Numerical Simulation And Experimental Study Of Dual-fiber Optical Tweezers

Fiber optical tweezers is one kind of micro-manipulation technology. It uses fiber output beam to trap and manipulate micro-particles. Compared to traditional tweezers, it has lots of advantages such as simple structure, easy to control and coupling, wide working range and so on. Based on these advantages, it is widely applied in various fields. In this thesis, a dual-fiber optical tweezers has been studied from three aspects:the preparation of fiber probe; the simulation of output optical field and optical trapping force; the construction of dual-fiber optical tweezers, and by using it, various experimental studies were accomplished.Firstly, a new method for preparing fiber probe was given. Based on the advantages and disadvantages of common etching and melting method, we combined both of them. Firstly, fiber was processed into a parabolic probe with smooth surface by melting method. Then by static etching, it was etched into finished parabolic fiber probe with large cone angle, smooth surface and high light transmission efficiency.In addition, the law of conservation of momentum of electromagnetic field and the limited time domain finite difference method were used to simulate the output optical field of fiber optical tweezers. Meanwhile, by taking the integral of Maxwell’s stress tensor, the transverse and axial optical forces were obtain. The result indicated that the parabolic fiber probe has the ability to trap micro-particles in three dimensions, and there is a linear relationship between optical force and laser power.Furthermore, a dual-fiber optical tweezers was constructed by us. By using this system, yeast cell was successfully captured, shifted and transferred in three dimensions. Additionally, multicellular capture in three dimensions was accomplished by single fiber probe. Both the experimental results were corresponding with simulation results.