Efficient 0.9-μm neodymium-doped single-mode fibre laser

An efficient cw single-mode double-clad Nd3+-doped fibre laser is developed which operates at room temperature in a quasi-three level scheme on the 925-nm F-4(3/2)-I-4(9/2) transition upon diode pump at 805 nm. The gain in the laser resonator at 1.06 mum is strongly suppressed due to a proper choice of the refractive index profile in the fibre core. The laser output power above 0.5 W is obtained with the slope efficiency exceeding 35%.