1 µJ erbium-doped Q-switched fiber laser based on Ag@C core-shell nanoparticles

Nowadays, pulsed fiber lasers at different wavebands have been realized by using plasmon nanomaterials as saturable absorbers (SAs). However, the performance improvement of pulsed lasers is limited by the low damage threshold of these SAs. Compared to traditional plasmon nanomaterials, core-shell nanomaterials present better chemical stability and photothermal properties. In this work, we propose and demonstrate Ag@C core-shell nanomaterials used as SA for pulsed laser generation. The Ag@C nanomaterials powder was mixed with sodium carboxymethylcellulose (NaCMC) water solution to form the Ag@C SA film. By inserting the Ag@C SA into an erbium-doped laser cavity, stable passively Q-switched laser at 1560 nm was achieved for a pump power threshold of 103 mW. The shortest pulse duration of 1.3 µs and the highest repetition rate of 30.3 kHz were obtained at the pump power of 430 mW. The maximum single pulse energy could reach 891 nJ. Our results indicate that the Ag@C core-shell nanomaterial is a type of versatile SA material for constructing high-energy pulsed lasers.