Simulation Of Focus Evanescent Field Based On FDTD And Experimental Design

Optical tweezers as a single particle beam trap, which consist of highly compact single-beam lasers, could capture flexibly biological large molecules particles (ball), cell vehicles from several nm to tensμm, and basically does not affect surroundings of the catch, a non-contact, non-destructive bacterial operation. At present the fiber optical trapping uses an optical fiber instead of objective lens.This system has simple structure and wide capture range.The study includes the principle of optical tweezers, the finite difference time domain method(FDTD) theory, using the finite difference time domain (FDTD) method, we calculated and simulated the optimal angle of the axicon tip as a function of the working distance and dependence of anxial optical force on tip angle of trapered optical fiber. as well as design of the experiment platform for optical fiber trapping.First, introduce the principle of optical tweezers in detail, explain the process of optical tweezers trapping from different aspect, such as optical momentum, optical pressure, gradient force, scattering power and so on.Secondly introduce the basic principles of finite difference time domain method(FDTD), Yee cell and basic equations of FDTD. Base on the theory of optical tweezers, using the finite difference time domain (FDTD) method, we calculated and simulated the optimal angle of the axicon tip as a function of the working distance and dependence of anxial optical force on tip angle of trapered optical fiber .The simulation results are in good agreement with the experiment observation.Finally, we design a experiment platform for optical fiber trapping. this technology greatly enlarges the application range of the laser micro- manipulation in life sciences.