This article demonstrates the use of the Geometric Image Analysis feature to compute multi-mode fiber coupling efficiency. Fiber-to-fiber coupling between two different fibers is a state of the art technology. We have, however, always been forced to accept a certain loss in beam. Optical Fibre Sensors Research Centre (OFSRC), Dept. of Electronic and Computer Engineering, University of Limerick, V94 T9PX Limerick, Ireland Center of Research in Optoelectronics, Communication and Computational Systems (BU-CROCCS), School of Engineering, Bangkok University, Pathumthani 12120. In this paper, we present a new and more realistic theoretical framework for lightwave propagation in a multimode graded index (GRIN) optical fiber when the fundamental mode is selectively excited into the fiber with constant radius bending, causing coupling between the various modes of the fiber. Using the power flow equation (PFE), this article investigates mode coupling in step-index (SI) multimode (MM) polymer optical fiber (POF). This equation's coupling coefficient was initially fine-tuned so that it could appropriately reconstruct previously recorded far-field (FF) power. Fiber coupling efficiency depends on mode overlap, numerical aperture matching, and beam quality. NA matching is critical for efficient power transfer into fiber.
