Coupling Efficiency Optimization for the Optical Fiber Lens with Oval-Shaped Endfaces by Applying Uniform Design and Kriging Interpolation

摘要

The purpose of this study is to optimize the coupling efficiency of an optical fiber lens by applying the uniform design of experiments and Kriging interpolation methods. A third-generation optical fiber endface polishing machine is applied to polish the optical fiber endfaces into oval shapes. A type-36 optical fiber fusion splicer is used to fuse the optical fibers into a lens. In the polishing process, the control factors are polishing angle, feeding rate, and rotation speed. Firstly, the uniform design of experiments method is used to construct a set of experiments. The constructed experiments are scattered uniformly in the design space formed by the control factors. Secondly, the coupling efficiency of the lens in each experiment is measured using a 980 nm laser diode and a power meter. Thirdly, the Kriging interpolation method is used to transform the discrete data of coupling efficiency into a continuous surrogate model of coupling efficiency. Finally, a mixed optimization algorithm combining a global search algorithm, genetic algorithm (GA), and a local search algorithm, Nelder-Mead simplex (NMS) algorithm, is used to optimize the coupling efficiency. The optimal solutions of polishing angle, feeding rate, and rotation speed are 56°, 289 rpm, and 52 μm/rev, respectively. By integrating the uniform design of experiments method and Kriging interpolation method, the coupling efficiency of the optical fiber lens can be improved from 60.89% to 79.63%. The improved rate of the coupling efficiency is 30.8%.