Extraction of 100-mJ Level Pulse Energy at High Repetition Rates by a ns-class, 49-core Fiber Laser

Multicore Fibers (MCF), the integrated alternative to spatially separated amplification in fibers, are a promising laser architecture thanks to their capability to deliver high pulse energy and average power in a compact format. The introduction of 7x7 MCF laser systems represents a significant advancement of this technology, bringing us closer to realizing multi-kilowatt and J-class fiber laser amplifiers. In this context, Ytterbium-doped MCFs have already demonstrated power scalability proportional to the number of amplifying cores. Using 4x4 MCFs already showcases high pulse energy and high average power and, if coherently combined, offers nearly diffraction-limited beam quality. This work complements the Coherent Beam Combination (CBC) testbed by Incoherent Beam Combination (IBC). IBC emerges as a straightforward and robust solution, providing the opportunity to achieve performance capabilities equivalent to Multimode Fibers (MMFs) while demonstrating a better beam quality. These IBC systems are appealing for various applications, including pumping solid-state lasers and incoherent frequency conversion towards shorter wavelengths, e.g., to the Extreme Ultraviolet (EUV) or soft-Xray through laser-produced plasma sources.