Passively mode-locked erbium-doped fiber laser based on a nanodiamond saturable absorber

In this paper, we propose nanodiamond (ND) material as a saturable absorber (SA) to generate short pulses from a mode-locked erbium-doped fiber laser (EDFL). The ND-SA is fabricated by the drop-casting method using polyvinyledenedifluoride-trifluoroethylene as a host polymer and methyl ethel ketone as a solvent liquid. The SA, which possesses 20% ND concentration, has a 5.46% modulation depth with 2000MW/cm² saturation intensity. Sequentially, the performance of the EDFL is investigated after integrating an ND-SA within the laser ring. The results reveal that the presented ND-SAs produce stable ultrashort laser pulses. Moreover, the fabricated ND film is a promising solid film for many photonic schemes. The proposed mode-locked EDFL-based ND-SA starts a mode-locking operation at a pumped power of 116 mW. The generated mode-locked pulses have a pulse duration of 0.84 ps, a repetition rate of 1.93 MHz, and a power of 0.517 mW, at a pumped power of 187 mW. Finally, to the best of our knowledge, this is the first time that the ND-SA has been used as a mode locker within the EDFL as a thin film and with the suggested fabrication method.