Copper nanoparticles-chitosan based saturable absorber in passively Q-switched erbium doped fiber laser

Copper nanoparticles was utilized and coated with an organic polymer, chitosan to develop thin film saturable absorber (SA) for the formation of passively Q-switched pulses in an erbium doped fiber laser (EDFL). The CuNP/chitosan thin film able to generate stable Q-switching lasing output at operating wavelength of 1557 nm. At maximum pump power of 90.44 mW, the generated pulse indicates a maximum repetition rate of 91.24 kHz, minimum pulse width of 3.60 µs and maximum pulse energy of 74.53 nJ. These results demonstrated the potential performance of CuNP/chitosan based saturable absorber compared to other copper based saturable absorber.