75-femtosecond all-fiber ultrashort pulse laser

We report the direct generation of 75-femosecond pulses from a stretched-pulse fiber ring laser using the nonlinear polarization rotation mode-locking mechanism. As the gain media in the laser,the high-doped erbium-doped fiber working at positive dispersion was used to compensate the negative dispersion of standard single mode fiber. Under a 125 mW pump power,the average output power was higher than 15 mW,with a 25.9 MHz repetition rate and 53 nm spectrum width. Meanwhile,the pulse energy was greatly improved,which could reach 0.6 nJ. The laser easily achieved mode-locking and ran stably at room temperature. All-fiber construction makes it compactable and portable.