ABSTRACT Multicore fibers have found significant applications in laser coherent beam combining systems, but thermally induced spot drift (TISD) compromises the coherent combining efficiency. This paper, based on thermo‐optic effects and heat conduction theory, employs numerical simulation and parametric methods to establish a model of a 5 × 5 square array of ytterbium‐doped multicore fibers. It analyzes the characteristics of spot drift caused by thermal refractive index gradients and the degradation patterns of system performance. By investigating how fiber structural parameters affect thermal effects and analyzing the temperature distribution characteristics, we find that reducing the core size, increasing the core spacing, increasing the core–cladding refractive index difference, and adopting a distributed pumping strategy can effectively suppress the detrimental effects of thermal nonlinearity on beam quality. This study provides theoretical support for the thermal management design and structural optimization of high‐power fiber lasers, ensuring stable operation within an appropriate temperature range. It offers strategic guidance for performance breakthroughs in related applications.
Liu et al. (Mon,) studied this question.