Mode-locking pulse generation in cladding pumped Erbium-Ytterbium co-doped fiber laser with graphene PVA film

A passively mode-locked fiber laser is demonstrated in a cladding pump system using double-clad Erbium-Ytterbium co-doped fiber (EYDF) as a gain medium. A graphene embedded in polyvinyl alcohol (PVA) film is incorporated in a laser cavity with a total length of 217.5 m, and anomalous cavity dispersion of −4.571 ps2. The prepared saturable absorber has a modulation depth of 14%. The mode-locked EYDF laser operates at center wavelength of 1562.5 nm with a repetition rate of 0.92 MHz and pulse width of 387 ns. The maximum pulse energy 605 pJ is obtained at 300 mW pump power. The radio frequency (RF) spectrum shows a signal to noise ratio of 57 dB which indicates the stability of the laser.