Very Large-Mode-Area, Symmetry-Reduced, Neodymium-Doped Silicate Glass All-Solid Large-Pitch Fiber

This paper reports, for the first time to our knowledge, a very large-mode-area, Nd-doped silicate glass all-solid large-pitch fiber (AS-LPF) with a core diameter of up to 75 μm. The concepts of the delocalization effect and differential loss were considered simultaneously to evaluate the single-mode operation of the AS-LPF. By reducing the symmetry of the fiber, the single-mode operation of the 75-μm AS-LPF was theoretically predicted using the finite-difference time-domain method and was experimentally fabricated. An output power of ~9.3 W with a slope efficiency of 41% was obtained for a 60-cm-long fiber.