Optical Vortex Potential Well And Its Characteristics Based On Multi-core Fiber

Since Ashkin firstly used optical force to capture and manipulate particles, the optical tweezers technology has made a rapid progress. Because of its non-invasive and non-destructive characteristics, optical tweezers are widely used, especially in the field of biology. Conventional optical tweezers can manipulate particles, but cannot rotate them.However, optical spanner is able to rotate in additional three degrees of freedom while trapping the particles, which further expand the application of optical tweezers.In this thesis, a new type of multi-core fiber micro optical spanner that can produce vortex optical potential wells was designed and simulated. Our optical spanner is not only low-cost, space- saving, but also has higher rotation efficiency. The capture and rotation efficiency of the vortex optical potential well are mainly determined by those factors such as laser power, vortex angle, core numbers, working distance .etc. Specifically speaking, the rotation efficiency is proportional to laser power and nearly sinusoidally determined by vortex angle. The more is the number of the core, the higher the efficiency of the rotation is. Also the shorter the working distance is, the better the optical trap works.This paper contains five parts. The development and research of optical tweezers and optical spanner are introduced in the first chapter. The second chapter is mainly about the principle of optical spanner, which can be divided into spin angular momentum, orbital angular momentum and optical radiation pressure according to its operating mechanism. The third chapter describes the fiber end micro processing technology, and compares the advantages and disadvantages of these technologies, providing a basis for selecting the specific experiment processing method. The fourth chapter describes in detail how to polish the fiber by using micro-fabrication technology to produce the multi-core optical fiber micro spanner, how to construct the potential vortex well by using multi-beam optical lateral radiation force and the theoretical derivation. The fifth chapter shows the experimental system scheme of fiber optics spanner and simulation results, and additionally the regulation of optical vortex and dynamics evolution of angular momentum are described,which makes a solid ground for experimental application.