Numerical Simulation Of Single Fiber Optical Tweezers And Computation Of Optical Force

Single fiber optical tweezers is theoretically analyzed in this dissertation. The principle of optical tweezers is illustrated and three models for calculating the optical forces are given. One of the three models, the EM model, are the exact method for the simulation of the single fiber optical tweezers and for the numerically calculation of the optical trapping force. Some computational electromagnetic methods are usually needed in the EM model. FDTD(finite difference time domain) method is chosen to simulate the optical field distribution in and outside the fiber probe. A new method for the simulation of single fiber optical tweezers and calculation of the optical trapping force is presented: by using the FDTD method, first simulate the output laser beam from the fiber probe, then calculate the scattering field distribution surrounding the dielectric sphere, the optical trapping force can be computed according to the electromagnetic field momentum conservation law. This technique has been used to calculate the light field distribution from different types of fiber probes and optical forces exerted on different particles. Based on these numerical results, the experiments of the single fiber optical tweezers are theoretically verified.The experimental setup of single fiber optical tweezers system is designed and constructed. Based on the system, four kinds of fiber optical tweezers are introduced, three of which are single fiber optical tweezers. By using these systems the 3-D trapping and manipulation of yeast cells in water is easily achieved. This work has great significant for the research and development of the single fiber optical tweezers. It is of importance reference value to optical tweezers research in instrument design and its wider application in life science and biography technology.