Abstract

Free space optical (FSO) communication systems require high-performance receivers capable of converting high-frequency signals with wide bandwidths to support increasing data rates. An integrated photodetector array (PDA) enhances data reception efficiency by reducing receiver size and increasing the number of array elements. However, the small effective receiving area of single mode optical fibers poses significant alignment challenges and needs precise beam coupling. To address this, a microlens array (MLA) assisted PDA is proposed to improve alignment tolerance, reduce coupling losses and enhance optical coupling efficiency. This study explores the principles and design of a microlens array for a 10-element PDA operating at 1550 nm. The microlenses are arranged in a hexagonal configuration, which effectively manages incident light and compensates for alignment deviations. A spheri-cal microlens with a radius of curvature of 2.4 mm is designed to optimize beam collimation and redirection, reducing lateral displacement. The results demonstrate that the MLA assisted PDA significantly enhances optical cou-pling efficiency, improving overall system performance and reliability in FSO applications.