Numerical Study of the Dependence of the Parameters of Lensed Optical Fibers on Geometric Parameters

This article presents a comprehensive study on the dependence of key parameters of lensed optical fibers on the geometry of the lens and the diameter of the fiber core. Lensed fibers, which have microlenses at their ends, are crucial in integrated and fiber optics for enhancing the efficiency of radiation input/output into optical integrated circuits, laser diodes, and photodiodes. The study focuses on the impact of the lens's radius of curvature and the fiber core diameter on the mode field diameter (MFD) and the focal length of the lens. Numerical experiments were conducted using the COMSOL Multiphysics 6.2 program, which allows for the design, analysis, and testing of photonic components by solving Maxwell's equations using the finite element method. The investigation involved various types of fibers, including UHNA1, UHNA3, and standard single-mode fibers (SMF 9/125), with core diameters ranging from 1.8 μm to 9 μm. The results show that the MFD and focal length are significantly influenced by the lens's curvature radius and the fiber core diameter. For UHNA fibers, which have thinner cores, the lens is effective only at small curvature radii, and its focusing capability diminishes at larger radii. In contrast, SMF 9/125 fibers maintain their focusing capability even at larger curvature radii. These results are crucial for optimizing the design of lensed fibers for various applications, including fiber-optic communications, biomedical imaging, and laser systems, where efficient light coupling and precise focusing are essential.