Femtosecond mode-locked erbium-doped fibre laser with Alq3 saturable absorber

The authors experimentally demonstrated the generation of mode-locked pulses from all-fibre erbium-doped fibre laser cavity by using organic material, Alq(3), as a saturable absorber (SA). The SA film was integrated into a ring fibre laser cavity to act as a mode-locker. A mode-locking operation was achieved in three different experiments with pulse width/repetition rate of 1.26 ps/3.36 MHz, 970 fs/3.36 MHz and 820 fs/4.9 MHz by using cavity length/optical coupler (OC) of 61.5 m/80:20 OC, 61.5 m /95:5 OC and 42 m/80:20 OC, respectively. All the experiments produced a soliton and a very stable mode-locking operation at central wavelength of similar to 1561 nm. The experiments confirmed that organic material can readily be used as SA for a mode-locked operation in the 1.5 mu m region. This demonstration might shed new insights into the potentials and techniques for developing ultrafast fibre lasers by using organic materials as SAs.