Stability Analysis of Particle Trapping in Time-Division Optical Tweezers by the Generalized Lorentz-Mie Theory

Time-division multiplexing in the proposed holographic optical tweezers (HOT) has been used to quasi-simultaneously generate two different intensity patterns, a carrier beam spot and a beam array, by alternately feeding the corresponding hologram patterns to a spatial light modulator (SLM). Since the switching of the input holograms degrades the spatial stability of trapping a Brownian particle within the generated intensity spot area, it is necessary to numerically investigate the conditions in the time-division multiplexing for a particle to be stably trapped by a focused Gaussian beam. The Smoluchowski equation based on the generalized Lorentz-Mie theory (GLMT) model is evaluated numerically by an explicit method to estimate the relationship among particle size, switching rate, and focused laser beam power. Finally, the validity of the numerical analysis in this work is confirmed by experiments. (C) 2010 The Japan Society of Applied Physics