An increase in energy of pulses generated in a similariton mode-locked femtosecond fiber laser is shown experimentally by increasing the length while reducing the doping of the ytterbium-doped fiber gain medium. Mode-locking is achieved by nonlinear polarization rotation evolution in a cavity using a combination of fiber and bulk optical components. The level of doping of the gain medium is varied by using lengths of differently doped ytterbium fiber. Experimental results verify that an increase in length of gain medium with a lower doping results in an increase in the output pulse energy.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.