Impact of Refractive Index Contrast on Power Distribution in Dual-Core Optical Fibers

Erica Heritiana Nambinina, Nirina Ando ANDRIAMANALINA, Soloniaina RAKOTOARIJAONA

Abstract


Dual-core optical fibers have emerged as a promising technology for both high-capacity telecommunication systems and advanced optical sensing applications due to their ability to support complex mode interations and tailored power distribution. In this work, we investigate the influence of refractive index contrast on the power distribution between the two cores of a dual-core fiber, focusing on both the core-to-core index difference  and the core-to-cladding index contrast . Using a modal analysis approach, the propagation of guided modes is studied to assess the effect of varying refractive indices on mode confinement, inter-core coupling, and crosstalk. Our analysis reveals that a larger core-to-core index difference reduces the coupling efficiency between the two cores, resulting in stronger confinement of optical power in the higher-index core, while smaller differences promote efficient power exchange. Similarly, increasing the contrast between the cores and the surrounding cladding enhances mode confinement and reduces radiation losses, leading to lower propagation loss and minimized inter-core interference. Moreover, asymmetric core configurations allow for controlled power distribution, which can be exploited in mode-selective applications and high-sensitivity optical sensing, enabling the detection of external perturbations with greater precision. The results also provide insights into the design of dual-core fibers for applications requiring precise control of modal power, including spatial-division multiplexing in telecommunications and differential measurement schemes in sensing. Overall, this study offers a comprehensive understanding of the relationship between refractive index contrast and guided power dynamics, highlighting how careful engineering of refractive indices can optimize the performance of dual-core optical fibers in both communication and sensing domains. These findings serve as a practical guideline for fiber designers aiming to achieve specific modal characteristics and inter-core coupling behaviors, contributing to the development of next-generation optical fiber technologies with enhanced functionality and reduced crosstalk.


Keywords


Dual-core optical fiber, Refractive index contrast, Power distribution, Mode coupling, Optical sensing

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DOI: http://dx.doi.org/10.52155/ijpsat.v56.1.7882

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