Characteristics of double-pass backward (DPB) superfluorescent fiber source (SFS) manufactured by heavily doped erbium fiber are investigated. Advantages of the superfluorescent source are its high output power and broad bandwidth. We achieve the optimum fiber length for obtaining largest bandwidth with certain pump power by simulation. In the experiment, we use a 980 nm laser diode to pump a 10 m-length optimized Lucent-LRL fiber and use self-building fiber reflector loop to form the DPB SFS. Broad bandwidth superfluorescent fiber source with 26 mW output power is obtained with this configuration.