Application of the power flow equation in modeling bandwidth in polymer optical fibers: a review

Multimode polymer optical fibers (POFs) are considered to be the best choice for short-distance communication lines due to their advantageous properties. One must pay close attention to POFs’ most crucial transmission property, bandwidth (BW), which affects the fibers’ transmission capacity. The improvement of POF transmission qualities, particularly BW, which is its most crucial property, has been the subject of many researches during the past few decades. Both experimental and theoretical approaches have been used to address this issue. Up to now, there were no commercial simulation tools available for studying the transmission characteristics of multimode optical fibers. To overcome this problem, the modal continuum approach is employed to characterize light transmission in various kinds of multimode optical fibers. This modal continuum approach, which uses the time-dependent power flow equation (TD PFE), plays the most important role in the theoretical approaches. The PFE is the most comprehensive because it takes into account attenuation, mode coupling and modal dispersion, which significantly affects the BW. It can also be modified to accommodate various refractive index profiles, including step-index (SI), W-type index and graded index (GI) profiles. This review analyzes the pertinent literature related to the use of modal continuum-based models for BW modeling in conventional and microstructured multimode POFs. An overview of methodologies for optical fiber analysis with a focus on modal continuum approximation, and solutions to the TD PFE for various multimode fiber types, is provided.