976 nm all-fiber Raman laser with high beam quality at multimode laser diode pumping

Abstract

A 976 nm all-fiber Raman laser enabling high beam quality at direct multimode laser diode pumping with low beam quality (M2 > 30) is demonstrated. The laser is performed in a 100/140 multimode graded-index fiber with special in-fiber Bragg gratings that secure generation of the Stokes beam with relatively good quality (M2 ⩽ 2) and high slope efficiency of the pump-to-Stokes conversion (70%) at output powers of up to ~50 W.