Nd-doped double-clad fiber amplifier at 1.06 /spl mu/m

We propose and demonstrate a double-clad neodymium (Nd)-doped fiber amplifier (IVDFA) at 1.06 /spl mu/m for a compact configuration of a high-power optical amplifier. The proposed 125 /spl mu/m first cladding diameter in the double-clad fiber, provides the single-mode propagation of the signal lightwave into its doped core without misguiding the signal lightwave into the outer core (first cladding), by simply splicing with a standard single-mode fiber. Furthermore a fiber grating in a single-mode core of the double-clad fiber allows the double-pass configuration for the signal lightwave at 1.06 /spl mu/m and also allows the pump lightwave coupling at 0.81 /spl mu/m into the first cladding without employing a bulk dichroic mirror. We demonstrate the signal output power of 110 mW for a 550-mW pump input from a multimode fiber coupled pump source. Theoretical results predict an efficient high-power operation of the amplifier by improving the signal scattering loss in the double-clad fiber.