However, the practical use of MMFs is limited by the challenges posed by fiber bending, which leads to mode coupling. In this study, we present evidence that MMFs possess principal modes, named curved principal modes, that can resist significant bending. ABSTRACT Multimode fibers (MMFs) have found wide application across various fields, such as optical communications, mode-locked lasers, and endoscopy. Inadvertent tight bends are common in high-density installations and in plants which are frequently reconfigured (e. When stressed by bending, light in the outer part of the core is no longer guided in the core of the fiber so some is lost, coupled from the core into the cladding, creating a higher loss in the stressed section of the fiber. Multi-mode links can be used for data rates up to 800 Gbit/s.