High power neodymium-doped single-mode all-fiber laser at 922 nm using chirped tilted fiber Bragg gratings

We report the demonstration of a neodymium-doped silica all-fiber laser delivering a single-mode output power of 17.7 W at 922 nm in continuous wave operation. The system is based on an in-house developed step-index fiber, having its core co-doped with neodymium, aluminum, phosphorus, and cerium to reduce ion clustering, hence increasing efficiency while keeping the numerical aperture low to ensure a single-mode laser operation. Unwanted amplified spontaneous emission (ASE) around 1060 nm was suppressed using custom chirped tilted fiber Bragg gratings (CTFBGs) integrated at multiple points within the fiber laser system for the first time, thus ensuring a robust all-fiber laser architecture. To the best of our knowledge, this represents the highest reported output power near 920 nm achieved in a single-mode step-index neodymium-doped silica fiber. The experimental results confirm the effectiveness of both the fiber design and the CTFBGs.