Sub-90 fs a stretched-pulse mode-locked fiber laser based on a graphene saturable absorber

In this paper a stretched-pulse, mode-locked Er-doped fiber laser based on graphene saturable absorber (SA) is presented. A 60 layer graphene/polymer composite was used as a SA. The all-fiber dispersion managed laser resonator with the repetition frequency of 21.15 MHz allows for Gaussian pulses generation with the full width at half maximum (FWHM) of 48 nm. The generated chirped pulses were compressed outside the cavity to the 88 fs using a piece of standard single mode fiber. The average output power and pulse energy were of 1.5 mW and 71 pJ, respectively.