To improve the robustness and integration of free-space ultrashort pulse (USP) laser systems for industrial deployment, hollow-core fiber delivery enables compact and sealed architectures. However, efficient injection into hollow-core fibers requires high beam quality and long-term pointing stability.

In this work, we report an experimental demonstration of a passive beam stabilization approach based on Multi-Plane Light Conversion (MPLC) combined with hollow-core fiber delivery for high-power femtosecond lasers The MPLC module provides passive stabilization through modal filtering of the input beam, enabling Gaussian beam conditioning and reducing sensitivity to pointing perturbations

Initial characterization and especially beam pointing measurements over two hours, show a fourfold reduction of angular fluctuations compared to a reference configuration without stabilization. In addition, endurance tests demonstrate stable operation with an optical transmission of approximately 77% maintained over 17 hours. Coupling experiments representative of hollowcore fiber injection further show reduced output beam pointing variations and improved robustness when using the MPLC-based module.

Building on these results, the system is being scaled up toward highpower operation. The MPLC module will be operated at power levels up to 300 W, using a Tangor 300 laser delivering pulse energies up to 1 mJ with pulse durations ranging from below 500 fs to above 10 ps. Longterm stability over 24 hours, together with maximum operating power and transmission efficiency, will be characterized. The approach will also be investigated in an application-relevant environment through integration into a robotic processing system.