Design of large mode area all-solid anti-resonant fiber for high power lasers

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High-power fiber lasers have experienced a dramatic development over the last decade. Further increasing the output power needs an upscaling of the fiber mode area, while maintaining a single-mode output. Here, we propose an all-solid anti-resonant fiber (ARF) structure, which ensures single mode operation in broadband by resonantly coupling high order modes (HOMs) into the cladding. A series of fibers with core sizes ranging from 40 to 100 μm are proposed exhibiting maximum mode area exceeding 5000 μm². Numerical simulations show this resonant coupling scheme provides a HOMs suppression ratio more than 20 dB, while keeping the fundamental mode loss lower than 1 dB/m. The proposed structure also exhibits high tolerance for core index depression.