Modeling and Analysis of Optical Time-domain Reflectometry in Strongly-coupled Multi-core Fiber

【Objective】In the modern field of communications, optical fibers have become an important transmission medium in optical network systems due to their ultra-high transmission bandwidth and excellent optical properties. Multi-core optical fibers integrate multiple cores within a single fiber cladding to significantly enhance the data transmission capacity of a single fiber. However, an increase in the number of cores can also lead to additional channel impairment effects, which in turn affect the transmission performance and communication quality of the fiber link. Therefore, studying the theoretical model of the channel effects in coupled-core optical fibers, especially clarifying the relationship between the optical time-domain reflectometry process and channel response, can provide important references for the practical deployment and application of multi-core fibers.【Methods】To refine the model of optical time-domain reflection effects in coupled-core optical fibers, the article begins with basic principles, outlining the theories of forward transmission and backward Rayleigh scattering in coupled-core optical fibers. It details the derivation of coupled mode equations and the general expression for Rayleigh scattering power, including definitions and calculation methods for various coefficients such as the total capture factor. Based on the theoretical research, the article also proposes a modeling scheme for Rayleigh scattering effects in coupled-core optical fibers, taking into account the impact of fiber end-face reflection on the transmission process and providing a technical route to verify the Rayleigh scattering effects. Finally, the article processes the transmission data simulated by the model and conducts a comparative analysis based on the set parameters.【Results】The article constructs a simulation model for Rayleigh scattering effects, calculating the scattering power curve received after optical time-domain reflection. The simulation results show that the received scattering power is consistent with the set parameters, with an error within 5%.【Conclusion】The high precision of the results indicates that the model proposed in the article effectively reflects the Rayleigh scattering effects in coupled-core optical fibers, laying a theoretical foundation for accurately testing parameters of coupled-core optical fibers using optical time-domain reflectometry technology.