Fast automatic fiber coupling using global optimization algorithms approaching the experimental efficiency limit.

Perfect laser mode is required in many research fields such as quantum computing and precision measurement. Fiber optics provides a useful tool for maintaining a high quality laser when transmitting the laser over a long distance. Fiber link between modular structures of complicated optical paths increases the effectiveness and robustness of the optical experiment. It is a key element in coupling the laser into fiber with high efficiency in fiber optics applications. However, in confined or vacuum environments, such as spacecraft cabins, manual alignment is nearly impossible, highlighting the need for automated solutions. In this study, we experimentally investigated several automatic coupling algorithms, including the iterative scanning method and three global optimization algorithms. The results show that Bayesian optimization, by exploiting multidimensional control and high-precision actuation, enabled the coupling efficiency to reach its maximum of higher than 93% within 10 s. These algorithms provide repeatable and high-precision fiber alignment solutions for all-optical experiments under different conditions.