Theoretical analysis of fiber coupling and image transmission for flexible micro-LED near-eye displays.

A fiber image bundle is a key component connecting a high-density micro-display panel and an imaging lens group in a near-eye display (NED) system. Its inherent flexibility, high resolution, and aperture confinement capabilities bring unique features to micro-LED NED applications. However, the coupling and image transmission processes of these systems are influenced by multiple factors, and existing theoretical models often fail to accurately capture the complex interactions between microscale light sources and the fiber interface. This study presents a three-dimensional (3D) model that integrates micro-LED emission profiles with fiber acceptance cones, employing multiple integrals and radiative transfer theory to analyze the coupling efficiency. A piecewise function characterizes efficiency variations over distance, while different array models are used to describe crosstalk, clarifying critical conditions for vertical and diagonal configurations. Simulations and experiments validate the theoretical models, revealing how the pixel misalignment and tilt significantly affect both efficiency and crosstalk. Results show that coupling performance can be substantially enhanced by higher fiber numerical aperture, smaller micro-LED size and pitch, and improved alignment precision. This work provides a crucial theoretical basis for flexible NED systems and outlines optimization pathways for future fiber-optic imaging applications.