基于T矩阵双光束光阱的模拟仿真与优化设计

Simulation and Optimization Design of Dual Beam Optical Trap Based on T-matrix

基于T矩阵方法，建立了双光束光阱中米氏微粒的光阱力计算模型。分析了光束相干性对光阱力的影响，即当捕获光为相干光时，两束光产生干涉，形成驻波，虽然能增加光阱力的大小，但由于形成包络峰，使得光阱力线性区域大大减少，不利于对光阱力进行分析以及标定。研究了在非相干条件下，被捕获微粒尺寸、光束辐射角、相对折射率和捕获激光波长对光阱力的影响。通过仿真，得出知被捕获微粒半径为1～5 μm、捕获波长为980～1064 nm、光束辐射角为40°～60°时，双光束光阱的捕获效果最好，且随着相对折射率的增大，光阱阱深减小，捕获范围增加。

The calculation model of optical trapping force of Mie particle in dual beam optical trap based on T-matrix is built. The influence of coherence on optical trapping force is analyzed. The result shows that trapping force increases because of interference and the formation of standing wave. Because of the formation of envelope peak produced by interference, the optical trap force linear area is greatly reduced, which is unfriendly to analysis and calibration of optical trapping force. The influence of particles′ radius, beam half angle, relative refractive index and wavelength of capture laser on optical trapping force is researched. The simulated result shows that when particles′ radius, beam half angle and wavelength of capture laser are set as 1～5 μm, 980~1064 nm and 40°～60°. The performance of dual beam optical trap is optimized. Meanwhile, along with the relative refractive index increasing, the optical trap depth decreases, and the capture range increases.