Generation of 9.3-W Multimode and 4-W Single-Mode Output From 7-cm Short Fiber Lasers

We generate 9.3-W continuous-wave 1535-nm multimode output from a 7.0-cm short-length Er-Yb codoped phosphate fiber laser. A slope efficiency of 29% is obtained at pump powers below 27 W. Very high output power per unit fiber length of 1.33 W/cm is achieved. From another 7.1-cm Er-Yb codoped fiber laser, 4.0-W single-transverse-mode output with M/sup 2//spl ap/1.1 is generated.