is concerned, is expected to be their use as medical diagnostic tools, where in parallel, manipulation, sorting, and diagnosis of large number of biological particles, using the optical trapping technique will make the current clinical procedures quicker and cheaper. However, most of the current optical tweezers are based on objective lenses, which are bulky, expensive, and hard to integrate. Optical tweezers based on optical fibers have great potential to solve the abovementioned limitations. This paper attempts to provide solutions in order to overcome the limitations of current conventional optical tweezers with the objective of achieving fundamental understanding and improving the performance of fiber-based optical tweezers. Thus, we develop an optical fiber tweezers using a continuous wave diode GaAlAs laser operating at 659-nm for trapping dielectric nanoparticles (900-nm diameter and 3-?m diameter), suspended in deionized water. We systematically measure the optical trapping force and the effective trapping quality factor. We also investigate the dependence of the trapping force on both the insertion angle of the fiber into the sample chamber and the size of the trapped particle.