Yb^3+-doped double-clad phosphate fiber for 976 nm single-frequency laser amplifiers

Highly ytterbium (Yb3+)-doped double-clad phosphate fiber was fabricated for the investigation of power scaling of a 976 nm single-frequency laser. Over 3 W single-frequency laser output power was obtained with gain fibers shorter than 10 cm. Our experimental results show that Yb3+-doped phosphate fiber is a promising gain medium for 976 nm laser amplifiers.