Stable　mode-locked　operation　in　a　simple　normal-cavity　dispersion　laser　oscillator　that　consists　of　only　Yb-doped　Photonic　crystal　fibers　(PCFs)　and　SESAM　saturable　absorber　is　studied.　Without　any　discrete　dispersion　compensation　components　or　conventional　spectral　filters,　the　SESAM　works　with　the　strongly　chirped　pulse.　The　laser　generates　55　nJ　stable　mode-locked　pulses　with　45.2　MHz　fundamental　repetition　rate　at　1030.8　nm　central　wavelength.　This　kind　of　mode-locked　fiber　oscillators　can　compete　in　terms　of　pulse　energy　and　peak　power　with　most　advanced　bulk　solid-state　Ultra-short　pulsed　lasers.　©　2011　IEEE.